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. Addison Miller. Department of Geology and Environmental Geosciences, College of Charleston, Charleston, South Carolina 29424, USA. addisonemiller12@gmail.com Matthew Gibson. Charleston Museum, Charleston, South Carolina 29403, USA. mgibson@charlestonmuseum.org Robert Boessenecker, Mace Brown Museum of Natural History and Department of Geology and Environmental Geosciences, College of Charleston, Charleston, South Carolina 29424, USA. Corresponding Author. boesseneckerrw@cofc.edu