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
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Subclass Prototheria — Monotremes
Characteristics
- Most primitive extant mammals
- Lay eggs
- Mammary glands lack nipples
- Lack pinnae (external ears)
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Order Monotremata
- Echidnas and Platypus
- Only extant order in Subclass
- 5 living species are highly specialized, toothless
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Duck-billed Platypus Ornithorhynchus anatinus (Family Ornithorhynchidae), skull
Diet: aquatic invertebrates, worms
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Duck-billed Platypus Ornithorhynchus anatinus (Family Ornithorhynchidae), taxidermy mount
Short-nosed Echidna Skull, Tachyglossus aculeatus (Family Tachyglossidae)
Diet: ants, termites
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Short-nosed Echidna, Tachyglossus aculeatus (Family Tachyglossidae)
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Subclass Allotheria — Multituberculates & Relatives
Order Multituberculata
- Extinct: lived from late Jurassic to late Eocene (160 Ma to 35 Ma)
- Diverse and successful during Cretaceous and early Paleogene Periods
- Skulls superficially rodent-like
- Characterized by molars with large number of cusps, typically arranged in a double row
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Fossil molar of Mesodma formosa (Family Neoplagiaulacidae); Late Cretaceous Period, South Dakota
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A Multituberculate, Catopsbaatar catopsaloides (Family Djadochtatheriidae);
Source: Kielan-Jaworowska & Hurum 2006. Acta Palaeontologica Polonica. Creative Commons Attribution 2.0
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Subclass Metatheria — Marsupials
Characteristics
- 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
- 400 species in Neotropics, Australian region
- There are 4 additional orders not shown below nor represented in lab
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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.
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Virginia Opossum Skull, Didelphis virginiana (Family Didelphidae)
Diet: omnivore
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Virginia Opossum, Didelphis virginiana (Family Didelphidae); taxidermy mount
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Shorttailed Opossum, Monodelphis domestica (Family Didelphidae)
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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
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Tasmanian Devil Skull, Sarcophilus harrisii (Family Dasyuridae)
Diet: vertebrates
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Tasmanian Devil, Sarcophilus harrisii (Family Dasyuridae)
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Numbat skull, Myrmecobius fasciatus (Family Myrmecobiidae)
Diet: termites
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Saber-toothed Marsupial Skull Fossil, Thylacosmilus† sp. (Family Thylacosmilidae)
Diet: large vertebrates
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Eastern Quoll, Dasyurus viverrinus (Family Dasyuridae);
Source: A. E. Brehm. Het Leven der Dieren. Retrieved from Project Gutenberg
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Thylacine (aka Tasmanian Tiger), Thylacinus cynocephalus (Family Thylacinidae†);
Source: A. E. Brehm. Het Leven der Dieren. Retrieved from Project Gutenberg
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Order Diprotodontia
- Kangaroos, Wallabies, Koalas, Wombats, etc.
- Mostly herbivorous or omnivorous
- Includes largest marsupials
- Note broad grinding molars, diastema
- Australia
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Kangaroo skull, Macropus sp. (Family Macropodidae)
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Eastern Gray Kangaroo, Macropus giganteus (Family Macropodidae)
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Goodfellow's Tree Kangaroo, Dendrolagus matschiei (Family Macropodidae)
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Common Wombat skull, Vombatus ursinus (Family Vombatidae)
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Southern Hairy-nosed Wombat, Lasiorhinus latifrons (Family Vombatidae)
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Brush-tailed Bettong, Bettongia penicillata (Family Potoroidae)
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Parma Wallaby, Macropus parma (Family Macropodidae)
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Koala, Phascolarctos cinereus (Family Phascolarctidae)
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Sugar Glider, Petaurus breviceps (Family Petauridae)
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Subclass Eutheria — Placental Mammals
Characteristics
- Extended gestation with complex placenta
- Maximum dental formula: 3/3, 1/1, 4/4, 3/3
- Morphologically very diverse
- 6170 species, worldwide
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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
- 90 species total in 6 extant orders (including the Proboscidia listed below)
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West Indian Manatee, Trichechus manatus; Order Sirenia: FL
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West Indian Manatee, Trichechus manatus; Order Sirenia: FL
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Steller's Sea Cow† Skull, Hydrodamalis gigas; Order Sirenia
Diet: kelp (sea weed)
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Rock Hyrax skull, Procavia capensis; Order Hyracoidea
Diet: herbivore
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Yellow-spotted Hyrax, Heterohyrax brucei; Order Hyracoidea; Kenya
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Lesser Tenrec, Echinops telfairi; Order Afrosoricida
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Four-toed Elephant Shrew skull, Petrodromus tetradactylus; Order Macroscelidea
Diet: insects
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Round-eared Elephant Shrew, Macroscelides proboscideus; Order Macroscelidea
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Aardvark skull, Orycteropus afer; Order Tubulidentata
Diet: termites
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Order Proboscidia
- Elephants
- Part of Clade Afrotheria (above)
- 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
- Mostly hairless
- 3 species, Africa, Asia
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Asian Elephant Skull, Elephas maximus (Family Elephantidae)
San Diego Natural History Museum
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African Elephant molar, Loxodonta africana (length=205 mm)
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African (Bush) Elephants, Loxodonta africana (Family Elephantidae); Kenya
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Order Xenarthra
- Armadillos, anteaters, sloths
- No canines or incisors
- Cheek teeth small and simple or also absent
- Specialized insectivores
- 38 species; Neotropics
- Taxonomic note: sometimes split into 2 Orders: Pilosa (anteaters + sloths) and Cingulata (armadillos)
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Pale-throated Three-toed Sloth skull, Bradypus tridactylus (Family Bradypodidae)
Diet: herbivore
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Two-toed Sloth, Choloepus sp. (Family Megalonychidae)
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Nine-banded Armadillo, Dasypus novemcinctus (Family Dasypodidae); FL
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Giant Anteater skull, Myrmecophaga tridactyla (Family Myrmecophagidae)
Diet: ants, termites
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Giant Anteater, Myrmecophaga tridactyla (Family Myrmecophagidae)
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Nine-banded Armadillo skull, Dasypus novemcinctus (Family Dasypodidae)
Diet: insects, esp. beetle grubs
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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
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Brown Rat skull, Rattus norvegicus (Family Muridae)
See also labeled photo.
Diet: omnivore
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Common Muskrat skull, Ondatra zibethicus (Family Cricetidae)
See also labeled photo.
Diet: herbivore
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Plantain Squirrel skull, Callosciurus notatus (Family Sciuridae)
Diet: fruits, leaves
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Guinea Pig Skull, Cavia porcellus (Family Caviidae)
Diet: Purina Guinea Pig Chow
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American Beaver skull, Ondatra zibethicus (Family Cricetidae)
Diet: tree bark, aquatic vegetation
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North American Porcupine skull, Erethizon dorsatum (Family Erethizontidae)
Diet: herbivore, esp twigs, bark
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Yellow-bellied Marmot, Marmota flaviventris (Family Sciuridae); CA
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Western Harvest Mouse, Reithrodontomys megalotis (Family Cricetidae); CA
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Red-rumped Agouti, Dasyprocta leporina (Family Dasyproctidae)
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Rusty-nosed Rat, Oenomys hypoxanthus (Family Muridae); Kenya
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Naked Mole-rats, Heterocephalus glaber (Family Bathyergidae)
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Capybara, Hydrochoerus hydrochaeris (Family Hydrochoeridae), the world's largest rodent (up to 75 kg)
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Little Pocket Mouse, Perognathus longimembris (Family Heteromyidae); AZ
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North American Porcupine, Erethizon dorsatum (Family Erethizontidae)
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American Beaver, Castor canadensis (Family Castoridae); a semiaquatic rodent
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Order Lagomorpha
- Rabbits and pikas
- Similar to rodents
- Tail very short
- Two pairs of upper incisors (2nd pair behind first)
- Fenestrated skull
- 97 species; worldwide
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Rabbit Skull, Oryctolagus sp.? (Family Leporidae)
Diet: herbivore
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Desert Cottontail, Sylvilagus audubonii (Family Leporidae); CO
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American Pika, Ochotona princeps (Family Ochotonidae); CO
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Jackrabbit Skull, Lepus sp. (Family Leporidae)
Diet: herbivore
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Black-tailed Jackrabbit, Lepus californicus (Family Leporidae); AZ
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American Pika, Ochotona princeps (Family Ochotonidae); CO
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Minor Orders:
(Order Scandentia)
- Tree shrews
- Generally squirrel-like, but with more binocular vision
- Insectivore-like dentition; large orbits and complete post-orbital bar
- 23 species
(Order Dermoptera)
- Colugos (aka "Flying Lemurs")
- Large, arboreal gliders with membrane between legs
- Large, raised orbit; incisors comb-like
- 2 species
(Order Pholidota)
- Pangolins
- Covered in hard keratin scales
- Limbs short with long claws
- Skull simple; lack teeth
- 8 species
You do not need to know these orders
Order Scandentia:
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Order Dermoptera:
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Order Pholidota:
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Horsfield's Tree Shrew skull, Tupaia javanica (Family Tupaiidae)
Diet: insects
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Sunda Colugo skull, Galeopterus variegatus (Family Cynocephalidae)
Diet: herbivore (leaves)
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Sunda Pangolin skull, Manis javanica (Family Manidae)
Diet: ant/termite specialist
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Large Tree Shrew, Tupaia tana (Family Tupaiidae)
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Philippine Colugo, Cynocephalus volans (Family Cynocephalidae)
Source: F. Specht 1927, Brehms Tierleben.
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Pangolin, Manus sp. (Family Manidae)
Source: Anonymous 1881, National Encyclopedia.
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Order Primates
- Lemurs, monkeys, apes
- Cheek teeth squarish
- Large, forward-facing eyes
- Reduced muzzle but larger brain
- Grasping hands with nails instead of claws
- 523 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 (orangutans, gorillas, chimps, and humans).
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Sunda Slow Loris Skull, Nycticebus coucang (Family Lorisidae)
Diet: tree sap, nectar, fruit
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Hamadryas Baboon skull, Papio hamadryas (Family Cercopithecidae)
Diet: omnivore
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Chimpanzee skull, Pan troglodytes (Family Hominidae)
Diet: fruit, etc.
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Ruffed Lemur Skull, Varecia variegata (Family Lemuridae)
Diet: fruit
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Vervet Monkey Skull, Chlorocebus sp. (Family Cercopithecidae)
See also labeled photo.
Diet: omnivore
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Gorilla skull, male, Gorilla gorilla (Family Hominidae)
Diet: herbivore
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Strepsirhine "Prosimians":
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Bush Baby, Galago sp. (Family Galagonidae)
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Ring-tailed Lemur, Lemur catta (Family Lemuridae)
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Coquerel's Sifaka, Propithecus coquereli (Family Indriidae)
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Ceboidae — New World monkeys, tamarins and marmosets:
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Common Squirrel Monkey, Saimiri sciureus (Family Cebidae)
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Cotton-top Tamarin, Saguinus oedipus (Family Callitrichidae)
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Black-handed Spider Monkey, Ateles geoffroyi (Family Atelidae)
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Cercopithecoidae — Old World monkeys:
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Guereza Colobus, Colobus guereza, Kenya (Family Cercopithecidae)
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Olive Baboon, Papio anubis, Kenya (Family Cercopithecidae)
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Japanese Macaques, Macaca fuscata (Family Cercopithecidae)
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Hominoidea — Apes:
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Male Yellow-cheeked Gibbon, Nomascus gabriellae (Family Hylobatidae)
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Bonobo, Pan paniscus (Family Hominidae)
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Western Gorilla, Gorilla gorilla (Family Hominidae)
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Order Eulipotyphla
- Shrews, moles, hedgehogs.
- Generalized, ancestral characteristics
- Cusps on cheek teeth tytpically form triangular pattern
- Anterior pair of incisors enlarged
- Canines similar to incisors: tricky to determine dental formula
- Most are small sized
- Relatively small brains
- Pointed snouts with small eyes and ears
- Primarily insectivorous
- Formerly part of polyphyletic Order Insectivora
- 573 species
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European? Hedgehog skull, Erinaceus sp. (Family Erinaceidae)
Diet: invertebrates, fruit, etc.
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Eastern Mole skull, Scalopus aquaticus (Family Talpidae)
Diet: worms, insects
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Asian House Shrew skull, Suncus murinus (Family Soricidae)
Diet: insects
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European Hedgehog, Erinaceus europaeus (Family Erinaceidae)
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Short-tailed Shrew, Blarina carolinensis? (Family Soricidae)
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Common Shrew, Sorex araneus (Family Soricidae)
Image in public domain
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Order Chiroptera
- Bats
- Forelimb modified into wing
- Forearm, fingers greatly elongated
- Diet varies, including fruit, insects, nectar
- 1450 species; worldwide
- Two suborders (may not be monophyletic):
- Megachiroptera are the large, tropical fruit bats (aka flying foxes) with limited echolocation
- Microchiroptera are mostly smaller; all use echolocation and are predominantly insectivorous; they often have nose flaps and very large, complex ears
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Lyle's Flying Fox skull, Pteropus lylei (Family Pteropodidae)
Diet: fruit
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Lesser Dawn Bat skull, Eonycteris spelaea (Family Pteropodidae)
Diet: nectar
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Javan Pipistrelle skull, Pipistrellus javanicus (Family Vespertilionidae)
Diet: insects
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Hammer-headed Bat skull, Hypsignathus monstrosus (Family Pteropodidae)
Diet: fruit
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Long-tongued Nectar Bat skull, Macroglossus minimus (Family Pteropodidae)
Diet: nectar
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Bicoloured Roundleaf Bat skull, Hipposideros bicolor (Family Vespertilionidae)
Diet: insects
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Giant Fruit Bat, Pteropus giganteus (Family Pteropodidae)
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Rodriguez Fruit Bat, Pteropus rodricensis (Family Pteropodidae)
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Jamaican Fruit-eating Bats, Artibeus jamaicensis (Family Phyllostomidae)
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Big Brown Bat, Eptesicus fuscus (Family Vespertilionidae); CA
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Pipistrelle, Neoromicia sp.?(Family Vespertilionidae); Kenya
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Hollow-faced Bat, Nycteris sp. (dead) (Family Nycteridae); Kenya
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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
- 314 species, now worldwide
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Bobcat skull, Lynx rufus (Family Felidae)
See also labeled photo.
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Side-striped Jackal skull, Canis adustus (Family Canidae)
See also labeled photo.
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Saber-toothed Cat skull, Smilodon fatalis† (Family Felidae)
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Mink skull, Mustela vison (Family Mustellidae)
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Small Indian Mongoose skull, Herpestes javanicus (Family Herpestidae)
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California Sea Lion skull, Zalophus californianus (Family Otariidae)
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Aardwolf skull, Proteles cristatus (Family Hyaenidae)
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Northern Racoon skull, Procyon lotor (Family Procyonidae)
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Black Bear skull, Ursus americanus (Family Ursidae)
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Lesser Panda, Ailurus fulgens (Family Ailuridae)
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Sun Bear, Helarctos malayanus (Family Ursidae)
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Striped Skunk, Mephitis mephitis (Family Mephitidae)
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Red Fox, Vulpes vulpes (Family Canidae); CA
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Banded Mongoose, Mungos mungo (Family Herpestidae)
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African Lions, Panthera leo (Family Felidae); Kenya
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Northern Raccoons, Procyon lotor (Family Procyonidae); CA
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Aardwolf, Proteles cristatus (Family Hyaenidae)
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Spotted Hyaenas, Crocuta crocuta (Family Hyaenidae); Kenya
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Spot-necked Otter, Hydrictis maculicollis (Family Mustellidae)
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Northern Elephant Seals, Mirounga anguistirostris (Family Phocidae); CA
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California Sea Lions, Zalophus californianus (Family Otariidae); CA
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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
- 19 species
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Domestic Horse skull, Equus caballus (Family Equidae)
Diet: herbivore
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Burchell's Zebras, Equus burchelli (Family Equidae); Kenya
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Malayan Tapirs, Tapirus indicus (Family Tapiridae)
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Sumatran Rhinoceros skull, Dicerorhinus sumatrensis (Family Rhinocerotidae)
International Wildlife Museum
Diet: herbivore
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Indian Rhinoceros, Rhinoceros unicornis (Family Rhinocerotidae)
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Black Rhinoceros, Diceros bicornis (Family Rhinocerotidae)
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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
- 266 species, worldwide
- Taxonomic note: This traditional order is paraphyletic; the clade that includes artiodactyls and whales is called Cetartiodactyla
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White-tailed Deer skull, Odocoileus virginanus (Family Cervidae), ♂ with antlers
Diet: herbivore
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Impala skull, Aepyceros melampus (Family Bovidae), ♂ with horns
Diet: herbivore
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Collared Peccary skull, Pecari (Tayassu) tajacu (Family Tayassuidae)
Diet: herbivorous, omnivorous
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Common Warthog, Phacochoerus africanus (Family Suidae); note tusks
Diet: omnivorous
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Southern Giraffe skull, Giraffa giraffa (Family Giraffidae), ♂ with ossicones
Diet: herbivorous
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Pronghorn skull, Antilocapra americana (Family Antilocapridae), ♂ with horns
Diet: herbivorous
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Reeve's Muntjac, Muntiacus reevesi (Family Cervidae)
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Hippopotamus skull, Hippopotamus amphibius (Family Hippopotamidae)
Diet: herbivorous
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Alpaca skull, Vicugna pacos (Family Camelidae)
Diet: herbivorous
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♂ White-tailed Deer, Odocoileus virginianus (Family Cervidae); TX
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♂ Impala, Aepyceros melampus (Family Bovidae); Kenya
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Collared Peccary, Pecari (Tayassu) tajacu (Family Tayassuidae)
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Common Warthog, Phacochoerus africanus (Family Suidae); Kenya
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Dromedary, Camelus dromedarius (Family Camelidae)
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Hippopotamuses, Hippopotamus amphibians (Family Hippopotamidae); Kenya
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African Buffalo, Syncerus caffer (Family Bovidae); Kenya
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Masai Giraffe, Giraffa tippelskirchi (Family Giraffidae); Kenya
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Pronghorn, Antilocapra americana (Family Antilocapridae); WY
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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
- 98 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
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Gray Whale skull, Eschrichtius robustus (Family Eschrichtiidae)
San Diego Natural History Museum
Diet: filter feeder on benthic crustaceans
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Pacific White-sided Dolphin skull, Lagenorhynchus obliquidens (Family Delphinidae)
Diet: fish
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Bottle-nosed Dolphin, Tursiops truncatus (Family Delphinidae)
Bowhead Whale baleen, Balaena mysticetus (Family Balaenidae)
Diet: filter feeder on zooplankton
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Gray Whale, Eschrichtius robustus (Family Eschrichtiidae)
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Beluga Whale, Delphinapterus leucas (Family Monodontidae)
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