BIO 1130 Lecture Notes - Lecture 27: Cambrian Explosion, Snowball Earth, Hydroxylapatite

• School: University of Ottawa
• Department: Biology
• Course: BIO 1130
• Professor: Francois Chapleau

Document Summary

Great glacial periods (snowball earth): a lot of ice. Not much life: rare fossils (not real fossils- imprints in rocks that preserve traces of the organisms) Diversified fauna, multicellular(very simple), large sizes, soft body, no vascular system, fed via diffusion. No bones = no fossils = presented in fossil body helped by presence of bacterial mats that preserved traces. Appearance of most modern animal groups and strange fossils in short period. Hard structures (skeleton) characterized this period and phanerozoic eon. Skeleton: important in quest for fossils (bones fossilize) Could be caused by environment with too little calcium so organisms stored it or could be caused by environment with too much calcium so it was recycled into a defense mechanism. Function: lifted constraint of size, attachment site of muscles, mineral resource, locomotion, calcium reserve. In chordates: hydroxyapatite or calcium phosphate in collagen matrix. In other animals: calcium carbonate, silica, keratin, chitin. Groups with unique morphologies appeared and disappeared quickly.