GEO 103 Lecture 24: Evolution of Communities
Document Summary
Invertebrate marine communities largely recovered during early carboniferous. Reef-formers declined and replaced by small patch reefs. Bryozoans and crinoids (echinoderm - we are related to them of some kind, but group of organisms that include sea cucumbers and starfish) achieved greatest diversity - major skeletal producers of extensive mississippian limestone deposits. Permian characterized by restriction of shallow seas due to regression. Fusulinids - benthic foraminifera are important pennsylvanian - permian index fossils. Permian ended with greatest mass extinction ever recorded. In addition to decimation of marine biota, affects 65% of amphibians - reptiles and 33% of insects. This was larger than the previous two mass extinctions in the late ordovician and late devonian. Extinction event took place over ~8 million years. Meteorite impact (extinction event too long - perhaps contributed) Widespread marine regression resulting from glacial conditions (took place too late to have effect - pennsylvanian glaciation.
