01:119:160 Lecture Notes - Lecture 2: Bipedalism, Dromaeosauridae, Saurischia
1 Nov 2016
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Document Summary
The first reptiles appeared in the carboniferous period, the period when amphibians were dominant. Reptiles were small, amphibians were large - with small bodies, reptiles were tree- dwellers, insect hunters, and had efficient thermoregulation - warm up and cool down (basking in the sun and finding shade) Amphibians go through metamorphosis (tadpole to frog), reptiles sport direct development. Amphibians have sensitive, naked skin, many glands, reptiles have scales and few glands. Amphibians have jelly eggs with no shells, no amniotic egg, reptile eggs have shells, amniotic egg. Amphibians have external fertilization, reptiles have internal fertilization. Amphibians breathe through gills, skin, lungs (some), reptiles breathe through lungs. For amniotic eggs, there is no larval stage, the embryo is protected in a shell and nourished for an extended period of time. In an amniotic egg, there is a large yolk sac for nourishment, waste removal via amnion, and gas exchange and protection via a hard but permeable shell.
