Comparisons of the patterns of embryology exhibited by animals has been the major resource in attempts to reconstruct their evolutionary history, ever since the first phylogeny was constructed by the comparative embryologist Ernst Haeckel in the 1870s. The attempt has always been to infer the nature of deep ancestors by identifying common embryological features among living relatives, but these inferences invariably rely upon incomplete information, and conclusions are often fine balanced. If only there were a fossil record of embryology, to provide direct insight into the embryology of animals from the time at which the major groups of animals first emerged.

Although embryos have the preservation potential of snot, amazingly, over the past decade fossilised embryos have been discovered from sites in China, Siberia, Australia and the USA, providing unforseen insights embryology before, during and after the Cambrian evolutionary explosion of animal diversity.

SEM images of fossilised embryos of Markuelia hunanensis (Dong et al. 2004)

Together with a worldwide team of collaborators, our group is working to elucidate the embryology, affinity and phylogenetic significance of the embryo fossil record. In particular, we have applied state-of-the-art techniques in computed tomography (SRXTM) to fully characterise these fossils.

Rendered virtual models of fossilized embryos based upon SRXTM scan data (Donoghue et al. 2006)