BIO SCI 94 Lecture Notes - Lecture 20: Amnion, Chondrichthyes, Amniote

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 94
• Professor: Brandon Stuart Gaut

Document Summary

The vertebrate fossil record: there"s evidence of vertebrates that extends to the cambrian period (and perhaps just a bit before the. Jaws: developed from the pharyngeal arches: some ray-finned fishes like moray eels also have developed a 2nd set of jaws--the pharyngeal jaws- To help capture prey & process food: first appeared in sharks, chondrichthytes - sharks, rays, skates. Internal bones: evolved after the sharks diverged from the rest of the vertebrates: showed first in fishes, most vertebrate species have internal bones, w/ only the small slice of the pie corresponding to sharks, rays, hagfish, & lampreys. *from textbook: sharks & other cartilaginous fishes (rays & skates) don"t have hard bones made of calcium phosphate (like us) but they do have a skeleton made of softer cartilage tissue. Important ecologically: most amphibians need to lay their eggs in water to keep them from drying out, but species w/ amniotic eggs can lay them out of water.