ZOO-3713C Study Guide - Midterm Guide: Sacrum, Avemetatarsalia, Crocodylomorpha
21 Jan 2017
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2,3,4,5,4 (3) phalangeal formula: found by counting # of bones beginning with the thumb. Amnion: innermost of the extraembryonic membrane that surrounds the embryo and encases the embryonic fluid. The resulting cleidoic egg is self contained, and this is what allowed earlier tetrapods to break tides with the water. Astragalus ankle bone: fusion of 3 ankle bones tibiale, intermedian, centrale into one element. 2 or more sacral vertebrae: the vertebrae near the butt. Diapsid skull: the reptilian skull in which 2 temporal fenestrae (openings) are present. Transverse cloacal slit (the butt/vagina/penis hole): the cloaca is the posterior (butt end) chamber of most fishes, nonmammalian tetrapods, and monotreme mammals into which the digestive and urogenital tracts discharge. The slit is the external opening of the cloaca in lepidosauria and runs transversely. Thin, rod-like columella: (thin looking wishboneish bone at the top part of the head) allowing more sensitivity to high frequency sound.
