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Apsgnathus - A Scincomorph Lizard of the Cretaceous

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  • Neal Robbins
          Apsgnathus was a lizard of the Cretaceous. The systematic paleontology of it is: Reptilia Laurenti 1768 Squamata Oppel 1811 Lacertilia Owen 1842
    Message 1 of 1 , Sep 16, 2013
       
          Apsgnathus was a lizard of the Cretaceous. The systematic paleontology of it is:
       
      Reptilia Laurenti 1768
      Squamata Oppel 1811
      Lacertilia Owen 1842
      Scincomorpha Camp 1923
      Apsgnathus Nydam et al. 2013
      Apsgnathus triptodon Nydam et al. 2013
       
          The holotype (TMM 43057-264) is a mandible (partial left dentary). It was found in the Aguja Formation (Upper Shale Member) at the Terlingua locality in Brewster County, Texas. This fossil specimen dates to the Campanian age (83.5 - 70.6 million years ago) of the Cretaceous. [Note - The source of this information is The Paleobiology Database.]
          Randall L. Nydam, Timothy B. Rowe, and Richard L. Cifelli wrote an article titled Lizards and snakes of the Terlingua Local Fauna (late Campanian), Aguja Formation, Texas, with comments on the distribution of paracontemporaneous squamates throughout the Western Interior of North America. It was published in 2013 in the Journal of Vertebrate Paleontology 33(5): 1081-1099.
      This quote from the abstract says:
       
      The late-Campanian-aged (=Judithian) squamates from the Terlingua Local Fauna of the Aguja Formation, southern Texas, includes four scincomorphans: a new taxon (Catactgenys solaster, gen. et sp. nov.), referable to Xantusiidae, that has massive teeth and tooth crown morphology similar to that of contogeniid lizards; an indeterminate scincomorphan (Apsgnathus triptodon, gen. et sp. nov.) with robust teeth and two unnamed scincomorphan morphotypes. Anguimorphans in the fauna include Odaxosaurus piger, cf. Parasaniwa wyomingensis, and a likely xenosaur. Ophidian jaw fragments confirm the presence of a snake in the fauna. The Aguja squamate assemblage is one of the most southerly of a series of paracontemporaneous squamate faunas extending from central Alberta to northern Mexico. Comparison of these faunas reveals that, although two taxa are endemic to the Aguja Formation, others show some latitudinal trends. Odaxosaurus and Parasaniwa are present in all well-sampled faunas from Alberta to Texas. The mammal-like Peneteius and snakes are found only in faunas from southern Utah to New Mexico. The sole representatives of Contogeniidae and Xantusiidae are restricted to southern Utah and southern Texas, respectively. These hypotheses of distributional patterns must continue to be tested through ongoing investigations of all of the relevant faunas from the late Campanian of the Western Interior.   
       
          Neal Robbins
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