Spinosaurs in review (sort of)

So I have a new paper out written with Tom Holtz and looking at the spinosaurs. It covers a number of issues and should have something for everyone working on this group be it taxonomy, behaviour, ecology or anatomy. This is an odd paper for a number of reasons and while I think it came out just fine, it might be worth looking at the background.

It was originally penned to be part of a special volume of papers which then never happened and this lead to major delays between submission and publication and thus while the title harks back to the original description of Spinosaurus, it is now a little dated. It is also odd because it was conceived originally as something close to a chapter from The Dinosauria (2nd ed) but obviously focused on a much smaller group. That means it’s something of a review of both the history and state of the art of spinosaur research, but was then an opportunity to clear up a few issues and introduced some ideas and corrections and thus while it is a review generally, it also has novel material and corrections. That means it rather awkwardly straddles the boundary between ‘review’ and ‘original paper’ and while it leans more to the former than the latter, it’s certainly got elements of both.

The spinosaurs have had a real renaissance of attention in recent years. Leaving aside the huge interest (positive and negative) surrounding the new Spinosaurus material there have been a bunch of new taxa named recently (Ostafrikasaurus, Oxalaia Ichthyovenator) as well as revisions of others (Sigilmassasaurus) and plenty of new finds like sets of teeth and cranial remains of even well-known taxa. In short, we’ve never had more material to work from but in many ways we’re hampered. Major taxa still await decent descriptions and many taxa, while valid, are based on limited material. That makes comparisons difficult and hampers research.

One area where we hope we have made a real contribution was in tweaking various taxonomic definitions. Baryonyx is a real case in point as its definition has not really been revised for some time and numerous characters that were once considered unique to the genus are now known to be present in many other spinosaurs and thus are not diagnostic to this animal. That really means little more than a bit of housekeeping in terms of sorting out some character states but it needs doing and (hopefully) we have now cleared up a few issues with the various diagnoses.

The other area we take a look at in more detail is some of the hypotheses about the behavioural ecology of the group. There have been lots of hypotheses about how these animals lived, and especially the function of the jaws, claws and sail. Many of these are mutually contradictory and the supporting evidence and arguments greatly limited or frankly non-existent. We try to critically appraise a few of them and put things on a firmer footing, but we do also note that spinosaurs may have been decent diggers.

There are whole suites of characteristics seen on animals that are good at digging and these are seen in some dinosaurs not least the alvarezsaurs. The spinosaurs and not anything like this specialised but do show at least a couple of these traits (the large claws and robust humerus for example) suggesting this is a hypothesis worth of some consideration in the future.

I’ll leave it there as obviously the real place to read all of this is in the paper which is online here. Good reading!

Hone, D.W.E., & Holtz, T.R. 2017. A century of spinosaurs – a review and revision of the Spinosauridae with comments on their ecology. Acta Geological Sinica.