The Jurassic–Cretaceous (J/K) transition is a geological interval of important faunal turnover in Mesozoic terrestrial ecosystems, often hypothesised to represent a poorly understood mass extinction event. However, our understanding of faunal change is limited by the generally poor global record of the latest Jurassic and earliest Cretaceous fossils.
The Purbeck Group is a lithostratigraphic unit which outcrops along part of the Jurassic Coast World Heritage Site in Dorset, UK, and dates back to the latest Jurassic to earliest Cretaceous. The rocks of the Purbeck were deposited in marginal and shallow marine environments, and historically have yielded over 60 species of amphibians, dinosaurs, crocodilians, lepidosaurs, turtles, pterosaurs and mammals. This faunal diversity makes the Purbeck Group perhaps the best location globally to examine tetrapod communities and diversity changes through the J/K interval.
My research project will systematically sample suitable horizons within the Purbeck Group, both vertically through stratigraphy, and laterally at different outcrops along the coast and inland. Vertebrate microfossils will be extracted via screenwashing, identified, and combined with historical data to assess the diversity and ecological structure of Purbeck ecosystems, and their stability and variation through time. I will also be re-examining historically collected fossil material using the collections of the Natural History Museum in London using CT scanning approaches.
These data will be drawn together and combined with those from Late Jurassic (e.g. Morrison Formation, USA) and later Early Cretaceous (e.g. Wealden Group, England) ecosystems to better understand changes in community composition and ecological diversity through the J/K transition.