We are studying turtle, tortoise and terrapin (chelonian) fossils to better understand the potential impact of current threats to their biodiversity.
The fossil record preserves the responses of chelonians to major environmental changes and extinctions. We are using these fossils to produce the first comprehensive analysis of chelonian biodiversity and distribution through time.
Chelonians are a successful group of vertebrates that have endured for more than 220 million years. They have survived several major environmental changes incuding:
- global hot-house conditions in the Late Cretaceous and Eocene (and associated cooling events)
- the end-Cretaceous mass extinction
- post-Eocene global cooling trends.
Turtles, tortoises and terrapins are ideal for studying the response of cold-blooded vertebrates to long-term environmental change because they:
- inhabit all three major global ecosystems (marine, freshwater, terrestrial)
- have an established taxonomy
- are exceptionally common in the fossil record
- have well-defined habitat preferences.
Chelonians are globally threatened. We can predict the impact of future climatic threats by studying their responses to major events in the past.
The project aims to determine whether significant events in chelonian evolution coincide with major episodes of global environmental change.
We are creating a database of chelonian occurrences in the Mesozoic and Paleogene fossil record using data from a comprehensive literature search. It will include information on depositional environments and preservation types.
We will use the database to construct estimates of global chelonian biodiversity through the Mesozoic and Paleogene. We also hope to clarify how patterns of biodiversity differ among habitats and regions.
By comparing biodiversity with climate data (such as mean annual temperature and precipitation rates) we will show how changing environmental factors may have affected chelonian evolution.
Using standard and new statistical methods, we aim to separate changes in biodiversity from noise resulting from uneven sampling and other biases in the fossil record.