University:
California State University, Northridge
Course:
BIOL 211 | Human Anatomy
Academic year:

2023
Views:

245

Pages:

4
Author:

Charlee Buchanan

Chordate Origins and Phylogeny § Comparative vertebrate anatomy - the study of structure, of the function of structure, & of the range of variation in structure & function among vertebrates: § Kingdom: Animal § Phylum: Chordata § Subphylum: Vertebrata § Vertebrate characteristics: § 1 - notochord (at least in the embryo) § 2 - pharynx with pouches or slits in wall (at least in the embryo) § 3 - dorsal, hollow nervous system § 4 - vertebral column § Notochord = rod of living cells ventral to central nervous system & dorsal to alimentary canal § Fate of notochord during development: § Head region - incorporated into floor of skull § Trunk & tail - surrounded by cartilaginous or bony vertebrate (except in Agnathans) § Adults: § Fishes & amphibians - notochord persists the length of the trunk & tail but is constricted within the centrum of each vertebra § Reptiles, birds, & mammals - notochord almost disappears during development (e.g., remains as a pulpy nucleus in the vertebrae of mammals) § Protochordates - notochord remains as the chief axial skeleton § Agnathans - lateral neural cartilages are located on notochord lateral to the spinal cord §