GEOL 107 Lecture Notes - Lecture 12: Plate Tectonics, Extinction Event, Devonian
Document Summary
Lecture 12: life in a changing world - diversity & extinction: diversity and faunas animal diversity of the oceans has increased throughout the phanerozoic (cowen, 2013, fig. 6. 4 and 6. 5) increase is evident in both shelly fossil record and soft-bodied animals. Sepkoski has divided all phanerozoic marine animals into three overlapping evolutionary faunas (cowen, 2013, p. 73-75, especially fig. 6. 9-6. 10). all three date back to the cambrian explosion and extend to the present day, but each has had a different acme and evolutionary history: cambrian fauna (cowen, fig. 6. 10a) trilobites, archaic molluscs, archaic echinoderms, and inarticulate brachiopods: mainly mudgrubbers, dominate the cambrian, reduced in the ordovician, insignificant since then, armoured mud-grubbers (remember this), this is what most of the cambrian fauna is. 6. 10b) reflects the advent of armoured filter-feeders and pelagic predators during the ordovician. In the ordivician the group of pelagic carnivours showed up (mlluscs-cephalopods: modern fauna (cowen, fig.