A WELL-PRESERVED PROBABLE SQUIRRELFISH FROM THE COON CREEK FORMATION (LATE CRETACEOUS), WESTERN TENNESSEE

The Late Cretaceous Coon Creek Formation Lagerstätte of West Tennessee preserves a diverse ecosystem of abundant unaltered shelly invertebrates, swimming and flying reptiles, rare hadrosaur bone and teeth, and occasional terrestrial and marine plant remains. Fish are typically represented by otoliths, but can also occur as isolated vertebrae and teeth. We extracted fossil teleost material from multiple individuals of similar taxonomic affinity from an exposure of the upper dark, micaceous, shaley lithofacies. Rather than being preserved as bone on bedding planes, typical of most vertebrates, our specimens' preservation consists of three-dimensional body form with intact scales enclosing the internal skeleton intact. We used μCT imaging to non-destructively reveal details of external and internal skeletal features. Consistent among all specimens are ctenoid scales in life position and articulated vertebrae; two specimens preserve fins in a closed position. The largest specimen is laterally flattened and deteriorated on its left side, but the right side body form is well preserved with intact scales, ribs, neural spines, and an anal fin. The smallest specimen is a right side head segment possessing gill arches and an eye orbit. A third specimen of a partial head and body has a mixture of features shared by the other two specimens, but also preserves a pelvic fin. All specimens most closely align with acanthomorph holocentrid squirrelfish. We tentatively assign the specimen to the taxon “Beryx” insculptus Cope, 1870.