Cretaceous Research 44 (2013) 64e82
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Cretaceous Research
journal homepage: www.elsevier.com/locate/CretRes
The turtles from the uppermost Jurassic and Early Cretaceous
of Galve (Iberian Range, Spain): Anatomical, systematic,
biostratigraphic and palaeobiogeographical implications
A. Pérez-García a, *, T.M. Scheyer b, X. Murelaga c
a
Departamento de Paleontología, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, C/José Antonio Novais, 2. 28040
Ciudad Universitaria, Madrid, Spain
Paläontologisches Institut und Museum, Universität Zürich, Karl-Schmid-Strasse 4, CH-8006 Zürich, Switzerland
c
Departamento de Estratigrafía y Paleontología, Facultad de Ciencia y Tecnología, Universidad del País Vasco, UPV/EHU, Apartado 644,
48080 Bilbao, Spain
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 29 November 2012
Accepted in revised form 29 March 2013
Available online 6 May 2013
The faunal associations of the uppermost Jurassic and Early Cretaceous Villar del Arzobispo, El Castellar,
and Camarillas formations of the Spanish town of Galve (Maestrazgo Basin of the Iberian Range) are
composed of more than fifty taxa belonging to Chondrichthyes, bony fishes, lissamphibians, mammals,
and reptiles. Although the presence of turtles has been recognized in these three formations, being very
abundant, the published information is limited. The detailed study of these turtles allows us to recognize
at least nine taxa, several of them previously not identified in the Spanish record. These taxa correspond
to stem Testudines (Solemydidae), members of Paracryptodira (Pleurosternidae), several representatives
of Plesiochelyidae and taxa closely related with this clade, representatives of the stem group of Cryptodira (Xinjiangchelyidae) and members of crown Cryptodira. The chelonian fauna of Galve increases the
systematic, anatomical, biostratigraphic, and paleobiogeographic knowledge on several clades, represented by taxa shared with other European regions, clades also present in Early Cretaceous sites of North
America or Asia, as well as taxa exclusive of the Iberian record.
Ó 2013 Elsevier Ltd. All rights reserved.
Keywords:
Galve
Stem Testudines
Paracryptodira
Plesiochelyidae
Xinjiangchelyidae
Cryptodira
1. Introduction
Galve (Maestrazgo Basin of the Iberian Range, Teruel Province, NE Spain) is a town where abundant and diverse uppermost Jurassic and, especially, Early Cretaceous vertebrate
associations have been found. Since the 1950s, more than fifty
taxa belonging to Chondrichthyes, bony fishes, lissamphibians,
mammals, and reptiles have been recognized in the discontinuous sedimentary succession, including marginal marine and
continental deposits, recorded in the syncline of Galve. Reptiles
are represented by turtles, squamates, crocodyliforms, pterosaurs, and dinosaurs (see Ruiz-Omeñaca et al., 2004; SánchezHernández et al., 2007). In contrast to the currently available
knowledge on most of these groups, turtles have received little
attention. However, recent studies have allowed us to observe
that the diversity of turtles from the Early Cretaceous of the
Iberian Peninsula was very high, higher than that hitherto
* Corresponding author.
E-mail address: [email protected] (A. Pérez-García).
0195-6671/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.cretres.2013.03.011
known in other European countries (Pérez-García and Murelaga,
2012a,b; Pérez-García et al., 2012, 2013).
The material of turtles from Galve is very abundant. It comes
from three formations: Villar del Arzobispo (late Tithoniane
upper part of the early Berriasian), El Castellar (Valanginian?e
early Barremian), and Camarillas (early Barremian) (Díaz-Molina
and Yébenes 1987; Ruiz-Omeñaca et al. 2004; SánchezHernández et al. 2007; Canudo et al., 2011). SánchezHernández et al. (2007) identified three undetermined turtle
taxa. A preliminary review of these specimens detected four
forms (Pérez-García et al., 2010a), of which only one has been
described. It has been assigned to a new taxon, Galvechelone
lopezmartinezae Pérez-García and Murelaga, 2012a. Therefore,
most of the material of turtles from Galve was, so far, unpublished and, with the exception of Galvechelone lopezmartinezae,
the precise taxonomic position of the other taxa recovered from
there has not been analyzed.
The material of turtles from Galve is analyzed in this paper.
We recognize the presence of at least nine taxa. The study of
material of turtles from the same locality, from different levels,
allows us to analyze changes in the taxonomic composition of
this group of reptiles (Fig. 1). Thus, the fauna of turtles
A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
65
Fig. 1. A, Geographical location of the fossil area of Galve (Teruel, Spain), modified from Pérez-García and Murelaga (2012a). B, Location, on a stratigraphic column modified of DíazMolina and Yébenes (1987), of the sites of Galve where the turtles studied in this paper have been found. C, Known stratigraphic distribution of the clades of turtles identified in
Galve both in the European Mesozoic record (in black) and, specifically, in the Iberian Mesozoic record (in grey).
recognized in Early Cretaceous levels is composed of clades
that differ from those recognized in the Jurassic outcrops of
Galve. The fauna of turtles recognized in this town is composed
of stem Testudines (Solemydidae), members of Paracryptodira
(Pleurosternidae), several representatives of Plesiochelyidae and
taxa closely related with this clade, representatives of the stem
group of Cryptodira (Xinjiangchelyidae) and members of the
crown Cryptodira. These turtles correspond to members of
several clades distributed in both European Late Jurassic and
Early Cretaceous levels, but also in the synchronous North
American record, due to they were present in both regions
before the opening of the Atlantic ocean (Solemydidae, Pleurosternidae); forms exclusive of the European Jurassic record
(Plesiochelyidae and related forms); and groups originated in
Asia, which probably arrived in Europe during the Early
Cretaceous (Xinjiangchelyidae and members of the clade of
Cryptodira that includes taxa such as the representatives of
“Macrobaenidae” and “Sinemydidae”).
This study also allows us to identify taxa hitherto unrecognized
in the Iberian record, and to improve the knowledge on the anatomy and systematics of some poorly known taxa, expanding their
geographic and stratigraphic distributions. Additionally, shell bone
histology of several turtle taxa recognized in Galve is surveyed,
revealing that all of them show histological peculiarities, which
may help to improve the diagnosis of some of them. The shell bone
microstructures were found to be indicative of a potential lifestyle
of several of the taxa recognized, corresponding to terrestrial,
freshwater and coastal marine forms.
These systematic and histological studies allow us to expand our
knowledge of the turtle fauna from the uppermost Jurassic and
Early Cretaceous of the Iberian Peninsula, and to establish a comparison with the synchronous faunas identified in other European
countries and in other continents.
Institutional abbreviations. MPG, Museo Paleontológico de Galve,
Galve, Teruel, Spain. UPUAM, Unidad de Paleontología, Universidad
Autónoma de Madrid, Madrid, Spain.
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Fig. 2. Shell elements, in dorsal and anterior views, corresponding to Plesiochelyidae and to other taxa closely related with that clade, from several outcrops of the of Villar del
Arzobispo formation, in the town of Galve. AeB, MPG-374, shell of Tropidemys sp., from Cuesta Lonsal. CeP, MPG-730-1 to 14, elements of the carapace of one or more individuals of
Plesiochelys sp., from an outcrop near Las Cerradicas. QeR, MPG-730-15 and MPG-730-16, elements of the plastron which could correspond to the specimen of Plesiochelys sp. to
A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
2. Systematic paleontology
2. 1. Plesiochelyidae and aff. Plesiochelyidae
Testudinata Klein, 1760
Testudines Batsch, 1788
Pan-Cryptodira Joyce, Parham and Gauthier, 2004
Plesiochelyidae Baur, 1888
Tropidemys Rütimeyer, 1873
Tropidemys sp.
Fig. 2AeB
Material. MPG-374, some articulated plates of a partial shell in which
the third, fourth and sixth complete neurals, the first, second and fifth
partial neurals, the posterolateral region of the nuchal plate, the first
two right peripherals, the partial first to fifth left costals, and the
partial first, third, fifth and sixth right costals are identified.
Locality and horizon. Cuesta Lonsal site, Galve. Villar del Arzobispo
Formation.
Description. The specimen MPG-374 is superficially altered. Therefore, the boundaries between the scutes cannot be recognized. The
length of the preserved fragment exceeds 30 cm (Fig. 2A). The
plates are thick. This specimen has a shallow notched nuchal
(Fig. 2B). The morphology of the nuchal plate cannot be described
because of its poor preservation. The anterior margin of the first
neural is convex. The second to sixth neurals are hexagonal. The
latero-anterior margins are almost as long as the latero-posterior
ones. These plates are relatively wide, with the width of the third
one being nearly equal to its length. The first pair of costals is longer
than the second one. This specimen has a sagittal keel (Fig. 2B),
with a rounded apex. The angle between the two planes of the
sagittal keel is approximately 100 .
Plesiochelys Rütimeyer, 1873
Plesiochelys sp.
Fig. 2CeR, TeV
Material. Several plates, most of them disjointed, corresponding to
elements of the carapace and plastron. Several of them were found
together, which may correspond to a single, probably adult individual
(Fig. 2CeR). These elements include the nuchal plate, several costals,
three neurals, several anterior, middle and posterior peripherals, a
fragment of the posterior suprapygal, much of the anterior plastral
lobe, and the right hypoplastron and xiphiplastron. Other elements,
corresponding to other individuals, includes both articulated regions
of carapaces (Fig. 2TeU), and disarticulated plates (Fig. 2V).
Locality and horizon. Outcrops very close to Las Cerradicas (Galve)
and stratigraphically equivalent. Villar del Arzobispo Formation.
Description. This taxon lacks a sagittal keel. The nuchal plate MPG730-1 (Fig. 2C) presents a shallow notch, restricted to this plate. Its
lateral margins are straight and slightly convergent anteriorly. The
preserved neural plates, hexagonal in morphology, are more than
twice as long than wide (Fig. 2IeK). Its latero-anterior margins are
noticeably shorter than the latero-posterior ones. The pygal plate is
67
shorter than the plates of the last pair of peripherals. This taxon has
at least two suprapygal plates. Both plates are wider than long, the
first being wider than the second, but both having a similar length
(Fig. 2PeT). The depressions observed on the nuchal plate indicate
the presence of three cervical scutes (Fig. 2C). All of them are situated on the antero-medial area of that plate. The vertebral scutes
are relatively wide and overlap more than half of the width of the
costal plates (Fig. 2CeO, UeV). The limit between the third and
fourth vertebrals is medially situated on the posterior region of the
fifth neural (Fig. 2K). The preserved marginal scutes do not overlap
on the costal plates. However, the last pair of marginals overlaps the
posterior region of the second suprapygal (Fig. 2P, T). The plastral
lobes are elongated and narrow (Fig. 2QeR). The anterior plastral
margin is rounded. The epiplastra are wider than they are long.
Their contacts with the hyoplastra are perpendicular to the axial
plane. The entoplastron is elongated. Its morphology is subrhombic, with sinuous latero-posterior margins. They are considerably longer than the latero-anterior margins (Fig. 2Q). The
thickness of the antero-medial area of the hypoplastron is thinned
in comparison with the rest of the plate due to the possible presence of a small notch in the centre of the plastron. The contact line
between the hypoplastra and the xiphiplastra zigzags slightly
because laterally the hypoplastra protrude farther into the xiphiplastra. This taxon lacks an anal notch (Fig. 2R). A pair of intergular
scutes is present. This pair of scutes overlaps the anterior region of
the entoplastron. The area occupied by the intergular scutes is
similar to that occupied by the gulars. The gulars are restricted to
the epiplastra. The humeral-pectoral sulcus is placed in a position
significantly posterior to that of the entoplastron (Fig. 2Q). The
presence of inframarginal scutes is recognized. Due to the preservation and the absence of hyoplastra, the number of these scutes is
not known. The sulcus between the abdominal and femoral scutes
is laterally directed towards the inguinal notch. Medially, the
femoro-anal sulcus is situated near the contact area between the
hypoplastra and the xiphiplastra (Fig. 2R).
Plesiochelyidae indet.
Fig. 2WeZ
Material. MPG-720-1 and MPG-720-2, two fragments of costal
plates, corresponding to adult or subadult individuals (Fig. 2WeX).
MPG-730-20 and MPG-730-21, two fragments of costal plates,
corresponding to juveniles (Fig. 2YeZ).
Locality and horizon. The first two specimens are from Cuesta
Lonsal. The other two were found in the same outcrop near Las
Cerradicas where the plates of Plesiochelys sp. Have been found.
Villar del Arzobispo Formation.
Description. These elements do not have a marked ornamental
pattern, such as occurs in other plates attributed to Plesiochelyidae.
In further members of that group the plates are well ossified and
relatively thick, and the lateral vertices of the vertebral scutes
constitute acute angles.
aff. Plesiochelyidae
Fig. 2S
Material. MPG-731, a fragment of the anterior region of a carapace
consisting of a high percentage of the nuchal plate, the first neural,
which the plates of the carapace belong. S, MPG-731, anterior region of a carapace attributed to aff. Plesiochelyidae, from El Cantalar. T, MPG-730-17, posterior region of a carapace of
Plesiochelys sp., from the outcrop near Las Cerradicas. UeV, MPG-730-18 and MPG-730-19, costal plates attributed to Plesiochelys sp., from the outcrop near Las Cerradicas. WeX,
MPG-7230-1 and MPG-720-2, fragments of costals of Plesiochelyidae indet., from Cuesta Lonsal. YeZ, MPG-730-20 and MPG-730-21, fragments of costals of Plesiochelyidae indet.,
from the outcrop near Las Cerradicas.
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Fig. 3. Shell elements of several taxa, in dorsal and anterior views, from the El Castellar and Camarillas formations of Galve. AeE, MPG-725-1 to 5, fragments of plates of the
carapace and plastron of Solemydidae (aff. Helochelydra), from the site of Poca. FeK, MPG-728-1, MPG-724-1, MPG-725-6, UPUAM-Gv130, MPG-722-1, MPG-722-2, plates and
fragments of plates of Pleurosternidae, correspondiendo last tres primeras a una especie diferente a la de las placas J and K, being F from Pelejón, G from Colladico Blanco, H from
A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
the first right costal, the first right peripheral, and the posteromedial half of the second one.
Locality and horizon. El Cantalar site, Galve. Villar del Arzobispo
Formation.
Description. The specimen MPG-731 has a shallow anterior notch.
The nuchal plate is wider than it is long. Its lateral margins are
markedly convergent towards the anterior region. However, their
most anterior ends are divergent. The first neural plate is subrectangular. The first costal plate is more than two times wider than
it is long. The anterior peripherals are wider than long. This specimen has a single cervical scute, wider than long. The lateral margins of the first vertebral scute are subparallel.
2. 2. Stem Testudines: Solemydidae
Testudinata Klein, 1760
Solemydidae Lapparent de Broin and Murelaga, 1996
aff. Helochelydra Nopcsa, 1928
Fig. 3AeE
Material. Several specimens corresponding to both fragments of the
carapace and plastron are assigned to Solemydidae (Fig. 3AeE).
Locality and horizon. The material attributed to Solemydidae has
been identified in fossil sites of the Early Cretaceous corresponding
to the El Castellar Formation (Pelejón), and to the Camarillas
Formation (Poca).
Description. The characters present in the material from the El
Castellar and Camarillas formations suggest it belongs to a single
taxon. Partial costal and peripheral plates, and partial elements of
the plastron, probably corresponding to fragments of hyoplastra
and hypoplastra, are identified. The ornamental pattern of all of
them is the same. It consists of isolated tubercles, with a rounded
apex, and with a circular to slightly elliptical section. The height of
these tubercles is usually equal to or slightly less than their width.
The diameter of tubercles is about 1 mm.
69
Description. The external surface of all these elements is ornamented by small, regular and clearly defined pits, and with fine
striations perpendicular to the margins of the plates. Many of the
specimens identified are fragments of costal plates. A groove corresponding to the boundary between a vertebral and pleural scute
is identified on one of them (Fig. 3H). The specimen MPG-728-1
corresponds to an epiplastron (Fig. 3F). A gular scute is observed
on this plate. The boundary between the intergular and humeral
scutes is medially directed towards the posterior region.
Pleurosternidae sp. 2
Fig. 3JeK
Material. Several disarticulated plates, corresponding to peripherals
(Fig. 3JeK).
Locality and horizon. These specimens are from the Early Cretaceous
of Galve, but the site and formation from which they come are not
known.
Description. The external surface of all these elements is ornamented by vermiculations, and with fine striations perpendicular
to the margins of the plates. One of the identified elements corresponds to a right first peripheral (Fig. 3J). This plate is wider than it
is long. It has a posterior curved contact with the nuchal plate. It is
wedged towards the medial region.
2. 4. Pan-Cryptodira: Xinjiangchelyidae
Testudinata Klein, 1760
Testudines Batsch, 1788
Pan-Cryptodira Joyce, Parham and Gauthier, 2004
Xinjiangchelyidae Nessov in Kaznyshkin et al., 1990 sensu Tong
et al., 2012
Xinjiangchelyidae spp.
Fig. 3LeAG
Material. Numerous plates, most of them disarticulated, corresponding to plates of both the carapace and plastron of several
individuals (Fig. 3LeAG).
2. 3. Paracryptodira: Pleurosternidae
Testudinata Klein, 1760
Testudines Batsch, 1788
Pan-Cryptodira Joyce, Parham and Gauthier, 2004
Paracryptodira Gaffney, 1975a
Pleurosternidae Cope, 1868
Pleurosternidae sp. 1
Fig. 3FeI
Material. Several disarticulated plates, corresponding to various
elements of the shell (Fig. 3FeI).
Locality and horizon. Some elements come from the site of Colladico
Blanco (Galve), El Castellar Formation (Fig. 3G); others from Pelejón
(Galve), El Castellar Formation (Fig. 3F); others from Poca, Camarillas Formation (Fig. 3H). Elements from indeterminate sites of
Galve are also identified (Fig. 3I).
Locality and horizon. The material here attributed to Xinjiangchelyidae comes from several outcrops situated in the town of Galve,
corresponding to sites of the El Castellar Formation (Pelejón,
Fig. 3AC, AF; and Colladico Blanco, Fig. 3MeN), of the Camarillas
Formation (Poca, Fig. 3L, OeR, T-Z, AB, ADeAE; and Cabezo Santa
Bárbara, Fig. 3AG), and of indeterminate outcrops (Fig. 3S, AA).
Description. The two preserved neurals are hexagonal and significantly wider than long (Fig. 3W, AF). An ornamental pattern consisting of grooves radiating forwards is observed in both specimens.
However, these are broader, stronger, and fewer in number in
specimen MPG-728-3 (Fig. 3AF) than in MPG-725-15 (Fig. 3W).
Although the number of neurals is not known, the medial region of
the preserved costals (third, fourth, sixth and seventh plates)
indicate that they contacted with neurals. In fact, the morphology
of the medial margin of the seventh costal MPG-725-17 (Fig. 3Y)
allows us to recognize that this plate contacted with two neurals
(seventh and eighth). Therefore, there was no medial contact of the
Poca, and IeK from indeterminate sites of Galve. LeAG, MPG-725-7, MPG-724-2, MPG-724-3, MPG-725-8 to 11, UPUAM-Gv131, MPG-725-12 to 18, UPUAM-Gv132, MPG-725-19,
MPG-728-2, MPG-725-20, MPG-725-21, MPG-728-3, MPG-373, plates of the shell of several members of Xinjiangchelyidae, being L, OeR, TeZ, AB and ADeAE from Poca; MeN from
Colladico Blanco; AC and AF from Pelejón, AG from Cabezo de Santa Bárbara; S and AA from indeterminate sites of Galve.
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last pairs of costals in this specimen. The costal plates have strong
lateral processes for contacting the peripherals. The first peripheral
plate is longer than it is wide (Fig. 3L). All identified anterior peripherals are much shorter than the posterior ones. The laterodorsal margin of the anterior and middle peripherals is dorsally
directed. The posterior peripherals are expanded. The preserved
plates do not have a defined ornamental pattern. Certain reliefs
related to their growth during ontogeny are preserved in some of
them. They are more developed on some costal plates as well as in
the anterior peripherals.
The first vertebral scute overlaps the posterior half the length of
the first peripheral plate (Fig. 3L). The second vertebral overlaps
less than half of the width of the second and third costals (Fig. 3T,
V). Although the anterior and posterior marginal scutes are located
only on the peripheral plates, those corresponding to the region of
the bridge are laterally overlapping the lateral region of the costals.
The preserved elements of the plastron are scarcer than those of
the carapace. A right epiplastron (Fig. 3AC), an entoplastron
(Fig. 3AE), and a left hyoplastron (Fig. 3AD) are recognized. The
contact between the epiplastron and the hyoplastron is partially
ligamentous, with a linear ridge in the anterior margin of the
hyoplastra that slots into a furrow in the posterior margin of the
epiplastra. However, the disposition of their scutes indicates that
this taxon lacked plastral kinesis. The morphology of the anterior
margin of the epiplastron is rounded. It is not possible to know if
this plate had a dorsal process since, viscerally, the posteromedial
edge is broken. The process of the hyoplastron is high, but only
contacted with peripheral plates. The preserved entoplastron
(Fig. 3AE) is wider than long. Its morphology is elliptical. However,
the entoplastron corresponding to the preserved epiplastron had
an anterior more acute angle. The gular scute corresponding to the
preserved epiplastron (Fig. 3AC) did not contact the entoplastron.
However, the intergular scute overlapped the anterior region of
that plate. Only the humeral scutes overlapped onto the known
entoplastron (Fig. 3AE). The hyoplastron (Fig. 3AD) shows that its
humero-pectoral sulcus was significantly posterior relative to the
position of the entoplastron. The presence of inframarginal scutes
are identified on that plate as well.
2. 5. Cryptodira: Galvechelone lopezmartinezae
Testudinata Klein, 1760
Testudines Batsch, 1788
Pan-Cryptodira Joyce, Parham and Gauthier, 2004
Cryptodira Cope, 1868 sensu Joyce, Parham and Gauthier, 2004
Galvechelone lopezmartinezae Pérez-García and Murelaga, 2012a
Fig. 4AeB
Material. MPG/CR(m3), the holotype of Galvechelone lopezmartinezae, including the articulated antero-medial area of a carapace of
the holotype MPG/CR(m3) (Fig. 4A), and an unpublished fragment
of hyoplastron or hypoplastron corresponding to the same individual (Fig. 4B).
Locality and horizon. Cerrada-Roya mine outcrop, Galve. Camarillas
Formation.
Description. The preserved region of the carapace of MPG/CR(m3),
consisting of the nuchal plate, the first three neurals and the
anterior region of the fourth, the medial area of the first three pairs
of costals, the medial area of the first pair of peripherals, the
proximal areas of the first four pairs of dorsal ribs, the dorsal region
of the eighth cervical vertebra, the complete first three dorsal
vertebrae and the anterior half of the fourth one, was recently
described by Pérez-García and Murelaga (2012a). A fragment of a
plate, preserved near the visceral region of the carapace, is identified herein and assigned to a fragment of a hyoplastron or hypoplastron of the same individual.
3. Systematic discussion
3. 1. Plesiochelyidae and aff. Plesiochelyidae
The absence of decoration; presence of relatively wide anterior
margin of carapace, being the first peripherals wider than long;
presence of a shallow nuchal notch; high shell height and presence
of tightly sutured plates observed in the specimen MPG-374 is
shared with the representatives of Plesiochelyidae, a group of turtles very abundant and diverse in European Late Jurassic coastal
environments. This group is represented by the genera Craspedochelys Rütimeyer, 1873, Plesiochelys, Portlandemys Gaffney, 1975b,
Tholemys Andrews, 1921 and Tropidemys Rütimeyer, 1873. The size
of this specimen, the morphology, and the presence of thick plates
are compatible with those of Tropidemys, sharing with this taxon
three exclusive characters: the presence of neurals almost as wide
as long, the length of the latero-anterior margins of these plates
similar to that of the latero-posterior margins and the presence of a
sagittal keel on the carapace (Lapparent de Broin et al., 1996).
Differences in the development of the keel have been observed
comparing several specimens attributed to this taxon (Puentener
et al., 2012). The limited number of characters available in the
Spanish specimen precludes assessing whether it belongs to the
type species, Tropidemys langii Rütimeyer, 1873, or to a different
species. This identification is the first reference of Tropidemys in the
Iberian record. Tropidemys was defined based on material from the
late Kimmeridgian of Solothurn, Switzerland (Rütimeyer, 1873).
This taxon, poorly known due to the limited and generally fragmentary specimens attributed to it, has also been identified in the
Kimmeridgian of France and Germany. Although it has been stated,
with doubt, that it might be present in the Early Cretaceous
(Lapparent de Broin, 2001), represented by “Chelone” valanginiensis
Pictet in Pictet and Campiche (1858e1860), it is possible that the
material attributed to it comes from Jurassic levels, with synonymy
having been proposed with other genera currently not included in
Plesiochelyidae (Karl et al., 2007). In fact, due to the recent refutation of the identification of “Plesiochelys” valdensis Lydekker,
1889a and “Plesiochelys” vectensis Hooley, 1900 as members of
Plesiochelyidae, and the identification of Hylaeochelys Lydekker,
1889b as a taxon outside that clade, the known distribution of
Plesiochelyidae is considered to be restricted to the Jurassic (Bardet,
1994; Pérez-García, 2012a). Therefore, the specimen of Tropidemys
described here, from Cuesta Lonsal, is the youngest known representative of this genus, allowing extending the confirmed stratigraphic distribution of this taxon into the upper Tithonian.
The precise age of the site of Las Cerradicas is currently under
dispute. Some authors (e.g., Díaz-Molina and Yébenes 1987) proposed that it is a Tithonian site. However, other authors have
indicated that it is Berriasian in age (e.g., Castanera et al., 2011). The
Villar del Arzobispo Formation has been deposited between the
Tithonian and the Berriasian, taking into account the association of
benthic foraminifera (Aurell et al., 2010). Castanera et al. (2011)
identified Las Cerradicas as Berriasian based on the hypotheses
derived of the charophyte studies performed by Canudo et al.
(2011). However, Canudo et al. (2011) only analyzed charophytes
from the Camarillas Formation, situating the classic site of las
Zabacheras in Valanginian levels. Therefore, robust evidence suggesting that the members of Plesiochelyidae found near Las Cerradicas correspond to specimens that lived in the lower part of the
Cretaceous are not currently available. As it has been indicated,
A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
71
Fig. 4. MPG/CR(m3), holotype of Galvechelone lopezmartinezae, from the Cerrada-Roya mine outcrop of Galve. A, anterior area of the carapace, in dorsal view. B, fragment of
hyoplastron or hypoplastron, in visceral view.
several taxa closely related with Plesiochelyidae (e.g., Hylaeochelys)
are identified both in the Late Jurassic and in the Early Cretaceous
record. Therefore, a distribution similar to some members of Plesiochelyidae could also have occurred, but the currently available
evidence does not allows to confirm this hypothesis.
In addition to the available characters in the specimen of
Tropidemys which assign it to Plesiochelyidae, the material
collected near Las Cerradicas allows us to identify others states of
character present in this clade, such as: the osseous contact between the carapace and plastron; the presence of short plastral
processes, in contact with the lateral margin of the costal plates;
the absence of fontanelles in the area of the bridge but the probable
presence of a small central plastral fontanelle in adult specimens;
the presence of three cervical scutes; the presence of at least two
suprapygal plates; and the presence of inframarginal scutes. The
presence of neural plates noticeably longer than wide, with the
latero-anterior margins shorter than the latero-posterior ones, and
the absence of a sagittal keel are shared with the other representatives of Plesiochelyidae known by the shell: Craspedochelys, Plesiochelys and Tholemys. The presence of a perpendicular contact to
the axial plane between the epiplastra and the hyoplastra, the
overlap of the intergular scutes on the entoplastron, and the longer
than wide morphology of that plate differ from the characters
present in the only known specimen of Tholemys, from the Kimmeridgian or Tithonian of England. The record of Plesiochelyidae is
abundant and diverse in the Late Jurassic of the Iberian Peninsula,
especially in Kimmeridgian and Tithonian sediments of Spain and
Portugal (Antunes et al., 1988; Pérez-García et al., 2008, 2010b),
where Plesiochelys and Craspedochelys have been identified. The
available information on Craspedochelys and Plesiochelys is limited
despite numerous European specimens has been assigned to these
genera. The detailed analysis on the validity of several of the species
attributed to Craspedochelys and Plesiochelys, as well as on the
interspecific and intraspecific variability, is necessary to formulate
an unequivocal diagnosis of both genera and of their species. The
relatively elongated morphology of the shells from Galve, the
presence of wide vertebral scutes, and of long plastral lobes differs
from that observed in the representatives of Craspedochelys. However, these characters are consistent with those of several
representatives of Plesiochelys. Due to the need of revision of
several species attributed to Plesiochelys we assign the material
from Galve to Plesiochelys sp.
The availability of characters of the isolated material collected in
both Cuesta Lonsal and near Las Cerradicas is compatible with
those of the members of Plesiochelyidae. This attribution is
confirmed by the histological analysis performed in this study.
Although the specimen from El Cantalar shared with the traditional members of Plesiochelyidae the absence of decoration, the
thickness of the plates, the presence of anterior peripherals being
wider than long, and the presence of a shallow nuchal notch, it does
not share the autapomorphy of that group (sensu Lapparent de
Broin et al., 1996): the presence of three cervical scutes.
Hylaeochelys, a taxon also closely related to Plesiochelyidae but
differing from their representatives, among other characters, by the
absence of three cervical scutes is identified in Late Jurassic and
Early Cretaceous levels of Europe. The specimen from Galve differs
from Hylaeochelys belli (Mantell, 1844), the only currently valid
species of this genus, by the presence of a more elongated cervical
scute relative to its width, and a narrower first costal relative to its
length. Furthermore, it lacks the ornamental pattern present in
some specimens of Hylaeochelys. The presence of lateral margins of
the nuchal tending to converge towards the anterior region except
in the anterior-most area, where they diverge, is shared with that
taxon, but also with some representatives of Plesiochelyidae
(Pérez-García, 2012a). Therefore, and given the limited information
available, we assign this material to an indeterminate taxon related
with Plesiochelyidae.
3. 2. Stem Testudines: Solemydidae
The presence of tubercles in the elements of the plastron and
carapace of one of the taxa from the El Castellar and Camarillas
formations (Fig. 3AeE) allows its assignment to Solemydidae. This
clade, belonging to the stem group of Testudines, has been recognized in the Late Jurassic to uppermost Cretaceous record of Europe
and North America (Lapparent de Broin and Murelaga, 1996, 1999;
Joyce et al., 2011). Solemydidae is relatively common in the Iberian
record, having being identified in Early Cretaceous (Bergounioux,
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A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
1957; Pérez-García et al., 2011), Cenomanian (Torices et al., 2012)
and Campano-Maastrichtian levels (Lapparent de Broin and
Murelaga, 1996, 1999). The material from the uppermost Cretaceous is very abundant and it defines the species Solemys vermiculata (Lapparent de Broin and Murelaga, 1996, 1999). However, the
other members of this clade recognized in the Iberian Peninsula are
poorly known due to their scarce record. Only a single fragment of a
plate of indeterminate anatomical position has been assigned to the
taxon identified in the Cenomanian (Torices et al., 2012). This
element has been attributed to an undetermined solemydid, whose
ornamental pattern differs from that present in the other taxa
recognized in the Iberian record. The only material attributed to
Solemydidae from the Teruel Province could correspond to the
British genus Plastremys Owen, 1881 (in Parkinson, 1881) or to a
closely related form (Pérez-García et al., 2011). This material consists of a fragment of a costal plate preliminarily attributed to Trachydermochelys Seeley, 1869 (Canudo et al., 2005), and in four
fragmentary but articulated peripheral plates corresponding to the
holotype of “Trachyaspis” turbulensis Bergounioux, 1957. The ornamental pattern present in the specimens of Solemydidae from
Galve is compatible with that of the Spanish material previously
assigned to aff. Helochelydra, with tubercles smaller and higher
than those of Plastremys. This material comes from several localities
of the Barremian and Aptian, which is distributed over different
areas of the Iberian Range (Eastern Cameros Basin, Western
Cameros Basin and the Morella Sub-basin of the Maestrazgo Basin)
(Pérez-García et al., 2011).
The morphology, size, density, and distribution of the tubercles,
and the presence or absence and arrangement of the vermiculations, are specific to each taxon of Solemydidae (Lapparent de Broin
and Murelaga, 1999; Joyce et al., 2011). Several characters in the
Spanish specimens different to those present in the British taxon
Helochelydra nopcsai Lapparent de Broin and Murelaga, 1999 (e.g.,
the lack of vermiculations, the morphology of the first neural plate,
as well as in the morphology and position of the entoplastral scute)
have been identified (Pérez-García et al., 2011). However, it is
possible that the discovery of new Spanish material enables us to
recognize some of these characters as being subject to variability
and to assign previously recovered and described material to this
genus.
et al., 2010). However, no specimens had been hitherto described
or figured, and these attributions had never been justified. These
references were made in general faunal studies, in which the systematic diversity of the sites of La Cantalera (Oliete Sub-basin of the
Maestrazgo Basin, Iberian Range, Teruel Province, Hauteriviane
Barremian) (Canudo et al., 2010), Buenache de la Sierra (Serranía de
Cuenca Basin, Iberian Range, Cuenca Province, Upper Barremian)
(Buscalioni et al., 2008), Uña (Serranía de Cuenca Basin, Iberian
Range, Cuenca Province, Upper Barremian) (Krebs, 1995), and the
area of Hornillos de Cameros (eastern Cameros Basin, Iberian
Range, La Rioja, BarremianeAptian) (Viera and Torres, 1996) were
analyzed. The only review of one of these identifications, i.e., that of
Hornillos de Cameros (Viera and Torres, 1996), called this into
question, with the material being reassigned to Chitracephalus
dumonii (Pérez-García, 2012c). The study of the material of turtles
from Galve confirms the presence of Pleurosternidae in the Early
Cretaceous of the Iberian Peninsula.
The taxon here identified as Pleurosternidae sp. 1 shares its
ornamental pattern with the Iberian Late Jurassic taxon Selenemys
lusitanica and with the British Early Cretaceous Pleurosternon bullockii, but also with some isolated plates from the Hauteriviane
Barremian levels of Angeac (Charente, south-west France), assigned
to an indeterminate member of Pleurosternidae (Néraudeau et al.,
2012). The epiplastron from Galve MPG-728-1 (Fig. 3F) is not
complete. However, this plate is posteriorly wider than those of
Selenemys lusitanica and Pleurosternon bullockii, probably due to it
correspondence to a different taxa. It is necessary to find new
material in order to confirm this hypothesis and to characterize the
member of Pleurosternidae, ornamented by pits, registered in the
early Barremian of Spain.
The available information on the taxon identified as Pleurosternidae sp. 2 is also very limited. The morphology of the first
peripheral plate differs from that present in taxa such as the
American Glyptops plicatulus, Dinochelys whitei, Compsemys victa
Leidy, 1856, and the European Pleurosternon bullockii and “Glyptops”
typocardium, being more similar to that of Selenemys lusitanica.
However, the ornamental pattern is different of that of this taxon. It
is therefore likely that this material belongs to a yet undefined
taxon.
3. 4. Pan-Cryptodira: Xinjiangchelyidae
3. 3. Paracryptodira: Pleurosternidae
The presence of fine striations perpendicular to the margins of
the plates observed in all elements here attributed to Pleurosternidae is a character shared with the members of this clade.
Some of the plates from Galve have an ornamental pattern consisting of small pits while others have low tubercles and vermiculations. The ornamental pattern that characterizes the members of
this clade is diverse and can be constituted by pits (e.g., Pleurosternon bullockii Owen, 1842, Selenemys lusitanica Pérez-García and
Ortega, 2011), tubercles and vermiculations (e.g., Glyptops plicatulus
Marsh, 1890, Berruchelus russelli Pérez-García, 2012b) or lacking
ornamentation (e.g., Dinochelys whitei Gaffney, 1979). The coexistence of taxa with different patterns has been recognized in some
European areas, as for example in localities of the Late Jurassic of
Portugal and Spain, where Selenemys lusitanica and a yet undefined
new taxon can be identified (Pérez-García et al., 2010b; PérezGarcía and Ortega, 2011), and in the Early Cretaceous of Britain,
represented by Pleurosternon bullockii and “Glyptops” typocardium
Seeley, 1869 (Milner, 2004; Pérez-García, 2012b). Therefore, at least
two indeterminate members of Pleurosternidae are recognized in
the area of Galve. The presence of Pleurosternidae had been
tentatively proposed in Iberian Early Cretaceous locations (Krebs,
1995; Viera and Torres, 1996; Buscalioni et al., 2008; Canudo
The availability of characters of the material identified in several
sites of Galve is compatible with that of Xinjiangchelyidae (sensu
Tong et al. 2012): size less than 400 mm; hexagonal second to
penultimate neurals; anterior peripherals with prominent guttered
edges; mediolaterally expanded posterior peripherals; marginals of
the bridge region extending onto second through fourth costals;
absence of mesoplastra; humeral-pectoral sulcus situated far
behind the posterior margin on the entoplastron; presence of
inframarginals; absence of contact of the axilar and inguinal buttresses with the costal plates; absence of sculpturing of pitted or
vermiculated ridge pattern. The presence of members of Xinjiangchelyidae in the Early Cretaceous of Europe, and specifically in
the Iberian Peninsula, has been confirmed in recent papers (PérezGarcía and Murelaga, 2012b; Pérez-García et al., 2013). Three representatives of this group have been recognized so far in Europe:
Brodiechelys brodiei (Lydekker, 1889a), from the BarremianeEarly
Aptian of the British Wessex Sub-basin (Pérez-García, 2012a), a new
Spanish species of Brodiechelys (Pérez-García et al., 2013) from the
Early Aptian of the Morella sub-basin (Maestrazgo Basin, Iberian
Range), and Larachelus morla Pérez-García and Murelaga, 2012b
from the Late HauterivianeEarly Barremian of the western
Cameros Basin (Cameros Basin, Iberian Range) (Pérez-García and
Murelaga, 2012b; Pérez-García et al., 2013). Because most of the
A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
material from Galve corresponds to indeterminate plates, it is
impossible to perform a generic or specific determination. A
thickening of the dorsolateral region of the anterior and middle
peripherals, not present in the specimens attributed to Brodiechelys
brodiei, is developed in the other Asian and European taxa attributed to Xinjiangchelyidae. Therefore, the anterior peripherals
found in Galve are not compatible with those of that species,
hitherto known only from United Kingdom (Pérez-García, 2012a).
Some plates such as the epiplastron MPG-728-2 (Fig. 3AC) are
consistent with the diagnosis of the genus Larachelus (sensu PérezGarcía and Murelaga, 2012b) but not with that of Brodiechelys
(sensu Pérez-García et al., 2013). In fact, the type of contact of this
plate with the hyoplastron could allow its assignment to that genus.
The smooth outer surface of most of the plates here attributed to
Xinjiangchelyidae, on which only irregularities related to the
growth are observed, is also shared with Larachelus. The costal
plates analyzed differ from those of the Spanish species of Brodiechelys because the sixth and seventh marginals overlap the
lateral margins of these elements (Fig. 3OeP, U). This character is
also shared with Larachelus morla. However, one of the found
neurals (MPG-728-3, Fig. 3AF) is sculptured by grooves radiating
forwards. In fact, these grooves are broad, strong, and few in
number, as are those that diagnose the Spanish Brodiechelys.
Furthermore, the presence of a marked change of profile in the area
of contact of two vertebral scutes on the neural is also shared with
this taxon. The morphology of the entoplastron MPG-725-21
(Fig. 3AE), differs from Larachelus, in which it is rhombic and
longer than wide, but it is compatible with the variability described
for Brodiechelys (Pérez-García, 2012a). Although the intergular
scutes are superimposed onto the antero-medial area of the entoplastron in the known specimens of Brodiechelys and Larachelus,
this overlap is not present in the entoplastron from Galve (Fig. 3AE).
However, it is possible that the absence of that overlap could
correspond to individual variability given the wide variation in the
disposition of some of the plastral scutes of a taxon (e.g., the overlap
or absence of overlap of the anal scutes on the hypoplastra
described in Brodiechelys brodiei by Pérez-García, 2012a). Therefore,
the discussed characters reveal the presence of at least two indeterminate representatives of Xinjiangchelyidae in the Early Cretaceous of Galve. Although some of the plates cannot be assigned to
the European Larachelus or Brodiechelys, elements such as the
epiplastron MPG-728-2 (Fig. 3AC) could belong to a taxon closely
related or belonging to Larachelus, while others (e.g., the neural
MPG-728-3, Fig. 3AF), could correspond to a form closely related or
belonging to Brodiechelys. However, the medial contact of the
seventh costal with two neurals differs from the condition
observed in Larachelus, the taxon in which the medial contact of the
last three pairs of costals is present, and from the members of
Brodiechelys, the taxon in which the medial contact of the seventh
or seventh and eighth pairs of costals occurs.
3. 5. Cryptodira: Galvechelone lopezmartinezae
The holotype of Galvechelone lopezmartinezae is the most complete articulated specimen of turtle found in the Early Cretaceous
levels of Galve. However, the review of the abundant material of
turtles from the Cretaceous fields of this town precludes recognizing other elements assignable to it. The reduced thickness
diagnosing the plates of this taxon probably hindered both their
preservation and their discovery and extraction. In fact, the breaks
observed in the margins of the holotype indicate that this specimen
was much more complete when it was exhumed. The histological
study of this poorly represented taxon, performed here, increases
our knowledge about it.
73
As stated by Pérez-García and Murelaga, 2012a, Galvechelone
lopezmartinezae is part of a clade of turtles that includes the European taxa Hoyasemys jimenezi Pérez-García, de la Fuente and
Ortega, 2012 and Chitracephalus dumonii Dollo, 1885, both also
represented in the Iberian range (Pérez-García et al., 2012, PérezGarcía, 2012c). The presence of these forms in Europe, as well as
that of the members of Xinjiangchelyidae (Pérez-García et al., 2013)
shows that close paleobiogeographic relations between Early
Cretaceous turtle fauna of Asia and Europe were present. This idea
is consistent with several hypotheses previously proposed, underscoring the presence of close relationships among the members of
other groups of vertebrates recorded in the Early Cretaceous of Asia
and Europe such as crocodyliforms (Ortega et al., 2000), dinosaurs
(Canudo et al., 2002) and mammals (Cuenca-Bescós and Canudo,
2003; Canudo et al., 2010). In addition, close phylogenetic relationships between representatives of some groups of invertebrates recorded in the eastern and western areas of Eurasia
during the Early Cretaceous (e.g., molluscs) have also been reported
(Delvene et al., 2011). These occurrences probably reflect several
diachronic dispersal events. In fact, the presence of members of
Xinjiangchelyidae in BerriasianeValanginian levels of the Hastings
Group of Sussex (Weald Sub-basin, Great Britain) shows that some
of these dispersions were performed during the lowermostCretaceous or even earlier. However it has been interpreted that
the gobiconodontids (Mammalia, Eutriconodonta) migrated to
Europe during the Barremian (Cuenca-Bescós and Canudo, 2003).
4. Shell bone histology
4. 1. Material and methods used
In this study, the bone histology of the five taxa from the Late
Jurassic and Early Cretaceous fossil localities of Galve was surveyed.
The bones sampled from the five taxa in question are: (1) Plesiochelyidae indet.: one costal plate, probably from a juvenile
specimen (MPG-730-2, Fig. 2Z); and two (MPG-730-18 and MPG730-19, Fig. 2UeV) from larger and presumably older specimens
found near Las Cerradicas, Villar del Arzobispo Formation, (2)
Pleurosternidae indet.: a costal plate (MPG-724-1, Fig. 3G) from
Colladico Blanco, El Castellar Formation; one costal plate (MPG725-6, Fig. 3H) from Poca, Camarillas Formation; and one (UPUAMGv130, Fig. 3I) from an indeterminate locality of the El Castellar or
Camarillas formations, (3) Solemydidae (cf. Helochelydra): a
possible plastron fragment (MPG-725-4, Fig. 3D), and a peripheral
(MPG-725-3, Fig. 3C) from Poca, Camarillas Formation, (4) Galvechelone lopezmartinezae: shell fragment of the holotype, probably a
fragment of a hyoplastron or hypoplastron (MPG⁄ CR(m3), Fig. 4B)
from Cerrada Roya, Camarillas Formation, and (5) Xinjiangchelyidae indet.: a peripheral (UPUAM-Gv132, Fig. 3AA) and a costal
fragment (UPUAM-Gv131, Fig. 3S) from an indeterminate locality of
the El Castellar or Camarillas formations.
All specimens were sampled either longitudinally or transversely to allow comparison between the taxa. Thin sections were
analyzed and documented using a LEICA compound microscope
DM 2500 M, mounted with a digital camera LEICA DFC420 C.
4. 2. Results
Plesiochelyidae
In both the purported juvenile and adult specimens, the external
cortices in the diploe structures of the shell bones are thick and well
developed (Fig. 5AeB), whereas the internal cortices are reduced in
thickness in areas adjacent to the ventral rib bulge compared to the
external cortices.
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Fig. 5. Bone histology of shell bones of Plesiochelyidae from Galve. Images A, C, E and H are viewed in normal transmitted light, B, D and F in polarized light and G in polarized light
using a lambda compensator. AeB, overview of section of small costal plate (MPG-730-2), probably from a juvenile, and external bone surfaces. CeD, detail of the external cortex of
the larger costal plate (MPG-730-18) showing intervowen structural fibre bundles and reticular primary vascular canals. EeF, detail of the internal cortical bone of MPG-730-18
A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
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Fig. 6. Bone histology of shell bones of Pleurosternidae from Galve. Images A and C are viewed in normal transmitted light, B and D in polarized light. AeB, detail of the external
cortex of the indeterminate shell fragment UPUAM-Gv130. Note inner and outer zone of the cortical bone, which are distinguishable from each other for example by showing
coarser fibre bundles of the interwoven structural fibre matrix in the inner zone and the presence of growth marks in the outer zone. CeD, detail of the internal cortical bone of
UPUAM-Gv130 showing a lamellar-zonal structure with parallel-fibred and lamellar bone matrix vascularized by scattered simple primary vascular canals. Abbreviations: FB, fibre
bundles; ICO, internal cortex; ISF, interwoven structural fibre bundles; PC, primary vascular canal; PFB-LB, parallel-fibred and lamellar bone; SO, secondary osteon.
External cortex. The external cortex comprises fine-fibred interwoven structural fibre bundles, with bundles generally being of
similar thickness and length (Fig. 5CeD). The bone tissue is dominated by fibre bundles that extend perpendicular to the external
surface of the bone. Growth marks are clearly visible throughout
the cortical bone. The external cortex, although largely compact, is
vascularized by an intricate reticular network of primary vascular
canals. Many of the primary canals open up as small foramina onto
the bone surface. In the juvenile specimen (MPG-730-31, Fig. 2Z),
scattered secondary osteons appear more frequently in the external
cortex, compared to the larger and presumably older specimens.
Cancellous bone. The cancellous bone is mainly composed of a
mixture of short, thick trabeculae and more slender and gracile
ones (Fig. 5A, EeF). Larger and smaller vascular cavities are not
restricted to certain areas in the cancellous bone. The trabecular
system is still largely primary, although bone remodelling,
especially in the interior-most parts of the bone is locally extensive.
Interstitial primary bone is present in many trabeculae and
branching areas. Others are completely composed of secondary
lamellar bone.
Internal cortex. The internal cortex consists of parallel-fibred bone
(Fig. 5EeG). Some layers within the cortex are vascularized by
string-like arrangements of primary osteons, as well as scattered
larger secondary osteons. The vascularized layers often intercalate
with avascular layers. Growth marks are also found in the internal
cortex; however, they are not as conspicuous as in the external
cortex. As is the case in the external cortex, scattered secondary
osteons appear more frequently in the juvenile specimen (Fig. 5G)
compared to the older specimens.
Sutures. The two larger specimens (MPG-730-18 and MPG-730-19,
Fig. 2UeV) have suture zones preserved, showing a shallow relief
showing parallel-fibred bone and abundant secondary osteons. G, close-up of the internal cortical bone of n de MPG-730-21. Note extend of secondary osteons towards the internal
(visceral) bone surface. H, close-up of the suture zone present between the two adjacent costal plates preserved in MPG-730-18. Sutural pegs and sockets are only weakly
interlocking. Abbreviations: CB, cancellous bone; ECO, external cortex; ICO, internal cortex; ISF, interwoven structural fibre bundles; LB, lamellar bone; PC, primary vascular canal;
PFB, parallel-fibred bone; SO, secondary osteon.
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Fig. 7. Bone histology of shell bones of Solemydidae (aff. Helochelydra) from Galve. Images A, C, E, G and H are viewed in normal transmitted light, B, D and F in polarized light. A-B,
detail of the external cortex and interior cancellous bone of the peripheral plate MPG-725-3. Note regular ornamentation pattern with valleys and saddles and wide-meshed
framework of trabeculae and large intertrabecular spaces. CeD, close-up of the externo-proximal part of the external cortical bone of the peripheral plate showing a coarse
A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
77
Fig. 8. Bone histology of the hyoplastron or hypoplastron fragment of the holotype of Galvechelone lopezmartinezae, MPG/CR(m3). Images A and C are viewed in normal transmitted
light, B and D in polarized light. AeB, overview of the diploe structure of the flat, plate-like section. CeD, close-up of the diploe structure of “bend” section of the fragment.
Abbreviations: CB, cancellous bone; ECO, external cortex; ICO, internal cortex; ISF/PFB, interwoven structural fibre bundles intercalated with parallel-fibred bone; LB, lamellar bone;
PFB, parallel-fibred bone; ShF, Sharpey’s fibres.
with short pegs and sockets (Fig. 5H). In these marginal suture
zones, the bone tissue is similar to that found in the external cortex.
Growth marks, which are visible in the external cortex, can also be
traced through the sutural zone, extending sub-parallel to the
marginal surface of the bone. The reticular pattern of primary
vascular canals is present in the sutural zones as well.
Pleurosternidae
The bone histology of shells of Pleurosternidae, including material of the North American taxa Glyptops plicatulus and Compsemys sp., as well as material of cf. Selenemys and Pleurosternidae
indet. from Guimarota coal mine near Leiria and from Porto das
Barcas, Portugal, was studied in detail by Scheyer and Anquetin
(2008). One of the main characteristics of Pleurosternidae shell
bones encountered in that study was a partition of the well
developed external cortex into an external fine-fibred showing
wavy growth marks and a more internal coarse fibred zone. This
characteristic is also clearly present in the costal plates of Pleurosternidae (MPG-725-6 and UPUAM-Gv130) studied herein
(Fig. 6AeB), but less obvious in the costal MPG-724-1, because of
strong diagenetic alteration in this part of the bone. All three
specimens however, show differences in vascularization, with
UPUAM-Gv130 and the costal fragment MPG-724-1 showing only
few scattered primary vascular canals in the more internal zone,
whereas the costal fragment MPG-725-6 shows abundant primary
vascular canals and primary osteons in this zone. Concerning this
variation in vascularization, a size effect between the former,
thinner specimens (up to 2 mm in thickness) and the latter, thicker
element (up to 4 mm in thickness) cannot be ruled out. With the
exception of some scattered foramina opening up to the external
bone surfaces, the more external zone is usually avascular in all
three specimens. The cancellous bone of all three specimens is
rather compactly built, with short and thick trabeculae. The internal cortices, on the other hand, show a lamellar-zonal structure
(Fig. 6CeD) with parallel-fibred and lamellar bone matrix vascularized by scattered simple primary vascular canals.
Solemydidae (aff. Helochelydra)
The two specimens, a peripheral and a purported plastron
fragment (MPG-725-3 and MPG-725-4) of Solemydidae (aff. Helochelydra) both show a diploe structure with cortices of equal
thickness framing interior cancellous bone.
External cortex. The external cortex shows a more external zone,
the ornamentation pattern (Fig. 7AeD), with low valleys and raised
wider saddles and narrower tubercles composed of parallel-fibred
bone, followed by a thin, more internally located zone of coarse
interwoven structural fibres visible as longitudinally and
meshwork of longitudinally and transversely sectioned fibre bundles internal to the ornamentation. EeF, close-up of the interno-proximal part of the external cortical bone of the
peripheral plate. Note scalloped bone surface and the lack of a clear ornamentation pattern. GeH, close-ups of the suture zones preserved in the peripheral (G) and the plastral
fragment (H). In the peripheral, pegs and sockets give only a shallow relief, whereas in the purported plastral fragment, pegs and sockets are well interdigitating. Abbreviations: CB,
cancellous bone; ECO, external cortex; ICO, internal cortex; LB, lamellar bone; lsFB, longitudinally sectioned fibre bundles; OP, ornamentation pattern; PC, primary vascular canal;
PFB-LB, parallel-fibred and lamellar bone; SO, secondary osteon; trFB, transversely sectioned fibre bundles.
78
A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
Fig. 9. Bone histology of shell bones of Xinjiangchelyidae. Images A, C, E and G are viewed in normal transmitted light, B, D, F and H in polarized light. AeB, detail of the external
cortex (dorsal part) of the peripheral plate UPUAM-Gv132. Sharpey’s fibres and growth marks are well visible. CeD, close-up of the interno-proximal part of external cortex of
peripheral UPUAM-Gv132. Here, the bone tissue is dominated by the insertion of coarse Sharpey’s fibres. E-F, overview of the free rib part (broken off tip towards the left) of the
A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
transversely sectioned fibre bundles. In the more proximal part of
the peripheral, the ornamentation in the ventrally situated part of
the external cortex is only composed of the coarse fibre bundles of
the more internal zone (Fig. 7EeF). This is interpreted as an
erosional artefact, however, as the relief, i.e., the differentiation into
valleys and saddles/tubercles, is mostly not present in this part of
the peripheral and the bone surface appears rough and scalloped.
The cortical zones are both present again in the ventral aspect of
the distal tip of the peripheral, as well as in the dorsal aspect of the
external cortex. The more internal zone is vascularized by a reticular network of primary vascular canals, whereas the more external
zone is, with the exception of few small foramina, avascular.
Sharpey’s fibres insert perpendicular to the external bone surface
into the ornamental saddles and tubercles. Growth marks are
present but difficult to trace through the slides.
Cancellous bone. The cancellous bone is composed of a widemeshed framework of trabeculae and large intertrabecular spaces
(Fig. 7AeB, G). The trabeculae consist of secondarily remodelled
lamellar bone, with several phases of remodelling being apparent.
Internal cortex. The internal cortex, as observable in the purported
plastron fragment from Poca, consists of parallel-fibred bone
grading into lamellar bone. Bone cell lacunae are of oblong and
flattened shape. At the transition to the interior cancellous bone,
larger erosion cavities, often not yet lined with secondary lamellar
bone, invade into the compact bone. Besides, only a few simple
vascular canals were found in the internal cortex (Fig. 7H).
Sutures. The suture zone in the peripheral is characterized by a
shallow relief of wide-spaced pegs and sockets where the peripheral articulates with the costal and plastral bones (Fig. 7G). In the
purported plastron fragment (Fig. 7H) pegs and sockets are more
elongated, creating a relatively deep relief compared to the “thinness” of the shell bone (max. 4 mm in both specimens).
Galvechelone lopezmartinezae
The thin shell fragment (Fig. 4B) of the holotype of the recently
described Galvechelone lopezmartinezae (Pérez-García and Murelaga,
2012a), from Cerrada Roya, shows a diploe structure with welldeveloped cortices framing interior cancellous bone (Fig. 8). Both
cortices are sub-equal in thickness, with the internal cortex locally
being of greater thickness. Due to the particular “bend” in the plate
visible in cross-section, this specimen is interpreted as a fragment of a
hyoplastron or hypoplastron, being consistent with the position
where it was found, in contact with the visceral region of the carapace. At the transition from the internal- and external-most regions
of the cancellous bone to the cortices, an irregular erosion line is
visible in the “bend” region of the plate, probably connected with the
directed growth of the bone in this area.
External cortex. The external cortex is composed of interwoven
fibre bundles intercalated with areas of parallel-fibred bone
(Fig. 8B, D). Sharpey’s fibres and growth marks are both most
conspicuous in the “bend” region where the cortical bone is
thickest.
Cancellous bone. The cancellous interior consists of thick, short
irregular trabeculae in various stages of remodelling, framing
79
irregular shaped vascular spaces (Fig. 8A, C). Most of the trabeculae
are lined with a thick layer of secondarily deposited lamellar bone.
At the transition from the internal-most region of the cancellous
bone to the internal cortex, an irregular erosion line is visible in the
bend region of the plate, probably connected with the directed
growth of the bone in this area.
Internal cortex. The internal cortex is a smooth layer of parallelfibred bone. Sharpey’s fibres are visible in all regions of
the cortex but most conspicuous in the “bend” region of the
plate.
Xinjiangchelyidae
The peripheral UPUAM-Gv132 and the distal part of the costal
fragment UPUAM-Gv131 both show well developed diploe structures with external and internal cortical layers framing an extensive
interior cancellous bone core. The internal cortex is thinner
compared to the external cortex.
External cortex. The external cortex consists of interwoven
structural fibre bundles, vascularized by an extensive reticular
network of primary vascular canals, showing more transversally
sectioned canals in the peripheral (Fig. 9AeD) and more longitudinally sectioned canals in the costal fragment (Fig. 9EeH).
Growth marks extend sub-parallel to the external bone surface,
mirroring the external ornamentation of the bone (Fig. 9A). In the
costal fragment, Sharpey’s fibres inserting perpendicularly into
the bone tissue are visible throughout the external cortex
including the distal tip of the rib. In the peripheral, the more
proximally situated parts of the external cortex (on the dorsal and
ventral sides of the peripheral) are dominated by large amounts of
coarse Sharpey’s fibre bundles (Fig. 9D), which insert into the
bone tissue in a various set of angles (ranging from flat to high
angles). The more distally situated parts, on the other side, again
show finer Sharpey’s fibres perpendicularly arranged to the bone
surface.
Cancellous bone. Trabeculae are usually long and slender building a
gracile framework around smaller and larger vascular cavities,
especially in the interior part of the peripheral (Fig. 9AeD). In the
costal fragment, wide-meshed vascular spaces of circular sub-shape
surrounded by trabeculae are present only in the interior-most
areas of the bone. In other areas, the vascular cavities are flattened
and elongated within a highly ordered trabecular meshwork,
dominated by proximodistally extending trabeculae (Fig. 9EeH).
Internal cortex. The internal cortex consists of parallel-fibred bone
(Fig. 9H). Sharpey’s fibres insert into the bone tissue, but are less
conspicuous compared with those found in the external cortex. In
the costal fragment, the internal cortex shows longitudinally
sectioned primary vascular canals as well as primary osteons and
secondary osteons, basically mirroring the flattened oblong
vascular cavities of the cancellous bone (Fig. 9H). Few scattered
secondary osteons are also encountered in the cortical tissue.
4. 3. Discussion
All five taxa sampled from the fossil localities of Galve show
histological peculiarities. As such, the pleurosternid samples (MPG-
costal fragment UPUAM-Gv131. Note oblong intertrabecular cavities in the cancellous bone. GeH, close-up of the interior cancellous and internal cortical bone of the costal
fragment, adjacent to the free rib part. Note abundance of longitudinally sectioned primary vascular canals and primary osteons within the parallel-fibred bone matrix. Abbreviations: CB, cancellous bone; ECO, external cortex; GM, growth marks, ICO, internal cortex; ISF, interwoven structural fibre bundles; PC, primary vascular canal; PFB, parallel-fibred
bone; ShF, Sharpey’s fibres.
80
A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
424-1, MPG-725-6 and UPUAM-Gv130) clearly show the unique
bone microstructural character set of shell bone previously reported for the clade Pleurosternidae (Scheyer and Anquetin, 2008).
The plesiochelyid samples studied were also found to be very
similar in their microstructures to those of Plesiochelyidae and
Thalassemydidae preliminarily reported by Scheyer (2007). The
genera included in these two groups, however, do not differ much
in their bone histology, with variations being subtle and, in some
cases, may represent artefacts of diagenetic alteration or preparation (Scheyer, 2007). Among the present sample, the variation in
remodelling of cortical bone, i.e., the increased appearance of
scattered secondary osteons in the juvenile specimen (MPG-73021) compared to the larger specimens (MPG-730-18 and MPG-73019), is apparent. This variation is here interpreted as an ontogenetic
feature, in which the compacta are subject to a decreasing trend of
remodelling during development, with higher numbers of scattered secondary osteons in ontogenetically younger individuals
(pertaining to the outer regions of the cancellous bone in larger,
ontogenetically older specimens), and decreasingly abundant secondary osteons in the compact cortices of the larger, ontogenetically older specimens.
Furthermore, the histological composition of the external cortex
of the samples (MPG-725-3 and MPG-725-4) of Solemydidae
(cf. Helochelydra) was found to be highly peculiar and indeed may
represent some diagnostic features of the whole Solemydidae. Note
that the shell bone histology of the clade is currently being studied
elsewhere.
Galvechelone lopezmartinezae shows rather conserved shell bone
microstructures, which do not readily allow a detailed comparison
with a specific lineage of turtles. On the other hand, the xinjiangchelyid material from Galve (UPUAM-Gv131 and UPUAM-Gv132)
shows certain microstructures, i.e., the organization of the cancellous bone into a highly ordered, almost rectangular trabecular
meshwork, reminiscent of those described for, e.g., dermatemydid
turtles, i.e., Baptemys garmanii (Cope, 1872) and Dermatemys mawii
Gray, 1847 (see Scheyer, 2007) or the stem-pleurodiran Platychelys
oberndorferi Wagner, 1853 (see Scheyer, 2007). In these taxa, the
highly ordered organization of the trabecular bone was interpreted
to be a functional signal linked to a more or less exclusive aquatic
(in freshwater habitat) lifestyle (Scheyer and Sander, 2007), so a
similar functional signal is postulated for this Galve taxon as well.
5. Conclusions
The turtles from the well-known faunal associations of the Villar
del Arzobispo, El Castellar, and Camarillas formations of the Spanish town of Galve are here analyzed. Abundant material of turtles
corresponding to at least nine taxa is identified there.
The knowledge of the turtles present near the Late Jurassice
Early Cretaceous transition, limited in Europe, and particularly in
the Iberian Peninsula, is considerably increased here. All the material of turtles found in the levels of the Late Jurassic of this town
can be attributed to Plesiochelyidae and closely related forms.
However, the presence of other synchronous groups identified in
the European record, either another group of littoral turtles
exclusive of the Late Jurassic European record (Eurysternidae), or
groups present in the record of the Late Jurassic and Cretaceous of
both North America and Europe (e.g., the terrestrial Solemydidae
and the aquatic Pleurosternidae) are not yet identified in Galve. The
presence of Pleurosternidae has been previously recognized in
other regions of the Late Jurassic of the Iberian Peninsula, such as in
the Lourinhã Group, in central-western Portugal, and in the Tereñes
Formation, in the Spanish province of Asturias (Pérez-García and
Ortega, 2011; Pérez-García et al., 2010b). However, both groups
have not been identified in the same site in any of these locations,
probably because Plesiochelyidae and Pleurosternidae inhabit
different environments (the first one coastal marine waters and the
second one probably brackish waters). The oldest evidence of
Solemydidae and Pleurosternidae registered in Galve comes from
the El Castellar Formation, with both groups being also present in
the Camarillas Formation. The presence of members of Xinjiangchelyidae is recognized in both Early Cretaceous formations.
Furthermore, Cryptodira is identified in the Camarillas Formation
by the presence of Galvechelone lopezmartinae.
The clade present in the Villar del Arzobispo Formation is represented by several taxa. One of them is assigned to the plesiochelyid Tropidemys. This shell is the first known representative
of the hitherto little known taxon Tropidemys in the Iberian
Peninsula. In addition, it expands the known distribution of this
genus, being the only confirmed post-Kimmeridgian reference to
this genus. Tropidemys has a sagittal keel on the carapace. However,
abundant material of a plesiochelyid which lacks a keel is also
recognized in Galve. It is identified as a member of Plesiochelys. This
identification is the first reference to Plesiochelys in the Spanish
record. However, this genus had been previously identified in the
Iberian Peninsula, in Portuguese levels corresponding to the upper
part of the Early TithonianeUpper Tithonian interval (Pérez-García
et al., 2008). A third taxon is also identified in the Villar del Arzobispo Formation. It cannot be assigned to Plesiochelyidae, but it is
identified as a form closely related to this clade, as well as with the
European taxon Hylaeochelys. Therefore, a high diversity of coastal
marine turtles is recognized in this formation.
All the specimens of Solemydidae so far identified in Galve are
compatible with a single taxon. The availability of characters allows
its identification as a form related to the British genus Helochelydra.
It could be the same taxon recognized by fragmentary elements in
other areas of the Early Cretaceous of the Iberian Peninsula. The
record of Pleurosternidae from Galve comprises at least two taxa,
which differ, among other characters, due to their different ornamental pattern. The record of this clade is relatively abundant in the
Late Jurassic levels of South-western Europe. However, the information on taxa present there during the Early Cretaceous is very
limited. This study confirms the presence of Pleurosternidae in the
Early Cretaceous of the Iberian Peninsula. Furthermore, the identification of two taxa is consistent with the Early Cretaceous British
record (Pérez-García and Ortega, 2011).
Xinjiangchelyidae is an abundant and diverse group of turtles in
the two formations analyzed here. The presence of this clade in
Europe has only recently been confirmed (Tong et al., 2012; PérezGarcía et al., 2013). In fact, its presence has been identified in the
Iberian Peninsula, with the description of the taxa Larachelus morla
and a new species of Brodiechelys (Pérez-García and Murelaga,
2012b; Pérez-García et al., 2013). Several xinjiangchelyid taxa are
represented in Galve. Some of the plates found are compatible with
those of Larachelus, while others might be more closely related to
Brodiechelys. Further, some elements that do not share the diagnosis of these taxa are also identified. The material attributed to this
group corresponds to disjointed and isolated plates. For this reason,
it is not possible to perform any specific or generic determination.
The specimens from Galve represent the first evidence supporting
the presence of more than one member of Xinjiangchelyidae in one
European location. These specimens allow us to expand the known
diversity for this group on the European continent.
In this study, a high taxonomic diversity, comprised by stem
Testudines, representatives of Paracryptodira, members of Plesiochelyidae and closely related taxa, and members of both the
stem and the crown group of Cryptodira were identified in one
location. This taxonomic composition consists of members of clades
identified in the synchronous record of North America and Europe
(Solemydidae
and
Pleurosternidae),
Asia
and
Europe
A. Pérez-García et al. / Cretaceous Research 44 (2013) 64e82
(Xinjiangchelyidae and the clade grouping the members of “Macrobaenidae” and “Sinemydidae”), and clades only distributed in
Europe (Plesiochelyidae and related forms).
Acknowledgements
The authors thank the family Herrero (MPG) for their cooperation and assistance, Lisa Rager, Leonie Pauli, Julia Huber and Fiona
Straehl (all PIMUZ) for their various helps in preparing and documenting specimens, and John W.M. Jagt and two anonymous reviewers for comments and suggestions. This study was partly
funded by the FPU subprogramme of the “ Ministerio de Ciencia e
Innovación” (grant no. AP2007-00873 to APG), and by the Swiss
National Science Foundation (grant no. 31003A 127053 to TMS).
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