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9-Early_Actinopterygii

9-Early_Actinopterygii - ActinopterygiiPart1...

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 9/14/10 Click to edit Master subtitle style Actinopterygii Part 1:  Early ray-finned fishes Lecture 9: Chp. 11,13 DOF
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 9/14/10
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 9/14/10
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 9/14/10 Cladistia  (Gnathostomata:Actinopterygii) Bichirs (15 spp.; Polypterus ) and Reedfish (1 sp.; Erpetoichtyes) Large predators (up to 90cm) Fossil forms from Mid-Cretaceous  Modern cladistians represented by two genera confined to west and  central tropical Africa
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 9/14/10 Bichirs and Reedfish  Weird mix of old and new features:  Obligate air breathers, paired lungs  lobelike fins Two gular plates (analogous to the Coelacanth)  young with feathery external gills (analogous to lungfish)
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 9/14/10 Cladistia,  pectoral fins “peculiar and over elaborated development” A.S.  Romer Unique morphology to the pectoral fin unlike any  other fish. Supporting structures of the pectoral fin are shaped  like a wishbone with a flat plate.
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 9/14/10 Bichirs and Reedfish  Cladistians have in various times been placed in  phylogentic groupings with lungfishes, stem  sarcopterygians, or actinopterygians. DNA evidence and other traits place them as sister  to all other living “Actinopterygians”
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 9/14/10 Cladistia Fossil Cladistians mostly African like the extant members  but two genera from South America Earliest fossils from 95-91 mya (Cretaceous) Body encased in heavy, interlocking ganoid scales Only animal to use recoil aspiration to  inhale  through their  mouth.
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 9/14/10 Cladistia 5-18 dorsal finlets Paired highly vascularized  ventral lungs Spiracle used to exhale not  inhale like in other groups Resistant to drying: can be  kept alive for days in a wet 
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 9/14/10 Cladistia  habitat Freshwater, Africa, 10 extant species Swampy habitats Can reach .5 meters in length
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 9/14/10
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 9/14/10 Acipenseriforms (=Chondrostei) Sturgeon 24 spp. (Acipenseridae) Paddlefish (Polyodontidae) 2 spp. extant Mix of primitive and derived Strongly heterocercal tails, spiral valve in intestine Cartilaginous internal skeleton (2ndarily lost bone)
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 9/14/10 Acipenseriforms (fossils) Rich record 200 mya Many fossils with a fully ossified (endochondral and  dermal internal skeleton)
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 9/14/10 Acipenseriformes Holarctic group of freshwater and anadromous fishes  that inhabit large rivers. Sturgeons feed on  invertebrates strained from bottom sediments,  American paddlefish is planktivorous, Chinese spp.,  now probably extinct was pisciverous
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 9/14/10 Sturgeon (Acipenseridae)
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