A Specimen of Squalicorax from the Pierre Shale of Wyoming Preserving Articulated Dentition and Postcrania

Although shark teeth are the most common vertebrate fossils, articulated remains of their cartilaginous skeletons are rare. Despite the abundance of its teeth in Cretaceous-aged exposures from the Western Interior Seaway of North America, Squalicorax is only known from a handful of complete or partial skeletons. Here, we describe a well-preserved specimen of Squalicorax Whitley from Campanian aged exposures of the Pierre Shale in Niobrara County, Wyoming. This specimen (KUVP 152224) preserves teeth, vertebrae, and portions of the cartilaginous postcrania in articulation. Notably, while we believe that KUVP 152224 most generally resembles Squalicorax pristodontus (Agassiz), several aspects of its anatomy compare favorably to Squalicorax kaupi (Agassiz). If KUVP 152224 is indeed Squalicorax pristodontus, it is likely to be the only specimen to date preserving articulated dentition. KUVP 152224 is characterized by closely articulated dentition with no apparent overlap between adjacent teeth, indicating that at least some species of Squalicorax possessed teeth in juxtaposed arrangement.