Term
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Definition
| w/in group, trend towards reduction in armor |
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Term
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Definition
| plates of dermal bone; true teeth w/ dentine arose in other gnathostomes; bony dermal plates, produced by dermal cells, in placoderms subject to breakage and couldnt be replaced |
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Term
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Definition
| depressed; dorsoventrally flattened |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| separate from neurocranium |
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Term
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Definition
| short history; upper Silurian, 420 mya; very diverse in Devonian; remained into Carboniferous; coexisted w/ more derived groups for 100 my |
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Term
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Definition
| marine, later in fresh; initially benthic, when less armored were pelagic |
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Term
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Definition
| not more closely related to chondrichthyans or bony fishes; not ancestral to other jawed fishes, sister taxon |
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Term
| common ansestor w/ plesiomorphies with chondrichthyes and osteichthyes |
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Definition
| jaws, paired fins, internal skeleton |
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Term
| other jawed fishes: scales |
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Definition
| made of bone, with other materials on outside. all gnathostome scales are homologous to eachother and share evolutionary origin w/ teeth |
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Term
| other jawed fishes: real teeth |
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Definition
| like scales: bone on inside, dentine deposited on outside by ectoderm; homologous with scales |
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Term
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Definition
| coming out at same time; active pursuit of food, maneuverability |
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Term
| traits shared w/ ostracoderms |
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Definition
| negative bouyant (heavy plates); benthic and near benthic; dorsoventrally flattened |
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Term
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Definition
| placoderms bigger and slightly lighter and more flexible, articulated armor |
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Term
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Definition
| diversity-greater than any other group of fishes in devonian; 8 or 9 orders w/in single class; duration 440-350mybp |
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