BIOL 172 Chapter 34: BIOL 172 Chapter 34 (34) Notes
Document Summary
365 million years ago the evolution of limbs in one lineage of vertebrates set the stage for vertebrates to colonize land. Three groups of terrestrial vertebrates alive today: amphibians, reptiles (including birds, mammals. Two groups of deuterostomes that are more closely related to vertebrates than they are to other vertebrates, thus classified within the chordates: cephalochordates, urochordates. Four key characters of chordates: a notochord, a dorsal, hollow nerve cord, pharyngeal slits or clefts, a muscular post-anal tail. Chordates are named for a skeletal animals with a vertebrae, the series of bones that make up the vertebral column, or backbone. structure, the notochord, present in all chordate embryos and in some adult chordates. In most vertebrates, a more complex, jointed skeleton develops around the ancestral notochord, and the adult retains only remnants of the embryonic notochord. Nerve cord of a chordate embryo develops from a plate of ectoderm that rolls into a tube located dorsal to the notochord.
