Home > Uncategorized > Earth Claw is here!

Earth Claw is here!

aard-new-reconToday saw the publication of a paper that I’ve working for years to produce. It is an extremely proud moment for me since it doesn’t just represent a new dinosaur I’ve named but a new dinosaur that was found and excavated on my own expeditions. So in a sense it is more ‘my’ dinosaur than any of the others I’ve named, all of which had been found, excavated, prepared and curated long before I ever set eyes on them. I’ll have a lot more to say about the discovery of this new dinosaur, which I and my co-authors have called Aardonyx celestae, in posts over the next few days.
For now I just want to introduce Aardonyx the dinosaur, and say a little about why I think its special beyond its sentimental significance to me.

What is it?
Aardonyx is a sauropodomorph dinosaur. That is a long-necked, small-skulled, plant-munching branch of the lizard-hipped dinosaur group. Sauropodomorpha includes (as the name would suggest) the well-known giant quadrupedal sauropods as well as a range of more primitive forms that don’t appear to have survived beyond the Early Jurassic. Aardonyx is a relatively primitive member of the group and is excluded from Sauropoda (at least under some definitions of Sauropoda), although it appears to be more closely related to them than most other non-sauropod (=basal) sauropodomorphs.


Where was it found?
The bones were excavated from a single small but dense bone-bed that we nicknamed Marc’s Quarry (after my student Marc Blackbeard who studied the taphonomy of the site as part of his honours degree). Marc’s Quarry is one of several sites on the farm Spion Kop, part of a game farm complex in the Senekal District of the Free State South Africa.

How much of it was found?
We were actually quite lucky. We found the bones of two individuals thoroughly comingled. Between the two of them we found a remarkable amount of the skeleton, including the frequently missing skull. The major missing elements were the nasal and quadrate bones of the skull, the humerus of the forelimb and the ilium of the pelvis.


12-aardonyx-skeletonA skeletal reconstruction of Aardonyx scaled to the size of the smaller individual (but using parts from both)

How big was it?
My skeletal reconstruction (scaled to the size of the smaller individual) is just over 7 metres in length when the neck is held straight out in front of the body and stands 1.5 metres high at the hips. Assuming no major proportional changes the larger individual would have been close to 9 metres long and nearly 2 metres high at the hips. The histological work of Anusuya Chinsamy suggests that neither individual was mature at the time of death, indicating that Aardonyx got even bigger. Thus it is one of the largest known non-sauropod sauropodomorphs.

When did it live?
The geology of the site is fairly clear. There are no complex folds or faults, just simple, horizontal layer-cake stratigraphy. Thus there can be little doubt that Marc’s Quarry lies in the upper Elliot Formation, between the lower Elliot Formation and the Clarens Formation. That puts it in the Early Jurassic, somewhere between 183 and 200 million years old. Exactly where in this time range is far less certain but I would guess closer to 183ma than to 200ma.

What makes it a new species?
Aardonyx is blessed with many characters that enable it to be distinguished from all other known basal sauropodomorphs. These unique characteristics include features of the skull, neck, forearm and foot. Within the skull the apparently giant bony aperture of the nostril is especially noticeable. It is true that is a feature of the reconstructed skull and could therefore be prone to error. However I am confident that this is not the case. Firstly The premaxilla and maxilla used to reconstruct definitely come from the same taxon (they share the same set of unusual features such as pointed, virtually unserrated and longitudinally ridged teeth and a wide band of dense ‘micropits’ along the alveolar margins of both bones. Secondly the scar on the maxilla for articulation with the posterior process of the premaxilla is a perfect match. Other unusual skull features include the relatively tiny size of the major blood vessel and nerve openings on the maxilla bone and a very deep, sharply defined groove on the inside of the maxilla- you simply don’t see that elsewhere.
The neck vertebrae are distinctive in their simplicity. Generally sauropodomorph vertebrae become more complex as you progress towards the trunk, with the neck rib attachment scars projecting on well marked processes that are supported by thin buttresses of bone. None of the neck vertebrae of Aardonyx, from front to back, have a trace of a bony lamina or a projecting rib attachment.
As we look at the rest of the anatomy we continue to see odd features, for example the radius carries an extremely large highly rugose biceps scar (present on both individuals) while the fourth metatarsus of the foot meets the ankle in a broad racket-like expansion. All this indicates that although Aardonyx is intermediate between more typical ‘prosauropods’ and basal true sauropods it had been doing plenty of its own evolution since it split from the sauropod line and had accrued a bunch of weird characters that make it highly recognizable.

What makes it special?
Aardonyx seems to lie at the very heart of the transition from basal sauropodomorphs, that we could label ‘typical’ or ‘core’ prosauropods to true sauropods. When I plugged Aardonyx into two different cladistic matrices Aardonyx came out as the sister taxon of Melanorosaurus (or Melanorosauridae) + Sauropoda in both cases. Moreover this result was one of the most robust nodes in the analyses. This is interesting because as we say in the paper we think that committed quadrupedality is diagnostic for the latter clade. However Aardonyx is probably not a quadruped that makes it the closest known outgroup to Sauropoda before their move on to all fours.
Aardonyx also reveals that the sequence of evolution of derived characteristics on the line leading to sauropods involved more convergences and/or reversals than we previously suspected. But more about that later.

PrintAardonyx in its place in a simplified family tree of dinosaurs. Image courtesy of Matt Bonnan

Yates, A. M., Bonnan, M. F., Neveling, J., Chinsamy, A. and Blackbeard, M. G. 2009. A new transitional sauropodomorph dinosaur from the Early Jurassic of South Africa and the evolution of sauropod feeding and quadrupedalism. Proc. R. Soc. B doi:10.1098/rspb.2009.1440

  1. November 11, 2009 at 1:07 pm

    Fantastic! Do you have a visualization of this guy? Would you like one?

  2. Evelyn Wolke
    November 11, 2009 at 3:45 pm

    Wow, great work! My kids are still into dinos at 15, they think this is excellent too. This is hard, generally less than well appreciated work, and deserves a w00t at least!

  3. November 11, 2009 at 4:27 pm

    By the way, it is featured in my dinosaur course exam on Friday (I have set of questions about basal sauropodomorph -> eusauropod transitions, and through Aardi into the cladogram figure when I knew it was coming out.)

  4. November 11, 2009 at 4:38 pm

    Also, you’ve managed to name the first Mesozoic dinosaur for all “A-to-Z” lists!

  5. 220mya
    November 11, 2009 at 8:35 pm


    Congratulations! This is a fantastic paper, and after staring at the skull at the top of your blog for so long, its really nice to see it out. I was particularly intrigued to see how your matrix and the modified version of the Upchurch matrix have converged so closely now on the same answer.

    Any chance you could provide a higher-resolution version of the last figure in your blog post – its a little hard to read at its current size.

  6. Grant
    November 11, 2009 at 9:37 pm


    Great article and well done on being involved in such an importand find, you must be
    very excited.

    Anyway, I just think you should know that the worlds largest repository of knowledge needs your help!

    The first stop shop for almost a billion people when looking for answers is wikipedia…


    As you can see, 2 lines is hardly a fitting tribute to such an impressive species.

    I would like to ask you to please devote whatever time you can on helping to educate and inspire future palaeontologists or just those interested in a part of history.

    Choose “edit this page” and you’ll find the process amazingly simple…

    Good luck in the future and I hope to read about your next discovery!

  7. Alfredo
    November 11, 2009 at 10:29 pm


  8. November 12, 2009 at 1:53 am

    What a wonderful animal. Congratulations!

  9. Lars
    November 12, 2009 at 2:39 am

    Thought that you might like to know – this made the news on the radio today, not only the CBC (nationwide) but on the local public radio here in Alberta. The announcer even pronounced “sauropod” correctly.

  10. November 12, 2009 at 4:14 am

    You just wanted to be first in the alphabetical dinosaur dictionaries. 😉

    Figure 4 in your paper says you deleted Camelotia, Blikanasaurus and Isanosaurus a priori from your analysis, which I was all set to write a long complaint about, but the supplementary info indicates that was only done after you ran the analysis with these taxa included and found they were causing polytomies. So good job. 🙂

    What I find most interesting about Aardonyx is that it kills Upchurch and Galton’s monophyletic Prosauropoda, making the tree very similar to Yates’.

  11. November 12, 2009 at 9:30 pm

    Excellent job describing the fossil!

  12. Heinrich Mallison
    November 12, 2009 at 10:44 pm

    Awesome! You did not promise too much back in Bristol 🙂 And Matt….. I’ll have to kick his sorry ass for leaving me totally in the dark that he was involved in this (grrrrrr!).


  13. Jaime A. Headden
    November 13, 2009 at 12:53 am

    I am interested in the dentition and mandibular morphology of Aardonyx. Is there a planned work in progress on a more complete anatomical atlas or description? I noticed initially that the dentition seems very small and sparsely erupted on the jawline, and so the spacing and size of the dentition were at first indicative of the name, given a sim ilar aspect in the jaws of the Aardwolf, but then you blew that idea away by alluding to its preservation instead!

  14. November 13, 2009 at 5:51 am

    Congratulations, Adam. It’s so cool to have a new taxon help resolve interesting bits of the phylogeny for a major group, and more so to be involved in all stages from discovery to analysis.

    Now the race is on to come up with a sensible dinosaur name to beat ‘Aard-‘ on an alphabetical list. What are the rocks like around Aachen, anyone?

  15. November 13, 2009 at 3:03 pm

    Congrats! That’s a really very interesting specimen! 🙂

  16. November 13, 2009 at 6:20 pm

    Congratulations, Adam. Fair and extremely interesting.

  17. Michael Erickson
    November 16, 2009 at 9:16 am

    Congrats on an awesome new discovery! 🙂

  18. Daniel
    November 16, 2009 at 10:17 pm

    Early sauropodomorph near to the Triasic-Jurassic edge, bipedal but also showing the way to quadrupedalism, V-shaped jaws but whitout fleshy cheeks…

    ¿what more could ask to a transitional fossil?

    Congratulations from Chile…

  19. Jorge González (from Mexico)
    September 11, 2011 at 3:48 pm

    Adam Yates,

    i´m from Mexico, so that only I can speak and write in Spanish or German and therefore I can not write well in English. Excuse me please if my comment is not well written. Hopefully not.

    I have 10 years, but still I know I’m going to be big. I’ll be a paleontologist as you. I’ve always loved paleontology, that is why I understand you’re excited about Aardonyx celestae. Each new species of dinosaur is a breakthrough for paleontology. And if I ever find a dinosaur I am sure that excite me much. I am very proud of you and am also an admirer of yours, like many other paleontologists. Thanks to you and your colleagues, Matthew Bonnar, Johann Neveling, Anusuya Chinsamy and Marc Blackbeard could find an early Jurassic dinosaur prosauropod helped us to reveal further the evolution of giant sauropods over 30 feet long, helped us know how and from whom quadrupeds evolved giants.

    Many congratulations
    your admirer of Mexico Jorge Gonzalez

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