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Late Paleozoic Marine Life
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Lecture 19
4/1/98
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| | On Monday we looked at changes in the marine biosphere during the Early Paleozoic. Today we will continue this discussion into the Late Paleozoic |
| | The diversity of the Paleozoic Fauna does not change significantly during the late Paleozoic |
| | Two additional groups become important in late Paleozoic, the ammonites and the fishes. |
| | Radiation of the jawed fishes in the Devonian was a key event in the late Paleozoic marine biosphere. |
| | Paleozoic fauna is stable with slight declines |
| | Decline is probably related to radiation of the fishes and ammonites |
| | concentrated in the Devonian |
| | three major groups of fish appear in the Early Devonian |
| | Fish become important predators |
| | first appear in the Ordovician |
| | modern jawless fish include hagfish and lampreys |
| | gills are supported by cartilage arches |
| | mutations and selection modify the front-most gill arches |
| | The first jawed fishes evolved in the Silurian |
| | probably lived near the bottom |
| | armor on the head made movement though the water difficult |
| | most placoderms became extinct by the end of the Devonian |
| | relatively unchanged since the Devonian |
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