JVP Journal of Vertebrate Paleontology Program and Abstracts Volume 29, Supplement to Number 3 September 2009 69th Annual Meeting Society of Vertebrate Paleontology and the 57th Symposium of Vertebrate Palaeontology and Comparative Anatomy (SVPCA) University of Bristol Bristol, United Kingdom September 23-26, 2009 Society of Vertebrate Paleontology ISSN 0272-4634 Technical Session IX, Thursday, 1:45 pm TAPHONOMY OF A FLUVIALLY DERIVED BONE DEPOSIT: A NATURAL EXPERIMENT IN THE SANTA FE RIVER, FL BRYK, Alexander, Penn State University, University Park, PA, USA: ECCLES, Laurie, Penn State University, University Park, PA, USA: KITA, Zach, Penn State University, University Park, PA, USA Fluvial hydrodynamics bias many fossil deposits and these processes often create graded or ‘sorted’ accumulations along energy gradients. Flume experiments identify key parameters in fluid transport of bones and sediments but do not accurately reproduce sorted deposits because of scaling problems and simplifications endemic to laboratory work. Therefore we studied a natural system and an incipient fossil deposit that is undergoing sorting along a riverbed, although the fossils are being reworked in a secondary taphonomic event. Our study site, the Graveyard, is a karst depression located in a meander bend of the Sante Fe River in Alachua County, Florida. This depression reduces stream flow velocity, promoting the deposition and sorting of sediments and fossils. The Penn State Science Diving Program collected fossils in 50 x 50 cm units, spread at five foot intervals along a transect parallel to flow. We investigated the role of element, taxon, animal body mass and the shape, size, and density of each bone and bone fragment in determining the final location of any bone in a sorted deposit. Preliminary results show position depends primarily on the physical properties of each bone (shape, size, density) at the time of deposition. These are, in turn, strongly influenced by taxon, element, and body mass. The greatest taxonomic diversity is found in the smallest size fraction of the sorted assemblage because teeth and tooth fragments are more common in this size fraction. This study provides a starting point for paleontologists to recognize and interpret fluvially derived fossil deposits.