So I have a new paper out describing what is probably not only the first baryonychine in Asia, but also the first in the Late Cretaceous. Why probably? Well because it’s based on a single isolated tooth and while I and my colleagues are pretty confident of the identification (as indeed were several other colleagues who took a look at the tooth), it’s pretty hard to be absolutely sure when that is all you have to go on.
The truth of course is that any theropod (and indeed most vertebrate clades) are tricky to diagnose off of a single tooth, but fortunately spinosaurids (the larger group that contains both the baryonychines like, well, Baryonyx and the spinosaurines like, errr, Spinosaurus) are better than most having more diagnostic features in their teeth than many others. Even so, the group as a whole are not as well studied as they might be and various definitions for spinosaurs and more specifically baryonychines vs spinosaurines are not always in perfect harmony. I won’t through all the details since a) I don’t want to bore the reader silly and b) that’s what the paper is for, but it’s still worth noting the major points.
The tooth (shown here with a 1 cm scale bar) has far more features in common with those of the baryonychines that the spinosaurines and is almost certainly a spinosaur being quite different from other theropods (and for that matter, other reptiles). The tooth lacks any ornamentation (more common in baryonychines), and has clearly defined carinae with very fine denticles (denticles are far more commonly present in baryonychines). It is laterally compressed to a degree seen in other baryonychines, is curved posteriorly along its length, and is relatively small. Don’t worry about the technical terms too much, the context and distribution is the most important thing (though I cover some of them here). Hopefully it’s clear that of the features present that can help separate baryonychines from spinosaurines (and there are quite a few for a single tooth lacking the root) the weight does fall down fairly solidly on one side.
The tooth itself came from Henan and I found it sat on display in a cabinet at the Xixia museum though at the time largely still buried in matrix with not much more than the tip showing. The staff there were kind enough to get it out for the case for us to a take a better look and on deciding that it was worth some further investigation it was taken back to Beijing for preparation. Once it was freed of the matrix it was clear that we had something unusual and a good dig through the literature and consultation with various colleagues led us to think we had, as advertised, the first Asian and Late Cretaceous baryonychine.
This is, in a sense, no great surprise. Given the rarity of the baryonychines (the only two taxa that I think most researchers are happy to call genuine are Baryonyx and Suchomimus and even these are often suggested to be synonymous) it is not a great surprise that they might have a much greater range (both geographically and temporally) that we expect from the available fossils. The overlap in morphology between the teeth means that a number of teeth considered spinosaurine or spinosaurid might well belong to baryonychines but we simply can’t tell. So while this find does (assuming our identification is right) extend their range quite considerably, it’s not a massive shock (to me anyway) though of course very interesting to have demonstrated by finding these animals in Asia and a considerable time after the next oldest one baryonychine is known and if fact this is the youngest record of any spinosaur.
Hone, D.W.E., Xu, X. & Wang, D. A probable baryonychine tooth from the Late Cretaceous of Henan Province, China. Vertebrata Palasiatica, 48: 19-26.
Share this Post