BIO 370 Vertebrate Zoology
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Vertebrate Diversity
Class Mammalia Mammals

(Click on any image for larger version)

Mammalia Characteristics

  • Presence of hair (endothermy)
  • Mammary glands
  • 3 inner ear bones
  • Dentary-squamosal jaw articulation
  • Heterodont dentition (varied teeth)
  • Presence of pinnae (external ears)
  • Diaphragm and 4-chambered heart

Subclass Prototheria Monotremes


  • Most primitive extant mammals
  • Lay eggs
  • Mammary glands lack nipples
  • Lack pinnae (external ears)

    Order Monotremata
    • Echidnas and Platypus
    • Only extant order in Subclass
    • 5 living species are highly specialized, toothless
Platypus Skull
Duck-billed Platypus Ornithorhynchus anatinus (Family Ornithorhynchidae), skull
Echidna Skull
Short-nosed Echidna Skull, Tachyglossus aculeatus (Family Tachyglossidae)
Short-nosed Echidna, Tachyglossus aculeatus (Family Tachyglossidae)

Subclass Metatheria Marsupials


  • Young complete development in pouch
  • Maximum dental formula: 5/4, 1/1, 3/3, 4/4
  • More complex limb musculature
  • Angle of jaw bends inward
  • 330 species in Neotropics, Australian region

    Order Didelphimorphia
    • American Opossums
    • Diverse habitats
    • Most are omnivorous
    • 5/4 incisors per side is unique
    • Sagittal crest (along skull midline) usually present
    • Neotropics to southern U.S.
Virginia Opossum Skull, Didelphis virginiana (Family Didelphidae)
Opossum Mount
Virginia Opossum, Didelphis virginiana (Family Didelphidae); taxidermy mount
Shorttailed Opossum
Shorttailed Opossum, Monodelphis domestica (Family Didelphidae)

    Order Dasyuromorphia
    • Marsupial Mice, Quolls, Tasmanian Devil, etc.
    • Most are insectivorous or carnivorous
    • 4 upper incisors per side; large canines
    • Sagittal crest usually absent
    • Australasian Region
Tasmanian Devil Skull
Tasmanian Devil Skull, Sarcophilus harrisii (Family Dasyuridae)
Tasmanian Devil
Tasmanian Devil, Sarcophilus harrisii (Family Dasyuridae)
Numbat Skull
Numbat skull, Myrmecobius fasciatus (Family Myrmecobiidae)

    Order Diprotodontia
    • Kangaroos, Wallabies, Koalas, Wombats, etc.
    • Mostly herbivorous or omnivorous
    • Includes largest marsupials
    • Note broad grinding molars, diastema
    • Australia
Kangaroo Skull
Kangaroo skull, Macropus sp. (Family Macropodidae)
E Gray Kangaroo
Eastern Gray Kangaroo, Macropus giganteus (Family Macropodidae)
Tree Kangaroo
Goodfellow's Tree Kangaroo, Dendrolagus matschiei (Family Macropodidae)
Southern Hairy-nosed Wombat, Lasiorhinus latifrons (Family Vombatidae)
Brush-tailed Bettong, Bettongia penicillata (Family Potoroidae)
Koala, Phascolarctos cinereus (Family Phascolarctidae)

Subclass Eutheria Placental Mammals


  • Extended gestation with complex placenta
  • Maximum dental formula: 3/3, 1/1, 4/4, 3/3
  • Morphologically very diverse
  • 5100 species, worldwide

See also
Mammal Anatomy page

    Clade Afrotheria
    • A monophyletic grouping that branched off near the base of the Placental mammal tree
    • Primarily African distribution
    • Very diverse in body form and lifestyle
    • Characterized by high number of vertebrae
    • Permanent teeth erupt relatively late
    • Many have a long, mobile snout
    • 82 species total in 6 extant orders
    • Order Proboscidia (Elephants)
      • Huge size
      • Upper incisors enlarged into tusks
      • Molars formed of fused vertical plates that are replaced front to back
      • Nose and upper lip form trunk
African Elephant Molar
Asian Elephant Skull, Elephas maximus (Family Elephantidae)
San Diego Natural History Museum
African Elephants
African (Bush) Elephants, Loxodonta africana (Family Elephantidae); Kenya
West Indian Manatee, Trichechus manatus; Order Sirenia: FL
Rock Hyrax Skull
Rock Hyrax skull, Procavia capensis; Order Hyracoidea
Yellow-spotted Hyrax
Yellow-spotted Hyrax, Heterohyrax brucei; Order Hyracoidea; Kenya
Lesser Tenrec, Echinops telfairi; Order Afrosoricida
Elephant Shrew Skull
Four-toed Elephant Shrew skull, Petrodromus tetradactylus; Order Macroscelidea
Elephant Shrew
Round-eared Elephant Shrew, Macroscelides proboscideus; Order Macroscelidea
Aardvark Skull
Aardvark skull, Orycteropus afer; Order Tubulidentata

    Order Xenarthra
    • Armadillos, anteaters, sloths
    • No canines or incisors
    • Cheek teeth small and simple or also absent
    • Specialized insectivores
    • 31 species; Neotropics
    • Taxonomic note: formerly part of polyphyletic Order Edentata
    • Taxonomic note: sometimes further split into 2 Orders: Pilosa (anteaters + sloths) and Cingulata (armadillos)
Armadillo Skull
Nine-banded Armadillo skull, Dasypus novemcinctus (Family Dasypodidae)
Anteater Skull
Giant Anteater skull, Myrmecophaga tridactyla (Family Myrmecophagidae)
2-Toed Sloth
Two-toed Sloth, Choloepus sp. (Family Megalonychidae)
9-Banded Armadillo
Nine-banded Armadillo, Dasypus novemcinctus (Family Dasypodidae); FL
Giant Anteater
Giant Anteater, Myrmecophaga tridactyla (Family Myrmecophagidae)

    Order Rodentia
    • Rodents
    • Mostly small size
    • 1 pair of continuously growing incisors
    • Large diastema between incisors and cheek teeth
    • Diverse diets, but majority herbivores, seed-eaters
    • Includes 40% of all mammal species
Rat Skull
Brown Rat skull, Rattus norvegicus (Family Muridae)
See also labeled photo.
Muskrat Skull
Common Muskrat skull, Ondatra zibethicus (Family Cricetidae)
See also labeled photo.
Porcupine Skull
North American Porcupine skull, Erethizon dorsatum (Family Erethizontidae)
Yellow bellied Marmot
Yellow-bellied Marmot, Marmota flaviventris (Family Sciuridae); CA
W Harvest Mouse
Western Harvest Mouse, Reithrodontomys megalotis (Family Cricetidae); CA
Red-rumped Agouti, Dasyprocta leporina (Family Dasyproctidae)
Rustynosed Rat
Rusty-nosed Rat, Oenomys hypoxanthus (Family Muridae); Kenya
Naked Mole Rats
Naked Mole-rats, Heterocephalus glaber (Family Bathyergidae)
Capybara, Hydrochoerus hydrochaeris (Family Hydrochoeridae), the world's largest rodent (up to 75 kg)

    Order Lagomorpha
    • Rabbits and pikas
    • Similar to rodents
    • Tail very short
    • Two pairs of upper incisors (2nd pair behind first)
    • Fenestrated skull
    • 91 species; worldwide
Rabbit Skull
Rabbit Skull, Lepus sp. (Family Leporidae)
Desert Cottontail
Desert Cottontail, Sylvilagus audubonii (Family Leporidae); CO
American Pika
American Pika, Ochotona princeps (Family Ochotonidae); CO

    (Order Scandentia)
    • Tree shrews
    • Generally squirrel-like, but with more binocular vision
    • Insectivore-like dentition; large orbits and complete post-orbital bar
    • 20 species
    (Order Dermoptera)
    • Colugos (aka "Flying Lemurs")
    • Large, arboreal gliders with membrane between legs
    • Large, raised orbit; incisors comb-like
    • 2 species

    You do not need to know these orders
Large Tree Shrew
Large Tree Shrew, Tupaia tana (Family Tupaiidae)
Tree Shrew Skull
Horsfield's Tree Shrew skull, Tupaia javanica (Family Tupaiidae)
Colugo Skull
Sunda Colugo skull, Galeopterus variegatus (Family Cynocephalidae)
Order Scandentia Order Dermoptera

    Order Primates
    • Lemurs, monkeys, apes
    • Cheek teeth squarish
    • Large, forward-facing eyes
    • Reduced muzzle but larger brain
    • Grasping hands with nails instead of claws
    • 388 species, tropics (humans worldwide)
    • Notable subgroups:
      • Strepsirhini ("Prosimians" in part) include the more primitive lemurs, bush babies, and lorises.
      • Anthropoids are the monkeys, tamarins, marmosets, and apes
      • Hominoidea are the lesser apes (gibbons and siamangs) and great apes (orangutan, gorilla, chimps, and humans).
Slow Loris Skull
Sunda Slow Loris Skull, Nycticebus coucang (Family Lorisidae)
Baboon Skull
Hamadryas Baboon skull, Papio hamadryas (Family Cercopithecidae)
Chimp Skull
Chimpanzee skull, Pan troglodytes (Family Hominidae)
Ruffed Lemur Skull
Ruffed Lemur Skull, Varecia variegata (Family Lemuridae)
Monkey Skull
Vervet Monkey Skull, Cercopithecus aethiops (Family Cercopithecidae)
See also labeled photo.
Gorilla Skull
Gorilla skull, male, Gorilla gorilla (Family Hominidae)
Bush Baby
Bush Baby, Galago sp. (Family Galagonidae)
Ring-tailed Lemur
Ring-tailed Lemur, Lemur catta (Family Lemuridae)
Squirrel Monkeys
Common Squirrel Monkey, Saimiri sciureus (Family Cebidae)
Cottontop Tamarin
Cotton-top Tamarin, Saguinus oedipus (Family Callitrichidae)
Olive Baboon
Olive Baboon, Papio anubis, Kenya (Family Cercopithecidae)
Japanese Macaques
Japanese Macaques, Macaca fuscata (Family Cercopithecidae)
Crested Gibbon
Male Yellow-cheeked Gibbon, Nomascus gabriellae (Family Hylobatidae)
Bonobo, Pan paniscus (Family Hominidae)
Western Gorilla, Gorilla gorilla (Family Hominidae)

    Order Eulipotyphla
    • Shrews, moles, hedgehogs.
    • Generalized, ancestral characteristics
    • Cusps on cheek teeth form triangular pattern
    • Most are small sized
    • Relatively small brains
    • Pointed snouts with small eyes and ears
    • Primarily insectivorous
    • Formerly part of polyphyletic Order Insectivora
    • 442 species
Mole Skull
Eastern Mole skull, Scalopus aquaticus (Family Talpidae)
European Hedgehog, Erinaceus europaeus (Family Erinaceidae)
Short-tailed Shrew
Short-tailed Shrew, Blarina carolinensis? (Family Soricidae)

    Order Chiroptera
    • Bats
    • Forelimb modified into wing
    • Forearm, fingers greatly elongated
    • Diet varies, including fruit, insects, nectar
    • >1100 species; worldwide
    • Two suborders:
      • Megachiroptera are the large, tropical fruit bats (aka flying foxes) with no echolocation
      • Microchiroptera are mostly smaller; all use echolocation and are predominantly insectivorous; they often have nose flaps and very large, complex ears
Fruit Bat Skull
Lyle's Flying Fox skull, Pteropus lylei (Family Pteropodidae); a frugivore
Lesser Dawn Bat Skull
Lesser Dawn Bat skull, Eonycteris spelaea (Family Pteropodidae); a nectivore
Fruit Bat Skull
Javan Pipistrelle skull, Pipistrellus javanicus (Family Vespertilionidae); an insectivore
Rodriguez Fruit Bat
Rodriguez Fruit Bat, Pteropus rodricensis (Family Pteropodidae)
Big Brown Bat
Big Brown Bat, Eptesicus fuscus (Family Vespertilionidae); CA
Jamaican Fruit Bats
Jamaican Fruit-eating Bats, Artibeus jamaicensis (Family Phyllostomidae)

    Order Carnivora
    • Dogs, cats, bears, weasels, seals, etc.
    • Carnassial dentition: last upper premolar & 1st lower molar form specialized cutting teeth
    • Well developed canines
    • Most are predators
    • Pinnipeds are aquatic, with limbs modified into flippers
    • 282 species, now worldwide
Bobcat Skull
Bobcat skull, Lynx rufus (Family Felidae)
See also labeled photo.
Jackal Skull
Side-striped Jackal skull, Canis adustus (Family Canidae)
See also labeled photo.
Black Bear Skull
Black Bear skull, Ursus americanus (Family Ursidae)
Mink Skull
Mink skull, Mustela vison (Family Mustellidae)
Mongoose Skull
Small Indian Mongoose skull, Herpestes javanicus (Family Herpestidae)
Sea Lion Skull
California Sea Lion skull, Zalophus californianus (Family Otariidae)
African Lions
African Lions, Panthera leo (Family Felidae); Kenya
Red Fox
Red Fox, Vulpes vulpes (Family Canidae); CA
Sun Bear
Sun Bear, Helarctos malayanus (Family Ursidae)
Northern Raccoons, Procyon lotor (Family Procyonidae); CA
Meerkats, Suricata suricatta (Family Herpestidae)
Striped Skunk
Striped Skunk, Mephitis mephitis (Family Mephitidae)
Spotted Hyaenas
Spotted Hyaenas, Crocuta crocuta (Family Hyaenidae); Kenya
Northern Elephant Seals
Northern Elephant Seals, Mirounga anguistirostris (Family Phocidae); CA
Sea Lions
California Sea Lions, Zalophus californianus (Family Otariidae); CA

    Order Perissodactyla
    • Odd-toed Ungulates
    • 1 or 3 toes per foot
    • Large size
    • Elongated rostrum
    • Herbivorous; hind-gut fermenters
    • Unlike Artiodactyls, rhino horns are entirely keratinous and lack a bone core
    • 16 species
Horse Skull
Domestic Horse skull, Equus caballus (Family Equidae)
Burchells Zebras
Burchell's Zebras, Equus burchelli (Family Equidae); Kenya
Malayan Tapirs
Malayan Tapirs, Tapirus indicus (Family Tapiridae)
Rhino Skull
Sumatran Rhinoceros skull, Dicerorhinus sumatrensis (Family Rhinocerotidae)
International Wildlife Museum
Indian Rhinoceros
Indian Rhinoceros, Rhinoceros unicornis (Family Rhinocerotidae)
Black Rhinoceros
Black Rhinoceros, Diceros bicornis (Family Rhinocerotidae)

    Order Artiodactyla
    • Even-toed Ungulates
    • 2 or 4 toes per foot
    • Diverse in size, shape
    • Omnivorous or herbivorous; many are foregut fermenters
    • Many have horns, ossicones, or antlers
    • 239 species, worldwide
    • Taxonomic note: This traditional order is paraphyletic; the clade that includes artiodactyls and whales is called Cetartiodactyla
Deer Skull
White-tailed Deer skull, Odocoileus virginanus (Family Cervidae), ♂ with antlers
Impala Skull
Impala skull, Aepyceros melampus (Family Bovidae), ♂ with horns
Peccary Skull
Collared Peccary skull, Pecari (Tayassu) tajacu (Family Tayassuidae)
Warthog Skull
Common Warthog, Phacochoerus africanus (Family Suidae); note tusks
Giraffe Skull
Southern Giraffe skull, Giraffa giraffa (Family Giraffidae), ♂ with ossicones
Peccary Skull
Pronghorn skull, Antilocapra americana (Family Antilocapridae), ♂ with horns
♂ White-tailed Deer, Odocoileus virginianus (Family Cervidae); TX
♂ Impala, Aepyceros melampus (Family Bovidae); Kenya
Collared Peccary
Collared Peccary, Pecari (Tayassu) tajacu (Family Tayassuidae)
Common Warthog, Phacochoerus africanus (Family Suidae); Kenya
Dromedary, Camelus dromedarius (Family Camelidae)
Hippopotamuses, Hippopotamus amphibians (Family Hippopotamidae); Kenya
African Buffalo
African Buffalo, Syncerus caffer (Family Bovidae); Kenya
Masai Giraffe, Giraffa tippelskirchi (Family Giraffidae); Kenya
Pronghorn, Antilocapra americana (Family Antilocapridae); WY

    Order Cetacea
    • Whales & Dolphins
    • Fully aquatic
    • Very large size with streamlined shape
    • Front flippers; no hind limbs
    • Broad crescent-shaped tail fluke
    • Nostril on top of head (blowhole)
    • Skulls often asymmetric
    • 88 species; oceans and some rivers
    • Two extant suborders:
      • Odontoceti (toothed whales, dolphins) have simple homodont teeth
      • Mysticeti (baleen whales) lack teeth but have baleen: keratin sheets used to strain food
Gray Whale Skull
Gray Whale skull, Eschrichtius robustus (Family Eschrichtiidae)
San Diego Natural History Museum
White-sided Dolphin Skull
Pacific White-sided Dolphin skull, Lagenorhynchus obliquidens (Family Delphinidae)
Bottle-nosed Dolphin
Bottle-nosed Dolphin, Tursiops truncatus (Family Delphinidae)
Bowhead Whale Baleen
Bowhead Whale baleen, Balaena mysticetus (Family Balaenidae)
Gray Whale
Gray Whale, Eschrichtius robustus (Family Eschrichtiidae)
Beluga Whale, Delphinapterus leucas (Family Monodontidae)
This page last updated 22 December 2017 by Udo M. Savalli ()
Images and text Udo M. Savalli. All rights reserved.