Triassic tetrapod paleontology and taphonomy of the Boren quarry, Dockum group, Garza county, Texas

Date

2016-05

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Abstract

ABSTRACT

The Late Triassic (Norian) fossil tetrapod vertebrate paleontology of MOTT VPL 3869, the Boren Quarry, in Garza County, Texas, USA, is described as a result of this research. A number of undescribed, un-named taxa were identified during this research, including a dicynodont taxon, a drepanosaurid taxon, a trilophosaurid taxon, an azendohsaurid-like taxon, and a phytosaurian taxon. A very diverse fauna was identified from the locality. Some taxa also extend the geographic and/or chronostratigraphic ranges for those taxa. The relationships of the occurrence of the various taxa to each other was examined showing a transition from larger, more aquatic taxa in the lower portion of the strata in the quarry to a smaller, more terrestrial taxa in the upper strata. A sedimentary pebble conglomerate marked this transition at many sites. There were two depressions marked by steeply dipping sandstone strata. The western depression was smaller and the eastern one was larger. These depressions were possibly due to the dissolution of subsurface Permian salt deposits. Around the margins of these depressions are where most of the dicynodont fossils were discovered and where the large fossil logs occurred. The lacustrine sediments filling the basins contained very few vertebrate fossils. Some of the fossil sites were concentrations of vertebrate fossils in the overbank flood-plain deposits where fragmented bones were most likely concentrated by transport. There were no articulated skeletons excavated. Some were "associated" but not articulated. Occasionally small sections of articulated vertebrae were found. Some specimens exhibited partial disarticulation prior to burial such a phytosaur skull where the posterior portion of the skull was disarticulated prior to burial but the anterior half of the skull was intact. There were some concentrations that indicate the climate was seasonal with some fossil concentrations due to the arid environments.

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Keywords

Triassic, Vertebrate paleontology, Dockum Group, Texas

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