ZOOL224 Lecture Notes - Lecture 8: Tetrapodomorpha, Yolk Sac, Lungfish
28 Sep 2018
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Document Summary
Jaw mobility comes from mobility within the skull itself: muscular fins, which still have radials and lepidotrichia like actinopterygians, diversified during devonian (called the age of fish) Jaw mobility comes from movement within the skull: large brain, early sarcopterygians, cylindrical, 20-70cm long, 2 dorsal fins, heterocercal tail, fleshy paired fins. Lineages: actinistia, coelacanths - 3-lobed tail fin, no maxilla (upper jaw bone), lungs are vestigial and used for buoyancy, basal form; extant but rare, dipnoi. Square scales: tristichopterids, teeth with enamel, bone marrow, elpistostegalians. Fish that resemble tetrapods - long snout, dorsal eyes, reduced caudal fin, includes tiktaalik: choanae (internal nostrils), fin skeleton. Can swim backwards: reproduction, actinopterygians show a high reproductive diversity, most lay eggs. Some take care of eggs for a long time, some do(cid:374)"t take care of the eggs at all. Sex is determined genetically but some can change sex: oviparity.
