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11/26/08
“Ungulata” (various supraordinal ranks) has included:
Cetacea: whales
Artiodactyla: even-toed ungulates
Perissodactyla: odd-toed ungulates
Hyracoidea: hyraxes
Proboscidea: elephants
Sirenia: manatees & dugongs
Tubulidentata: aardvarks
Various fossil orders...
“Ungulata” (various supraordinal ranks) has included:
Cetacea
Artiodactyla
Perissodactyla
Hyracoidea
Proboscidea
Sirenia
“true” ungulates
paenungulates
(Superorder Paenungulata);
“subungulates”
Tubulidentata Superorder Protoungulata
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11/26/08
“Ungulata” (various supraordinal ranks) has included:
Cetacea
Artiodactyla
Perissodactyla
Hyracoidea
Proboscidea
Sirenia
Tethytheria
Tubulidentata
Tethys sea
“Ungulata” (various supraordinal ranks) has included:
Cetacea
Artiodactyla
Perissodactyla
Hyracoidea
Proboscidea
Sirenia
“true” ungulates
paenungulates
(Superorder Paenungulata);
“subungulates”
Tubulidentata Superorder Protoungulata
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“Ungulata”
Whales & dolphins
Artiodactyls
Artiodactyls
Carnivorans
Pangolins
Perissodactyls
Bats
Solenodons
Moles
Shrews
Hedgehogs
Primates
Treeshrews
Colugos
Lagomorphs
Rodents
Xenarthrans
Golden moles
Tenrecs
Elephant shrews
Aardvarks
Dugongs & manatees
Hyraxes
Elephants
paenungulates
Superorder Paenungulata
•Began diverging in early Eocene (ca. 54 mya)
•Much more diverse in the past
Very different superficially, but several similarities:
1. No clavicles
2. Digits have short nails
3. 4 toes on forefeet (except Asian elephants)
4. 2 pectoral mammae (2 additional inguinals
in hyraxes)
5. No scrotum, testes abdominal, no bacula
6. Herbivorous, hindgut fermenters
Tethytheria
Cheektooth replacement horizontal, not
vertical (“mesial drift”)
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Order Proboscidea
1 LIVING family: Elephantidae
2 LIVING genera & species:
Elaphus maximus (India, SE Asia)
Loxodonta africana (subsaharan Africa)
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Why be big?
Advantages:
Avoid competition
More mobile over large distances
Reduce predation
Thermal inertia
Disadvantages:
Thermal inertia!
Biomechanical constraints
Tusks: 220-440 lbs!
Enamel only on
tip of tusk (I2); rest is dentine, calcium.
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Cementum
Enamel
Dentine
Graviportal locomotion
Limb bones
“stacked”
vertically
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Radius & ulna, tibia & fibula
well-developed, distinct
“Subunguiligrade” foot posture
Massive bulk requires 3 feet to be on ground;
Hindfoot occupies place vacated by forefoot.
Weight bearing has put anatomical restrictions on
limb versatility: limited locomotion only...no other
interaction with environment.
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...but some got smaller
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Order Hyracoidea
1 LIVING family: Procaviidae
3 LIVING genera & ??? species (ca. 6-8):
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Heterohyrax (top)
Megalohyrax† (bottom)
Order Sirenia
2 LIVING families: Dugongidae & Trichechidae
2 genera: Dugong (1 sp.) and Trichechus (3 sp.)
Steller’s Sea Cow
manatee
dugong
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Fusiform bodies, vestigial hindlimbs.
Bones dense and massive (“pachyostotic”) to help them
sink.
Trichechids have only 6 cervical vertebrae (vs. 7)
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