30 September 2014
Taking Away Fossils
There was a time when Stokesosaurus had a fairly large number of fossils attributed to it. There was even a second species considered for a short number of years not too long ago. This has since, along with all other fossils, including this braincase that was added to the pile of Stokesosaurus material, been overturned and assigned elsewhere. Juratyrant, the new genus generated from the reassigned second species, was described and reassigned by Roger Benson (with Stephen Brusatte as lead author of the reassignment paper). Brusatte and Benson's 2012 paper not only reassigned the second species as Juratyrant and removed a lot of the attributed material, but also investigated tyrannosaur systematics as a whole and re-envisioned their particular family tree (it was also rebuilt by Loewen et al. 2013 which was referenced here last year). Bickering about placements and materials should really be placed into the pile for later, however, for the casual paleontologist. The first step should always be to go to the source and attempt to understand how and why someone considered a fossil, isolated bone or otherwise, to be a unique species. We can go and read about the novel character interpreted by Brusatte and Benson along iliac surface, but first Madsen's reasoning behind attributing this isolated element to new genus/species should be reviewed. Thankfully, that paper is available online through JSTOR. The description is very traditional in format: introduction, systematics, measurements, images, description, discussion, and conclusion. However, the description is quite detailed and describes other material originally attributed to the animal that is no longer associated with it, allowing for a comparison of attributed materials between that and the 2012 paper.