BIOL108 Lecture Notes - Lecture 21: Depth Perception, Bipedalism, Homo Erectus

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Heather Proctor

Document Summary

Vertebrates have 52,000 living species, variability in characteristics like body. Chordates probably rose 530 mya, earliest known fossil ones are 505 mya size or weight (pikaia sp. From burgess shale, bc) 525 mya (haikouella sp. and. Notochord is the main feature of chordates but cephalochordata, Urochordata and myxini don"t have vertebral column but share traits of vertebrates. Characteristics: most characteristics are found in embryonic stage. Notochord cartilaginous, flexible skeletal rod supporting the body in all. Muscular, post-anal tail extends beyond anus, reduced or absent in some adult forms non-chordates have anus at the very end of their body. Segmented muscle blocks present in most but not all chordates, contraction allows body to flex. Non-chordates: have digestive tract along the entire length of the body. Chordates with heads have brains, sensory organs (eye, ears, mouth), and. Haikouella has anterior eyes, mouth and brain but no ears or skeletal elements around the brain so it seems like an ancestor to craniates.