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.