Ungulates and Subungulates
Ungulata
• Subungulates
– Proboscidea
• elephants
– Hyracoidea
• hyraxes
– Sirenia
• dugongs and manatees
• Ungulates
– Perrisodactyla
• odd toed ungulates
• horses, tapirs, and
rhinos
– Artiodactyla
• even toed ungulates
Subungulates
• This seems to be an odd grouping of
organisms. However, it is not by accident,
and does not represent another ‘garbage’
group.
• Proboscideans, Hyraxes, and Sirenians are
all derived from Condylarthrans, that
evolved in the Paleocene about 65mya.
Subungulates
• The Paenungulata was one group within the
Condylarthra, and by the Eocene of Africa,
they gave rise to the Proboscidea, Sirenia,
and Hyracoidea.
• If that is the case, you would expect some
morphological similarities between the
groups.
Subungualta
• They all lack clavicles.
• They all have short nails on their digits.
• Females have 2 pectoral mammae (Hyraxes have 2
inguinal pairs as well).
• All females have a bicornuate uterus.
• All males have abdominal testes and have no baculum.
• All are non-ruminating, hind gut fermenting,
herbivores.
• All have a cecum.
• Elephants and Sirenia have horizontal molariform tooth
replacement.
Subungulata
• Proboscideans and Sirenians were much
more diverse during the Oligocene and
Miocene.
• Their future does not look promising.
Proboscidea
• There is but 1 family (Elephantidae) and 2
species: African elephant - Loxodonta
africana, and Asian elephant - Elaphas
maximus.
• African elephants are much larger than
Indian (Asian) elephants. The teeth differ,
Africans have higher shoulders, larger ears,
and a more complex trunk.
African vs. Asian Elephant
Proboscidea
• Reproduction is not easy
– Females are sexually mature by 9 to 12 years,
with peak reproductive value between 25 and
45 years. Gestation is 22 months, but estrus
lasts only 2 to 4 days, with about 4 years
between estrus events.
– Copulation is no simple deal either.
– There is sexual dimorphism, and young small
males generally do not reproduce.
Proboscideans
• Size of the males tusks seems to be an
important character for reproduction.
African elephant females look for a
minimum tusk length, and will not mate
with ‘short’ males even if no ‘long’ males
are available. This has some implications
for the ivory industry.
Proboscideans
• African elephant males weigh up to 7500kg,
while Indian elephants weigh about 4500kg.
• They exhibit indeterminant growth.
• They have graviportal limbs, and are
capable of one gait only.
Proboscideans
• Feldhammer claims that large size in
elephants is a consequence of ‘competition’
with other herbivores.
– Is this the most parsimonious explanation?
– Does it reduce the importance of predation?
– What about the cost of transport?
• What does large size mean for an
endotherm?
Proboscideans
• Elephants are inefficient herbivores, and
require large home ranges. They are usually
found in groups. Thus, as they move long
distances each day, they are capable of
significant habitat modification.
• Consider what it means to be so large. How
is it possible that 50% of what passes
through the gut of an elephant is
undigested?
Proboscideans
• The trunk of elephants is actually part of the
upper lip and the nostrils.
• It is prehensile, and is essential since the
animal can not reach the ground with its
mouth.
• It is used to manipulate food, suck up water
(and then spray water into the mouth), and
suck up dust and mud as well.
Proboscideans
• Dental formula is 1/0, 0/0, 3/3, 3/3 = 28.
• Tusks are dentine (with only the tip covered
in enamel).
• Tooth replacement is horizontal, they are
worn and replaced from the rear. Note:
although they have 6 molariform teeth in
each jaw, only one is functional at any time.
Proboscideans
• Elephants were once much more diverse
than they are today.
• In the Pleistocene they were in Europe and
North America. In fact, until just recently,
there were 2 species in N. America at the
same time, mastadons (Mammut
americanus), and Mammoths.
Proboscideans
• Oldest fossils are from the Eocene of Africa
• We have fossil evidence from Asia, Europe,
Africa, and N. America.
• Moeritheriids were relatively small (1m) in
Africa during the Eocene and Oligocene,
while Deinotheriids were in Asia and
Europe from the Miocene to the Pliocene.
Proboscideans
• The Deinotheriids had weird tusks, based on
the lower incisors rather than upper.
• Gomphotheriidae were contemporaries, and
had tusks in upper and lower jaws.
• Mammutidae were the mastodons from the
early Miocene.
• Stegodontidae were from the mid-Miocene.
A) Moeritherium, B) Deinotherium, C) Gomphotherium, D) Wooly
Proboscideans
• Only the Elephantidae persist today.
• The genus Primelephas from the late
Miocene/early Pliocene is probably
ancestral to modern elephants as well as the
Wooly Mammoths.
Hyracoidea
• There are 5 species of rock hyraxes, and 3
species of bush hyraxes, all inhabiting rocky
habitats in Africa and the middle east.
• Were first thought to be rodents, but are
clearly subungulates.
• They are not ruminants, but have a large
cecum as well as a smaller paired cecum.
Hyraxes
• Have a mid-dorsal gland surrounded by
light hair.
• They have unique pads on the feet, which
function as suction cups on rocky surfaces.
Glands on the feet provide moisture for
‘suction’
• Toes have hoof-like nails (except 2nd on
rear, which has a grooming claw).
Hyraxes
• They have no canines, and have a
diastemma, hence the early confusion with
rodents.
• Upper incisors are pointed and triangular
with no enamel on posterior.
• Unlike elephants and sirenians, dentition is
not replaced horizontally.
Modern Hyrax vs.
Megalohyrax
from the
Oligocene. Note
the diastemma in
the modern form.
Rock Hyrax: Procavia capensis
Rock Hyrax: Procavia capensis
Rock Hyrax: Procavia capensis
Hyraxes
• Fossils are known from the Eocene of
Europe and Africa.
• There is always the speculations that the
diversity of Hyraxes suffered as a
consequence of competition with ungulates.
More about this later.
Sirenians
• These are the dugongs and manatees.
• 2 families: monotypic Dugongidae from
western Pacific, and Trichechidae (3
species) form the Atlantic.
• Essentially tropical, feeding on aquatic
vegetation.
• Poor thermoregulatory abilities and low
metabolic rates - hence warm waters.
Sirenian Morphology
• Large fusiform bodies - valvular nostrils, no
pinnae, horizontal tail, no external hindlimbs, and flipper-like fore-limbs.
• Dense bone to facilitate negative bouyancy.
• Lungs run nearly length of body to even out
bouyant forces.
• Teeth replaced horizontally.
Stellar’s Sea
Cow
(Extinct),
Manatee, and
Dugong
Note position of lungs in the
Manatee.
Dugongs
Manatees
Dugongs vs. Manatees
• Dugongs eat aquatic vegetation which is
much softer than that consumed by
manatees.
• Feldhammer uses competition to explain
distribution of species.
Dugong vs Manatee
Sirenian Fossil History
• There were once at least 20 genera of
Sirenians.
• There are Eocene sirenians from india,
Europe, and N. America (Protosiren).
• Eocene sirenians are unique in that thay
have a fifth premolar.
Dusisiren: Miocene sea cow.
Dugong vs
Manatee:
Deflected rostrum
in Dugong is
‘adaptation’ to
bottom feeding.
Perissodactyla and Artiodactyla
• Both forms of modern ungulates are
digitigrade.
• Teeth are usually hypsodont.
• Limbs operate in a single plane, and are
designed for cursorial locomotion.
• Calcaneum usually does not articulate with
the fibula.
A) Tapir
B) Rhino
C) Horse
D) Pig
E) Deer
F) Camel
G) Pronghorn
Calcaneum is
shaded and
articulates w/
Astragalus (H)
Perissodactyla
• Horses, Tapirs, and Rhinos.
• Odd toed ungulates, with the 3rd digit bearing most
of the weight (Mesaxonic).
• Teeth are usually hypsodont and lophodont.
• Horses and tapirs have upper incisors, rhinos
generally do not.
• Stomach is simple, but they have a cecum. Gut
retention times are half that of ruminating
artiodactyls. Thus, only about 70% as efficient.
Malayan tapir
Indian
Rhino
Perissodactyla: Fossil History
• The Condylarthra are ancestral to the
Perissodactyla, as well as the Artiodactyla,
Proboscidea, Sirenia, and Cetaceans.
• It is not necessarily true that the
Perissodactyla and Artiodactyla are
monophyletic.
• Based on 67 hard and soft morphological
characters, we can propose the following:
Ungulate Evolution
• Note the implications:
– Closest relatives of the perissodactyls are the
cetaceans.
– Mammals invaded wate completely at least
twice independently (Cetceans and Sirens).
– Note the close relationship between hyraxes,
elephants, and sirenians.
Perissodactyl Evoltuion
• Originally 14 families at their peak in the
Eocene.
• By the end of the Oligocene there were only
4 families.
• They were the dominant ‘medium to large’
herbivores of the Tertiary.
• Both the Brontotheres and Chalicotheres
went extinct.
Chalicothere: went
extinct in
the
Pleistocene
Note the
fore-limb
dominance
.
Tapirs
• Origin and early differentiation in the
Paleocene
• Heptodon is one of the earliest, and comes
from the Eocene of Wyoming.
• Modern Tapirus is remarkably similar to
Heptodon, but bigger. Both have 4 toes in
front and 3 in rear, both have ulna and
fibula complete and unfused.
Tapirs
• Both Heptodon and Taprius have complete
dentition w/ a small diastemma; upper
canine is reduced and lateral incisor is
caniniform.
• Upper molars have 3 lophs, the lower
molear have 2 transverse lophs (as in
Rhinos)
Malayan tapir
Tapir teeth - sort of
Tapirs
• Compare the teeth of Tapirus with those of
the rhino
Black Rhino
Tapirs
• This similarity in structure is one of the
reasons why tapirs and rhinos are generally
considered to share a common ancestor.
• The cladogram for Perissodactyla lumps
tapirs and rhinos, with horses as the
outlying sister group.
Tapirs
• Tapirs persist in S. America and Central
America, and in Southeast Asia. Can you
explain this distribution?
• Hyrachyus (Family Hyrachyidae) may be
transitional between tapirs and rhinos. It
was abundant in the eocene of n. America
and Europe.
• Hyracodontids and Amynodontids were
abundant in the Eocene and oligocene of N.
America and Asia.
Hyracodontids
•
•
•
•
•
About 12 genera
Moderate size
Slender limbs like horses w/ light builds.
Cursorial
incisors were spatulate (primitive) and equal
sized.
• Canines were moderate size.
Hyracodontids
• In the Oligocene, from Hyracodont lineage,
came a series of gigantic hornless rhinos in
the subfamily Indricotherinae
• Indricotherinae ranged from central Asia to
China.
• Indricotherium was the largest land
mammal to ever live.
Hyracodontids
• Indricotherium was 5.4m tall at the
shoulders, had a long neck and a skull
which was 1.3m long.
• Could reach vegetation 8m above the
ground.
• Had a probable weight of 30 tons, 4.5 times
greater than Loxodonta, and about twice as
great as the largest Mammoth.
Amynodontids
•
•
•
•
•
•
About 10 genera
Large heavy bodies
Short stocky limbs
Short faces
Prominent canine tusks.
The bulk of the Amynodontid radiation was
over by the close of the Oligocene.
Rhinocerotidae
• Hyracodontids during the Oligocene
obtained a unique dental variation: chisel
like I1 and tusk like I2. This formed the
basis of a 2nd radiation… the
Rhinocerotidae.
Rhinocerotidae
• About 50 genera
• N. America, Eurasia, and Africa from the
Miocene to Pleistocene.
• Rhinocerotids included wooly rhinos and
rhinos w/ horns (Elasmotherium) as long as
2m.
• Wooly rhinos show up as cave paintings by
palaeolithic man.
Rhinocerotidae
• Elasmotherium’s horn was not nasal like
most, but originated on the forehead. It had
no incisors.
• Today, rhinos occur only in India, Java,
Sumatra, and Africa.
Black Rhino
Black Rhino
Black Rhino
Black Rhino
Chalicotheres
• From the Eocene on in N. America, Eurasia,
and Africa.
• Simple premolars and bunolophodont
molars.
• Probably a bipedal browser.
• Had long forearms and hooked claws - very
un-ungulate like.
Chalicothere: went
extinct in
the
Pleistocene
Note the
fore-limb
dominance
.
Titanotheres (=Brontotheres)
• From the early Eocene to early Oligocene of
N. America and eastern Asia.
• Medium to very large size.
• Probably succeeded in Asia by Indricothere
Rhinos.
• Had graviportal limbs and nasal horns
which were probably covered by skin.
Horses
• Evolution of horses has been used as best
example of gradualism.
• Over 55 million years, the progression from
Eohippus to Equus has involved:
– Increase in size from small lamb size to present size.
– Reduction of toes from 3 to 1.
– Increased complexity of enamel pattern on molars.
Horses
• Eohippus (= Hyracotherium)
• Eocene of N. America, W. Europe, and E.
Asia.
• 4 toes fromt, 3 rear.
• Horses died out (Together w/ horse-like
Tapirs) in W. Eeurope by the Oligocene.
Also died out in Asia by this time.
Horses.
• In Oligocene, N. America horses are
Mesohippus and Miohippus.
• Sheep size, 3 toes w/ middle digit largest.
• Snout elongating.
• Premolars beginning to look like molars w/
lophs and lophids.
Horses.
• By Miocene, Anchitherium had split off
from other N. American horses, and
migrated through Europe and Asia.
• By the end of the Miocene, forest-dwelling
Hypohippus migrated into China.
• From Oligocene Anchitheres came the
Miocene Parahippus, a precursor to midmiocene Merychippus.
Horses.
• Merychippus is first grazer horse.
• True hypsodont cheek teeth, elaborately
lophed and had cementum.
• Had fused ulna/radius and tibia/fibula to
improve gallop and minimize twisting of
legs.
• All later horses evolved from Merychippus.
Horses
• First successful descendent of Merychippus
were the Hipparionines, which included as
many as 6 lineages. They invaded the old
world several times and were finally extinct
by the late Pleistocene.
• In the late Miocene, Merychippus was
replaced by Pliohippus, the 1st one-toed
horse.
Horses
• Pliohippus gave rise to Equus during the
Pleistocene of N. America, from where it
radiated to the old world.
• Equus became extinct in the N. American
recent. Why?
Artiodactyla
• 1/3 of all mammalian genera are Herbivores. Of
these, 50% are Artiodactyla or Perissodactyla.
• Origin is probably I the Palaeocene.
• Today, there are 6 genera of Perissodactyls vs. about
80 genera of Artiodactyls.
• Whereas perissodactyls were once most diverse,
artiodactyls now have significant edge. Why?
Artiodactyls
• Currently there are 12 famillies of
herbivores, there are 24 extinct families.
• Origin is probably in northern continents
with movements into southern ones (except
Australia).
Horns, Antlers, Ossicones.
Diacodexis: early Eocene
artiodactyl.
Artiodactyls
• Primary axis of support is between 3rd and
4th toes (paraxonic).
• 2nd and 5th digits are absent or nonfunctional.
• Pigs (Suiformes) are plantigrade, while
ruminants are digitigrade (Unguligrade).
• Dentition varies from bunodont and
brachydont to solenodont and hypsodont.
Artiodactyls
• Upper incisors and canines are reduced or
absent.
• Suids and Tayasuids have non-ruminating
stomachs while more derived families have
4 chambered ruminating stomachs.
Suiformes: Suidae
• 5 genera and 16 species.
• Simple stomachs and bunodont teeth, large
ever-growing canines.
• Cartilaginous disk on snout.
• Endemic to Europe, Africa, and Asia.
Introduced almost everywhere else.
Pig
Warthog, Babirusa, and Wild Boar.
Suiformes: Tayassuidae
• Least specialized of the suiformes.
• Peccaries - legs are thin and feet end in
hooves. Upper canines point downward
rather than upward as in pigs.
• Restricted to the New World, from the
desert southwest to Argentina.
Peccaries
Suiformes: Hippopotamidae
• 2 species only.
• Little or no hair, also lack sweat glands for
thermoregulation.
• They do have glandular skin that produces
pigmented secretions to protect against sunlight.
• Bunodont cheek-teeth, ever-growing tusk-like lower
canines and incisors, with alveoli for canines
anterior to those for incisors.
Hippos
• Not ruminants, but septa in stomach
increase gut retention times.
• H. amphibius grazes on land at night fo rup
to 6 hrs.
• Hexaprotodon liberiensis is less aquatic.
• Both are African.
Hippo: note elevated eyes and nares.
Hippos
Pigmy hippo
Tylopoda: Camelidae
• North American origin in Eocene, extinct here by
the Pleistocene.
• 3 genera and 6 species
• Dromedaries, Bactracians, Quanaco, Llama, Alpaca,
and Vicugna.
• Small head, long snout, cleft upper lip, long thin
neck, long legs w/ canon bone.
• Upper and lower canines, and selenodont cheek
teeth.
• Toes spread out under load.
Tylopoda: Camelidae
• Outer spatulate upper incisor is retained in
adults.
• 3-chambered stomachs and a cecum.
• Dromedary was once throughout the Middle
East, but now exists only in domestication.
• Bactracians were once throughout Asia, but
are now restricted to the Gobi.
Tylopoda: Camelidae
• Vicunas and Llamas are restricted to S.
America.
• Camelids consume plants w/ high salt
content, foods avoided by other grazers.
• Unique gaits in Camels.
• Heat and water strategies - the hump is not
what you think.
Dromedary
Dromedary
Dromedary
Llama
Lama glama
Lama glama
Lama glama
Lama
glama
Ruminantia: Tragulidae
• 3 genera and 4 species of Chevrotains in
Africa and Asia.
• Most underived of all ruminants, once had a
worldwide distribution.
• Mouse deer is smallest artiodactyl at 2.5kg.
• No antlers, but curved upper canines.
• 3-chambered ruminating stomach.
Tragulus napu
Ruminantia: Giraffidae
• 2 genera and 2 species: Giraffa
camelopardalis and Okapia johnstoni.
• Small brachydont teeth, prehensile tongues,
ossicones.
• Consider circulatory problems of great
height.
Giraffa camelopardalis incisors
Ruminantia: Moschidae
• 4 species of musk deer.
• Lack antlers, but have curved canines.
• Distributed from Siberia to the Himalayas.
Musk deer
Musk deer
Hydropotes inermis: water deer F
Hydropotes inermis: water deer M
Hydropotes
Hydropotes
Hydropotes
Cervidae
• 16 genera and 42 extant species, ranging in
size from the pudu at 8kg to Alces alces at
800kg.
• Absent only from sub-Saharan Africa and
Antarctica, were introduced to Australia and
New Zealand.
• Sexually dimorphic - males have antlers,
females (except caribou) do not. Why?
Caribou
Moose cow and calf
Moose bull
Mule deer
White tail
White tail nasals
Ruminantia: Antilocapridae
• 1 genus, 1 species.
• Restricted to N. America and Mexico.
• Unique horns.
• Forage on Artemisia tridenta.
Pronghorn
Pronghorn nasals
Pronghorn
Ruminantia: Bovidae
• 45 genera and 137 species.
• 4 chambered ruminating stomachs.
• All have 2 horns except the the four-horned
antelope.
• Worldwide distributin except S. America
and Australia. Why?
African buffalo
Bush Buck
Caribou
Eland
Greater Kudu
Nyala