Abstract
The Arkadelphia Formation—Midway Group (Maastrichtian—Paleocene) contact near Malvern, Arkansas preserves a K-Pg boundary assemblage of turtle species consisting of skull, shell, and non-shell postcranial skeletal elements. The Malvern turtles are preserved within a coquina lag deposit that comprises the basalmost Midway Group and also contains an abundance of other reptiles, as well as chondrichthyans, osteichthyans, and invertebrates. This coquina lag deposit records a complex taphonomic history of exhumation and reburial of vertebrate skeletal elements along a dynamic ancestral shoreline in southwestern Arkansas during the late Cretaceous-early Paleocene. Based on stratigraphic occurrence, the Malvern turtle assemblage indicates that these marine reptiles were living at or near the time of the K-Pg mass extinction and represent some of the latest Cretaceous turtles yet recovered from the Gulf Coastal Plain of the United States.
Highlights
To date, only a few published reports identify the occurrence of fossil turtles from theLate Cretaceous of Arkansas
InteriorSeaway; Seaway; physiographic provinces in Arkansas turtle discussed in this study indicated by by (X);(X); (C)(C)
Formation—Midway Group turtle site discussed in this study identified by arrows
Summary
Only a few published reports identify the occurrence of fossil turtles from the. The earliest of these reports was written over half a century ago [1], and described a new species of turtle from the Brownstone Formation which Schmidt named Podocnemis barberi. Schmidt [2] described two additional turtle species, Phyllemys barberi and Catapleura arkansasensis from the Marlbrook Marl. The present report identifies an assemblage of skull, shell, and non-shell postcranial turtle skeletal elements of uncertain taxonomic status. This turtle assemblage consists of nineteen specimens preserved in matrix and was recovered from a coquina lag deposit composing the basalmost Midway Group along the Ouachita River in Hot. Spring County, Arkansas (Figures 1 and 2).
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