Body length estimation of Neogene macrophagous lamniform sharks (Carcharodon and Otodus) derived from associated fossil dentitions

The megatooth shark, Otodus megalodon, is widely accepted as the largest macrophagous shark that ever lived; and yet, despite over a century of research, its size is still debated. The great white shark, Carcharodon carcharias, is regarded as the best living ecological analog to the extinct megatooth shark and has been the basis for all body length estimates to date. The most widely accepted and applied method for estimating body size of O. megalodon was based upon a linear relationship between tooth crown height and total body length in C. carcharias. However, when applying this method to an associated dentition of O. megalodon (UF-VP-311000), the estimates for this single individual ranged from 11.4 to 41.1 m. These widely variable estimates showed a distinct pattern, in which anterior teeth resulted in lower estimates than posterior teeth. Consequently, previous paleoecological analyses based on body size estimates of O. megalodon may be subject to misinterpretation. Herein, we describe a novel method based on the summed crown width of associated fossil dentitions, which mitigates the variability associated with different tooth positions. The method assumes direct proportionality between the ratio of summed crown width to body length in ecologically and taxonomically related fossil and modern species. Total body lengths were estimated from 11 individuals, representing five lamniform species: Otodus megalodon, Otodus chubutensis, Carcharodon carcharias, Carcharodon hubbelli, and Carcharodon hastalis. The method was extrapolated for the largest known isolated upper tooth of O. megalodon, resulting in a maximum body length estimate of 20 m. Victor J. Perez. Department of Vertebrate Paleontology, Florida Museum of Natural History, 1659 Museum Rd., Gainesville, Florida 32611, USA and Department of Geological Sciences, University of Florida, 241 Williamson Hall, PO Box 112120, Gainesville, Florida 32611, USA and Department of Paleontology, Calvert Marine Museum, Solomons, Maryland 20688, USA Victor.Perez@calvertcountymd.gov Ronny M. Leder. Department of Vertebrate Paleontology, Florida Museum of Natural History, 1659 Museum Rd., Gainesville, Florida 32611, USA and Natural History Museum City of Leipzig, Lortzingstraße PEREZ, LEDER, & BADAUT: ESTIMATING LAMNIFORM BODY SIZE 2 3, 04105 Leipzig, Germany. ronnymaik.leder@leipzig.de Teddy Badaut. Independent Researcher, Thoirette, France. kieffer_stirlling@hotmail.fr