A megatoothed shark (Carcharocles angustidens) nursery in the Oligocene Charleston Embayment, South Carolina, USA

Abstract

Many extant sharks are cosmopolitan as adults but inhabit nursery areas as youngsters -often shallow, dynamic ecosystems with abundant prey for neonates and juveniles. Megatoothed sharks (Otodontidae) were the largest sharks of all time, and nursery areas have been demonstrated for Carcharocles megalodon in the Miocene of Panama, Spain, Florida, and Maryland. An earlier study hypothesized a nursery area for Carcharocles angustidens in the upper Oligocene (23-25 Ma) Chandler Bridge Formation of Charleston, South Carolina. We tested this by reporting and analyzing two collections (n=127) dominated by small teeth of C. angustidens from the Chandler Bridge Formation and some teeth from the underlying lower Oligocene (29-26.57 Ma) Ashley Formation (n=9). Correcting for tooth position, published body length estimation equations yielded body length estimates of 1.5-6.5 m for most individuals. Size-based assignment to age classes (neonates, juveniles, adults) is modified from the larger C. megalodon and scaled based on the largest available specimens of C. angustidens, reported herein. These assemblages are dominated by small individuals (juveniles and neonates) and include few adults. The Oligocene Charleston embayment therefore represents the first documented paleo-nursery area for C. angustidens.

New Skeletons of the Ancient Dolphin Xenorophus sloanii and Xenorophus simplicidens sp. nov. (Mammalia, Cetacea) from the Oligocene of South Carolina and the Ontogeny, Functional Anatomy, Asymmetry, Pathology, and Evolution of the Earliest Odontoceti

“…The Ashley Formation preserves calcareous marine invertebrates including the gastropod Epitonium sp., the oyster Cubitostrea sp., and the barnacle Concavus sp., though little formal study of the marine invertebrate assemblage has been published [58]. Fossil vertebrates from the Ashley Formation include sharks [59], bony fish [60], sea turtles [55,[61][62][63], sea birds (Boessenecker, pers. obs.…”

“…These traces are best interpreted as the serrated edge of a large tooth being drawn parallel to the bone surface rather than the tip incising into the bone surface as in Linichnus. The grooves in Knethichnus parallelum on CCNHM 1077, spacing of the grooves, and large size of certain Linichnus traces (specifically, the two Linichnus serratus traces on CCNHM 168) unequivocally identify the trace maker as Carcharocles angustidens, which is the only large shark with serrated teeth in the Oligocene of the western North Atlantic [59,76].…”