Taphonomic Distortion and Fossil Shape

One of the major goals in paleobiology is to reconstruct biological trends in deep time to ask questions about speciation, sexual dimorphism, allometry, and the relationship between morphology and ecology. However, answering biological questions in fossil taxa is undoubtedly impacted by taphonomic overprinting, which alters biological shape and potentially clouds biological trends. This is especially pronounced in shape analyses that simplify complex biological shapes into either 2D or 3D coordinates. I first examine the impacts of taphonomic shape change on discriminating closely related taxa using crania of the dinosaur Psittacosaurus. I then approximate the magnitude of taphonomic deformation in Psittacosaurus using the difference in magnitudes of asymmetry in fossil limbs compared to magnitudes of asymmetry in the limbs of extant taxa. Using these Psittacosaurus data as a baseline, I evaluate similar trends in a mammal-like reptile fossil taxon Diictodon. Finally, I artificially deform a specimen with known biological shape, extant Virginia opossums, to establish whether the taphonomic trends in fossil taxa can be replicated artificially. These analyses all provide a better picture of how taphonomy impacts fossil shape data with an emphasis on understanding how it can then obfuscate biological trends in those data.