Last week, a memorial volume was published by the Royal Geological Society in honour of Professor Martin Brasier, who tragically died in 2014. In this volume, a posthumous publication reports extraordinary preservation of brain tissue in an Early Cretaceous Iguanodon relative, associated with a naturally-formed fossil cast of the interior of the cranium. This remarkable find provides further testimony of Professor Brasier's life-long devotion to meticulous research and illumination of the fossil record.
Professor Brasier looking for the Gunflint Chert in Ontario, 2009. Photo courtesy of Alex Liu.
The fossils were recovered in 2004, next to other Iguanodontian fossils in Sussex, UK. Over the next decade, a multi-disciplinary team led by Professor Brasier analysed the mineralised fragments using a combination of scanning electron microscopy and X-ray microtomography. This revealed preservation of the meninges, blood vessels and associated collagen strands surrounding the brain itself. Comparison with living archosaurs (such as birds and crocodiles) shows structural similarities consistent with previous interpretations of iguanodontian dinosaurs.
Although fossilised soft tissues are well known, as are endocasts, this is the first report of fossilised brain tissue, not only from a dinosaur but in fact any terrestrial vertebrate: fossil brain tissue is also known from Cambrian marine arthropods from the Chengjiang and Burgess Shale formations. In this case the unusual fossilisation is thought to be due to death of the dinosaur within or adjacent to an anoxic or eutrophic environment.
Brasier, M.D. et al “Remarkable preservation of brain tissues in an Early Cretaceous iguanodontian dinosaur” in Earth System Evolution and Early Life: a celebration of the work of Martin Brasier (eds Brasier, A. et al) Geological Society, London, Special Publications, 448 http://dx.doi.org/10.1144/SP448.3