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Acanthodes - A Fish of the Carboniferous and Permian

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  • Neal Robbins
        This link has an illustration of Acanthodes. http://en.wikipedia.org/wiki/File:Acanthodes_BW.jpg     A fossil photo of Acanthodes is on this link.
    Message 1 of 1 , Jan 6, 2013
       
          This link has an illustration of Acanthodes.
       
          A fossil photo of Acanthodes is on this link.
       
          Acanthodes was a genus of fishes that lived during the Carboniferous and Permian. The systematic paleontology of Acanthodes is:
       
      Gnathostomata Gegenbaur 1874
      Acanthodii Owen 1846
      Acanthodiiformes Berg 1940
      Acanthodidae Huxley 1861 sensu Carroll, 1988
      Acanthodes Agassiz 1833
      Acanthodes Agassiz 1833
      Acanthodes bronni Agassiz 1833
      A. sulcatus Agassiz 1835
      A. gracilis Beyrich 1848
      A. wardi Egerton 1866
      A. nitidius Woodward 1891
      A. ovensi White 1927
      A. lundi Zidek 1976
      A. bridgei Zidek 1976
      A. luedersensis Dalquest et al. 1988
      A. lopatini Rohon 1889
      A. tholeyi Heidtke 1990
      A. kinney Zidek 1992
      A. boyi Heidtke 1993
      A. bourbonensis Heidtke 1996
      A. sippeli Heidtke 1996
      A. fritschi Zajic 1998
      A. stambergi Zajic 2005
       
          Acanthodes was quite numerous and had a very wide distribution. Fossil remains of Acanthodes borbonni have been found in Germany. They date to the early Permian. Late Carboniferous remains of Acanthodes bridgei were discovered in Kansas. Other Acanthodes fossils have been unearthed in various places, including France, the Czech Republic, Russia (Siberia), and Kansas and New Mexico in the USA.
          Samuel P. Davis, John A. Finarelli, and Michael I. Coates wrote an article titled Acanthodes and shark-like conditions in ancestor of modern gnathostomes. It was published in 2012 in Nature 486, 247-250. This quote from the abstract says:
       
      Acanthoddians, an exclusively Palaeozoic group of fish, are central to a renewed debate on the origin of modern gnathostomes: jawed vertebrates comprising Chondrichthyes (sharks, rays, and ratfish) and Osteichthyes (bony fishes and tetrapods). Acanthodian internal anatomy is primarily understood from Acanthodes bronni because it remains the only example preserved in substantial detail, central to which is an ostensibly osteichthyan braincase. For this reason, Acanthodes has become an indispensible component in early gnathostome phylogenies. Here we present a new description of the Acanthodes braincase, yielding new details of external and internal morphology, notably the regions surrounding and within the ear capsule and neurocranial roof. These data contribute to a new reconstruction that unexpectedly resembles early chondrichthyan crania. Principal coordinates analysis of a character-taxon matrix including these new data confirms this impression: Acanthodes is quantifiably closer to chondrichthyans than to osteichthyans. However, phylogenetic analysis places Acanthodes on the osteichthyan stem gnathostomes. As such, perceived chondrichthyan features of the Acanthodes cranium represent shared primitive conditions for crown group gnathostomes. Moreover, this increasingly detailed picture of early gnathostome evolution highlights ongoing and profound anatomical reorganization of vertebrate crania after the origin of jaws but before the divergence of living  clades.
       
          The complete text is on this link.
       
          Jaroslav Zajic wrote an article titled Czech and Moravian Permian acanthodians. It was published in 2008. The abstract is on this link.
       
          Neal Robbins
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