BIOL10005 Study Guide - Cambrian Explosion, Burgess Shale, Extinction Event
21 Jan 2017
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Earliest known complex animals (metazoans could be cnidarians) All major phyla that are triploblastic and coelomate (mollusca , annelida, arthropoda, Platyhelminthes (triploblastic but lack acoelomate) may have appeared in between the pre- Many unrecognisable forms also appeared (eg. hallucigenia) Exoskeleton, segmentation, jointed legs, one pair of antennae, biramous appendages. Abundance of fossilised animals in burgess shale (in canadian rocky mountains) the region where the fossils lay used to be immersed in water where there was anoxic mud (mud lacking oxygen). Mass extinction = extinction event =period of sudden major decline in biodiversity. Average species life span of mammals = 1 million years. Current rate of extinction = 27 000 species per year. Largest extinction event in history of earth 90% species lost. Cause of extinction: massive volcanic activity ash blocked sun nuclear winter build-up of atmospheric gases eg. so2, co2, global warming (inc. in global temperature) Appearance of angiosperms more food sources (dinosaurs = mostly herbivore)
