A Late Cretaceous, Asian, Baryonychine. Probably.

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.

Probably baryonychine tooth from China. Modified from Hone et al., 2010.

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.

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21 Responses to “A Late Cretaceous, Asian, Baryonychine. Probably.”

  1. 1 SuperRaptor 25/01/2010 at 8:57 am

    A very interesting find; we already knew there were spinosaurs from Asia (“Sinopliosaurus” fusuiensis), but this is pretty exciting.

    • 2 David Hone 25/01/2010 at 9:03 am

      Spinosaurines are in Asia yes (nown from several sets of teeth in both China and Thailand) and thus by extension spinosaurids, but not baryonychines.

  2. 3 SuperRaptor 25/01/2010 at 9:25 am

    Ah, sorry. Didn’t get much sleep, so I missed the distinction. I await finding out more about it with bated breath. 😀

  3. 5 Karl Zimmerman 25/01/2010 at 9:33 am

    Late Cretaceous is a pretty wide range. Is it post Turonian?

  4. 7 SuperRaptor 25/01/2010 at 10:00 am

    You only specified that it’s the latest from Asia. Which spinosaurs, if any, lived later than this one?

  5. 9 220mya 25/01/2010 at 10:12 am

    So, ah, you didn’t provide the actual reference for those of us who might like to chase down the actual paper.

    • 10 David Hone 25/01/2010 at 10:21 am

      Oh yeah, good point Randy. It’s in Vertebrate PalAsiatica so you’ll have a job to hunt it down though of course I can send out a PDF. I mean, it’s not like I’m trying to hide it. You, and of course anyone can ask me for it which might be easier than trying to hunt it down yourself in any case. But yes, I should have put the citation up.

      This is what happens when you have to do things in a rush because the journal doesn’t tell you when the thing will be published. I’ll stick it in now.

  6. 11 David Stern 25/01/2010 at 2:24 pm

    ANU’s library stopped getting that journal in 1999…

  7. 15 David Stern 26/01/2010 at 10:34 am

    I had a look at that journal online now and it seems to be loaded with Chinglish gibberish. Don’t you think you could have published your paper in a better journal? Everyone thinks the Spinosauridae were extinct by 84 million years ago and you can show otherwise. Isn’t that important?

    • 16 David Hone 26/01/2010 at 11:18 am

      Well the site’s not great no, but the journal is fine and getting better (incidentally my colleague Corwin Sullivan is overhauling the submission guidelines etc. right now to improve things).

      Secondly, it’s not a bad journal at all – some good papers do get published here. While I perhaps could have got this paper into a better journal, the fact remains that this is a single partial tooth from a group notorious for having a confused dental taxonomy in terms of characteristics and as I note, while I’m quite happy the ID is right I’m also happy to concede that I could be very wrong. As such the impact of the discovery is lessened rather considerably without something really concrete.

      Thirdly, since I work in China, I think I have something of an obligation to try and help them better their palaeontology, so publishing a paper that will likely be of international interest (if not importance) is a good thing. No pressure was put on me to do this at all, but this is a short paper on a single tooth so I thought it a good opportunity to put pen to paper (as it were) in a Chinese journal.

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