Using Forensic Science to Determine the Taphonomic History of a Sauropod Dinosaur Quarry

Congratulations to Kenneth Bader. Kenneth has worked in the fossil preparation lab at Petrified Forest National Park since last summer. Prior to this he completed his Master of Science Degree at Kansas University. Kenneth's first paper from his thesis was just published in the journal Palaios. It is an interesting paper which looks at the taphonomy of sauropod skeletons from a quarry in the Jurassic Morrison Formation of Wyoming.

Kenneth closely examined the skeletons and documented hundreds of trace fossils of varying morphologies. Some were interpreted as tooth marks from predators and/or scavengers, but more interestingly many of the trace fossils can be attributed to various arthropods. Comparisons were made with arthropod traces and modern bones and from this a taphonomic hypothesis using forensic entomology can be proposed.

Bader et al. hypothesize that based on this evidence these sauropods died during the dry season, were scavenged, and then went through several detailed stages of decomposition, including a "dry stage" where tracemakers tunneled through dried flesh and created pupation chambers adjacent to bones. Larvae hatched and then contributed to the final removal of soft tissue from the bones. Total time from death until complete burial was estimate to be about 1-3 years.

Congrats again to Kenneth on a very interesting study.

BADER, K., HASIOTIS, S., & MARTIN, L. (2009). APPLICATION OF FORENSIC SCIENCE TECHNIQUES TO TRACE FOSSILS ON DINOSAUR BONES FROM A QUARRY IN THE UPPER JURASSIC MORRISON FORMATION, NORTHEASTERN WYOMING PALAIOS, 24 (3), 140-158 DOI: 10.2110/palo.2008.p08-058r

Abstract- Trace fossils on sauropod skeletons from a quarry in fluvial deposits of the Morrison Formation, Wyoming, are used to reconstruct the taphonomic history of the dinosaur bone accumulation. Shallow pits; rosettes; hemispherical pits; thin, curvilinear, branching grooves; and U- to V-shaped linear grooves make up trace fossils found on sauropod skeletons. The traces were interpreted by comparisons to traces on modern bone. Rosettes are circular rings of modified bone and are likely an early stage in the production of shallow pits. They are interpreted as pupation chambers constructed in dried flesh in contact with sauropod bone. Hemispherical pits are circular with a U-shaped cross section and interpreted as dermestid pupation chambers completed in sauropod bone. Thin, curvilinear, branching grooves are semicircular in cross section, form irregular dendritic or looping patterns, and are interpreted as root etchings. U- to V-shaped linear grooves are interpreted as theropod or crocodilian bite marks. Skeletal articulation and condition and distribution of bone modification traces suggest the skeletons accumulated at this site over no more than 3.5 years, with the bulk of the skeletons contributed during the dry season in the final 3–6 months. Carcasses went through all stages of decomposition—including the dry stage, represented by shallow pits, rosettes, and hemispherical pits. Vertebrate scavengers and necrophagous arthropods fed on the carcasses during all decomposition stages prior to burial of the assemblage.