9/14/10Click to edit Master subtitle styleActinopterygii Part 1: Early ray-finned fishesLecture 9: Chp. 11,13 DOF
9/14/10Cladistia (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
9/14/10Bichirs and Reedfish Weird mix of old and new features: Obligate air breathers, paired lungs lobelike finsTwo gular plates (analogous to the Coelacanth) young with feathery external gills (analogous to lungfish)
9/14/10Cladistia, pectoral fins“peculiar and over elaborated development” A.S. RomerUnique morphology to the pectoral fin unlike any other fish.Supporting structures of the pectoral fin are shaped like a wishbone with a flat plate.
9/14/10Bichirs 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”
9/14/10CladistiaFossil Cladistians mostly African like the extant members but two genera from South AmericaEarliest fossils from 95-91 mya (Cretaceous)Body encased in heavy, interlocking ganoid scalesOnly animal to use recoil aspiration to inhale through their mouth.
9/14/10Cladistia5-18 dorsal finletsPaired highly vascularized ventral lungsSpiracle used to exhale not inhale like in other groupsResistant to drying: can be kept alive for days in a wet
9/14/10Acipenseriforms (=Chondrostei)Sturgeon 24 spp. (Acipenseridae)Paddlefish (Polyodontidae) 2 spp. extantMix of primitive and derivedStrongly heterocercal tails, spiral valve in intestineCartilaginous internal skeleton (2ndarily lost bone)
9/14/10Acipenseriforms (fossils)Rich record 200 myaMany fossils with a fully ossified (endochondral and dermal internal skeleton)
9/14/10AcipenseriformesHolarctic 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