Mammalogy Lecture #3
Insectivora, Macroscelidea,
Scandentia, and Dermoptera
Insectivores
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The 4 orders we are considering now
were once all grouped in the
insectivora. The group was once, and
continues to be a ‘garbage basket’ of
families. Often, it is unclear where else
these organisms belong.
An important question is: why do they
end up in an assemblage like this?
Insectivores
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1) It really has nothing to do with diet some are herbivores, some have a
cecum others do not.
2) Perhaps all are in some sense less
derived than other mammals?
3) Perhaps their morphologies reflect
arboreality?
Why are other groups easier to classify?
Insectivora
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Erinaceidae:
hedgehogs and
gymnures
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Chrysochloridae:
golden moles.
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Solenodontidae:
solenodons.
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Talpidae: moles and
desmans.
Tenrecidae: tenrecs
and otter shrews.
Soricidae: shrews
Insectivora
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Morphologically, they appear to be less
derived than other mammals. It is
possible that they reflect the ancestral
stock of eutherian mammals.
This is convenient because we often
assume that the first mammals were
small insect eating forms.
Insectivora: Morphology
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Generally small.
Pentadactyl w/ plantigrade locomotion.
Rostrum tends to be long.
Pelage often consists only of guard hair
(modified in some forms as spines).
Pinnae small or absent.
Small braincase w/ smooth cerebral
hemispheres.
Insectivora: Morphology
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Auditory bullae are absent - instead
there is a ring-shaped tympanic bone.
Anterior vena cavae are paired.
Testes usually abdominal, or if in
scrotum, then anterior to penis (as in
marsupials).
Claoca is present in some.
Jugal is reduced or absent.
Pubic symphysis is reduced.
Blarina brevicauda
Insectivora: Morphology
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Some insectivores retain the
tribosphenic tooth.
Teeth are rooted, so do not grow
throughout life.
Molars have 4 or 5 cusps and form
either a V shape (zalambdodont) or W
shape (dilambdodont) occlusal pattern.
Dental formula is often pleisomorphic
3/3, 1/1, 4/4, 3/3 = 44
Talpa & Potamogale
Cryptotis parva
Insectivora: Fossil History
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Earliest insectivores data to the midCretaceous (100MYA)
Recognizable soricids and talpids date
to the Eocene (50MYA).
Zalambdalestes & Kennalestes
from the Cretaceous
Erinaceidae
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7 genera and 21 species.
Hedgehogs have barbless spines while
gymnures do not.
Found in the Old-World.
Hedgehogs are nocturnal and mainly
terrestrial, or semiarboreal.
They are omnivorous - invertebrates,
eggs, fruit, carrion.
Erinaceus sp
Cheekteeth of Erinaceus sp.
Erinaceidae
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Spines in hedgehogs are soft at birth,
and have not broken the skin. They
harden a few weeks after birth.
In a defensive posture, the animal rolls
up in a ball, using a band of muscle
lateral to the ventrum - might this be
similar to patagial musculature in
gliders?
Erinaceidae
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Hedgehogs also self-annoint. They rub
saliva over their spines. Interestingly,
there are reports of hedgehogs killing
toads, and self-annoiinting with the
parotid glands to produce ‘venemous
spines.’
Erinaceus europaeus is the only
insectivore to use hibernation. Others
may estivate.
Erinaceidae
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Gymnures do not have spines.
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Closely associated with wetlands.
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Phillipine moon rats have anal scent
glands.
Talpidae
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17 genera and 42 species, distributed
throughout Europe, the Palaearctic,
Asia, Japan, and North America.
Fossorial w/ consequent morphology:
– fusiform
– pinnae reduced or absent
– small eyes
– keeled sternum
Talpidae
– Extreme modification of the pectoral girdle
and appendages - including rotation of the
fore-feet.
Scalopus aquaticus
Upper & lower molars of Sorex vagrans
(A&B) and Scalopus aquaticus (C&D)
Talpidae
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Desmans are restricted to the Old
World.
– Eat aquatic invertebrates and fish
– Some species have long, laterally
compressed tails.
– Some evidence that they use echolocation
to locate prey.
Tenrecidae
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24 species. 21 species of Tenrecs are
found in Madagascar only (this is bad
news), while there are 3 species of otter
shrews found in west-central Africa.
There is extreme morphological
variation in this group, w/ forms
resembling hedgehogs, shrews,
muskrats, and moles.
Tenrecidae
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Bruce Patterson from the Field Museum
in Chicago has been working furiously
in Madagascar trying to understand the
diversity and evolution of Tenrecs. Just
within the last few years, they have
discovered several new species. If you
are interested in this group, you have a
rich resource nearby.
Tenrec ecaudatus
Tenrec ecaudatus
Tenrecidae
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Otter shrews (not surprisingly) look a lot
like otters and are actually quite large.
Some Tenrecs can hibernate, and most
have relatively low body temperatures.
The common Tenrec has as many as 32
offspring in a single litter!
Chrysochloridae
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7 genera and 18 species, found in
central and southern Africa.
These are the golden moles - they have
iridescent fur. It is truly an amazing
sight.
No pinnae, vestigal eyes.
Convergent w/ Talpids, but forelimbs are
not rotated.
Chrysochloridae
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They push soil w/ the snout, then push
soil under the body with the limbs.
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Claw on 3rd digit is enlarged.
Chlorotalpa sclateri
Chlorotalpa sclateri
Solenodontidae
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2 species. 1 restricted to Cuba, the
other to Haiti and the Dominican
Republic (this is not good news).
They are large (TL = 600mm)
Look like a cross between a rat and a
shrew.
Omnivorous.
Solenodon paradoxus
Solenodon paradoxus
Solenodontidae
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May be capable of echolocation - they
produce high frequency clicking sounds.
Has anyone recorded them w/ a bat
detector?
Submaxillary glands produce toxic
saliva, which flows into the bite via
grooved 2nd incisor.
Soricidae
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23 genera and 312 species.
Generally small (3g - 100g).
Organized into 2 subfamilies: Soricinae
and Crocidurinae.
Soricinae are the ‘red-toothed’ shrews.
Crocidurinae are the ‘white-toothed’
shrews.
Blarina brevicauda
Crocidura leucodon
Soricidae
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Smallest shrews are Suncus etruscus
and Sorex hoyi, while largest is Suncus
murinus.
Most have short legs, are plantigrade.
2 forms have webbed feet: Nectogale
elegans and Sorex palustris.
Small eyes, pointed rostrum, short dark
pelage.
Suncus murinus
Suncus murinus
Soricidae
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Many produce a musky odor - which
you will notice if we trap any this
semester.
No zygomatic arch, no auditory bullae.
1st upper incisor is unique w/ apparent
2nd cusp.
Sorex vagrans
Soricidae
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Most are insectivorous, although some
are functionally omnivorous.
This brings up a number of interesting
points:
– why are shrews so small?
– What are the consequences of small size
(note, they are incapable of hibernation or
migration)?
Soricidae
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Some use high frequency sound for
communication, orientation, and prey
detection - although this has not been
studied extensively.
Many exhibit caravanning.
Short lived.
Often associated w/ moist habitats.
Macroscelidae
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4 genera and 15 species of elephant
shrews.
Central and eastern Africa.
Insectivores to omnivores.
Can move bipedally.
Long, flexible snout, large eyes and
long ears.
Convergent w/ Dipodomys & Jerboa?
Macroscelidae
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Size ranges from 50g to 400g.
Hind-limbs longer than fore-limbs.
Have audotory bullae and a zygomatic
arch.
All but Rhynchocyon have functional
incisors.
Macroscelidae: Rhynchocyon chrysopygus
Macroscelidae
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Molars are quadrituberculate, and
occlusal surfaces are dilambdodont.
Possess a cecum.
Fossil history dates to the Oligocene of
Africa.
Scandentia
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Contains a singel family (Tupaiidae)
with 5 genera and 19 species.
Have long been considered primates. It
is important to realize that primates are
a poorly defined group, w/ most of their
distinguishing characteristics related to
arboreality.
Scandentia: Tupaiidae
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Restricted to Oriental faunal region.
Mostly diurnal and omnivorous.
Not all are arboreal, and they are not
shrews.
Most scent mark.
Resemble squirrels in general
morphology.
Tupaia sp.
Tupaia glis
Scandentia: Tupaiidae
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They resemble primates in that they
– 1 have a large braincase
– 2 have a postorbital bar
– 3 have scrotal testes
– 4 similar structure of carotid and
subclavian arteries.
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Tribosphenic molars
Unperforated palate.
Lower incisors are procumbent and
used for grooming.
Date to the Miocene of India
Tupaia glis
Dermoptera
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These are the ‘flying lemurs’ or
Colugos.
In the past, they have been classified
with bats, primates, and insectivores.
There is 1 family (Cynocephalidae), 1
genus (Cynocephalus) and 2 species.
Dermoptera
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Cynocephalus volans occurs in the
Philippines, while C. variegatus occurs
in Malaya, Sumatra, Java, Borneo, and
nearby islands.
They weigh up to 2kg, and can glide at
up to 25m/s which is very fast for a
glider.
Dermoptera
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Feldhammer claims they can glide
100m and lose only 10m in altitude.
This is hooey.
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They are very specialized arboreal
folivores, with long gut retention times.
They feed only on newly emergent
leaves of a few species of trees.
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Dermoptera
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They have the most extensive patagium
of any glider.
They have pectinate lower incisors.
They have a keeled sternum. Your
author claims other gliders have a
keeled sternum - I have never seen
one.
Fossil history dates to Paleocene of NA,
and Eocene of Europe (both for family
Plagiomenidae). No fossils in Asia.
Colugo variegatus
Colugo variegatus
Crocidura leucodon
Cryptotis parva