Classification and evolution Tiktaalik

in late devonian vertebrate speciation, descendants of pelagic lobe-finned fish – eusthenopteron – exhibited sequence of adaptations:




descendants included pelagic lobe-finned fish such coelacanth species. in 2000 p. ahlberg et al. described transitional form fish tetrapod, livoniana. creature dates 374 - 391 million years ago, successor panderichthys.

tiktaalik roseae species classified under genus. tiktaalik lived approximately 375 million years ago. paleontologists suggest representative of transition between non-tetrapod vertebrates (fish) such panderichthys, known fossils 380 million years old, , tetrapods such acanthostega , ichthyostega, known fossils 365 million years old. mixture of primitive fish , derived tetrapod characteristics led 1 of discoverers, neil shubin, characterize tiktaalik fishapod .

tiktaalik transitional fossil; tetrapods archaeopteryx birds, troodonts , dromaeosaurids. while may neither ancestor living animal, serve evidence intermediates between different types of vertebrates did once exist. mixture of both fish , tetrapod characteristics found in tiktaalik include these traits:

fish

fish gills
fish scales
fish fins


fishapod

half-fish, half-tetrapod limb bones , joints, including functional wrist joint , radiating, fish-like fins instead of toes
half-fish, half-tetrapod ear region


tetrapod

tetrapod rib bones
tetrapod mobile neck separate pectoral girdle
tetrapod lungs






^ shubin, neil (2008). inner fish. pantheon. isbn 978-0-375-42447-2. 
^ john noble wilford, new york times, scientists call fish fossil missing link, apr. 5, 2006.