9-Early_Actinopterygii

9-Early_Actinopterygii - 9/14/10 Click to edit Master...

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Unformatted text preview: 9/14/10 Click to edit Master subtitle style Actinopterygii Part 1: Early ray-finned fishes Lecture 9: Chp. 11,13 DOF 9/14/10 9/14/10 9/14/10 Cladistia  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 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) 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. 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 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. 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 9/14/10 Cladistia  Freshwater, Africa, 10 extant species  Swampy habitats  Can reach .5 meters in length 9/14/10 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) 9/14/10 Acipenseriforms (fossils)  Rich record 200 mya  Many fossils with a fully ossified (endochondral and dermal internal skeleton) 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 9/14/10...
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9-Early_Actinopterygii - 9/14/10 Click to edit Master...

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