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ZOOL 320 - CH 22
Primitive Mammals
Question | Answer |
---|---|
reversed triangles in molar teeth | holotheria |
tribosphenic molars with protocone and talonid | tribosphenida |
braincase. double rooted cheek teeth. initially quadrate-articular and squamosal-dentary in jaw articulation. | early mammals |
middle ear evolved independently three times in | early mammals |
expansion of cerebrum from dorsal ventribular ridge of dorsal pallium | bird |
expansion of cerebrum from lemnopallium of dorsal pallium | mammal |
docodont. triconodont. symmetrodont. dryolestid. holotheria. tribosphenida. | mesozoic mammals |
glenoid cavity oriented horizontally. scapula immobile. both clavicle and interclavicle. | primitive shoulder girdle |
cusps on their molars are concave anteriorly on the uppers and concave posteriorly on the lowers, indicating retraction of the mandible during chewing. | multituberculate |
cusps on their molars are concave posteriorly on the uppers and concave anteriorly on the lowers, indicating protraction of the mandible during chewing. | rodents |
forelimb placed under girdle closer to midline. shoulder girdle moves with forelimb during the stride. | excursion of the shoulder girdle in therian mammals |
shoulder joint immobile. glenoid laterally oriented. both coracoid and procoracoid. | primitive |
scapulocoracoid fused | Derived (A) |
acromion process of scapula strongly overturned. glenoid oriented downward. proximal head of humerus spherical and inturned. procoracoid reduced or lost. | theriiformes |
interclavicle lost. supaspinous fossa. | theria |
platypus. long-nosed echidna (New Guinea). short-nosed echidna (Australia). | monotremes |
modern forms have reduced teeth as juveniles before losing them | monotremes |
early forms had teeth, not tribosphenic molars | monotremes |
cochlea structure uncoiled | early mammals |
cochlea structure half a coil | monotreme |
cochlea structure coiled up to 360 degrees | theria |
ampulla, utriculus, sacculus, cochlea, semicircular canals | multiple coils of therian mammals |
obturator foramen first appears in | synapsids |
ilium extended farther forward in | mammals |
bone present in monotremes, marsupials, and earliest placentals | marsupial bone |
monotreme, lays eggs, suckles young | platypus |
passages from the uterus, bladder, and intestine open into the cloaca as in reptiles. | monotremes |
passages form uterus and bladder exit together but the anal exit is separate. | marsupials |
usually separate openings for the uterus, bladder, and intestine. | placental mammals |
sidewall of braincase is from alisphenoid | therian synapomorphy |
lost interclavicle. procoracoid lost with theriiformes. coracoid reduced as process on scapula. supraspinous fossa is new. | therian shoulder girdle |
have small cervical ribs | monotremes |
superposition of astragalus over calcaneum in | therians |
marsupial bones originally thought to support the pouch, but present in monotremes, basal placentals, and even tritylodont cynodonts. | epipubic |
the bones stiffen the trunk in them during walking when one hindlimb and diagonally opposite forelimb are forward and others back. | the opossum |
jugal forms portion of jaw glenoid. flared nasal bones. 5 upper incisors and 4 lower. 3 premolars. 4 molars. inflected angle to jaw. | marsupial (opossum, Didelphis) |
rectangular nasal bones. jugal ends before glenoid. auditory bulla. noninflected angle to jaw. 2 molars. 4 premolars. 3 upper and lower incisors. | placental (raccoon, Procyon) |
shrew opossum, monitor del monte, tasmanian devil, rabbit-eared bandicot, koala, rat kangaroo, honey possum, marsupial mole, and opossum are examples of | marsupials |
shearing teeth in carnivorous forms is an adaptation of this marsupial | borhyaena |
divergent first toe for climbing is an adaptation of this marsupial | opossum |
syndactylous 2nd and 3rd toes in this marsupial for grooming fur | kangaroo |
a giant herbivorous marsupial from the Pleistocene of Australia, about 11 feet in length. | diprotodon |
dog-like carnivore, cat-like carnivore, arboreal glider, fossorial herbivore, and digging ant feeder are examples of this. | strongest examples or convergent evolution in biology. |
How do tribosphenic molars work? | occlusion between teeth of upper and lower jaw. |
group of primitive placentals with lower metabolic rates. tongue retractor muscles originate on sternum. | xenarthra |
lost all incisors and canine. large, recurved claws. caniniform premolar. gets name from extra articular surfaces of vertebrae. | xenarthra |
have interclavicle and coracoid bones | marsupial newborns |
front claws act as holdfasts, shoulder arch assist in wriggling crawl of body. | marsupial newborns |
in mammalian placenta, choriovitelline placenta is associated with the | yolk sac |
in mammalian placenta, chorioallantoic placenta is in | basic placental mammal |
used for countercurrent flow for thermoregulatiton | vasular plexus |
carnivorous marsupials of South America of upper Oligocene to Miocene age, was as large as a wolf. | Borhyaena |
of Pliocene age, was comparable to a jaguar in size and paralleled in a remarkable way the large sabertooth cats. | Thylacosmilus |