Nose dive upside down: A new look at the ichthyosaur taphonomy and implications for paleobiology

• Applicant: Dr. Oliver Wings, since 7/2023
• Subject Area: Geology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 461387258

One of the most successful groups of marine reptiles, with an origin and early diversification in the Triassic, was the Ichthyosauria. These animals occupied various different niches and exhibited many body forms. The research on their taphonomy, especially when comparing morphologically disparate taxa can be difficult with existing methods. It is for this reason the taphonomical studies on ichthyosaurs so far focused on single localities or a handful of species. Throughout collections of ichthyosaur skeletons, an interesting phenomenon is noticed. In many cases the carcass reached the sea floor headfirst resulting in spectacular fossils with the skull perpendicular to the bedding. This is often coupled with a “belly-up” embedding position. Here, we will develop a method which will prove valuable for comparing a large number of genera. This quantitative manner of describing taphonomy is used here on ichthyosaurs but will be applicable to all vertebrate fossils in conservation deposits, both terrestrial and marine. The quantitative analysis will be accompanied by a semi-quantitative analysis and description of the recurring patterns. The head-first and belly-up deposition of ichthyosaurs is referred to as an anterodorsal landing (ADL) in this study, and can be seen in various taxa, size classes, and geological ages. Therefore, it is expected to be a common phenomenon for all ichthyosaurs caused by an anterodorsally positioned center of mass (CoM). We will quantify the occurrences of the ADL and see for which ichthyosaur genera it was most common. This quantification of the landing modes will be compared to a modelling of the ichthyosaur landing using a 3D sinking simulation. The input in these simulations will be the reconstruction of ichthyosaur carcasses of all morphotypes. These reconstructions will be further used to assess the biomechanical implications of an anterodorsal CoM on the swimming mechanics of ichthyosaurs. In conclusion, this project will produce new insights on the biomechanics and lifestyle of the diverse Ichthyosauria by studying their death, decay, and final burial. Moreover, these methods will prove useful for a wide array of taxa.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Professor Dr. Martin Sander, until 6/2023