THE PRESENT IS THE KEY TO THE PAST: SIMULATING TAPHONOMIC DEFORMATION TO DETECT BIOLOGICAL SIGNAL IN VERTEBRATE FOSSILS

Separating meaningful biological signal from surrounding noise is essential for conducting robust comparative morphological analyses. This is especially true for fossils, whose original biological shapes have been taphonomically altered due to burial in rock over geological time scales. To understand the effect of taphonomy on organismal shape, we simulated taphonomic deformation on a large dataset (n = 68) of raccoon (Procyon lotor) crania using 3D geometric morphometrics. While biological signals are apparent in the undeformed raccoon crania, these trends are obscured following artificial deformation. These results were compared with an extensive sample (n = 59) of crania of Diictodon feliceps, a basal therapsid from the Late Permian Karoo Basin of South Africa. We categorized the D. feliceps crania into five taphomorphotypes – bilateral, dorsoventral, rostrocaudal, shear (left and right), and saddle-backed, which formed distinct clusters in morphospace. Like the artificially deformed raccoon crania, biological trends were not detected in the taphonomically deformed D. feliceps crania, suggesting that taphonomic overprinting is driving shape trends in D. feliceps. Through the lens of artificially deformed specimens that have known biological shape, we are able to better understand how fossil deformation may be impacting biological signal. Ultimately, distinguishing the real signals from taphonomic noise will enhance our understanding of macroevolutionary change over deep time.