ZOO 2090 Lecture Notes - Lecture 4: Endochondral Ossification, Neurocranium, Facial Skeleton

• School: University of Guelph
• Department: Zoology
• Course: ZOO 2090
• Professor: Jinzhong Fu

Document Summary

Zoology lecture 4: diversity of fishes part 2. Used for water circulating, goes into the spiracle and out the gill slits. Fish in shallow water: can also bring air into since they are located near the top of the head. Spiracle could have allowed them to venture on land, since they were able to draw air in. Gnathostomes: vertebrates with jaws, a vertically biting device (chondrichtyans; cartilaginous) (osteichthyans; bony vertebrate) More bone in endoskeleton compared to previous groups. Actinopterygians (eg. seahorses) presently the most diversified group of vertebrates. Small overlapping scales articulating with each other. Kinetic head skeleton allowing wide gap, highly mobile, able to open their mouths wider. Palaeonisciforms: formerly much more diverse, now most of the remaining species are endangered. Gar and bowfin lineages diverged before appearance of teleost"s in the triassic. Ossified (turn into bone) vertebrae and homocercal (appearing outwardly symmetrical but with the backbone passing into the upper lobe) tail for better swimming, circular scale.