The Cambrian ‘explosion’ of trilobites: revealing the drivers behind an iconic early animal radiation

Description

The Cambrian ‘explosion’ is the most important evolutionary radiation in the history of life on Earth. At this time, almost all major animal body plans (phyla) appear in the fossil record, and the first complex ecosystems emerge. Trilobites (marine arthropods similar to modern crustaceans) are an iconic early group that appear abruptly during this event, c. 520 million years ago. Quantifying the development of morphological diversity (‘disparity’) through time in fossil groups like trilobites is therefore critical in understanding radiations like the Cambrian ‘explosion’. The major aim of this project is to reveal the drivers behind the Cambrian trilobite radiation, by exploring relationships between disparity and potential causative factors related to ecology and palaeobiogeography. Leveraging vast museum collections for source data, detailed morphology will be quantified in hundreds of Cambrian trilobite species using landmark-based geometric morphometrics, and relationships between disparity in important functional structures (e.g. eyes) and palaeoenvironment will be tested. Patterns will then be compared with recent (e.g. adaptive, geographic) radiations. Results will show if processes observed in recent diversification events were operating soon after the dawn of animal life, and provide critical evidence as to whether radiations such as the Cambrian ‘explosion’ can be explained by such processes.