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Zoological Journal of the Linnean Society, 2014, 171, 623–655. With 18 figures
The anatomy, phylogenetic relationships, and
stratigraphic position of the Tithonian–Berriasian
Spanish sauropod dinosaur Aragosaurus ischiaticus
RAFAEL ROYO-TORRES1*, PAUL UPCHURCH2, PHILIP D. MANNION3, RAMÓN MAS4,
ALBERTO COBOS1, FRANCISCO GASCÓ1, LUIS ALCALÁ1 and JOSÉ LUIS SANZ5
1
Fundación Conjunto Paleontológico de Teruel-Dinópolis/Museo Aragonés de Paleontología, Avda.
Sagunto s/n, 44002 Teruel, Spain
2
Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK
3
Department of Earth Science and Engineering, Imperial College London, South Kensington Campus,
London SW7 2AZ, UK
4
Departamento de Estratigrafía, IGEO (CSIC), Universidad Complutense de Madrid, Ciudad
Universitaria 28040 Madrid, Spain
5
Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, 28049
Madrid, Spain
Received 16 October 2013; revised 16 January 2014; accepted for publication 30 January 2014
The first dinosaur to be named from Spain, the sauropod Aragosaurus ischiaticus Sanz, Buscalioni, Casanovas
and Santafé 1987, is known from associated postcranial remains of one individual from the Las Zabacheras site
in Galve, Teruel Province, Spain. Results of recent fieldwork confirm that the Las Zabacheras site represents a
deltaic sediment complex in the Villar del Arzobispo Formation with a Tithonian–Berriasian (latest Jurassic–
earliest Cretaceous) age. Description of the anatomy of Aragosaurus (including several previously undescribed elements) enables a re-evaluation of this taxon’s relationships. Aragosaurus ischiaticus has six autapomorphies in
the axial and appendicular skeleton, including the presence of epipophysis-like protuberances on middle caudal
postzygapophyses. Phylogenetic analyses, using three independent data sets, support the view that Aragosaurus
is a basal macronarian sauropod, lying outside of Titanosauriformes. Aragosaurus possesses derived states that
are shared with basal Titanosauriformes, indicating that some characters previously considered to represent
titanosauriform synapomorphies have a slightly wider distribution. A tooth, previously described as Aragosaurus,
cannot be referred to this taxon as it was recovered from a different locality, and there are no overlapping elements with the holotype; it is here regarded as representing an indeterminate titanosauriform. These results,
combined with new data on the stratigraphic age of Aragosaurus, demonstrate that basal macronarian sauropods
were present in Europe at the end of the Late Jurassic, alongside more derived titanosauriforms. Aragosaurus is
one of four genera of sauropod recovered from the Villar del Arzobispo Formation in Spain, making the latter an
important contributor to our understanding of Late Jurassic sauropod diversity alongside the well-known contemporaneous faunas of the African Tendaguru Formation and the North American Morrison Formation.
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655.
doi: 10.1111/zoj.12144
ADDITIONAL KEYWORDS: Berriasian – Cretaceous – Jurassic – Macronaria – Spain – Tithonian – Villar
del Arzobispo Formation.
*Corresponding author. E-mail: [email protected]
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655
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INTRODUCTION
Sauropoda have been widely recorded in the Mesozoic, from their origin in the Late Triassic until their
extinction at the end of the Cretaceous (McIntosh, 1990;
Upchurch, Barrett & Dodson, 2004a). During their evolutionary history, the diversity of sauropod groups fluctuated, including a trough in the Oxfordian, and a peak
in the Kimmeridgian–Tithonian, with more than 30
taxa recorded (Upchurch & Barrett, 2005; Mannion
et al., 2011; Upchurch et al., 2011). Following an apparent extinction at the Jurassic–Cretaceous boundary, the earliest Cretaceous (Berriasian–Hauterivian) is
characterized by particularly low diversity, with less
than ten sauropod taxa known from each stage (Hunt
et al., 1994; Upchurch & Barrett, 2005; Mannion et al.,
2011; Upchurch et al., 2011). This reduction in the
diversity of sauropod taxa seems to reflect some important faunal turnover events among dinosaur communities at this time (Sereno, 1997, 1999; Upchurch
et al., 2011). The Villar del Arzobispo Formation in
Spain reveals a high diversity of sauropods living
on the Iberian Plate during the Jurassic–Cretaceous
transition. To date, diplodocids, turiasaurs, and
titanosauriforms have been recovered (Royo-Torres,
Cobos & Alcalá, 2006; Royo-Torres et al., 2009; Suñer,
Santisteban & Galobart, 2009). In this work we reevaluate the first dinosaur ever described in Spain: the
sauropod Aragosaurus ischiaticus Sanz, Buscalioni,
Casanovas and Santafé 1987. The site where this dinosaur was found, Las Zabacheras, is here placed in
its correct stratigraphical context. Moreover, as well
as re-describing previously considered elements of the
Aragosaurus holotype, we present the first description and illustrations of additional elements (e.g. thoracic ribs, coracoid, humerus, carpal, four metacarpals,
and pedal phalanges). Comparisons of Aragosaurus with
other sauropods result in the recognition of several new
autapomorphies for the Las Zabacheras taxon. We
analyse the phylogenetic relationships of Aragosaurus
using revised versions of the ‘traditional’ data sets presented by Wilson (2002) and Upchurch et al. (2004a)
that include improved sampling of Iberian sauropods
(Royo-Torres & Upchurch, 2012; Royo-Torres, Alcalá
& Cobos, 2012). We also discuss its position based on
a recent analysis of titanosauriform interrelationships (Mannion et al., 2013).
INSTITUTIONAL ABBREVIATIONS
CPT, Museo Aragonés de Paleontología (Fundación
Conjunto Paleontológico de Teruel-Dinópolis),
Spain; GMNH, Gunma Museum of Natural History,
Gunma, Japan; IG, Museo Provincial de Teruel, Spain;
IVPP, Institute of Vertebrate Paleontology and
Paleoanthropology, Beijing, China; MCNV, Museo de
Ciencias Naturales de Valencia, Spain; MG LNEG,
Museu Geológico do Laboratório Nacional de Energia
e Geologia, Lisboa, Portugal; MPG, Museo Paleontológico
de Galve, Spain; MPZ, Museo Paleontológico de la
Universidad de Zaragoza, Spain; USNM, National
Museum of Natural History Smithsonian, Washington DC, USA; YPM, Peabody Museum, Yale, USA.
COLLECTION HISTORY
Las Zabacheras, the type locality of A. ischiaticus, is
located 150 m north of Galve village (Fig. 1) in Teruel
Province, Aragón, north-eastern Spain (grid coordinates Universal Transverse Mercator 679 266 and
4 503 362). In 1934, construction of the old road to Galve
led to the discovery of the type locality, initially named
‘La Carretera’ (Fernández-Galiano, 1958; 1960). The
first recorded discovery of dinosaur bones was in 1958,
when a resident of the village, José María Herrero,
reported dinosaur bones from Galve in the local newspaper Lucha, and then informed the service of excavations of the Diputación Provincial de Teruel (Instituto
de Estudios Turolenses, IET; Millán, 2004;
Ruiz-Omeñaca et al., 2004; Cobos, 2011). Dimas
Fernández-Galiano and Purificación Atrián, members
of IET, visited Galve and located elements of
Aragosaurus held in private hands by members of the
local population. After this, Fernández-Galiano returned to Galve in order to excavate new remains from
the Las Zabacheras site, including some of the vertebrae and long bones (Fernández-Galiano, 1958). All of
these elements, including those collected from villagers and the vertebrae and long bones collected later,
were housed in the Museo Provincial de Teruel (Cobos,
2011). Albert F. de Lapparent (1905–1975), from the
Institut Catholique, Paris, was the first palaeontologist to suggest that these remains represented a new
taxon of sauropod in the scientific journal Teruel
(Lapparent, 1960). This author was also responsible
for the change of the site name from ‘La Carretera’
to ‘La Zabacheras’ (ZH; Lapparent, 1960; Ruiz-Omeñaca
et al., 2004). Subsequently, in 1982, a team of palaeontologists comprising researchers from the Universidad
Autónoma de Madrid and the Instituto de Paleontología
de Sabadell (today the Institut Català de Paleontología)
informed José María Herrero of the intention to excavate the Las Zabacheras site during the following
year; however, it transpired that José María Herrero
had already excavated part of the site, so an agreement was made to carry out joint fieldwork (Sanz, 2007).
The resulting material, known as the ‘J.M. Herrero
Collection’, enabled the first dinosaur from Spain to
be named: Aragosaurus ischiaticus (Sanz et al., 1987,
1990). The holotype also included the material cited
as ‘the sauropod from Las Zabacheras’ by Lapparent
(1960), and a tooth was referred from a nearby unnamed
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ARAGOSAURUS ISCHIATICUS
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Figure 1. Geological map showing the locality where Aragosaurus was found in Spain. Modified from Díaz-Molina &
Yebenes (1987), Soria de Miguel (1997), and with data from Peropadre, Meléndez & Liesa (2012): 1, Upper Triassic (Keuper
facies); 2, Cortes de Tajuña, Cuevas Labradas and Barahona formations; 3, Turmiel Formation; 4, Chelva Formation;
5, Loriguilla Formation; 6, Higueruelas Formation; 7, Villar del Arzobispo Formation; 8, El Castellar Formation; 9, Camarillas Formation; 10, Artoles Formation; 11, Morella Formation; 12, Areniscas de las Parras de Martín Formation;
13, Utrillas Formation; 14, Upper Cretaceous; 15, Cenozoic; 16, Quaternary.
locality (Sanz, 1982; Sanz et al., 1987). As a result of
these events, the holotype specimens are distributed
between two collections: (1) the material recovered by
Dimas Fernández-Galiano in the 1950s, which is deposited at the Museo Provincial de Teruel with the
acronym ‘IG’; and (2) the material excavated by
J.M. Herrero and the team of author J.L.S. in the 1980s,
with acronym ‘ZH’, now in the Museo Paleontológico
de Galve. In 2001, on the occasion of the inauguration of the Dinópolis museum in Galve, two of us (R.R.T. and A.C.) recovered the material (fragments of
vertebrae and ribs, coracoids, humerus, carpal, metacarpus, and ischia) deposited by Dimas FernándezGaliano in the Museo Provincial de Teruel (Royo-Torres,
Canudo & Ruiz-Omeñaca, 1999; Cobos, 2011), moving
it to a satellite museum of Dinópolis in Galve (today
belonging to the Museo Aragonés de Paleontologia), with
the other specimens remaining in the Museo
Paleontológico de Galve.
SYSTEMATIC BACKGROUND
Of the material comprising the Aragosaurus holotype,
Lapparent (1960) briefly described eight caudal vertebrae, ten fragments of ribs, a partial scapula, a radius,
an ulna, a carpal, fragments of metacarpus, two phalanges, a proximal portion of the left ischium, a left
pubis, and a left humerus (misidentified as a right
femur). This material was suggested to represent a new
sauropod genus related to ‘camarasaurids’, based on
the forelimb appearing more similar to Camarasaurus
than Apatosaurus, and was differentiated from
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655
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R. ROYO-TORRES ET AL.
rebbachisaurids and ‘titanosaurids’ by the caudal vertebral morphology (Lapparent, 1960). Twenty-seven
years later, a new taxon was erected based on this material (and newly recovered elements) in the Spanish
journal Estudios Geológicos (Sanz et al., 1987). The genus
name was dedicated to the region of Aragón, and the
species name referred to the ischium, i.e. Aragosaurus
ischiaticus. The diagnosis was based on the morphologies of the tooth, caudal neural spines, scapula, ischia,
and the humerus/femur length ratio (Sanz et al., 1987,
1990). Those authors separated Aragosaurus from
diplodocid taxa by the absence of pleurocoels and winglike lateral processes in the caudal vertebrae. They included Aragosaurus within Camarasauridae (sensu Steel,
1970), based on the presence of transversely expanded anterior caudal neural spines, a humerus/femur ratio
of 0.82, a lateral bulge below the greater trochanter
on the femur, and a ratio between the minimum and
maximum widths of the scapular blade similar to that
in Giraffatitan (= ‘Brachiosaurus’) (Sanz et al., 1987).
Later, in his revision of the Sauropoda, McIntosh (1990)
was in agreement, including A. ischiaticus within
Camarasauridae, based on a number of overall similarities with Camarasaurus, as well as Lourinhasaurus
alenquerensis, which was then considered a species of
Camarasaurus. Subsequent studies, however, indicated that there are difficulties with the referral of
Aragosaurus to the Camarasauridae. In particular,
Upchurch (1995) and all subsequent phylogenetic analyses have shown that McIntosh’s (1990) Camarasauridae
is a polyphyletic assemblage, including the
mamenchisaurid Tienshanosaurus (Sekiya, 2011), the
basal somphospondylan Euhelopus (Wilson & Upchurch,
2009), the derived titanosaur Opisthocoelicaudia
(Upchurch, 1995), as well as Aragosaurus and
Camarasaurus. Indeed, if Camarasauridae is defined
phylogenetically as all taxa more closely related to
Camarasaurus than to Saltasaurus, then the only
member of this family is Camarasaurus itself (see
Upchurch, 1995, 1998; Wilson, 2002; Upchurch et al.,
2004a; Harris, 2006; Wilson & Upchurch, 2009; Mannion
et al., 2013).
After McIntosh (1990), only a few works have provided new information on Aragosaurus. Firstly, in a
description of the pubis (Royo-Torres & Ruiz-Omeñaca,
1999; Royo-Torres et al., 1999), a position within
Camarasauromorpha (sensu Salgado, Coria & Calvo,
1997), in the clade Camarasaurus + Titanosauriformes
(sensu Wilson & Sereno, 1998), or in the clade
‘Brachiosauria’ (sensu Upchurch, 1998) was suggested. Canudo et al. (2001) proposed a slightly more precise
placement of Aragosaurus, arguing that the presence
of the lateral bulge on the proximal femur supported
its inclusion within Titanosauriformes, a character considered diagnostic for this clade (Salgado et al., 1997).
None of these studies included Aragosaurus in a cladistic
analysis, however. Aragosaurus was incorporated into
a phylogenetic data matrix for the first time in 2004,
although the limited available anatomical data meant
that many characters could not be scored and its
position was highly unstable, leading Upchurch
et al. (2004a) to consider it as Eusauropoda incertae
sedis. In this sense, Sanz (2009) shows a position based
on the matrix of Upchurch et al. (2004b), where
Aragosaurus is included in a polytomy within
Eusauropoda, but outside of Titanosauriformes. New
anatomical data were presented in the thesis of the
lead author (Royo-Torres, 2009), greatly increasing the
number of characters that could be scored. This work,
and a subsequent study exploring the evolutionary relationships of basal titanosauriforms (Mannion et al.,
2013), included Aragosaurus in a phylogenetic analysis, in both cases recovering it as a basal macronarian,
outside of Titanosauriformes. D’Emic (2012: table 9)
also assessed the relationships of Aragosaurus by
noting which synapomorphies of various clades were
present and absent in the published material. Based
on two features of the ischium, D’Emic (2012) provisionally included Aragosaurus as a non-titanosaur
titanosauriform.
GEOLOGICAL SETTING AND AGE OF THE
LAS ZABACHERAS SITE
The Las Zabacheras site is located in a syncline in the
Galve area of Teruel Province, Aragón, north-eastern
Spain, in the Central Iberian Range (Fig. 1). Here, there
is a Mesozoic sedimentary succession infilling one of
the sub-basins of the Maestrazgo Basin: the Galve subbasin (Salas et al., 2001). The Las Zabacheras section
shows a complete sequence of units spanning from the
Late Jurassic to the Early Cretaceous (Díaz-Molina et al.,
1984; Díaz-Molina et al., 1985; Díaz-Molina & Yebenes,
1987), formed as a consequence of the upper synrift
succession developed in the Iberian rift (Salas et al.,
2001; Liesa et al., 2006). Originally, the Las Zabacheras
site was included in the Early Cretaceous ‘Weald facies’
(Derréal, 1959; Lapparent, 1960). Detailed stratigraphic and cartographic work on the terrestrial sediments enabled Díaz-Molina & Yebenes (1987) to include
the Las Zabacheras site in their ‘Unit 3’, suggesting
a Hauterivian (?) age (Díaz-Molina et al., 1984, 1985;
Díaz-Molina & Yebenes, 1987). Subsequently,
Cuenca-Bescós et al. (1994) and Soria de Miguel (1997)
included this ‘Unit 3’ in the ‘Areniscas y Calizas de El
Castellar’ Formation, dated as Hauterivian–lower
Barremian. This placement was based on the identification of: [sic] ‘Esta discontinuidad es identificable
en el campo por un importante cambio litológico y
sedimentológico marcada por la presencia de las arcillas
rojas típicamente continentales de la base de la
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655
ARAGOSAURUS ISCHIATICUS
Formación Castellar’ (‘This discontinuity is identifiable in the field by a major lithological and
sedimentological change marked by the presence of the
typically continental red clays of the base of the
Castellar Formation’; Cuenca-Bescós et al., 1994: p. 51).
This view has recently been defended by Canudo et al.
(2012) based on the presence of synsedimentary faults
on the discontinuity between the Villar del Arzobispo
and El Castellar formations, and on charophyte and
palynological data; however, as outlined below, there
are a number of problems with these interpretations
of the data, and we here provide a revised view of the
geology of this area.
To test whether ‘Unit 3’ is equivalent to the lower
part of the El Castellar Formation, we have compared it with the stratotype of the latter, defined by
Salas (1987) in the Peñagolosa sub-basin, in Barranco
de Montoro, Teruel Province. The lower part of this
formation is characterized by purple- and ochrecoloured shales, which are interbedded with channelized
levels of tabular geometry and erosive bases of finegrained ochre-coloured sandstones, occasionally showing
parallel lamination and cross stratification. The upper
part of the El Castellar Formation is characterized by
an alternation of marls and grey limestones, with abundant charophytes, gastropods, and fish teeth, showing
frequent instances of plant bioturbation (Salas, 1987).
The lower part of the El Castellar Formation is interpreted as having formed in an alluvial fan environment (Soria de Miguel, 1997; Liesa et al., 2006), whereas
the upper part represents a lacustrine environment
(Salas, 1987; Soria de Miguel, 1997; Liesa et al., 2006).
Charophytes (Atopochara trivolvis triqueta) are present
only in the upper part of the type section of the El
Castellar Formation (Salas, 1987; Soria de Miguel, 1997;
Ruiz-Omeñaca et al., 2004). The Galve ‘Unit 3’ of
Díaz-Molina & Yebenes (1987) is an 85-m section comprising the following lithofacies: conglomerate with
rounded carbonate pebbles; fine- to middle-grained
quartz arenite sandstone, with glauconite grains showing
lenticular and channelized geometry, wave rippleformed cross-lamination, sand dune-formed crossstratification; red clay, and silt with root traces
associated with hydromorphic palaeosoils (Fig. 2). According to previous studies (Díaz-Molina et al., 1984,
1985; Díaz-Molina & Yebenes, 1987) and our own observations, these sediments can be interpreted as a
deltaic coastal plain with tidal channels and intertidal to supratidal interchannel areas (with the latter
showing hydromorphic palaeosoils) that were deposited during regressive–transgressive pulses in a
tide-influenced coastal realm. These facies, and our interpretation of the sedimentary environment, are very
different from the alluvial fan environment described
for the lower unit of the El Castellar Formation (Soria
de Miguel, 1997; Liesa et al., 2006).
627
Microfossils have not been found in ‘Unit 3’
(Díaz-Molina & Yebenes, 1987), and the only charophytes
located by Canudo et al. (2012), Globator maillardi
steinhauseri (latest Berriasian–Hauterivian in age) are
stratigraphically situated 90 m up the Las Zabacheras
section, at the top of the ‘local datum’ cited by Canudo
et al. (2012). This level is a calcrete layer (Fig. 2),
located just below ‘Unit 4’ of Díaz-Molina & Yebenes
(1987). Palynological data are currently unavailable
for the Las Zabacheras site, but preliminary analyses produced negative results (Bienvenido Díez pers.
comm. 2013). Furthermore, the palynological data used
by Canudo et al. (2012) comes from Piélago 0 (Díez
et al., 1995), which is located more than 4 km away
from Las Zabacheras. Piélago 0 has an unclear position in the column and even on maps, and is variably placed at the base or in the middle of their
stratigraphic section of the lower El Castellar Formation (i.e. Ruiz-Omeñaca et al., 2004; Ruiz-Omeñaca,
2006; Canudo et al., 2012). As such, we suggest that
it is not a reliable indicator for determining the
age of the Las Zabacheras site. In summary, although Canudo et al. (2012) included ‘Unit 3’, and thus
consequently the Las Zabacheras site, within the El
Castellar Formation, the available evidence does not
support this placement.
We conclude that the El Castellar Formation in Galve
is situated stratigraphically above ‘Unit 3’, and instead
corresponds to the ‘Unit 4’ of Díaz-Molina & Yebenes
(1987) (Figs 1 & 2). The contact between ‘Unit 3’ and
‘Unit 4’ is an angular nonconformity, and in the field
it is possible to observe changes of strike (5–28°) and
dip (5–20°) between both units (Figs 1 and 3; Table 1).
These values were measured in the last layer of
‘Unit 3’ and in the first layer of ‘Unit 4’ (Figs 1 and 3).
As Díaz-Molina & Yebenes (1987) indicated that a
lithological transition between ‘Unit 3’ and ‘Unit 4’ is
absent, the discordance described by Canudo et al. (2012)
should be placed within the Villar del Arzobispo Formation, which is generally represented by sequences
beginning with a subaerial exposure surface (incipient palaeokarst on top of carbonates), followed by a
clear vertical facies change from shallow marine carbonates to coastal siliciclastic sediments (shales, sandstones, and conglomerates). Within the Villar del
Arzobispo Formation, the transition between its dominantly carbonate part (‘Unit 2’) and its dominantly
siliciclastic part (‘Unit 3’) is a characteristic feature
(Mas, Alonso & Meléndez, 1984; Luque et al., 2005;
Santisteban & Santos Cubedo, 2010a). In addition, some
carbonated lithosomes from ‘Unit 2’ show a lateral
change to siliciclastic facies, equivalent to those of
‘Unit 3’, in the south-west of Galve. Furthermore, in
the Galve area, ‘Unit 4’ (El Castellar Formation) has,
at its base, a massive to nodular calcrete level (Fig. 2).
This level is particularly developed where this unit lies
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655
628
R. ROYO-TORRES ET AL.
Figure 2. General stratigraphic section indicating the stratigraphic settings for localities in the Villar del Arzobispo
Formation from Galve and the section of the Las Zabacheras site. Modified from Díaz-Molina & Yebenes (1987).
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655
ARAGOSAURUS ISCHIATICUS
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Figure 3. The ‘Fault in the Zabacheras area’ – Mesozoic syn-rift faults affecting the Villar del Arzobispo Formation (‘Unit 2’
and ‘Unit 3’) fossilized by the Castellar Formation (‘Unit 4’). Abbreviations: U2, Villar del Arzobispo Formation dominantly carbonate facies; U3, Villar del Arzobispo Formation dominantly siliciclastic facies; U4, El Castellar Formation;
U5, Camarillas Formation; ZH, Las Zabacheras site; black lines crossing U2 and U3, Mesozoic syn-rift faults; black lines
perpendicular to the latter only in U2, Cenozoic faults; contact between U2 and U3, sedimentary contact; contact between
units U3 and U4, unconformable contact; contact between units U4 and U5, sedimentary contact.
Table 1. Measurements of the strikes and dips between the sedimentary contact of the Villar del Arzobispo Formation
‘Unit 3’ and El Castellar Formation ‘Unit 4’ (Fig. 1) in Galve, Spain
Point 1
Point 2
Point 3
Point 4
Point 5
Point 6
Point 7
Grid coordinates
UTM
Strike and dip
Unit 3
Grid coordinates
UTM
Strike and dip
Unit 4
E 0678711
N 4502099
E 0678895
N 4502534
E 0679164
N 4503138
E 0680625
N 4502996
E 0681338
N 4502098
E 0681807
N 4500199
E 0682050
N 4499748
206° 50E
E 0678734
N 4502077
E 0678935
N 4502531
E 0678200
N 4503240
E 680618
N 4502988
E 0681338
N 4502098
E 0681791
N 4500197
E 0682020
N 4499762
217° 43E
198° 38W
230° 41S
315° 68S
325° 73S
336° 39W
005° 26W
226° 34W
225° 32S
338° 83 S
330° 75S
342° 40W
015° 24W
UTM, universal transverse mercator.
on the shaly facies of ‘Unit 3’ (the siliciclastic part of
the Villar del Arzobispo Formation); however, when lying
on sandstone bodies sandwiched between the shales
of ‘Unit 3’, the process of development of the calcrete
is less pronounced, and only develops a carbonated
nodulization when the contact surface is sandstone.
Moreover, it should also be noted that the faults affect
‘Unit 2’ and ‘Unit 3’, but not ‘Unit 4’, so it seems that
the overlying El Castellar Formation (= ‘Unit 4’) deactivated these faults (Figs 1 and 3).
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655
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R. ROYO-TORRES ET AL.
The thickness of the El Castellar Formation in Galve
(= ‘Unit 4’) is about 24 m, which is reduced in comparison with other areas of the Galve sub-basin, such
as those described by Liesa et al. (2006), or in comparison with the Peñagolosa sub-basin of the Maestrazgo
Basin (Salas, 1987), where it has a thickness of 35 m.
To sum up, in Galve, above the carbonated oolitic
grainstones of the top of the underlying Higueruelas
Formation (Gómez & Goy, 1979; Díaz-Molina & Yebenes,
1987), lies the Villar del Arzobispo Formation (‘Unit 2’
and ‘Unit 3’ of Díaz-Molina & Yebenes, 1987), with a
thickness of approximately 260 m. ‘Unit 2’ is more carbonated (‘Baldovar facies association’ of Santisteban
& Santos Cubedo, 2010a) and ‘Unit 3’ more detritical
(‘Riodeva facies association’ of Santisteban & Santos
Cubedo, 2010a), but both units share the same overall
lithology and sedimentary interpretation with the
holostratotype of the Villar del Arzobispo Formation
in the South Iberian Basin and the parastratotype in
the Peñagolosa sub-basin of the Maestrazgo Basin (Mas,
Alonso & Meléndez, 1984; Mas et al., 1984, 2004; Salas
et al., 2001). Therefore, the stratigraphical location of
the Las Zabacheras site is confirmed as within the Villar
del Arzobispo Formation (see also Luque et al.,
2006–2007; Alcalá et al., 2009; Royo-Torres et al., 2009;
Cobos, 2011; Cobos & Gascó, 2013). In addition, similar
stratigraphic revisions have been reported for this formation in several other basins of the Iberian Range
(Luque et al., 2005; Ipas et al., 2007; Santisteban &
Santos Cubedo, 2010a, b).
The Villar del Arzobispo Formation is generally considered as upper Tithonian–Berriasian in age (Mas
et al., 1984, 2004). In the Galve sub-basin, the more
carbonated part (‘Unit 2’ or Baldovar facies association) has been dated as Portlandian (= Tithonian),
based on the presence of the Foraminifera
Pseudocyclamina gr. lituus, Anchispirocyclina lusitanica,
and Rectocyclamina arrabidensis (Díaz-Molina &
Yebenes, 1987). It has also been dated as upper
Tithonian–middle Berriasian, based on the first appearance of the foraminifera Anchispirocyclina lusitanica
in the upper part of the underlying Higueruelas Formation (Aurell et al., 2010), and the presence of the
charophyte Globator maillardii incrassatus close to
the top of ‘Unit 2’ (Canudo et al., 2012). ‘Unit 2’ has
also been considered as Tithonian based on the presence of the turtles Tropidemys sp., Plesiochelus sp., and
aff. Plesiochelydae (Pérez-García, Scheyer & Murelaga,
2013). It is not currently possible to directly date the
Las Zabacheras site in ‘Unit 3’, although there is a
charophyte, Globator maillardi steinhauseri (latest
Berriasian–Hauterivian age) located 90 m up, in the
base of the El Castellar Formation (‘Unit 4’). In conclusion, the age of the Las Zabacheras site can be
constrained between the Tithonian and the Berriasian,
and is most likely Berriasian in age.
SYSTEMATIC PALAEONTOLOGY
DINOSAURIA OWEN, 1842
SAURISCHIA SEELEY, 1887
SAUROPODA MARSH, 1878
EUSAUROPODA UPCHURCH, 1995
NEOSAUROPODA BONAPARTE, 1986
MACRONARIA WILSON & SERENO, 1998
ARAGOSAURUS SANZ ET AL., 1987
Type species
Aragosaurus ischiaticus Sanz et al., 1987.
Generic diagnosis – see ‘Revised species diagnosis’.
ARAGOSAURUS
ISCHIATICUS
SANZ
ET AL.,
1987
Holotype
Aragosaurus ischiaticus is known from a partial,
associated postcranial skeleton, comprising: seven
dorsal rib fragments, IG 468 (V40), IG 481 (Cos), IG 487
(Phs1), IG 492 (Uls), V20; 14 caudal vertebrae, IG 453
(V8), IG 473 (V1), IG 474 (V2s), IG 450 bis (V5), IG 475
(V3), IG 476 (V4), IG 477 (V5), IG 479 (V7), IG 480
(V8), ZH-18, ZH-17, ZH-12, ZH-15, ZH-16; two caudal
neural arches, IG 468 (V55 and X3); one caudal neural
spine, IG 493 (V9s); eight chevrons, ZH-4, ZH-5, ZH7, ZH-8, ZH-9, ZH-11, ZH-13, ZH-14; a right scapula,
ZH-1; a distal fragment of the left scapula, IG 482 (Oms);
a left coracoid, IG 482 (Oms); a right humerus, IG 490
(Fes); a right ulna, IG 483 (Cu); a right radius, IG 484
(Ra); a right carpal, IG 485 (Cars); a right metacarpal I, IG 486 (rmc1); a right metacarpal II, IG 486 (rmc2);
remains of metacarpals III and IV, IG 486 (rmc3), IG 486
(rmc4); a right pubis, IG 489 (Pus); a right ischium,
ZH-3; a partial left ischium, IG 492 (Uls), IG 488 (Is);
a left femur, ZH-2; two pedal phalanges, ZH-6, ZH10; and one ungual pedal phalanx, ZH-19.
Type locality and horizon
Las Zabacheras site, Villar del Arzobispo Formation
(upper Tithonian–lower Berriasian).
Revised species diagnosis
Aragosaurus ischiaticus is diagnosed on the basis of
the following new autapomorphies identified in the
current study: (1) anterior caudal vertebrae possess
neural spine summits with shallow, dorsolaterally facing
concavities on either side of the midline; (2) small
epipophysis-like protuberances on the dorsal surfaces of middle caudal vertebral postzygapophyses; (3)
the long interosseous ridges on the ulna and radius
represent at least a local autapomorphy, which is convergent with derived titanosaurs; (4) the interosseous
ridge on the posterolateral face of the radial shaft terminates distally in a distinct tubercle; (5) carpal
subquadrangular in shape in proximal and distal views,
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ARAGOSAURUS ISCHIATICUS
with similar lateromedial and anteroposterior diameters; (6) proximal pedal phalanx (II-1 or III-1) possesses a midline ridge on its dorsal surface, where its
lateral and medial faces meet each other to form an
apex.
Additional comments
Despite the complicated history of the collection, all
the bones belong to a single individual. All of them
come from the same site, show the same preservation, there is no repetition of elements, and their relative sizes are consistent. A tooth described by Sanz
(1982) and subsequently assigned to Aragosaurus (Sanz
et al., 1987) came from a different locality, close to Las
Zabacheras (Sanz et al., 1987; Canudo et al., 2001). As
such, its isolation, and the lack of a preserved tooth
in the holotype, precludes its referral to Aragosaurus.
It was described and illustrated by Sanz (1982) as being
more similar to the teeth of Giraffatitan than
Camarasaurus. In labial view, the crown shows no constriction at its base, contrasting with non-neosauropods
(Calvo, 1994; Upchurch, 1998), and it has a D-shaped
cross section (with the greatest diameter oriented
mesiodistally), differing from the cylindrical shape of
diplodocoid and titanosaurian teeth (Wilson & Sereno,
1998). The slenderness index (apicobasal length of the
tooth crown divided by its maximum mesiodistal width;
Upchurch, 1998) of the crown is 2.45, comparable with
the values seen in basal titanosauriforms, but higher
than observed in most non-neosauropods and
Camarasaurus, and lower than diplodocoids and most
titanosaurs (Upchurch, 1998; Chure et al., 2010). The
apical half of the lingual surface of the crown is concave
between broad mesial (partly worn away) and distal
ridges, although there is no lingual ridge. Serrations
and denticles are absent. There is a V-shaped wear
facet, contrasting with the planar wear facets present
in diplodocoids and derived titanosauriforms (Wilson
& Sereno, 1998). This combination of features suggests that this tooth crown should be regarded as representing an indeterminate titanosauriform.
DESCRIPTION AND COMPARISONS
AXIAL SKELETON
Caudal vertebrae
Portions of 14 anterior to posterior caudal vertebrae
are preserved: IG 453 (V8) = Cd1, IG 493 (V9s) = the
spine of Cd1, IG 474 (V2s) = Cd2, IG 473 (V1) = Cd3,
ZH-18 = Cd4, IG 450 bis (V5) = Cd5, ZH-17 = Cd6, IG 475
(V3) = Cd7, IG 476 (V4) = Cd8, IG 477 (V5) = Cd9, ZH15 = Cd10, IG 479 (V7) = Cd11, IG 480 (V8) = Cd12,
ZH-12 = Cd13, ZH-16 = Cd14, IG 468 (V55, X3) = fragments of neural arches. Several vertebrae are relatively complete (Fig. 4; Table 2). Although these do not
631
represent a continuous sequence, they are referred
to here as Cd1–Cd14. Centra are amphicoelous/
amphiplatyan, with a concave anterior articular surface
and a flat to gently concave posterior surface (Sanz
et al., 1987; Royo-Torres, 2009). This type of articulation, termed ‘planiconcave’ by Tidwell, Carpenter &
Meyer (2001), whereby the depth of the concavity of
the anterior surface is greater than that of the posterior surface, is a feature common to most sauropods
lacking procoelous anterior caudal centra (D’Emic, 2012),
including Camarasaurus, Brachiosaurus, and
Sauroposeidon (= ‘Paluxysaurus’) (D’Emic, 2013).
Anterior caudal vertebrae of Aragosaurus differ from
the procoelous anterior caudal vertebrae of titanosaurs,
flagellicaudatans, mamenchisaurids, and turiasaurs
(McIntosh, 1990; Upchurch, 1995, 1998; Royo-Torres
et al., 2009; Mannion et al., 2013). All centra have a
cylindrical cross section. Unlike many diplodocoids and
titanosaurs (McIntosh, 1990; Upchurch, 1995, 1998;
Wilson, 2002; Upchurch et al., 2004a; Curry Rogers,
2005; Mannion & Barrett, 2013), the ventral surfaces lack a midline sulcus or ventrolateral ridges, although very weak ridges support the posterior chevron
facets. Anterior chevron facets are relatively weakly
developed, but posterior chevron facets are present on
all of the preserved centra.
The lateral surface of the centrum merges smoothly into the ventral surface on the anteriormost caudal
vertebrae, although this angle becomes slightly more
abrupt further along the tail. There are no lateral pneumatic openings on the centra. The most anterior vertebrae bear a bulge on their lateroventral surface below
the caudal rib (Fig. 4), probably in Cd1–Cd3. This is
a derived character state shared with Giraffatitan,
Abydosaurus (Chure et al., 2010), Tastavinsaurus, and
the titanosaur Andesaurus (D’Emic, 2012; Mannion
et al., 2013). This feature is absent in Cd4 and subsequent caudal vertebrae. This feature differs from the
moderately well-developed, anteroposteriorly oriented ridge that is present on Cd5–8 at approximately
two-thirds of the way up the lateral surface of the
centrum. This ridge divides the lateral surface into
two parts: the more ventral surface is the primary
and the more dorsal surface is the secondary (sensu
Salgado & Coria, 2002). The caudal ribs are simple,
dorsoventrally compressed, laterally projecting processes, differing from the strongly posterolaterally directed ribs of most titanosauriforms (Mannion & Calvo,
2011; Mannion et al., 2013), but comparable with those
of Brachiosaurus (Taylor, 2009). A prezygodiapophyseal
lamina (PRDL) extends from the anterodorsal margin
of the caudal rib (Fig. 4 of IG 473 and 474), a feature
that Aragosaurus shares with a number of basal
titanosauriforms, e.g. Tastavinsaurus (Canudo,
Royo-Torres & Cuenca-Bescós, 2008), Venenosaurus
(Tidwell et al., 2001), Abydosaurus (Chure et al., 2010),
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632
R. ROYO-TORRES ET AL.
Figure 4. Caudal vertebrae of Aragosaurus ischiaticus: A, the series of caudals in their relative positions from Cd1 to
Cd14 in lateral view; B, C fragment (IG 453, Cd1) of anterior caudal vertebral centrum in anterior (B) and posterior (C)
views; D, E, fragment (IG 474, Cd2) of anterior caudal vertebral centrum in lateral (D) and posterior (E) views; F, anterior caudal vertebral centrum (IG 473, Cd3) in anterior view from Lapparent (1960); G–I, anterior caudal vertebra (ZH18, Cd4) in left lateral (G), right lateral (H), and anterior (I) views; J–L, anterior caudal neural spine (IG 493, Cd1) in
posterior (J), anterior (K), and lateral (L) views; LL, M, middle caudal vertebra (ZH-17, Cd 6) in left lateral (LL) and
anterior (M) views; N, anterior caudal neural spine (IG 493, Cd1) in dorsal view; O, P, posterior caudal vertebra (ZH-15,
Cd 10) in left lateral (O) and posterior (P) views; Q, distal caudal vertebrae (ZH-12 and 16, Cd 13 and 14) in left lateral
view. Arrow 1: a bulge on the lateroventral surface below the caudal rib. Arrow 2: anterior caudal vertebrae possess neural
spine summits with shallow, dorsolaterally facing concavities on either side of the midline. Arrow 3: small epipophysislike protuberances on the dorsal surfaces of middle caudal vertebral postzygapophyses.
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655
ARAGOSAURUS ISCHIATICUS
633
Table 2. Measurements of Aragosaurus ischiaticus caudal vertebrae
Measurement
Cd1 Cd3 Cd4
Cd5 Cd6
Cd7
Cd8
Cd9 Cd10 Cd 12 Cd 13 Cd 14
Centrum length
Anterior centrum width
Anterior centrum height
Posterior centrum width
Posterior centrum height
Distance from front of centrum to arch
Distance from back of centrum to arch
Length of prezygapophyses
Anteroposterior length of base of spine
Transverse width of base of spine
Anteroposterior length of top of spine
Transverse width of top of spine
–
–
–
–
–
–
–
–
–
–
64
121
133
184
177
–
–
–
–
–
–
–
–
–
135
136
139
138
136
18ca
38
–
–
–
–
–
133
–
133
118
128
28ca
38
–
–
–
–
–
134
120
124
117
117
–
–
–
–
–
–
–
131
266
260
261
257
–
–
–
–
–
–
–
136
248
242
220
235
10
25
80
75
41
85ca
82
137
169
166
167
170
18
38
82
50ca
25
67
35
135
113
99
98
95
22
36
–
–
–
–
–
121
84
73
79
69
29
35
–
–
–
–
–
124
82
68
79
70
30ca
25ca
–
–
–
–
–
111
73
65
70
64
25ca
35
42
–
–
–
–
Cd1–Cd14 is the ‘series’ shown in Figure 4. All measurements are in millimetres.
Brachiosaurus, and Giraffatitan (Wilson, 2002), but
that is also present in more basal eusauropods such
as Mamenchisaurus (Young & Zhao, 1972), and most
diplodocoids (Wilson, 2002), including the putative basal
form Haplocanthosaurus (Hatcher, 1903).
The neural arches are slightly biased towards the
anterior margin of the centrum, but this is not the
strong anterior shift seen in most titanosauriforms
(Calvo & Salgado, 1995; Upchurch, 1995, 1998; Salgado
et al., 1997), and middle caudal neural arches are situated on approximately the central half of the centrum
(Fig. 4). The neural canal is circular in the most anterior caudal vertebrae, and is wider dorsoventrally than
transversely in the middle caudal vertebrae (Sanz et al.,
1987). Prezygapophyses project anterodorsally in the
anteriormost caudal vertebrae (Cd4 and Cd6), but are
directed mainly anteriorly in subsequent vertebrae. The
flat prezygapophyseal articular surfaces face medially and slightly dorsally (Sanz et al., 1987). As a consequence of poor preservation in the postzygapophyseal
region, it is not possible to determine whether a
hyposphenal ridge was present in any of the anterior
caudal vertebrae. Postzygapophyses are unusual in the
middle caudal vertebrae in that they project as short
processes posterolaterally from the underside of the
spine (Cd10, Fig. 4N and O). These project beyond the
posterior margin of the centrum but do not extend
as far posteriorly as the tip of the spine. Some
postzygapophyses also have epipophysis-like protuberances on their dorsal surfaces (Cd10, Fig. 4). This
postzygapophyseal morphology is considered an
autapomorphy of Aragosaurus.
A single intraprezygapophyseal lamina (with a
rounded anterior margin) floors the prespinal fossa,
and this fossa is bounded by well-developed, rounded
spinoprezygapophyseal laminae (SPRLs). The SPRLS
merge into the anterolateral margins of the spine and
diverge laterally at their anterior ends. This prespinal
fossa differs from that seen in the caudal vertebrae
of Tastavinsaurus (MPZ99/9) in that it is not slotlike or closed at its anterior end. Spinopostzygapophyseal
laminae (SPOLs) rapidly fade into the posterolateral
margins of the spine, meaning that there is no
postspinal fossa along the dorsal two-thirds of the spine
(Cd4, Fig. 4). The base of the neural spine is almost
square in cross section, but this is given the appearance of a more transversely compressed cross section
by the presence of the SPRLs.
Neural spines project posterodorsally in the
anteriormost caudal vertebrae, and are strongly directed posteriorly in middle caudal vertebrae. These
caudal neural spine orientations represent the
plesiomorphic condition, and thus differ from the derived
anterodorsal orientation of the neural spines in some
basal titanosauriforms such as Tastavinsaurus,
Cedarosaurus, and Venenosaurus (D’Emic, 2012;
Royo-Torres, Alcalá & Cobos, 2012). The ratio of the
height of the neural spine to centrum height is 1.25
in anterior caudal vertebrae. Towards the dorsal end
of the anteriormost neural spines (Cd1 and Cd4), the
spine becomes slightly compressed anteroposteriorly
and expands strongly transversely, giving the spine
a club-shaped outline in anterior view, similar to the
anterior caudal neural spines of Brachiosaurus,
Camarasaurus, Losillasaurus, Lourinhasaurus,
Tastavinsaurus, and Turiasaurus (Casanovas, Santafé
& Sanz, 2001; Canudo et al., 2008; Taylor, 2009;
Mannion et al., 2013; Mocho, Royo-Torres & Ortega,
2014). As a result of this expansion, the dorsal surface
of the spine is strongly convex transversely and forms
rounded projections that slightly overhang the lateral
surfaces (Cd1, Fig. 4). The anterior, posterior, and dorsal
surfaces are strongly rugose, whereas the lateral surfaces of the neural spine are smooth. Shallow
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655
634
R. ROYO-TORRES ET AL.
Figure 5. Dorsal ribs of Aragosaurus ischiaticus: A–D, anterior dorsal distal rib (IG 492 Uls) in lateral (A), posterior
(B), medial (C), and distal (D) views; E–H, posterior dorsal distal rib (IG 481) in medial (E), posterior (F), lateral (G),
and distal (H) views.
dorsolateral concavities are present on either side of
the expanded summits of anterior caudal neural spines
(Cd1 and Cd4, Fig. 4), a probable autapomorphy of
Aragosaurus. Subsequent caudal neural spines are laterally compressed plates with only slightly expanded
dorsal ends (Cd5, Fig. 4), whereas middle–posterior
caudal neural spines have cylindrical cross sections and
taper to a transversely thin, acute dorsal ridge (Cd10,
Fig. 4).
Dorsal rib fragments
Seven dorsal rib fragments [IG 468 (V40), IG 481 (Cos),
IG 487 (Phs1), IG 492 (Uls), V20] have been recovered, representing portions of the middle and distal
shafts. All of them have a solid bone texture and only
in two distal ribs is it possible to identify a distal rugose
surface. One of them is probably an anterior rib, with
a plank-like structure (Fig. 5A–C), a feature originally optimized as a titanosauriform character (Wilson,
2002), and the second is a posterior rib (Fig. 5D–F).
Haemal arches
A total of eight anterior–middle chevrons are preserved (ZH-4, ZH-5, ZH-7, ZH-8, ZH-9, ZH-11, ZH13, ZH-14; Fig. 6; Table 3). All of them are open
proximally, although in some cases (i.e. ZH-9) the proximal facets are very close (Sanz et al., 1987). Proximally open chevrons represent a derived state that
occurs in most macronarians, but are also found in
Shunosaurus and rebbachisaurids (Calvo & Salgado,
1995; Upchurch, 1998). Within Macronaria, several
Chinese titanosauriforms (Mannion & Calvo, 2011) and
Camarasaurus lewisi (McIntosh et al., 1996b) display
proximally bridged chevrons, and it is possible that
some (but not all) chevrons of Lusotitan are bridged
(Mannion et al., 2013). The ratio of haemal canal depth
to total chevron height varies along the tail: this ratio
is approximately 50% in the second most anteriorly
preserved chevron, but is only 29% in chevron ZH-4.
Figure 6. Haemal arches of Aragosaurus ischiaticus: A, B,
anterior chevron (ZH-4) in posterior (A) and anterior (B)
views; C, D, anterior chevron (ZH-5) in anterior (C) and
posterior (D) views; E, anterior chevron (ZH-7) in lateral
view; F, G, middle chevron (ZH-9) in anterior (F) and lateral
(G) views; H, posterior chevron (ZH-14) in lateral view.
Wilson (1999, 2002) and Curry Rogers & Forster (2001)
noticed that titanosaurs typically possess chevrons in
which the ratio of haemal canal height to total chevron
length is 0.5, whereas in other dinosaurs (including
basal eusauropods and diplodocoids) this ratio is typically 0.3 or lower. The observation that Aragosaurus
displays the derived state in some specimens and the
plesiomorphic state in others could indicate that
the derived condition first evolved in more anterior chevrons, and then spread to middle chevrons later in
titanosauriform evolution. If this interpretation is correct,
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ARAGOSAURUS ISCHIATICUS
635
Table 3. Measurements of Aragosaurus ischiaticus haemal arches, pectoral girdle, and forelimb elements
Element
Dimension
Measurement
Haemal arch ZH-4
Total length
Depth of haemal canal
Total length
Depth of haemal canal
Total length
Depth of haemal canal
Total length
Depth of haemal canal
Length
Proximal plate dorsoventral height
Dorsoventral height of blade at base (as preserved)
Anteroposterior length of glenoid
Transverse width of glenoid
Anteroposterior width (as preserved)
Transverse width of scapular articulation
(measured at midheight of preserved portion)
Maximum transverse width of glenoid
Anteroposterior length of ventral concave margin
Length
Maximum transverse width of proximal end
(as preserved)
Transverse width of shaft (at broken end)
265
126
∼272
137
∼261
78
115
61
1260
826
245
271
159
354
143
Haemal arch ZH-5
Haemal arch ZH-9
Haemal arch ZH-14
Right scapula ZH-1
Left coracoid IG 482
Right humerus IG 490
Anteroposterior width of shaft (at broken end)
Right ulna IG 483
Right radius IG 484
Carpal IG 485
Right metacarpal I
IG 486 (rmc1)
Right metacarpal II
IG 486 (rmc2)
Length
Length of anteromedial process
Length of anterolateral process
Maximum diameter of shaft at midlength
Anteroposterior diameter of distal end
Transverse diameter of distal end
Length
Proximal end transverse width
Proximal end anteroposterior width
Transverse width of shaft at midlength
Transverse width of distal end
Anteroposterior width of distal end
Transverse width
Anteroposterior width
Dorsoventral thickness at the thinnest margin
Dorsoventral thickness at the thickest margin
Length (on medial margin)
Length (on lateral margin)
Proximal end superopalmar height
Proximal end lateromedial height
Midshaft transverse width
Distal end transverse width
Length
Proximal end maximum transverse width
Midshaft transverse width
Distal end transverse width
180
80
1120 (Lapparent, 1960)
330+
131 (proximal portion),
128 (distal portion)
78 (proximal portion),
108 (distal portion)
820
298
269
95
164
140
792
175
126
87
172
134
171
160
55
87
289
291
125
75
53
96
∼370
90
70
100
All measurements are in millimetres.
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R. ROYO-TORRES ET AL.
Aragosaurus could be regarded as possessing an intermediate condition between the plesiomorphic and
derived states.
The proximal articular surfaces of the haemal arches
are flat, lacking the anteroposteriorly convex surfaces of several titanosauriforms (Mannion & Calvo,
2011), including Tastavinsaurus (Canudo et al., 2008).
The distal shafts of the two anteriormost preserved
chevrons are anteroposteriorly compressed and slightly widened transversely, whereas from the third chevron
onwards the distal shaft is transversely compressed.
The most distally preserved chevron comes from a
middle caudal vertebra, and is strongly curved in lateral
view, with the distal shaft projecting backwards and
downwards at an angle of approximately 45° to the
horizontal. There is no anterior expansion of the shaft,
suggesting that Aragosaurus lacked the ‘forked’ chevrons of most non-titanosauriforms (Berman & McIntosh,
1978; Upchurch, 1995, 1998; Wilson & Sereno, 1998).
The haemal arches are generally too incomplete for
measurements to be taken, although two measurements were obtained from the near-complete ‘chevron 4’
(Table 3).
PECTORAL
GIRDLE AND FORELIMB
Scapula
This element is known from the nearly complete right
scapula (ZH-1) and the distal end of the blade of the
left scapula (IG 482) (Fig. 7; Table 3). It will be described with the distal blade oriented horizontally, although in life it probably projected posterodorsally. The
right scapula is well preserved, although it is missing
portions from the anterodorsal part of the acromion
and the dorsal margin of the distal end of the blade.
This element is mounted with the medial surface
exposed and the lateral surface accessible but facing
a wall: consequently some aspects of the lateral surface
are difficult to observe directly. The lateral surface of
the acromion bears a well-developed acromial (‘deltoid’)
ridge. Immediately posterior to this ridge, the lateral
surface is shallowly concave as also occurs in most
sauropods, except for basal forms (e.g. Shunosaurus)
and some titanosaurs (e.g. Alamosaurus and
Opisthocoelicaudia; Upchurch et al., 2004a; Harris, 2006).
The angle between the acromial ridge and the blade
appears to be close to 90° or slightly less. The stout
glenoid region bears an articular surface that faces
anteroventrally: thus, Aragosaurus possesses the
plesiomorphic state rather than the derived medial deflection of the glenoid observed in somphospondylans
and Apatosaurus (Wilson & Sereno, 1998; Upchurch,
Tomida & Barrett, 2004b). The distinct bulge or triangular ventromedial process close to the proximal end
of the ventral margin of the blade observed in forms
such as Chubutisaurus (Carballido et al., 2011a),
Figure 7. Pectoral girdle elements of Aragosaurus ischiaticus:
A–D, left coracoid (IG 482) in lateral (A), ventral (B), medial
(C), and anterior (D) views; E, right scapula (ZH-1) in medial
view and partial left coracoid in lateral view; F, anatomical articulation between the coracoid and scapula in lateral
view.
Alamosaurus (D’Emic, Wilson & Williamson, 2011), and
Lourinhasaurus (P.U. and P.D.M., pers. observ., 2009),
cannot be observed in Aragosaurus, but this margin
might have been damaged. In cross section, the base
of the blade has a D-shaped profile, with a thinner
dorsal margin and wider ventral margin: this is a
derived state that occurs in most neosauropods, except
for some derived titanosaurs such as Opisthocoelicaudia,
where the cross section becomes subrectangular (Wilson,
2002). No ridges or rugosities are present on the medial
surface of the blade, unlike some advanced titanosaurs
such as Lirainosaurus (Sanz et al., 1999). It appears
that the scapular blade of Aragosaurus expanded in
dorsoventral height near its distal end, but the exact
degree of expansion cannot be determined because of
poor preservation; however, it is unlikely that the dorsal
margin was prominently expanded as in rebbachisaurids
(see Sereno et al., 2007; Mannion, 2009).
Coracoid
The left coracoid (IG 482) (Fig. 7; Table 3) will be described as if it were connected to a scapula, the distal
blade of which is directed horizontally backwards (see
above). Only the ventral half of the left coracoid is preserved. In lateral view, the anterior margin of the coracoid is gently convex dorsoventrally: this suggests that
this margin and the dorsal margin might have merged
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ARAGOSAURUS ISCHIATICUS
smoothly into each other (as occurs in most nonneosauropod eusauropods; Upchurch, 1998; Upchurch
et al., 2004a), but the specimen is not well enough preserved for this character state to be established with
confidence. The lateral surface of the coracoid is mildly
convex and, as in other sauropods, lacks the tubercle
on its anteroventral part that occurs in more basal
sauropodomorphs (Upchurch, Barrett & Galton, 2007;
Yates, 2007), and in the titanosaurs Lirainosaurus and
Opisthocoelicaudia (Borsuk-Bialynicka, 1977; Díez Díaz,
Pereda Suberbiola & Sanz, 2013). The anteroventral
portion of the coracoid forms a slightly acute projection that is emphasized by the mild upward concavity of the ventral margin that lies just posterior to this
corner. This concave, notch-like area is small (when
compared with the size of the glenoid) relative to those
observed in other sauropods. The very stout glenoid
region lies immediately posterior to this ventral
notch. The rugose glenoid articular surface faces
posteroventrally, and is not deflected to face medially. The glenoid forms the transversely widest part
of the coracoid (Table 3), largely because it expands
prominently along its lateral edge to form a ‘lateral
glenoid shelf ’. The lateral margin of this glenoid ‘shelf ’
curls upwards towards its edge, so that part of the
rugose articular surface can be observed in lateral view.
This feature is present in other neosauropods, e.g.
Lourinhasaurus (Mocho et al., 2014), Camarasaurus
grandis (Ostrom & McIntosh, 1966: pl. 46), Brachiosaurus (Riggs, 1903; 1904; Taylor, 2009), and Giraffatitan
(Janensch, 1961: fig. Abb.1ab; Taylor, 2009). Posterior to the glenoid, the lower part of the articulation for
the scapula can be observed. This is a robust area (although not as wide transversely as the glenoid), and
faced either posteriorly or posterodorsally. Only the
smooth posteroventral margin of the coracoid foramen
is preserved, indicating that this opening lies close to
the scapulocoracoid junction. The medial surface of the
coracoid is shallowly concave.
Humerus
The right humerus (IG 490; Fig. 8, Table 3) appears
to be nearly complete, but is preserved as separate proximal and distal halves. This bone was illustrated by
Lapparent (1960), but was not described. The broken
mid-shaft regions of each of these halves are nearly
identical in terms of their cross-sectional shape and
dimensions (Table 3), suggesting that little material has
been lost from this region (Fig. 8). The medial portion
of the proximal end is missing. In anterior view, the
proximal articular surface and lateral margin of the
humerus merge smoothly into each other to form
a convex region: thus Aragosaurus retains the
plesiomorphic state that occurs in most sauropods and
lacks the derived ‘squared’ proximolateral corner observed in many somphospondylans (Upchurch, 1999;
637
Figure 8. Right humerus (IG 490) of Aragosaurus ischiaticus:
A, humerus (in three portions) in anterior view; B, picture
of the humerus, after Lapparent (1960), in anterior view;
C, proximal portion in posterior view; D, proximal portion
in lateral view.
Wilson, 2002; Upchurch et al., 2004a; Mannion et al.,
2013). Also, unlike derived titanosaurs such as
Saltasaurus and Opisthocoelicaudia (Upchurch, 1998),
the proximolateral corner of the humerus of Aragosaurus
lacks a rounded supracoracoideus projection. The proximal part of the deltopectoral crest is preserved, but
the more distal (and presumably more prominent)
section of this crest is missing. The deltopectoral crest
projects mainly anteriorly, but is also deflected slightly laterally: as a result, the lateral surface of the proximal part of the crest is mildly concave. At approximately
midlength, where the shaft is broken, the horizontal
cross section has a suboval outline, with the long axis
of this oval oriented transversely. This cross-sectional
profile is formed by relatively straight anterior, rounded
lateral and posterior, and acute medial margins. Compared with the overall size of the humerus, the crosssectional area of the mid-shaft is relatively small, with
a transverse width of shaft at midlength/humerus length
ratio of approximately 0.12 (Table 3). Such gracile
humeri (where the mid-shaft width/humerus length ratio
is less than 0.15) also occur in some other sauropods,
including the basal eusauropod Lapparentosaurus,
several brachiosaurids, and the basal somphospondylan
Ligabuesaurus (Curry Rogers, 2005; D’Emic, 2012;
Mannion et al., 2013). The distribution of gracile humeri
suggests that this feature evolved several times among
different sauropod lineages, and it therefore does not
provide strong support for any particular identification of the affinities of Aragosaurus. The profile of the
lateral margin of the humeral shaft is concave rather
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638
R. ROYO-TORRES ET AL.
than the derived straight margin seen in some
titanosaurs (Curry Rogers, 2005). The humerus lacks
a pronounced tuberosity for the muscle latissimus dorsi,
unlike some derived titanosaurs (Otero, 2010; D’Emic,
2012).
The distal half of the humerus is damaged along its
lateral margin. As in other sauropods, the distal part
of the anterior surface is mildly convex transversely
and lacks the deep concavity observed in basal
sauropodomorphs and other dinosaurs (Upchurch et al.,
2007; Yates, 2007). There are two small projections situated close to the midline, where the anterior surface
meets the distal articular surface; as such, Aragosaurus
retains the plesiomorphic state of a divided anterior
condyle, differing from the condition in derived
somphospondylans (D’Emic, 2012). The anteromedial
part of the distal end is moderately expanded to form
a rounded projection: as a result, the distal part of the
medial surface faces posteromedially and is mildly
convex. Posteriorly, there is a well-developed anconeal
fossa that is defined medially and laterally by low
rounded ridges that extend from the distal end and
fade out proximally, but these are not the acute prominent ridges observed in many titanosaurs (Upchurch
et al., 2004a). The rugose distal articular surface does
not curve up onto the anterior or posterior faces of the
humeral shaft, unlike the derived condition that occurs
in several titanosaurs (Wilson & Carrano, 1999; Wilson,
2002).
The ratio between humerus and femur lengths is approximately 0.82 (Sanz et al., 1987; Royo-Torres &
Ruiz-Omeñaca, 1999), which is similar to most
titanosauriforms (Mannion et al., 2013), as well as
Lourinhasaurus (Mocho et al., 2014), but differs from
the condition in brachiosaurids, whereby this ratio is
closer to 1.0 (Wilson, 2002). In Aragosaurus, this ratio
is slightly higher than in other basal macronarians such
as Camarasaurus (0.75; Madsen, McIntosh & Berdman,
1995; Ikejiri, 2005) and Tehuelchesaurus (0.72; Carballido
et al., 2011b).
Ulna
The right ulna (IG 483; Fig. 9; Table 3) is nearly complete and resembles those of other sauropods in most
respects. The proximal end is triradiate, formed by long
anteromedial and anterolateral processes and a weakly
developed posterior process. There is a deep fossa
between the anteromedial and anterolateral processes, for reception of the proximal end of the radius.
The anteromedial and anterolateral processes are
subequal in length (Table 3): this state also occurs in
several other sauropods (e.g. Apatosaurus, Europasaurus,
Malawisaurus, and Mamenchisaurus), whereas the
former process is much longer [e.g. Camarasaurus,
Giraffatitan, and Sauroposeidon (‘Paluxysaurus’ material)] or even twice as long (Cedarosaurus and
Venenosaurus) as the latter process in several
macronarians (Mannion et al., 2013). The articular
surface of the anteromedial process is flat longitudinally and slopes strongly anterodistally at an angle
of approximately 45° to the horizontal. A similar,
potentially derived, condition occurs in the basal
macronarian sauropod Lusotitan (Mannion et al., 2013).
In contrast, the articular surface of the anterolateral
process is flat longitudinally and moderately convex
transversely.
On the anterior surface of the shaft, there is a strong
interosseous ridge that first appears on the proximal
half of the ulna, increases in prominence distally, and
finally disappears about 100 mm above the distal end.
Such a ridge is common in other sauropods and probably represents the attachment site of ligaments that
bound the ulna and radius together; however, this ridge
is normally restricted to the distal part of the ulna,
except in several titanosaurs where this structure can
occupy most of the length of the element (Curry Rogers,
2005, 2009; see ‘Radius’ below for further discussion
of this feature). Below the end of this ridge there is a
triangular striated concavity. Although the distal end
of the ulna is expanded relative to the shaft, this expansion does not seem to be particularly marked relative to that observed in most sauropods. The outline
of the distal end is between elliptical and subcircular.
Radius
The right radius is complete (IG 484; Fig. 9; Table 3).
The proximal articular surface is flat and has a suboval
outline, with the long axis of this oval oriented
mediolaterally. This element is relatively slender (proximal transverse width/radius length ratio = 0.22; Table 3),
as in most sauropods: thus Aragosaurus lacks the
apomorphically robust radius observed in many
titanosaurs, where the proximal transverse width is
often more than 30% of the radius length (McIntosh,
1990; Upchurch, 1995, 1998). In lateral view, the radial
shaft is bowed slightly anteriorly. On the lateral part
Figure 9. Right ulna (IG 483) of Aragosaurus ischiaticus
in: A, posterior, B, ventral, C, anteromedial, and D, medial
views. Right radius (IG 484) of Aragosaurus ischiaticus in:
E, anterior, and F, posterior views.
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ARAGOSAURUS ISCHIATICUS
of the posterior surface, a well-developed ridge extends
from the proximal end to approximately one-third of
the radius length from the distal end, increasing in
prominence distally, and corresponding with the ridge
described on the anterior face of the ulna (see above).
This ridge on the posterior face of the radius terminates in a rounded eminence or tubercle at a point approximately 25% of the shaft length from the distal
end of the radius. Curry Rogers (2005: character 283)
noted the presence of a well-developed interosseous ridge
as a derived state in many titanosaurs (e.g. Aeolosaurus,
Ampelosaurus, Neuquensaurus, Opisthocoelicaudia, and
Rapetosaurus). In at least some of these taxa (e.g.
Opisthocoelicaudia, Borsuk-Bialynicka, 1977: fig. 8C;
Rapetosaurus, Curry Rogers, 2009: fig. 36D), the
interosseous ridges extend along most of the length
of both the ulna and radius, as occurs in Aragosaurus.
As Aragosaurus is probably a basal macronarian (see
below) that is not closely related to such derived
titanosaurs, the elongated interosseous ridge is here
provisionally considered to be a local autapomorphy.
The tubercle at the distal end of this ridge is also potentially unique to Aragosaurus.
The distal end has a subrectangular outline, similar
to most sauropods (Wilson & Sereno, 1998), although
the posterior margin has a slightly concave profile. The
distal articular surface is rugose and strongly convex
and, in anterior view, slopes proximally towards its
lateral margin at an angle of 16–17° to the horizontal. This ‘bevelling’ of the lateral half of the distal articular surface occurs in a wide array of eusauropods
(Mannion et al., 2013), although it is more prominently developed and continuous across the distal surface
in derived titanosaurs such as Opisthocoelicaudia and
Saltasaurus (Wilson, 2002; Mannion et al., 2013; Mateus,
Mannion & Upchurch, in press).
Carpal
A single block-like carpal element is preserved (IG 485;
Fig. 10; Table 3). It is similar to the carpal bone (cat. no.
445) of Camarasaurus grandis (GMNH-PV 101) that
was described as a ‘radiale’ by McIntosh et al. (1996a).
Given that the other forelimb and manual elements
of Aragosaurus are all preserved from the right side,
for the purposes of description it will be assumed that
the carpal also belongs to the right manus. This element
is subquadrangular in proximal and distal views, with
rounded corners. The proximal articular surface is mildly
concave, as is also seen in the carpals of Camarasaurus
(McIntosh et al., 1996a), Turiasaurus, and Losillasaurus
(R.R.T., P.U., and P.D.M., pers. observ. 2009). In contrast, the distal surface is mildly rugose and possesses only a mild projection on its posterolateral part,
unlike Turiasaurus, where this projection is much more
prominent (Royo-Torres et al., 2006). The Aragosaurus
carpal also lacks the less prominent projection that
639
Figure 10. Right carpal (IG 485) of Aragosaurus ischiaticus
in: A, anterior, B, posterior, C, medial, D, lateral, E, ventral,
and F, dorsal views. Comparison between different carpals:
G, Aragosaurus; H, Turiasaurus; and I, Losillasaurus.
occurs on the posteromedial part of the distal surface
in Turiasaurus. Neither the proximal nor distal articular surfaces are divided into two or more separate regions by an anteroposteriorly oriented ridge,
differing from the proximal surface of the ‘scapholunar’ carpal described in Apatosaurus by Hatcher (1902:
367). In Aragosaurus, the anterior, posterior, lateral,
and medial margins are generally proximodistally
rounded, except at the posterolateral corner, where the
carpal has its greatest proximodistal thickness. Here,
the posterior part of the lateral surface is mildly concave,
partly as a result of a slight outwards projection of
the distal rim. This element maintains approximately the same proximodistal thickness over virtually all
of its extent: thus the bone does not thin towards one
or more of its edges, unlike the ‘scapho-lunar’ of Apatosaurus, where the anterior margin is much thinner
than the posterior margin (Hatcher, 1902). The
subquadrangular proximal outline of the carpal of
Aragosaurus is potentially autapomorphic because
the carpals of other sauropods are typically circular
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R. ROYO-TORRES ET AL.
or elliptical (e.g. Turiasaurus and Losillasaurus,
Royo-Torres et al., 2006; Apatosaurus, Hatcher, 1902;
Ostrom & McIntosh, 1966: pl. 54; and Camarasaurus,
McIntosh et al., 1996a).
Metacarpus
Portions of four metacarpals (I, II, III, and IV) from
the right manus are preserved [IG 486 (rmc1), IG 486
(rmc2), IG 486 (rmc3), and IG 486 (rmc4); Figs 11 and
12; Table 3]. In the following description, the orientations of these elements are based on the Camarasaurus
manus (Ostrom & McIntosh, 1966; McIntosh et al.,
1996a). In life, the metacarpals would have formed a
U-shaped arrangement with the long axes of their shafts
extending vertically, as in other eusauropods (McIntosh,
1990; Upchurch, 1998; Upchurch et al., 2004a); however,
for the purposes of description, the metacarpals are
treated as though they lie side-by-side with their long
axes extending forwards and the long axis of the distal
end of each metacarpal oriented transversely.
The articular surface of the right metacarpal I [IG 486
(rmc1); Fig. 11; Table 3], in proximal view, has a trans-
Figure 11. Right metacarpal I (IG 486, rmc1) of Aragosaurus
ischiaticus in: A, lateral; B, dorsal; C, ventral; D, distal;
E, medial; and F, proximal views.
Figure 12. Right metacarpal II (IG 486, rmc2) of
Aragosaurus ischiaticus in: A, proximal; B, medial; C, dorsal;
D, ventral; E, distal; and F, lateral views.
versely compressed D-shaped outline, with rounded
dorsal and medial margins, and flat and concave ventral
and lateral margins (Fig. 11). The proximal outline is
similar to metacarpal I of Giraffatitan (Janensch, 1961),
and differs from the more circular outline of
Camarasaurus (Ostrom & McIntosh, 1966; McIntosh
et al., 1996a). The proximal half of the lateral surface
forms a subtriangular and longitudinally striated concavity that extends along the shaft of the metacarpal
to approximately midlength. Just distal to midlength,
the shaft has an elliptical cross section, with the long
axis of this ellipse oriented transversely. There is a
ventrolaterally facing longitudinal groove on this central
region of the shaft, which is bounded by a distal ridge
along the lateral margin. The dorsolateral margin of
the shaft also forms a relatively acute ridge. In
Aragosaurus the distal end of metacarpal I terminates in two prominent condyles that are separated
along their midline by a wide groove. The medial condyle
is larger than the lateral one, mainly because it projects further ventrally. In distal end view, these condyles appear to slant ventrally and slightly medially.
There is a shallow pit on the lateral surface of the distal
condyle below the distal ridge on the lateral margin.
The medial surface of the distal condyle is flat and
striated.
In the right metacarpal II [IG 486 (rmc2); Fig. 12;
Table 3], the proximal end is between subtriangular
and D-shaped in outline, with a concave area on the
proximal part of the lateral surface for articulation with
metacarpal III, and a convex margin (with a slight
proximodistal ridge) forming the medial area for articulation with metacarpal I. In general, the dorsal and
medial surfaces are convex transversely and smooth,
whereas the palmar area is flat and rugose. The shaft
is triangular in transverse cross section and the distal
end has two condyles separated by a groove. These condyles are most strongly developed on the palmar surface.
The medial distal condyle is more prominent than the
lateral one, but the lateral distal condyle projects further
distally than the medial one. The distal articular surface
does not appear to extend onto the dorsal surface of
the metacarpal, a feature that Aragosaurus shares with
most titanosauriforms (D’Emic, 2012). This metacarpal is at least 37% of the radius length (Table 3), and
almost certainly much greater because of missing material: this suggests that Aragosaurus possessed the
derived state (longest metacarpal/radius length ratio
of 0.45 or greater) that occurs in most macronarians
(Wilson & Sereno, 1998). Metacarpal II of Aragosaurus
is different from those in Turiasaurus (Royo-Torres et al.,
2006), and is similar to the metacarpal of Camarasaurus
grandis (McIntosh et al., 1996a), because Aragosaurus
and C. grandis (McIntosh et al., 1996a) have two distinct distal condyles in palmar view where the articular surfaces of the distal ends curve down onto the
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ARAGOSAURUS ISCHIATICUS
palmar surface, whereas in Turiasaurus this surface
is flat and distinct condyles are absent.
Fragmentary remains of right metacarpal III [IG 486
(rmc3); Table 3] and right metacarpal IV [IG 486 (rmc4);
Table 3] are preserved. The distal end of metacarpal III has two distinct condyles similar to MC II.
The proximal end of metacarpal IV is triangular in
outline, lacking the ‘chevron’ profile seen in many
titanosauriforms (D’Emic, 2012; Mannion et al., 2013).
PELVIC
GIRDLE AND HINDLIMBS
Right pubis
Most of the right pubis is preserved [IG 489; Fig. 13;
Table 4); however, much of the symphyseal margin
(below the ischial articulation) is missing and has been
restored, and the obturator foramen is also not preserved in this portion. Royo-Torres et al. (1999) initially identified a separate portion of bone (IG 488) as
part of the pubis, but here it is reinterpreted as the
pubic peduncle of the left ischium. The articular surface
for the ilium is flat and strongly rugose. This articulation has a D-shaped outline in dorsal view, with the
convex margin facing anteriorly and laterally. This articular area therefore lacks the extreme transverse compression seen in some titanosaurs (e.g. Andesaurus;
Mannion & Calvo, 2011). Immediately below the iliac
articulation, the anterior surface of the pubis forms
a broad, slightly flattened triangular area that tapers
to a point ventrally (Royo-Torres et al., 1999). This
ventral tip extends forwards as a low, rounded projection. Thus, the ambiens process of Aragosaurus resembles those of other sauropods in most respects,
especially those of Lourinhasaurus (Royo-Torres, 2009),
Giraffatitan (Janensch, 1961), and possibly
Haplocanthosaurus (Rauhut et al., 2005), but there is
no prominent hooked ambiens process like the pubes
of several flagellicaudatans (e.g. Diplodocus, Barosaurus,
and Dicraeosaurus; McIntosh, 1990; Upchurch et al.,
Figure 13. Right pubis (IG 489) of Aragosaurus ischiaticus
in: A, medial; B, anterior; C, lateral; D, dorsal; E, ventral;
and F, posterior views.
641
2004a, b). The Aragosaurus pubis resembles those of
derived eusauropods, with a broad distal shaft that probably met its partner on the midline along an embayed
symphysis (i.e. the anterolateral margins of each pubis
lie in front of the plane of the symphysis, and so form
a V-shape in horizontal cross section; see Upchurch,
1995; Harris, 2006). The distal end of the pubis is expanded, especially medially. There is a flattened area
on the posteromedial surface of the distal end: this probably met a similar area on the left pubis to form a
strong ventral end to the midline symphysis. As in most
other sauropods, the distal end surface is strongly convex
and rugose. The distal end of the pubis is expanded
anteriorly, with the anterior margin of the very distal
end forming an acute angle with the remainder of the
anterior margin, similar to that seen in Camarasaurus
(Ostrom & McIntosh, 1966), but differing from the
rounded ‘boot’-like process that occurs in some
titanosauriforms, e.g. Giraffatitan and Tastavinsaurus
(Canudo et al., 2008; Mannion et al., 2013).
Ischium
The ischium is represented by the nearly complete right
element (ZH-3), the separate iliac peduncle and distal
end of the shaft (IG 492), and a fragment of the pubic
peduncle (IG 488) of the left element (Fig. 14; Table 4).
There is some reconstruction in the ventral region of
ZH-3, where the blade meets the proximal expansion, and at the ventral tip of the pubic articulation.
The length of the ischium is a little shorter than the
pubis (the ischium/pubis length ratio is 0.9). This value
is thus close to 1.0, as occurs in basal macronarians
such as Camarasaurus grandis (ratio = 1.07; McIntosh
et al., 1996a), Camarasaurus lentus (ratio = 0.98;
Gilmore, 1925; Royo-Torres, 2009), Lourinhasaurus
(ratio = 0.9–1.0; Mocho et al., 2014), and basal
titanosauriforms, such as Giraffatitan (ratio = 1.0;
Janensch, 1961). In more derived Titanosauriformes,
the typical condition is to have an ischium that is somewhat shorter than the pubis, with a ratio of less than
0.9 (e.g. Tastavinsaurus, Isisaurus, Opisthocoelicaudia,
and Saltasaurus; Calvo & Salgado, 1995; Salgado et al.,
1997; Upchurch, 1998; Upchurch et al., 2004a; Canudo
et al., 2008; Royo-Torres, 2009; Mannion et al., 2013).
The proximal expansion of the ischium resembles those
of most other sauropods in having mildly dorsoventrally
convex and concave lateral and medial surfaces, respectively, posterior to the pubic articulation. The latter
is transversely widest at its dorsal (acetabular) end,
and tapers ventrally. The iliac peduncle is widest
anteroposteriorly at its base and narrows slightly
towards its articular surface: thus, Aragosaurus
lacks the distinct ‘neck’ observed in the ischia of
several rebbachisaurids (Sereno et al., 2007) and some
derived titanosaurs (e.g. Muyelensaurus; Mannion &
Calvo, 2011). There is no tubercle on the lateral
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642
R. ROYO-TORRES ET AL.
Table 4. Measurements of Aragosaurus ischiaticus pelvic girdle elements and hindlimb
Element
Dimension
Measurement
Right pubis IG 489
Length
Transverse width of iliac articulation
Anteroposterior width of iliac articulation
Distance from proximal end to most prominent point of ambiens area
Anteroposterior width of distal end
Transverse width of distal end
Length
Length of shaft along ventral margin
Estimated dorsoventral height of proximal plate
Length of the pubic articulation
Anteroposterior diameter of iliac articulation
Transverse width of iliac articulation
Transverse width of shaft at midlength
Length of acetabular margin
Distal end transverse width
Distal end dorsoventral width
Length
Transverse width of proximal end
Lateromedial width of proximal end
Length from proximal end to top of fourth trochanter
Length of fourth trochanter
Anteroposterior width of proximal articular head
Anteroposterior width of greater trochanter
Anteroposterior width of tibial condyle
Anteroposterior width of the fibulal condyle
Transverse width of distal end
Anteroposterior width of midshaft
Transverse width of midshaft
Proximal transverse width in dorsal
Proximal superopalmar width
Distal transverse width
Distal superopalmar width
Medial proximodistal width
Lateral proximodistal width
Length
Proximal end dorsoventral height
Proximal end transverse width
868–880
220
240
132
350
190
875
552
543
355
118
132
91
166
119
50
1373
426
230
605
132
223
187
370
310
436
136
266
83
74
64
63
7.5
5.5
166
95
57
Right ischium ZH-3
Left femur ZH-2
Pedal phalanx II-1
ZH-10
Right pedal ungual ZH-19
All measurements are in millimetres.
surface of the iliac peduncle, unlike the ischia of the
titanosaurs Gondwanatitan and Opisthocoelicaudia
(Borsuk-Bialynicka, 1977; Kellner & de Azevedo, 1999;
Upchurch et al., 2004a). The acetabular surface curves
smoothly into the lateral surface of the proximal expansion, whereas the medial margin of the acetabulum meets the medial surface of the ischial plate at
an abrupt ridge-like edge (Sanz et al., 1987), contrasting with taxa such as Giraffatitan and Tastavinsaurus,
which have a shallower acetabulum (Sanz et al., 1987;
Canudo et al., 2008; Royo-Torres, 2009). The acetabular
surface does not display the morphology observed in
several rebbachisaurids (e.g. Demandasaurus; Mannion
et al., 2012), in which it is transversely wide at the
dorsal end of the iliac peduncle and pubic peduncle,
but very narrow in its central portion.
The ischium has a dorsoventrally long pubic peduncle in relation to the element’s total length (Sanz et al.,
1987). This character can be quantified by the next
ratio: the distance from the upper corner of the pubic
blade up to the posterior margin of the element, to the
dorsoventral length of the pubic articular surface
(Salgado et al., 1997: fig. 5). The derived state, characterizing Camarasauromorpha (sensu Salgado
et al., 1997), Macronaria (Wilson & Sereno, 1998), and
Apatosaurus (Royo-Torres, 2009), occurs when the
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655
ARAGOSAURUS ISCHIATICUS
643
Figure 14. Right ischium (ZH-3) of Aragosaurus ischiaticus
in: A, posterior; B, lateral views. Fragments of the left
ischium (IG 492) of Aragosaurus ischiaticus: C, D, pubic
peduncle in anterior (C) and lateral (D) views; E, F, iliac
peduncle in dorsal (E) and lateral (F) views.
distance from the upper corner of the pubic blade of
the ischium to the posterior border of the bone is shorter
than the pubic articulation. In Aragosaurus the distal
blade is well developed, and the morphology of the
midline symphysis of the distal blade suggests that
there would have been a V-shaped notch between the
left and right ischia in dorsal view when these
elements were articulated in life. Consequently,
Aragosaurus is likely to have possessed the
plesiomorphic style of ischiadic symphysis observed in
most sauropods, rather than the derived condition seen
in titanosaurs such as Alamosaurus, Andesaurus, and
Opisthocoelicaudia, in which the ventral emargination
is absent and the midline symphysis extends forwards to the ventral end of the pubic articulation
(McIntosh, 1990; Upchurch, 1998; Wilson, 2002). The
distal shaft is directed mainly posteriorly and only slightly ventrally: when the long axis of the distal shaft is
projected forwards, it passes through the centre of the
pubic articulation, contrasting with the derived condition that occurs in Giraffatitan (Janensch, 1961) and
Lapparentosaurus (Upchurch, 1995), where the shaft
is directed strongly downwards. The distal ends of the
ischia are subtriangular in outline and form a V-shaped
arrangement in distal end view. Thus, Aragosaurus
retains the plesiomorphic state that occurs in basal
sauropods (e.g. Vulcanodon, Cooper, 1984;
‘Bothriospondylus madagascariensis’, Mannion, 2010)
and flagellicaudatans, rather than the derived copla-
Figure 15. Left femur (ZH-2) of Aragosaurus ischiaticus
in: A, posterior; B, medial; and C, anterior views. Features observed in the femur: D, lateral bulge; E, head deflected medially; and F, bevelling of the distal end of the
femur relative to the long axis of the shaft.
nar arrangement that occurs in Haplocanthosaurus,
rebbachisaurids, and most macronarians (Upchurch,
1998: fig. 16; Wilson & Sereno, 1998).
Femur
The left femur is complete (ZH-2; Fig. 15; Table 4). This
element displays most of the features that are typical
in sauropod femora, including a dorsomedially directed proximal articular head, absence of the lesser trochanter, a shaft that is straight in both lateral and
anterior views, and well-developed distal condyles
(McIntosh, 1990; Upchurch, 1995, 1998; Wilson, 2002;
Upchurch et al., 2004a, 2007). There is no ‘neck’ or constriction between the proximal articular head and the
greater trochanter. The articular surface of the greater
trochanter, at its lateral end, curves convexly onto a
posteriorly projecting, low, rounded bulge, forming a
trochanteric shelf. A similar morphology has been reported in several rebbachisaurids (Sereno et al., 2007)
and titanosaurs (Otero, 2010; Mannion et al., 2013).
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R. ROYO-TORRES ET AL.
In anterior view, the lateral margin of the proximal
end is deflected medially relative to that of the shaft,
with the long axis of the diaphysis deflected 6° from
vertical (Fig. 15), and just below the level of the greater
trochanter there is a lateral ‘bulge’. This combined morphology characterizes most macronarians, although the
medial deflection is lost in some derived titanosaurs
(Royo-Torres, 2009; Royo-Torres et al., 2012; Mannion
et al., 2013). This 6° angle also occurs in Tastavinsaurus
and Lourinhasaurus (Royo-Torres, 2009; Royo-Torres
et al., 2012), so these Iberian taxa might have an intermediate state, with a more derived state represented
by an angle of at least 10° in titanosaurs (Wilson &
Carrano, 1999; Wilson, 2002).
As in most other eusauropods, the fourth trochanter of Aragosaurus is a low rounded ridge that
is situated on the posteromedial margin of the shaft
at approximately midlength, and is not visible in anterior view. Just anterior to the fourth trochanter, there
is a shallow concavity on the medial surface of the
shaft. At midlength, the femoral shaft is strongly
compressed anteroposteriorly (transverse width/
anteroposterior width ratio = 1.96). Wilson & Carrano
(1999) noted that the femoral shafts of titanosaurs tend
to be more compressed anteroposteriorly than those
of other sauropods, and Wilson (2002) defined the
derived condition as a transverse width/anteroposterior
width ratio of greater than 1.85, although several more
basal taxa (e.g. Brachiosaurus, Giraffatitan, and
Ligabuesaurus) also possess the derived state (D’Emic,
2012; Mannion et al., 2013). The distal condyle for articulation with the fibula bears a well-developed vertical groove on its posterolateral margin, as occurs in
other sauropodomorphs and most other dinosaurs. The
intercondylar groove is well developed, especially on
the posterior surface of the femur. The distal articular surface curves up onto both the posterior and anterior faces of the condyles: the latter feature is a derived
condition that occurs in many titanosaurs (Wilson &
Carrano, 1999) and Diplodocus (Wilson, 2002).
Pedal phalanges
The pedal phalanx ZH-10 most closely resembles the
left pedal phalanges II-1 and III-1 of other sauropods,
although III-1 is usually slightly longer than wide
in dorsal view (Upchurch, 1993), and so we consider
ZH-10 to be phalanx II-1 (Fig. 16; Table 4). It is
subrectangular in dorsal view, with the medial distal
condyle projecting slightly further distally than the
lateral distal condyle (Sanz et al., 1987). This element
is unusual in that it possesses a subtriangular transverse cross section at its midlength, with a dorsally
directed apex, convex lateral and medial surfaces, and
a mildly concave ventral (plantar) surface. The presence of the midline dorsal apex is provisionally regarded as an autapomorphy of Aragosaurus.
Figure 16. Right pedal elements of Aragosaurus ischiaticus:
A, ungual phalanx II (ZH-19) in dorsal view; B, ungual
phalanx II (ZH-19) and proximal phalanx (ZH-10) in medial
views; C, ungual phalanx II in lateral view.
Pedal phalanx ZH-6 is only partially preserved and
yields little anatomical data. This element was described by Sanz et al. (1987) as a bone with numerous faces for articulation.
ZH-19 is a typical, recurved eusauropod ungual claw
that probably belongs to digit II of the right pes (Fig. 16;
Table 4). It is laterally compressed throughout its length,
as occurs in other eusauropods (Wilson & Sereno, 1998;
Upchurch et al., 2007; Yates, 2007). The proximal articular surface lies in a plane that is slightly oblique
to the long axis of the ungual, so that in life the
claw would have been directed forwards and slightly
laterally. In dorsal view, the ungual also curves slightly laterally towards its distal tip. The medial surface
of the ungual is more convex dorsoventrally than is
the lateral surface. The ventromedial margin, in its
distal part, is slightly bulbous but does not form the
tuberosities seen in many titanosauriforms (Mannion
et al., 2013), including Gobititan (IVPP 12579; P.U.
and P.D.M., pers. observ. 2007) and Tastavinsaurus
(MPZ 99/9; P.U. and P.D.M., pers. observ. 2009). The
ungual has a smooth lateral groove that is less deep
than in Tastavinsaurus. This feature has also been observed in a possible second ungual phalanx from Galve
(MPG CA-1). It is a part of historic material from
the Villar del Arzobispo Formation according to
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ARAGOSAURUS ISCHIATICUS
Sánchez-Hernández (2005), and this phalanx appears
in photographs of the elements of Aragosaurus taken
by J.L.S. in the 1980s. This second ungual element
could therefore be from Las Zabacheras, but it was never
mentioned in the lists of bones from this locality
(Lapparent, 1960; Sanz et al., 1987).
PHYLOGENETIC AFFINITIES
OF ARAGOSAURUS
Although Mannion et al. (2013) incorporated Aragosaurus
into a phylogenetic analysis focused on basal
macronarians, recovering it as a basal member of this
clade, outside Titanosauriformes, this study excluded
a number of other contemporaneous Iberian taxa (i.e.
Losillasaurus, Lourinhasaurus, and Turiasaurus) that
might have some bearing on its relationships. In order
to further understand the phylogenetic position and
relationships of Aragosaurus with regard to other Iberian
taxa, we have used the updated matrices of Wilson (2002)
and Upchurch et al. (2004a), following Wilson & Upchurch
(2009), Royo-Torres et al. (2012), and Royo-Torres &
Upchurch (2012). In the case of the Upchurch et al.
(2004a) data matrix, Lapparentosaurus, Nigersaurus,
‘Pleurocoelus-tex’ (a chimera comprising material now
referred to Astrophocaudia, Cedarosaurus, and
Sauroposeidon; D’Emic & Foreman, 2012; D’Emic, 2013),
Andesaurus, and Argentinosaurus were omitted a priori.
For each data matrix, we have: (1) split the Brachiosaurus operational taxonomic unit (OTU) into Brachiosaurus altithorax and Giraffatitan brancai, following
Taylor (2009); and (2) added in or revised scores for
Cedarosaurus (based on Tidwell, Carpenter & Brooks,
1999 and D’Emic, 2012; Wilson matrix only),
Europasaurus (based on Sander et al., 2006),
Lourinhasaurus (based on Mocho et al., 2014),
Tehuelchesaurus (based on Carballido et al., 2011b), and
Venenosaurus (based on Tidwell et al., 2001; D’Emic,
2012). These new codings are provided in the Appendix. Data matrices were analysed using TNT 1.1 (Goloboff,
Farris & Nixon, 2003) in order to find the most parsimonious trees (MPTs). We implemented a heuristic
tree search, performing 1000 replications of Wagner
trees (using random addition sequences) followed by
tree bisection reconnection (TBR) as the swapping algorithm, saving 100 trees per replicate. In order to test
the support of the phylogenies, the Bremer support and
the bootstrap values were obtained (absolute frequencies based on 5000 replicates; Figs 17 and 18).
RESULTS
WILSON 2002 DATA SET
As in the original analysis, the multistate characters 8, 37, 64, 66, and 198 were ordered. This analy-
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sis includes 41 taxa and 234 morphological characters.
Analysis with TNT produces 66 MPTs with a length
of 534 steps (consistency index, CI = 0.538; homplasy
index, HI = 0.463; retention index, RI = 0.735). The strict
consensus tree places Aragosaurus in a polytomy with
Camarasaurus, Lourinhasaurus, Tehuelchesaurus,
Europasaurus, and the Titanosauriformes (Fig. 17). The
general topology obtained is similar to the proposal of
Royo-Torres et al. (2012) and Royo-Torres & Upchurch
(2012), and generally resembles the topology found
by Wilson (2002). Aragosaurus is retained inside
Macronaria but outside Titanosauriformes.
UPCHURCH
ET AL.
2004A DATA SET
This analysis includes 49 taxa and 309 morphological characters. The result of the parsimony analysis
yielded 18 MPTs with 703 steps (CI = 0.455; HI = 0.545;
RI = 0.765). The strict consensus closely matches the
main topology obtained in recent publications (e.g.
Wilson & Upchurch, 2009; Royo-Torres & Upchurch,
2012; Royo-Torres et al., 2012). Aragosaurus is placed
as a macronarian lying outside Camarasauromorpha,
as the sister taxon to Europasaurus + Titanosauriformes
(Fig. 18).
DISCUSSION
THE
PHYLOGENETIC POSITION OF
ARAGOSAURUS
Aragosaurus possesses a suite of characters supporting its inclusion in Macronaria: (1) anterior caudal chevrons with open proximal articulations (Upchurch, 1995;
Wilson & Sereno, 1998); (2) ischial distal shafts nearly
coplanar (Wilson & Sereno, 1998) (although note that
features 1 and 2 are both present in basal diplodocoids
such as Haplocanthosaurus and rebbachisaurids, and
thus it is equally parsimonious to conclude that these
two features are neosauropod synapomorphies that were
reversed in flagellicaudatans); (3) length of longest metacarpal at least 45% of radius length (Salgado et al.,
1997; Wilson & Sereno, 1998; Wilson, 2002); and (4)
puboischial contact dorsoventrally deep (Salgado et al.,
1997; Wilson & Sereno, 1998). Aragosaurus also possesses an ischium with a dorsoventrally long pubic
peduncle, similar to Camarasaurus and basal
Titanosauriformes (Salgado et al., 1997; Wilson & Sereno,
1998; Wilson, 2002). Aragosaurus also displays several
characters that have traditionally been optimized
as supporting a more derived placement, within
Titanosauriformes. For example, the proximal onethird of the femur of Aragosaurus is deflected medially (Wilson & Sereno, 1998), and there is a lateral
bulge (Salgado et al., 1997). According to the phylogenetic
results presented here, and in D’Emic (2012) and
Mannion et al. (2013), these features have a wider
distribution within Macronaria. Other characters
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646
R. ROYO-TORRES ET AL.
Figure 17. The strict consensus tree produced by phylogenetic analysis of the updated Wilson (2002) data set. Bootstrap values are shown as percentages (nodes lacking percentages have bootstrap values of less than 50%). Bremer supports are shown in square brackets.
previously suggested as synapomorphic of Titanosauriformes, but developed in Aragosaurus, include a ridge
on middle caudal centra, anterior (although not the
middle) caudal vertebrae with neural arches set on the
anterior half of the centrum (Salgado et al., 1997), and
an ischium with a raised tubercle on the dorsolateral
face (Wilson, 2002; D’Emic, 2012). In contrast,
Aragosaurus lacks a number of features proposed to
characterize Titanosauriformes, including: (1) the presence of small, vascular foramina piercing the lateral
or ventral surfaces of anterior–middle caudal centra
(Mannion et al., 2013); (2) a scapula with a tubercle
on the ventral margin of the base of the scapular blade;
(3) a humerus/femur length ratio greater than 85%;
(4) a long anteromedial process of the ulna; and (5) a
distally expanded ulna (Wilson, 2002; D’Emic, 2012).
Royo-Torres (2009) proposed Laurasiformes as a clade
comprising three taxa, Cedarosaurus, Tastavinsaurus,
and Venenosaurus, and was supported in Royo-Torres
et al. (2012), using the Wilson (2002) and Upchurch
et al. (2004a) data matrices. This clade was not supported by recent phylogenetic analyses focusing on
titanosauriform interrelationships, however (D’Emic,
2012; Mannion et al., 2013). According to the current
study, Aragosaurus shares some features previously
considered synapomorphies for Laurasiformes: (1) a
well-marked ridge on the lateral face of the neural
arch of middle–posterior caudal vertebrae; (2) the
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ARAGOSAURUS ISCHIATICUS
647
Figure 18. The strict consensus tree produced by phylogenetic analysis of the updated Upchurch et al. (2004a) data set.
Bootstrap values are shown as percentages (nodes lacking percentages have bootstrap values of less than 50%). Bremer
supports are shown in square brackets.
morphology of the articular surfaces of the centra of
anterior caudal vertebrae (except the first), in which
the anterior face is concave and the posterior face is
nearly flat or slightly convex. The latter state is difficult to distinguish from the amphiplatyan condition
of Eusauropoda (Wilson, 2002; Upchurch et al., 2004a;
D’Emic, 2012), and the basal titanosaur Andesaurus
also shares this morphology (Mannion & Calvo, 2011);
as such, it is not unique to any potential clustering
of laurasiaform taxa. Another putative Laurasiformes
feature, the femoral diaphysis slanted at an angle of
6° to the vertical, is also present in most macronarians
more derived than Camarasaurus (D’Emic, 2012;
Royo-Torres et al., 2012; Mannion et al., 2013). Two features proposed as Laurasiformes synapomorphies – the
presence of mild opisthocoely in the anteriormost
caudal centra, and anteriorly deflected anterior–
middle caudal neural spines (Royo-Torres, 2009;
Royo-Torres et al., 2012) – are absent in Aragosaurus.
The latter character state is present in the three genera
originally proposed as members of Laurasiformes (i.e.
Venenosaurus, Cedarosaurus, and Tastavinsaurus).
D’Emic (2012) did not support the monophyly of
Laurasiformes, but some of the character state scores
for Tastavinsaurus require revision. For example,
Tastavinsaurus shares with Cedarosaurus and
Venenosaurus the following derived character states in
the analysis of D’Emic (2012): (1) anterior caudal vertebrae with sporadically distributed, shallow fossae
on the lateral faces of the centrum; (2) middle caudal
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648
R. ROYO-TORRES ET AL.
vertebrae with neural spines that lean anteriorly; and
(3) metatarsal IV with distal end bevelled upwards
medially.
Finally, Aragosaurus is unlikely to be a
somphospondylan sauropod because it lacks the medial
deflection of the scapular glenoid (Wilson & Sereno,
1998), the humerus has a rounded rather than ‘squared’
proximolateral corner (Wilson, 2002), and the posterior articular surfaces of middle–posterior caudal centra
are flat rather than convex (Mannion et al., 2013).
In summary, Aragosaurus is a basal macronarian with
some, but not all, of the character states that diagnose the Titanosauriformes. Therefore, as proposed by
the cladistic analyses of Royo-Torres (2009), Mannion
et al. (2013), and this article, Aragosaurus ischiaticus
is a basal macronarian that is more closely related to
Titanosauriformes than is Camarasaurus.
TAXONOMIC
STATUS OF
ARAGOSAURUS
6.
7.
8.
AND
COMPARISON WITH CONTEMPORANEOUS
IBERIAN SAUROPODS
The autapomorphies originally listed by Sanz et al.
(1987) to diagnose Aragosaurus have since been demonstrated to have a wider distribution amongst
Sauropoda, and are summarized here.
1. Great widening of the neural spines of the
anteriormost caudal vertebrae. This character state
is shared with Losillasaurus, Camarasaurus,
Tastavinsaurus, Venenosaurus, and a caudal series
from Tendaguru (MBR 2091.1-30) originally referred to Janenschia (although see Bonaparte,
Heinrich & Wild, 2000), but more recently suggested to have turiasaur (Royo-Torres & Cobos,
2009) or mamenchisaurid (Mannion et al., 2013)
affinities.
2. Medium development of the distal expansion of the
scapular blade. This is similar to the condition in
Camarasaurus (Ostrom & McIntosh, 1966) and
Lourinhasaurus (Mocho et al., 2014), as well as many
other sauropods (e.g. Mannion et al., 2013).
3. Great dorsoventral development of the acromion–
glenoid region of the scapula (the ratio of the
minimum width of the blade to the acromion–
glenoid width is 0.27). This feature is present in
Omeisaurus and other neosauropods, whereby the
acromion process is more than 150% the minimum
width of the scapular blade (Upchurch et al., 2004a).
4. Iliac peduncle of the ischium is well developed. This
character is defined in vague terms, but similar proportions seem to occur in other sauropods, such as
Haplocanthosaurus and Lourinhasaurus (Royo-Torres,
2009).
5. Large pubic process of the ischium (ratio of the
length of this process to the length of the ischium
9.
is 0.63). A large pubic process is shared with
basal titanosauriforms such as Andesaurus,
Tangvayosaurus, Venenosaurus, and Tastavinsaurus
(Royo-Torres, 2009).
Ischial distal shaft terminates in a conspicuous
expansion. This feature can also be observed in
Lourinhasaurus and several other sauropods
(McIntosh, 1990; Upchurch et al., 2004a).
Humerus/femur length ratio is relatively high (0.82).
The value of this ratio in Aragosaurus is higher than
that in Camarasaurus grandis or C. lentus, but is
similar to other basal macronarians such as
Lourinhasaurus (McIntosh, 1990; P.U. and P.D.M.,
pers. observ. 2009).
The presence of a relative prominence, located distally to the large femoral trochanter. This character state is the lateral bulge originally noted by
Salgado et al. (1997) as a synapomorphy of
Titanosauriformes, but considered to be present in
most eusauropods by Mannion et al. (2013). The associated medial deflection of the proximal part of
the femur (Wilson, 2002) characterizes most
macronarians (Royo-Torres et al., 2012; Mannion
et al., 2013). Following Salgado et al.’s (1997) method
for quantifying the size of the lateral bulge,
Aragosaurus has an intermediate value between
basal macronarians (such as Camarasaurus and
Lourinhasaurus, with small lateral bulges) and
Titanosauriformes.
The ratio of the maximum anteroposterior width
of the distal tibial condyle of the femur to the transverse width of the distal end of the femur is 0.77.
Similar ratios occur in other neosauropods, such as
Ferganasaurus (0.78) and Apatosaurus (0.79)
(Royo-Torres, 2009).
Thus, none of the nine diagnostic character states
of Aragosaurus, proposed by Sanz et al. (1987), provides strong evidence for the uniqueness of this taxon;
however, we have been able to recognize six new
autapomorphies of Aragosaurus (see ‘Diagnosis’ and
‘Description and comparisons’ above), supporting the
validity of this genus.
Comparisons between Aragosaurus and other contemporaneous Iberian taxa, such as Lourinhasaurus,
Galveosaurus, Losillasaurus, and Turiasaurus, reveal
numerous differences, some of which have been noted
in the ‘Description and comparisons’ section. In general,
the forelimb proportions of Aragosaurus differ from those
of other Iberian taxa (see above). Aragosaurus differs
from Turiasaurus because the latter possesses
opisthocoelous distal caudals and a distal process on
the carpal. Aragosaurus also differs from Losillasaurus
in the articulation of the proximal caudal vertebrae
(procoelous in the latter taxon) and in the strong development of the distal part of the neural spines.
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655
ARAGOSAURUS ISCHIATICUS
Aragosaurus is different from Galveosaurus in the
shapes of the humerus and ischia, and the latter taxon
has a smooth acromion ridge, whereas in Aragosaurus
this ridge is prominently developed. Aragosaurus is distinct from Lourinhasaurus in that Lourinhasaurus possesses hooked-like processes emanating from the dorsal
surface of the most anterior caudal neural spines. The
femoral lateral bulge is also much more developed in
Aragosaurus than in Lourinhasaurus, and the latter
has a ridge and groove structure in the acetabular region
of the ischium.
Aragosaurus can also be distinguished from other,
non-contemporaneous Iberian taxa. For example,
Tastavinsaurus has anterodorsally oriented anterior and
middle caudal neural spines and a relatively short
ischium compared with pubis length (Canudo et al.,
2008; Royo-Torres, 2009). The rebbachisaurid
Demandasaurus is very different from Aragosaurus
(e.g. the latter lacks the diagnostic characters of
Demandasaurus in the anterior caudal vertebrae,
such as deep pneumatic cavities in the caudal ribs
and the development of complex laminae; Torcida
Fernández-Baldor et al., 2011).
These data corroborate the hypothesis, suggested in
previous studies, that basal macronarian sauropods were
present in the Villar del Arzobispo Formation in the
Iberian Peninsula at the end of the Jurassic (Royo-Torres
et al., 2009). This stratigraphic unit is important for
the study of sauropods across the Jurassic/Cretaceous
boundary, and for examining palaeobiogeographic
patterns in Europe at this time. As well as basal
macronarians, the Villar del Arzobispo Formation preserves turiasaurs (Royo-Torres et al., 2006), diplodocids
(Cuenca-Bescós, Canudo & Ruiz-Omeñaca, 1997;
Royo-Torres, Cobos & Alcalá, 2006; Royo-Torres et al.,
2009), and basal titanosauriforms (Suñer et al., 2009),
including the tooth previously referred to Aragosaurus.
Thus, the diversity of this formation is similar to those
of the Morrison Formation in North America and the
Tendaguru Formation of Tanzania. Once these various
Iberian taxa have been studied more fully and integrated into phylogenetic analyses, they should make
a substantial impact on our knowledge of Late Jurassic sauropod biodiversity and biogeography.
CONCLUSIONS
The complicated collection history of Aragosaurus, spanning more than 50 years, has resulted in a holotype
split between two institutions [the Museo Provincial
de Teruel (Dinopolis Exhibition) and the Museo
Paleontológico de Galve]. The Las Zabacheras site represents a deltaic sedimentary complex in the Villar del
Arzobispo Formation. Consequently, the age of this site
can be constrained to the Tithonian–Berriasian interval, with the latter stratigraphic stage being the most
649
likely. Aragosaurus ischiaticus, erected in 1987, is a
valid taxon based on the recognition of six new
autapomorphies: (1) anterior caudal vertebrae possess
neural spine summits with shallow, dorsolaterally facing
concavities on either side of the midline; (2) epipophysislike protuberances on the dorsal surfaces of middle
caudal postzygapophyses; (3) long interosseous ridges
on the ulna and radius; (4) the interosseous ridge on
the posterolateral face of the radial shaft terminates
distally in a distinct tubercle; (5) carpal subquadrangular
in shape in proximal and distal views, with similar
lateromedial and anteroposterior diameters; and (6) a
pedal phalanx (II-1 or III-1) that possesses a midline
ridge on its dorsal surface, where its lateral and medial
faces meet each other to form an apex. Aragosaurus
shares some, but not all, of the derived character states
that have been considered to characterize the
Titanosauriformes. Therefore, as supported by cladistic
analyses, Aragosaurus ischiaticus is a basal macronarian
that is more closely related to Titanosauriformes than
is Camarasaurus.
ACKNOWLEDGEMENTS
This study is part of the palaeontological research
projects of the Departamento de Educación, Universidad,
Cultura y Deporte, Gobierno de Aragón, and has been
supported by its Dirección General de Patrimonio Cultural, FOCONTUR (Grupo de Investigación Consolidado
E-62, Departamento de Industria e Innovación, Gobierno
de Aragón and Fondo Social Europeo), Instituto Aragonés
de Fomento, Fundación Conjunto Paleontológico de
Teruel-Dinópolis, and SIBELCO Hispania S.A. Collection visits to institutions in Spain by P.U. and P.D.M.
were supported by research grants awarded by The
Palaeontological Association and the Abbey International Collaboration Scheme. P.D.M.’s research is also
funded by an Imperial College London Junior Research Fellowship. R.M. thanks the CGL2011-22709
project from the Ministerio de Ciencia y Educación.
F.G. is the holder of a grant FPU (Formación de
Profesorado Universitario) from the Ministerio de
Educación (Ref. AP2008-00846). We thank the Museo
Aragonés de Paleontología, Museo Provincial de Teruel,
and the late José María Herrero (Galve) for allowing
us to study the material in their care. The photographs used in this work are from «Archivo López
Segura del Instituto de Estudios Turolenses», Museo
Provincial de Teruel, and José Luis Sanz’s team. We
are grateful to Mike D’Emic and an anonymous reviewer, whose critical reviews improved this article.
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MODIFICATIONS
TO
APPENDIX
THE WILSON (2002)
DATA MATRIX
Brachiosaurus is divided into two OTUs, Brachiosaurus altithorax and Giraffatitan brancai, after Taylor
(2009).
Brachiosaurus altithorax (Upchurch et al., 2004a;
Taylor, 2009)
W98 (from 1 to ?), W107 (we retain 0 rather than 1,
as proposed by Taylor, 2009), W130 (we retain state 0
and not the ?, as proposed by Taylor, 2009), W198 (from
1 to 2), W200 (from 1 to 0).
???????????????????????????????????????????????????????????
?????????????????1??????????????101011?111100100211010??
??000001100100000????????11??????1?????000?010101?????
??????????????11101???????1121000??????????????????????????
?????0
Giraffatitan brancai (Upchurch et al., 2004a;
Taylor, 2009)
W98 [we retain state 1 and not ?, as proposed by Taylor
(2009), because the character state is present, see
Janensch, (1950: 46, fig. 63)], W101 (we retain state 1
and not 0, as proposed by Taylor, 2009), W107 (we retain
state 0 and not 1, as proposed by Taylor, 2009), W130
(we retain state 0 and not ?, as proposed by Taylor,
2009), W146 [from 0 (Wilson, 2002; Taylor, 2009) to
1, based on Janensch (1950), Upchurch et al. (2004a),
and Royo-Torres (2009)],W198 (from 1 to 2), W200 [we
retain state 1 (Wilson, 2002) and not 0, as proposed
by Taylor (2009)].
111100111111000101011000010111111100101111000000
01100110011111121110011210001103011001100931010111
111100100211010?100000001100100000000???1011??11??1
10101000001010111101002111111111011110101110111121
100110111111110011110111?11?1??11?0
Cedarosaurus weiskopfae (Tidwell et al., 1999;
D’Emic, 2012)
?????????????????????????????????????????????????????????????
???????????????11??????????????01011010???010??????0?1?00
0000010110??10100??????10?11??11?10100001101?1110?10
02??1?1??????????????10?????1????1?????????????1?11????1?1
0111?0
Europasaurus holgeri (Sander et al., 2006)
1111?01111?1001101?01?10010111011100101???100000011
0011001111?1?1110?11110?101??0110000000?10101101111
00100210?001?000000011001000000000??11000910?0110
10000000101011110100???11??????111101?1110111110100
110111011110?11?1???1??1?1??11??
Lourinhasaurus alenquerensis (Mocho et al., 2014)
?????????????????????????????????????????????????????????????
???????????????01??011??0??1??1?1?110???1??1??2???10????0
0?001001100?00????????01??????1101010000010101111010
01?1??????????110001?101111101001101?1011?10??????????
?????????0
Tastavinsaurus sanzi (Canudo et al., 2008;
Royo-Torres et al., 2012)
?????????????????????????????????????????????????????????????
???????????????11?????????????10?0110110110100211010?12
0000000001101000100?????1?0911111???????????????????10
1????????????111010111011111110011111101?100011111110
11111001110
Tehuelchesaurus benitezii (Carballido et al., 2011b)
?????????????????????????????????????????????????????????????
???????????????01?????????????001?100101010100?1????????
???????????????????????01??????110001001?0101011110100?
????????????1???01110111110000????????????????????????????
????
Venenosaurus dicrocei (Tidwell et al., 2001; D’Emic,
2012; Royo-Torres et al., 2012)
?????????????????????????????????????????????????????????????
????????????????1???????????????????????????????????1?2000?
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655
ARAGOSAURUS ISCHIATICUS
000101101010000?????1???11??111001??????????1100100??
?111111????????0111011??????????????????????1101??1??????
???0
Aragosaurus ischiaticus
?????????????????????????????????????????????????????????????
??????????????????????????????????????????????????????????0??
??000000001100000000???????10110?110101?00?01010111
101001?1111?00????????01?1?111111100????????????????????
?????1???1?0
MODIFICATIONS
TO THE
UPCHURCH
ET AL.
(2004A)
655
0000111110221110110010111002111011100110000010001
011011101101111011001100[01]0000100000011010010011
1100011100011002000111010000100111001011111111010
1111110111000011111111111111011111111011111101111101
111??010111111
Europasaurus hogeri (Sander et al., 2006)
110011011110??111111?010100110??0?10110?0?00000?00?
0?00011001100111010011?1111?1011110010??1110????0?0
11110022??00110010?????0111101???1?0??10110010111010
011?1011011001??000000????00001?100100111100011?0??
111?20?????011???000????????111?????10111111???10?011??
11110101111?10111?1101111???1??1???????????????1?
DATA MATRIX
Brachiosaurus is divided into two OTUs, Brachiosaurus altithorax and Giraffatitan brancai, after Taylor
(2009).
Brachiosaurus altithorax (Upchurch et al., 2004a;
Taylor, 2009)
U126 (we retain state 0–2 and not ?, as proposed by
Taylor, 2009), U127 (from 1 to ?), U131 (from 1 to 0),
U135 (from 1 to 0), U137 (from 1 to ?), U149 (from 1
to 0), U152 (from 0 to 1), U155 (we retain state 0 and
not 1, as proposed by Taylor, 2009), U157 (from 0 to
1), U172 (from 1 to 0), U208 (from 1 to 0), U249 (from
1 to 0), U271 (from 1 to 0).
???????????????????????????????????????????????????????????
?????????????????????????????????????????????1???????????????
???????110011001?000?0100010010111011011110110011??
0????1???000?10101?001?????????????1002000111010000???
????????????????10111110???????????111111111100??????????
??????????????????????????1
Giraffatitan brancai (Upchurch et al., 2004a;
Taylor, 2009)
U124 (from ? to 0, because G. brancai has 12 dorsal
vertebrae), U126 (we retain states 0–2 and not ?, as
proposed by Taylor, 2009), U127 [we retain state 1
(Upchurch et al., 2004a) and not 0, as proposed by Taylor
(2009)], U135 (from 1 to 0), U140 (from 0 to 1), U141
(from ? to 0), U152 (from 0 to 1), U157 (from 0 to 1),
U172 (scored as 0&1), U187 (we retain state 1 and not
0, as proposed by Taylor, 2009), U208 (from 1 to 0),
U267 (from 1 to 0), U271 [we retain state 1 (Upchurch
et al., 2004a) and not 0, as proposed by Taylor (2009)].
110011011110001111111011100111110110110100001001
000100001100100111101011111111111001111000110101?0
Lourinhasaurus alenquerensis (Mocho et al., 2014)
?????????????????????????????????????????????????????????????
????????????????????????????????????????011111??2????11????
???00011100?1?110?????????1?0???1??????0110?1001???000
??1???010???1001?0?1?????1110??111?00001100010001001
1??0???????????10001111011?0000101111101111110111111?
101?1111?????????????????????0
Tastavinsaurus sanzi (Canudo et al., 2008;
Royo-Torres et al., 2012) – three characters have been
changed: U105 (from? to 1), U142 (from 0 to 1), U249
(from 0 to 1)
?????????????????????????????????????????????????????????????
???????????????????????????????????????????1?????????????????
???0?110111?01011?2111011000010001??01110010011?011
000100?0011111011001111101??????????????1??????????01??
?????????????1011111100100010101111101011110111101110
111110?11111001101?010111011
Tehuelchesaurus benitezii (Carballido et al., 2011b;
Mocho et al., 2014)
?????????????????????????????????????????????????????????????
??????????????????????????????????????????11?????????????????
???01110011??1000??11?01?00000000110?01???1???????????
???????????????????????111???011???????00010001011???????
????????????????01110000101111101111100?????????????????
???????????????????0
Aragosaurus ischiaticus
?????????????????????????????????????????????????????????????
?????????????????????????????????????????????????????????????
???????????????????????????????????????????00???00000?1000
000000?01100?111000111000????????1?000100010011??0?0
1?11?????????????011?000010?111111111110????????????????
???????????????????1?
© 2014 The Linnean Society of London, Zoological Journal of the Linnean Society, 2014, 171, 623–655