BIOL-2111 Chapter Notes - Chapter 1: Shoulder Girdle, Sauropsida, Chimaera
15 Sep 2013
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Document Summary
The number of species of terrestrial vertebrates reached its maximum in the middle. Miocene, 12-14 million years ago, and had declined since. Two major groups are amniotes and non-amniotes. Generally, amniotes are terrestrial and non-amniotes are aquatic, but there are a few exceptions. Amniotes: are animals that have an amnion which surrounds the embryo. Contains turtles, scaly reptiles, crocodilians, and birds. Extinct sauropsids include dinosaurs, pterosaurs (flying reptiles), ichthyosaurs, and plesiosaurs. Only vertebrates with pectoral girdle and pelvic girdle inside the ribs. Tuatara (2 species) only remnants of sphenodontida lineage. Lizards (5000 species) and snakes (3015) species are at the peak of their diversity. From same lineages as dinosaurs and birds (archosauria). Crocodilians range between less than a meter to 7 meters long. Skin contains bones (osteoderms) that act as armor. Lineage of dinosaurs that evolved for flight during the mesozoic. Dinosaur fossils with feather show they came before flight: synapsid amniotes ~4800 species.
