Archive for September, 2021

Ceratosuchops and Riparovenator: two new British Baryonychines

Today sees the publication of my most recent paper and it’s inevitably exciting as it describes two (yes two, count them) new, large theropods from the UK. Both join the burgeoning ranks of the spinosaurs, which have been increasing in lumber a lot of late and more specifically these are baryonychines.

While Spinosaurus tends to get all the attention, it and its kin, the especially large and sail-backed spinosaurines are known from extremely fragmentary remains and the smaller and less spiny baryonychines include Suchomimus and Baryonyx that are known from much more material.

In the case of the latter, this has been absolutely central to work on the spinosaurs as a whole as being the most complete and by far the best described specimen out there. The foundational monograph by Alan Charig and Angela Milner (who sadly passed away recently) being a cornerstone of spinosaur research. It’s also inevitably rather central to our work here since with two new baryonychines then we going to have to compare them to Baryonyx.

As usual, I don’t want to get into the minutia here since if you really want to look through the details of the diagnoses and traits and stratigraphy that’s all covered in the paper and this post is better placed to give some context to what we have done and why. The first thing of course is the names and their meanings. First off we have Ceratosuchops inferodios or the horned crocodile face hell-heron, the generic name referring to its appearance and species referring to the putative ecology of spinosaurs as a whole. After that is Riparovenator milnerae or Milner’s riverside hunter, in tribute to Angela’s work on these animals and again the ecology of these animals.

The second obvious thing to look at is what actually is there for the remains. Sadly, (if rather predictably) not that much though we do have nice snouts and parts of the skull roof and braincase for both, and in the case of Riparovenator, there’s also a nice section of tail. While pretty incomplete therefore, we do have more than some other spinosaurids and crucially we have the same parts of the skulls of both of these as we do for Baryonyx and Suchomimus. That’s obviously a huge bonus when it comes to the taxonomy work of sorting these animals out and we can make direct comparisons to these parts of the skulls that hold a lot of important traits.

Still, an obvious question about these British animals would be the vexed issue of ontogeny and if one (or both) were juveniles of each other. Happily, all three of the British ones are all extremely similar in size (within about 105 of each other) so it would be pretty hard to argue that they were very different ages and so the differences in anatomy are going to be ‘real’ and not part of their growth patterns. (And if they were very different ages but still the same size that would also suggest they have very different growth patterns and are therefore likely different taxa anyway). While we’re on the subject of the quality of the data here, it’s also worth noting that the specimens are generally really well preserved and not distorted so again, it’s a pretty safe bet to take the available features at face value as being genuine.

A major part of this paper is a new phylogenetic analysis done at the specimen level, with loads of odd bits and scraps of spinosaur material included for the first time in a comprehensive study (though some more things have appeared since we finished so it’s not 100% coverage). There’s not too many real surprises in there, but it should be a great start for resolving some other taxonomic issues for spinosaurs going forwards. One key thing though is the very clear signal that all of the earliest spinosaur material is European in origin and it looks to be a very strong case that this is a European group that then migrated out from here on multiple occasions.

Finally, there is the issue of the ecology of these animals. We don’t actually know if the two were contemporaneous with each either and either or both could be with Baryonyx and so while I’m sure some people will read this as ‘there were three together?!!’ we don’t actually say that. It’s perfectly possible from the data we have that all were somewhat separate in time and in space and of course niche partitioning is absolutely a thing too. I wrote this post on these issues a while back with this paper in mind to make the point about these kinds of situations and how it is easy to misinterpret them or assume that multiple species of large carnivores being together is somehow unusual or wrong. In the case of spinosaurs in particular, I’ve suggested that they are rather off in that they are except when they are common when they are suddenly very common (https://archosaurmusings.wordpress.com/2010/01/25/a-late-cretaceous-asian-baryonychine-probably/

) and this perhaps another example of that and hence the plethora of finds in the South of the UK.

I’ll finish up here, but obviously I want to thank Chris Barker and Neil Gostling for inviting me into this project and all my co-authors for their contributions to this publication. The paper is fully open access and available here: Barker, C.T., Hone, D.W.E., Naish, D., Cau, A., Lockwood, J.A.F., Foster, B., Clarkin, C.E., Schneider, P., and Gostling, N.J. 2021. New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European Origins of Spinosauridae. Scientific reports.

There’s lots more about these finds online with a Terrible Lizards podcast here with Chris Barker and Darren Naish, and both Darren and Andrea Cau have blogposts out on this too.


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