Monday, 5 March 2012

Brains, Fossils and X-Ray Machines

My last post on the Royal Society Summer Exhibition is partly to blame for my lack of blogging. I seem to be buried in my busiest teaching time, coupled with the research, design and build of the exhibit for the said event. However, my time has also been spent CT scanning some dinosaur brain cases...that are now winging their way back to the USA to the kind Institution (The Black Hills Institute) that loaned the fossil crania of some extinct beasties. 

Why would we want to CT scan a fossilized lump of bone? The answer is quite simple; to take a look at the internal morphology of the brain case, the endocast. The geometry and morphology of this 'inside' view of a dinosaurs brain case yields important information on the anatomy of the brain that once filled the said space. Given the soft tissue of brains have now long gone, we can begin to reconstruct the wiring (cranial nerves) and plumbing (vascular network) that once carried messages and nutrients to and from this rather important control centre, that is still locked in the fossil bone. All this work is undertaken at the Henry Moseley X-Ray Imaging Facility at the University of Manchester. 

To delve deep into the realm of prehistoric 'brain' surgery, we have to use the principle of the Extant Phylogenetic Bracket (EPB for short). The EPB helps us constrain the brain morphology (diagnosed from the CT data) using living ancestral and descendant groups, of the fossil beasties in question. In the case of dinosaurs, the EPB consists of crocodiles (ancestral) and birds (descendants). By viewing the brain case morphology of croc's and bird's, we are able to compare their endocast morphology and then use this help interpret the dinosaur brain cases. This is based upon the evidence interpreted from the soft tissue in the living EPB to help diagnose that of the extinct bracketed beasties. Hopefully we will have results to publish...soon!