8-The_transition_to_land - The Transition to Land:...

This preview shows page 1 - 12 out of 45 pages.

The preview shows page 10 - 12 out of 45 pages.
The Transition to Land:Sarcopterygii Part IILec.8 – Chap.11 DOF
Assignment 1Numerical grades are on-lineCapitalize common namesIn text citations (author,yr).Make a posterWhy did I ask you to useCatalog of Fishes
The Transition to Land:Sarcopterygii Part IILec.8 – Chap.11 DOF
AcanthodiiSarcopterygiiActinopterygii
Tetrapodamorphs(Sarcopterygii)Appeared with dipnoans in the Devonian, most disappearedby the end of the PermianMost were large predatory fishes (up to 4m) living in shallowfreshwater habitatsHad sarcopterygian features of having a jointed (kinetic) skull;lobed fins, and replacement teeth on the jaw margins
Osteolepidiforms(Sarcopterygii:Tetrapodamorphs )Eustenopteron foordi –close to the direct ancestor oftetrapods but unlikely to have moved on to landShows trends of tetrapodamorphs transitions including reductionin dermal bone thickness and transition to symmetrical caudalfins
The transition to land.Why breath air?Why would limbbones be useful inthe water?Why move on toland?Why did it take 100my?
Osteolepidiforms(=Rhipidistians)(Sarcopterygii:Tetrapodamorphs)Primarily predators in shallow,freshwater habitats2 dorsal finsteeth on jaw marginslobed finsjointed skulls (intercranial)choanae (the internal nostrils)Eustenopteron, Late Devonian
Fig 11.14EustenopteronKey traits that characterizedthe Sarcopterygian ancestorsof tetrapods: an intercranialjoint, arrangement of thedermal bones, axial elementsof the pectoral fin skeleton.
Elpistostegalians(Sarcopterygii:Tetrapodamorphs )Closest relatives of tetrapodsHomologies including:eye position (both have upward facing eyes set close together,with eyebrow ridges)skull roof bones (frontals, parietals, nasals)paired fins (humerus, radius, ulna; femur, tibia, fibula)Have well developed lungsdentition (infoldings of the dentine)Vertebral acccesories (ossified neural spines, from ring shapedcentra)
Fig 11.15(a)Eustenopteron,(b)Ichthyostega,(c)Neoceratodus

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 45 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Fall
Professor
Chakrabarty
Tags
Ichthyology, Actinopterygii, Sarcopterygii, Tetrapod, RAY FINNED FISHES, fin rays

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture