Unravelling the formation of Mesozoic bonebeds using rare earth element geochemistry of bioapatites integrated with in-situ dating

Fossil bonebeds are unique windows into ancient ecosystems and the biology of extinct vertebrate species. However, most existing datasets from bonebeds are collected in a qualitative manner and cannot differentiate efficiently between the various biological and geological processes responsible for bonebed formation. MORBID aims to solve this conundrum, by developing a cutting-edge geochemical toolkit focusing on determining the concentrations of rare earth elements within well-preserved bone and tooth material from Mesozoic bonebeds. This rapid in-situ workflow combines non-destructive micro-X-ray fluorescence element mapping with quantitative Laser Ablation ICP-MS profiling at a micrometer level spatial resolution. Bonebed material is selected based on varying geological age and palaeoenvironment and the presence of outstanding taphonomic and paleobiological questions. Once fossilized, bone and teeth retain a geochemical fingerprint of their early diagenetic conditions. This information will be used in MORBID to differentiate between a rapid burial or a reworked bone assemblage, to characterize the depositional environment, and to provenance fossils of unknown location and stratigraphy. In addition, innovative in-situ uranium-lead geochronology is applied on well-preserved bioapatite material to obtain minimum depositional ages of poorly age-constrained fossil strata. MORBID will be based at the Natural History Museum in London and will benefit from the ample experience in-house in dinosaur palaeontology and rare earth element applications, combined with the access to a world-class fossil reptile collection and state-of-the-art laser ablation ICP-MS facilities. This excellent working environment will lead to the development of an independent tool to disentangle post-mortem alteration effects versus potential behavioural components of fossil vertebrates in a critical period of their evolution.