REN R360 Lecture Notes - Pteridospermatophyta, Marine Invertebrates, Cenozoic
4 Mar 2013
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The permian (297-251 mya: continents coalesced into the supercontinent pangaea, near the end, reptiles greatly outnumbered the amphibians, late in the period, the lineage leading to mammals diverged from one reptilian group. In fresh waters, the permian period was a time of extensive diversification of ray-finned fishes: massive volcanic eruptions resulted in outpourings of lava that covered large areas of. Few organisms that survived found themselves in a relatively empty world at the start of the. Pangaea slowly separated into individual continents; oceans rose and reflooded continent shelves, forming huge, shallow inland seas. Atmospheric oxygen concentrations gradually rose to their former levels. Different groups of organisms came to dominate the earth: three groups of phytoplankton---dinoflagellates, cocccolithophores, and diatoms became ecologically important at this time. Earth"s biota became increasingly provincialized distinct terrestrial biotas evolved on each continent. Biotas of the shallow waters bordering the continents also diverged from one another.
