Mammalogy Lab --- October 27, 2009
Xenarthra, Pholidota, Lagomorpha, Probiscidea, Sirenia, Cetacea
* know to species, % know to genus, # know family
Order Xenarthra Anteaters, armadillos, and sloths
 “xenarthrous” articular surfaces between vertebrae (fig 17.2 in lab manual)
 formerly in order Edentata
 4 families: Myrmecophagidae, Dasypodidae, Megalonychidae, Bradypodidae
Family Dasypodidae Armadillos
 Most of body covered with epidermal scales
 Teeth are cylindrical, homodont, ever growing cheekteeth, no incisors or canines
* Dasypus novemcinctus
Nine banded Armadillo
Priodontes maximus
Giant Armadillo
#Family Myrmecophagidae Anteaters
 Edentulate (toothless)
 Thick hair coat
Myrmecophaga tridactyla – Giant anteater
Order Pholidota
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Pangolins
order name means “scaly ones,” covered with large epidermal scales
insectivorous
edentulate
one family, one genus, 7 species
#Family Manidae
Manis spp.
Order Lagomorpha
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Rabbits, Hares, and Pikas
2 pairs of upper incisors, second pair small and peglike, posterior to first pair
Tail indistinct or small
Forefeet are digitigrade, hindfeet are plantigrade; hindfeet large in hares
Soles of feet largely or entirely covered by fur
Large diastema, cheekteeth hypsodont, evergrowing
Leporids have a world-wide distribution (introduced in Australia)
Hares bear precocial young, rabbits produce altricial young in nests
Lagomorphs exhibit coprophagy
Large foramen in palatines, not found in rodents
2 families, Leporidae and Ochotonidae
Family Ochotonidae Pikas
 Pinnae, short and rounded
 Occur mostly in mountainous regions, herbivorous, and store food for winter
 Pads on digits exposed
 No supraorbital process
 Maxilla with single (occasionally 2 or 3) perforations, fenestra not covered with bony
latticework
 Cutting edge of 1st upper incisor V-shaped
 Jugal projecting beyond posterior margin of zygomatic arch (almost to auditory bullae,
forming long spine)
Ochotona collaris --- Collared pika
Family Leporidae Rabbits and Hares
 Pinnae long, pointed
 Supraorbital process present, fan-shaped
 Maxilla with numerous perforations
 Cutting edge of 1st upper incisor straight
* Lepus americanus – snowshoe hare (white in winter, brown in summer)
Lepus othus – Alaskan hare
% Sylvilagus floridanus – Eastern cottontail
Sylvilagus nuttallii – Mountain cottontail
Oryctolagus cuniculus – European rabbit (introduced to Aleutians & Middleton Is.)
Order Probiscidea
Elephants
 Largest living terrestrial mammals
 Long, slender proboscis (trunk)
 Upper incisors modified into long tusks, 6 cheekteeth (lophodont) which are replaced
continuously from the rear, each tooth is shed as it becomes worn, only one tooth (and
maybe part of another) is functional at a time
 Only one family, 2 species
#Family Elephantidae
Order Sirenia
Dugongs, Manatees
 Strictly aquatic
 Cheekteeth erupt in continuous series similar to elephants
 Strictly vegetarian, grind food with teeth and horny plates on palate
Family Dugongidae – Dugongs
Hydrodamalis gigas – Steller’s Sea Cow (extinct, 1st described on Bering’s voyage to AK)
#Family Trichechidae – Manatees
Trichechus manatus - manatee
Order Cetacea – Whales, Dolphins, Porpoises
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Fusiform, essentially hairless body
Horizontally flattened tail with terminal flukes
Thick layer of blubber
Telescoped skull
Paddle shaped front limbs, rear limbs absent
No pinnae, oil glands or clavicles
Nostrils on dorsal surface of head
2 suborders
Suborder Mysticeti
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Baleen present, teeth absent
Two slit like nasal openings (blowholes)
Skull usually symmetrical
Maxilla extending posteriorly as a long, narrow process interlocking with frontal, not
spreading outward over supraorbital process
Do not echolocate
Family Balaenidae Bowhead and right whales
 Head large, roughly 1/3 of body length
 Color dark gray to black
 Dorsal fin absent
 Baleen plates long and narrow
 Rostrum long, narrow and highly arched
* Balaena mysticetus – Bowhead Whale
Family Balaenopteridae Rorquals and Humpback whale
 Lower jaw bowed outward
 Color gray to black with varying amounts of white below
 Baleen plates short and broad
 Dorsal fin present, sickle shaped or small
 Numerous longitudinal throat grooves
 Largest animals on earth (blue whale)
Family Eschrichtiidae Gray whale
 Color gray to black with white mottling
 Dorsal fin absent
 Body slender
 Baleen plates short and narrow
 Throat with 2 (up to 4) longitudinal grooves in skin
* Eschrictius robustus Gray Whale
Suborder Odontoceti
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Teeth present, simple and homodont, no baleen
One crescent shaped blowhole
Skull usually asymmetrical, sometimes extremely so
Nasals reduced
Echolocate
Family Iniidae – river dolphins
 Large river dolphins
 Long, thick snout, dotted with sparse hair
 Low dorsal ridge
Inia geoffrensis Amazon dolphin
Family Delphinidae – Dolphins, killer whales
 Skull only slightly asymmetrical
 No boss (swelling anterior to nasal opening) on premaxilla
 Teeth spade-like with 2 or 3 poorly defined cusps
 External nares fully visible from dorsal view
Family Monodontidae
 No dorsal fin
 No boss on premaxilla
 Teeth simple, conical
 Skull only slightly asymmetrical
 Highly adapted to sea ice
*Delphinapterus leucus – Beluga whale
Family Phocoenidae Porpoises
 Snout without distinct beak
 Premaxilla with prominent boss immediately in front of external nares
* Phocoena phocoena Harbor porpoise
#Family Physeteridae Sperm whales
 Snout large, broad and blunt, undifferentiated from rest of head
 Throat with numerous short longitudinal grooves (Physeter) or indistinct or absent
(Kogia)
 Skull strongly asymmetrical, left nasal passage enlarged, right premaxilla enlarged
 Maxilla expanded posteriorly
Kogia simus Dwarf pygmy sperm whale
Moby dick Sperm whale