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26 Cards in this Set
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Key Characteristics of Monotremes
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• Skull Toothless, except in young platypuses
• Cranial sutures disappear early in life • Elongate and beak-like rostrum covered by leathery sheath • Electroreceptor present on rostrum • Sclerotic Cartilages in the eyes • Lacrimal and Frontal bones absent • Septomaxilla present in skull • Auditory bulla absent, but middle ear partially surrounded by oval tympanic ring • Cochlea curved, but not coiled • Sprawled posture of forelimbs, humerus remains roughly horizontal to substrate • Ankle spurs in adult males for transporting venom • Interclavicles, clavicles, precoracoids, coracoids, and scapula retained in pectoral girdle • Epipubic bones large • Cervical ribs present • Ten X chromosomes (females) and 5 X 5Y chromosomes (Males) • Oviparous (reproduction with laying eggs) • Telolecithal eggs with meroblastic cleavage • Left ovary functional in platypus, both ovaries functional in echidnas • “Egg tooth” present in fetus to break out of shell • Cloraca present, penis attached to wall of cloaca in males • Testes abdominal and seminal vesicles absent • Mammae lack nipples |
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Key Characteristics of Metatherians
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• Skull frequently with small, narrow braincase
• Cerebral Hemispheres small with simple convolutions • Auditory bullae ossified, when present usually formed largely by the alisphenoid bone • Palate characteristically has large vacuities • Angular process of the dentary bone inflected medially • Upper and lower incisors never equal in number (except in Vombatidae) • Only third upper and lower premolars (p3/3) replaced by adult teeth • Feet often specialized for arboreal or bipedal locomotion • Epipubic bones extend forward from the pubic bones in both sexes • Marsupium (an abdominal pouch) or abdominal folds containing nipples present in many species • Female reproductive tract bifid (vagina and uterus doubled) • Testes contained in scrotum anterior to penis (except in marsupial “moles”) |
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Key Characteristics of Afrosoricida
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• Cloaca (common opening for urogenital and anal openings)
• Tenrecs and otter shrews o Incomplete zygomatic arch o Zalambdodont molars o Males that retain abdominal testes (no scrotum) • Golden Moles o Zygomatic arch formed by elongate maxillae o Zalambdodont molars o Skull conical o Pair of tabular bones in occipital area (absent in other mammals) o Eyes vestigial o Snout with leathery pad o Malleus greatly enlarged |
Golden Moles
o Zygomatic arch formed by elongate maxillae o Zalambdodont molars o Skull conical o Pair of tabular bones in occipital area (absent in other mammals) o Eyes vestigial o Snout with leathery pad o Malleus greatly enlarged |
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Key Characteristics of Macroscelidae
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• Complete zygomatic arches and auditory bullae
• Double-rooted upper canines • Quadrate molars • Fenestrated palate • Snout long and flexible |
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Key Characteristics of Tubulidentata
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• Elongate, conical skull
• Elaborate turbinal bones • Complete zygomatic arches • Incisors and canines absent • Cheek teeth with hexagonal prisms of dentine coated with cementum • Cheek teeth rootless and ever-growing • Milk teek small and lost before birth • Stout nails resembling hooves on digits • Thick, sparsely haired skin • Long protrusible tongue |
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Key Characteristics of Proboscideans
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• Long, Muscular trunk
• Large ears • Pair of large tusks (upper incisors) • Sequentially replaced cheek teeth with many transverse lophs • Skull short and high, with a prominent lambdoidal crest • Splayed toes cushioned by a dense heel pad |
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Key Characteristics of Hyracoids
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• Rabbit-sized animals with short tails
• Three-toed hind feet with four-toed forefeet • Digits bear flattened, hoof-like nails, except clawed second digit of the pes • Feet mesaxonic (the plane of symmetry of the foot goes through the third digit) • Postorbital bar present • Small bullae • Single pair of tusk-like upper incisors, two pairs of lower incisors, with diastema between ever growing incisor and rooted cheek teeth • Molar lophodont |
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Key Characteristics of Sirenians
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• Large, nearly hairless body adapted for a fully aquatic lifestyle
• Forelimbs flipper-like, hindlimb bones • Horizontal tail fluke, no dorsal fin • Lungs and diaphragm greatly elongated, flattened and unilobed • Ear pinnae absent • Dorsally positioned, valve-like nostrils • Premaxillae ventrally deflected, with small upper tusks in dugongs • Nasal bones absent or reduced • Dentary broad • Sequentially replaced cheek teeth in manatees • Middle ear ossicles massive • Postcranial bones that are dense and heavy (show pachyostosis) |
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Key Characteristics of Xenarthrans
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• Lumbar vertebrae with xenarthrous articulations
• Incisors reduced or absent • Deciduous teeth absent • Cheek teeth, when present, lack enamel • Septomaxilla in skull • Tympanic bone annular • Armadillos o Plates or bony osteoderm covered by horny epidermis, present on head and body o Hair sparse and usually occurs between plates, on limbs, and ventral body surface o Skull elongate and dorsoventrally flattened o Zygomatic arch complete o Mandible slim and elongate o Teeth homodont and nearly cylindrical o Second and third cervical vertebrae anchor pelvis o Forefeet and hind feet bear large, heavy claws • Anteaters o Zygoma incomplete o Teeth absent o Dentary bone long and delicate, and mandibular rami unfused o Tongue long, slender, and protrusible and covered with sticky saliva o Tongue muscles originate from posterior sternum o Soft palate extremely long, extending posteriorly to the level of the fifth cervical vertebra o Third digit enlarged, bearing a stout, recurved claw • Sloths o Skull short with reduced rostrum o Zygomatic arch robust but incomplete and bearing a ventral jugal process o Premaxilla greatly reduced o Teeth, 5 maxillary and 4-5 mandibular teeth present o Teeth cylindrical with a central core of soft dentine surrounded by hard dentine and cementum o Eight to nine cervical vertebrae o Three syndactylous (fused) digits with long and laterally compressed claws |
• Sloths
o Skull short with reduced rostrum o Zygomatic arch robust but incomplete and bearing a ventral jugal process o Premaxilla greatly reduced o Teeth, 5 maxillary and 4-5 mandibular teeth present o Teeth cylindrical with a central core of soft dentine surrounded by hard dentine and cementum o Eight to nine cervical vertebrae o Three syndactylous (fused) digits with long and laterally compressed claws |
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Key Characteristics of Pangolins
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• Keratinous scales cover dorsal surface of body and tail
• Skull conical and dentary bones slender • Teeth absent • Tongue extremely long and vermiform and originates on xiphoid process of sternum • Manus and pes with long, recurved claws borne on unusual, deeply notched ungula phalanges |
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Key Characteristics of Colugos
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• Face lemur-like and eyes large
• Dorsal pelage cryptic against tree bark • Lateral upper incisor caniniform, and first two lower incisors are broad and comb-like • Canine double rooted • Broad, furred gliding membranes present from neck to finger, between limbs, and from hind foot to tail tip |
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Key Characteristics of Treeshrews
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• Upper incisors caniniform and upper canine reduced
• Tooth comb consisting of middle four lower incisors present • Zygomatic arch with prominent hole • Postorbital processes join zygoma to form postorbital bar |
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Key Characteristics of Primates
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• Primates radiated in arboreal habitats, and most of the characteristics of the group are arboreal adaptations
o Grasping hands and feet with opposable thumbs and toes o Nails present on all or most digits (may be lost secondarily) o Calcaneum elongated o Orbits rotated forward, interorbital narrowed, and orbital cavity enlarged o Ethmoid bone exposed on the inner orbital wall o Stereoscopic vision (retinal axons project to both ipsilateral and contralateral sides of the brain) o Increased fetal brain size compared to fetal body weight retained in neonates o Sylvain sulcus and triradiate calcarine sulcus both present on brain surface o Testes descend early in life o Urogenital sinus absent in females o Long gestation times relative to body size o Sexual maturity relatively late in life o Auditory bulla bony the floor derived from petrosal bone o Extension of the ectotympanic into the auditory meatus o Loss of one incisor and one premolar from the ancestral eutherian condition |
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Key Characteristics of Strepsirrhini
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• Lower incisors that form a tooth comb used in grooming (may be secondarily modified)
• Rhinarium naked and moist, with unfused nasal prominences, median cleft, and comma-shaped nostrils |
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Key Characteristics of Haplorrhini
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• Rhinarium dry, nostrils oval, and no median cleft
• Hemochorial placenta • Fovea centralis in the retine • Postorbital plate present |
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Key Characteristics of Rodents
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• One pair of enlarged upper and lower incisors, each tooth sharply beveled and ever growing
• Broad diastema (space) between incisors and cheek teeth of both upper and lower jaws • Canines and some cheek teeth absent • Incisor enamel restricted to anterior surface • Paraconid lost on lower cheek teeth • Orbital cavity lying just dorsal to cheek teeth • Anterior ramus of zygoma anterior to first cheek tooth • Glenoid fossa is an anterior-posterior trough, allowing fore and aft movement of the mandible • Well developed pterygoid region • Clavicle usually present • Portions of the masseter muscles originate from rostrum anterior to zygomatic arch |
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Key Characteristics of Lagomorphs
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• Skull fenestrated (having areas of thin, lattice-like bone)
• Two pairs of upper incisors, with the second posterior pair small and peg-like • Incisors ever growing • Canines absent, long diastema between incisors and cheek teeth • Cheek teeth hypsodont and rootless • Skull of leporids unique in having a joint at which slight movement occurs • Clavicle well-developed (Ochotonidae) or rudimentary (Leporidae) • Tibia and fibula fused distally • Tail short • Ears extremely large (Leporidae only) |
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Key Characteristics of Erinaceidae (Hedgehogs, Moon Rats and Gymnures)
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• Complete zygomatic arch
• Upper molars quadritubercular and bunodont • Lower molars with well-developed trigonids and talonid basins • Hair modified into sharp spines (hedgehogs) • Panniculus carnosus muscle extensive (hedgehods) |
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Key Characteristics of Soricidae (Shrews)
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• Skull long and narrow
• Zygomatic arches, auditory bullae, and postorbital processes absent • Tympanic bone annular (ring shaped) • Doubled condyloid processes on dentary form double jaw articulations • Enlarged first incisor “falciform” with forward projecting main cusp and small secondary cusp • Remaining incisors, canines and premolars (except P4) small and peg-like (unicuspid) • Upper molars dilambdodont, with W-shaped ectoloph • Milk teeth shed before birth |
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Key Characteristics of Talpidae (moles and desmans)
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• Body Fusiform
• Eyes tiny, sometimes covered by skin • Legs short and powerful, forelimbs rotated so palms face posteriorly • Forelimbs claws robust • Pinnae absent • Fur velvety (moles) allowing easy movement in the burrow • Skull long, flattened with narrow rostrum • Zygomatic arches complete • Auditory bullae present • Humerus broader than long • Clavicle short and broad • Molars dilambdodont • Snout snorkel-like (desmans) |
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Key characteristics of Solendons (Solenodontidae)
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• Snout long and flexible
• Feet large and clawed • Tail long nearly naked • Zygomatic arch incomplete • Auditory bulla absent • Os proboscidis bone supports tip of rostrum • Second lower incisor with deep groove for transferring toxic saliva |
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Key Characteristics of Chiroptera (bats)
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• Wings present, capable of sustained self-powered flight
• Wing surface covered by skin, supported by four digits, and attached to hindlegs • Uropatagium usually present between hindlimbs • Humerus and radius greatly elongated • Hindlimbs short and rotated 90 to 180 degrees from typical mammalian posture • Uropatagial spur supports uropatagium • Pteropodids o Face fox-like or lemur like o Eyes large o Nose usually unspecialized, without nose leaf o Tragus absent o Postorbital process well-developed o Wing with two clawed digits (I and II) • Nonpteropodids o Capable of echolocation using sounds produced in larynx o Eyes often reduced o Tragus present (except in rhinolophidae and hip-posideridae) o Wing with one clawed digit (digit I) o Calcar supports uropatagium |
• Nonpteropodids
o Capable of echolocation using sounds produced in larynx o Eyes often reduced o Tragus present (except in rhinolophidae and hip-posideridae) o Wing with one clawed digit (digit I) o Calcar supports uropatagium |
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Key Characteristics of Carnivora
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• Enlarged P4 and m1 form shearing carnassial pair (Secondarily reduced in bears, raccoons, and seals)
• Canines large and conical • Third molar lost skulls heavily built, with strong zygomatic arch • Braincase enlarged and frontoparietal suture located anteriorly • Well-defined, transverse glenoid fossa restricts jaw motion to dorsal-ventral plane • Sagittal crest prominent (secondarily reduced in some members) • Turbinals relatively large and complex • Fused scaphoid and lunar bones in carpals simple stomach • Simple stomarch • Caniformia o Auditory bullae composed of a single bone and not divided or only partially chambered o claws nonretractile o Baculum well developed • Pinnipedia o Body insulated with thick layer of blubber and may also be covered with hair o Body fusiform and adapted for swimming o Digits fused together and covered with skin to form flippers o Forelimbs and hindlimbs paddle like o Pinnae highly reduced or absent o Vibrissae well developed o Molariform teeth homodont o Tail very short or absent o External genitalia hidden within slits or grooves o Baculum present • Feliformia o Auditory bullae two-chambered, joined by septum o Rostrum shorter, teeth fewer, and carnassial teeth more sectorial than caniforms o Claws strong and sharp, retractile or semiretractile |
• Feliformia
o Auditory bullae two-chambered, joined by septum o Rostrum shorter, teeth fewer, and carnassial teeth more sectorial than caniforms o Claws strong and sharp, retractile or semiretractile |
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Key Characteristics of Perissodactyls
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• Skull thick, body stocky
• Foot structure mesaxonic (with symmetry of the foot passing through the central, or third, digit) • Digits bear hooves • Skull elongated and houses of a full set of cheek teeth • Molar and premolars hypsodont in grazing forms (brachydont in browser) • Dermal horns without bony cores located along midline of nasal and frontals in some species • Stomach simple; cecum enlarged and sacculate for microbial fermentation |
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Key Characteristics of Artiodactyls
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• Feet paraxonic, the plane of symmetry passes between the third and fourth digits
• First digits absent • Toes even in number, only two digits in extreme cases • Ankle bones reduced in number, and astragalus bear most of weight • Astragalus with double-trochlea (restricting lateral movement) • Femur lacks a third trochanter • Horns with bony core or antlers oftern present • Postorbital bar or process present • Cheek teeth bunodont or more commonly selenodont • Stomach often multichambered (four chamber in extreme cases) for microbial fermentation |
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Key characteristics of Cetaceans
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• Body fusiform
• Skin almost hairless and sebaceous glands absent • Thick layer of bludder under skin surrounding body • Rostrum elongated, cervical vertebrae compressed • External ear pinnae absent, auditory meatus closed • Nares located dorsally • Tail long muscular, terminating in horizontal flukes • Forelimbs flipper-like and lacking claws or nails • Clavicle absent • Elbow and wriste joints immobile • External hindlimbs absent • Pelvic girdle vestigial, not attached to vertebral column • Sacral Vertebrae separate • Diaphragm oblique • Gall bladder absent • Testes abdominal • Uterus bipartite • Placenta epitheliochorial • Mammae extrudable, elongated, in narrow cavities flanking urogenital opening • Mysticeti o Teeth absent in adults o Rows of baleen plates composed of flexible keratin plates o External nares (blowholes) paired o Skull symmetrical o Auditory bullae attached to skull • Odontoceti o Teeth homodont and monophyodont o Echolocate using complex nasal passages o Skull aymmetrical with concave profile o External nare (blowhole) single o Fatty melon present |
• Odontoceti
o Teeth homodont and monophyodont o Echolocate using complex nasal passages o Skull aymmetrical with concave profile o External nare (blowhole) single o Fatty melon present |
