A nearshore vertebrate assemblage from the late cretaceous (turonian) Atarque Sandstone, Socorro County, New Mexico
Justin A. Spielmann, Randy Pence, and Spencer G. Lucas

Abstract:

We have relocated and recollected the fossil vertebrate locality in the Upper Cretaceous (Turonian) Atarque Sandstone on the Sevilleta National Wildlife Refuge first documented by Baker and Wolberg in the 1980s. The locality (now NMMNH L-5153) yields numerous teeth and bone fragments from a localized, 0.7-m-thick intrabasinal ferruginous conglomerate
composed of limestone, tooth, bone, bivalve shell and chert pebbles in a section of fine-grained sandstone near the top of the Atarque Sandstone. Virtually all of the teeth and bones from this bed were broken prior to fossilization, and based on the lithology of the bonebed and fossil preservation, we interpret this fossil site as an allochthonous assemblage in a storm deposit. The following selachian taxa were previously known to be present in this assemblage: Hybodus sp., Ptychodus whipplei, P. cf. P. mammillaris, Chiloscyllium greeni, Scapanorhynchus raphiodon, Cretodus semiplicatus, cf. Paranomodon sp., Squalicorax falcatus, Rhinobatos sp., Pseudohypolophus mcnultyi, Ischyrhiza schneideri and Ptychotrygon triangularis. Our collection duplicates many of the selachian taxa previously known from this assemblage, and also includes numerous teleost teeth, especially of pycnodonts assigned to aff. Coelodus and Micropycnodon cf. M. kansasensis. Freshwater turtle shell fragments and a dromaeosaur tooth are also present, indicating a freshwater/terrestrial component to the assemblage. Scapanorhynchus dominates the assemblage, and the sedimentology, terrestrial taxa, assemblage diversity and rarity of Ptychodus suggest a nearshore association.


Citation:

  1. Spielmann, Justin A.; Pence, Randy; Lucas, Spencer G., 2009, A nearshore vertebrate assemblage from the late cretaceous (turonian) Atarque Sandstone, Socorro County, New Mexico, in: Geology of the Chupadera Mesa, Lueth, Virgil W.; Lucas, Spencer G.; Chamberlin, Richard M., New Mexico Geological Society, Guidebook, 60th Field Conference, pp. 315-320.

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