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					| Late Paleozoic Marine Life |  
					| 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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