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Aktiogavialis - A Gharial of the Oligocene

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  • Neal Robbins
            Aktiogavialis puertoricensis was a gharial of the Oligocene. The systematic paleontology of it is:   Reptilia Laurenti 1768 Crocodylomorpha Hay
    Message 1 of 1 , Oct 1, 2011
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          Aktiogavialis puertoricensis was a gharial of the Oligocene. The systematic paleontology of it is:
       
      Reptilia Laurenti 1768
      Crocodylomorpha Hay 1930
      Crocodylia Gmelin 1789 (sensu Benton and Clark 1988)
      Gavialoidea Hay 1930 (sensu Brochu 2008)
      Gryposuchinae Velez-Juarbe et al. 2007
      Aktiogavialis Velez-Juarbe et al. 2007
      Aktiogavialis puertoricensis Velez-Juarbe et al. 2007
       
          The holotype (UPRMP 3094) is a set of cranial remains. This fossil specimen was found in the San Sebastian Formation in Puerto Rico. It dates to the late Oligocene, which was 33.9 - 23.03 million years ago.
          Jorge Velez-Juarbe, Christopher A. Brochu, and Hernan Santos wrote an article titled A gharial from the Oligocene of Puerto Rico transoceanic dispersal in the history of a non-marine reptile. It was published in 2007 in Proc. R. Soc. B, vol. 274, no. 1615, 1245-1254. This quote from the abstract says:
       
          The Indian gharial (Gavialis gangeticus) is not found in saltwater, but the geographical distribution of fossil relatives suggests a derivation from ancestors that lived in, or were at least able to withstand, saline conditions. Here, we describe a new Oligocene gharial, Aktiogavialis, from deltaic-coastal deposits of northern Puerto Rico. It is related to a clade of Neogene gharials otherwise restricted to South America. Its geological and geographic settings, along with its phylogenetic relationships, are consistent with two scenarios: (i) that a single trans-Atlantic dispersal event during the Tertiary explains the South American Neogene gharial assemblage and (ii) that stem gharials were coastal animals and their current restriction to freshwater settings is a comparatively recent environmental shift for the group. This discovery highlights the importance of including fossil information in a phylogenetic context when assessing the ecological history of modern organisms.
       
          This excerpt from the main text says:
       
      A distinct fossa extends anteriorly from the supratemporal fenestra on the dorsal postorbital suture (figure 2a, b). The floor of the fossa is pitted and the posterior limit corresponds with the postorbital-parietal suture. This feature is unknown in any other crocodylian.
       
          The complete text is on this link. Fossil photos are included.
       
          Neal Robbins
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