Tetrapod Zoology


Congrats yet again to Sterling Nesbitt and colleagues on the publication of another one of those insane Triassic hellasaurs, this time the surreal archosauriform* Vancleavea campi (Nesbitt et al. 2009) [adjacent life restoration by Sterling Nesbitt]. Vancleavea was named by Long & Murry (1995) and is well represented by various bits and pieces from the Upper Triassic of the southwestern USA (interestingly, it seems to have been around for a long time: like, 20 million years or so). Its affinities were initially unclear: all that was clear was that it was a weird, armoured diapsid reptile, with relatively small limbs and a covering of assorted osteoderms. But, as everyone knows, a new, very well preserved, articulated skeleton was later discovered at Ghost Ranch Quarry in New Mexico, and this is the specimen described in the new paper. Finally, we know what Vancleavea is, and what it looked like…

* Archosauriformes corresponds with Archosauria of tradition, with Archosauria now being restricted to the archosauriform crown-group (the crocodilian-bird clade).


Vancleavea was about 1.2 m long and, as is clear from the reconstruction shown here (from Nesbitt et al. 2009) was long-bodied and short-limbed. It was covered in rows of osteoderms, and 30 particularly tall osteoderms formed a vertical fin along the top of the tail. The latter is totally unique (archosauriformes, and reptiles [and tetrapods!] in general, tend to use elongated neural spines to increase the depth of the tail) and suggests that Vancleavea was a semi-aquatic swimming animal, and thus very different ecologically from other basal archosauriforms.

The skull is also really weird…


Check out the dorsally directed external nostril openings, the big caniniform fangs, and absence of a supratemporal fenestra (this absence is not primitive, but seems to represent secondary closure). Whether the animal is freakishly weird and disturbing, or beautiful and really cute, depends on your point of view. I intended here just to showcase a few pics: for more information check out Bill Parker’s thoughts at Chinleana (Bill published on this taxon in 2008: Parker & Barton (2008)). Very, very cool – and yet more striking evidence for really profound diversity within the Triassic archosauriform assemblage.

For previous articles on freaky Triassic reptiles (I think Neil Kelley patented the term ‘hellasaurs’), check out…

Thanks to Sarah Werning for the heads-up.

Ref – –

Long, R. A. & Murry, P. A. 1995. Late Triassic (Carnian and Norian) tetrapods from the southwestern United States. New Mexico Museum of Natural History and Science Bulletin 4, 1-254.

Nesbitt, S. J., Stocker, M. R., Small, B. J. & Downs, A. 2009. The osteology and relationships of Vancleavea campi (Reptilia: Archosauriformes). Zoological Journal of the Linnaean Society 157, 814-864.

Parker, W G. & Barton, B. J. 2008. New Information on the Upper Triassic archosauriform Vancleavea campi based on new material from the Chinle Formation of Arizona. Palaeontologia Electronica 11 (3); 14A: 20p.


  1. #1 David Marjanović
    November 28, 2009

    The antorbital fenestra is missing, too!!!

    Impressive caniniforms.

    The latter is totally unique (archosauriformes, and reptiles in general, tend to use elongated neural spines to increase the depth of the tail)

    Crown-group tetrapods in general do that. Outside of the crown group, we have the claim in Clack’s 2002 book that an unspecified anthracosaur has supraneural radials, but if that’s not true, we have to go all the way to Ichthyostega to find such things (…which are, of course, not homologous to the osteoderms of Vancleavea).

  2. #2 David Marjanović
    November 28, 2009

    …to find such things documented, that is. Tail ends tend to be badly preserved and hardly, if at all, described. There go Tulerpeton, all (other??) whatcheeriids, Crassigyrinus, all baphetids, and so on… I’ll try to check out Greererpeton on Monday, but I think I’ve already done that…

  3. #3 Laelaps
    November 28, 2009

    Kirk Johnson and Ray Troll also mentioned Vancleavea in their book Crusin’ the Fossil Freeway (p. 186). They do not give much space to it, but they did include a restoration of Vancleavea by Troll (similar to Nesbitt’s, but more pop art in style). It really surprised me when I saw it and I am glad it has finally been described! Thanks for blogging this, Darren.

  4. #4 Alex Downs
    November 28, 2009

    Sterling’s life restoration seen here and at Chinleana is modified from Phil Bircheff’s life-size sculpture he made for Ghost Ranch. This scupture can be seen at Matt Celeskey’s Hairy Museum of Natural History blog August 12, 2007. Matt also did his own life restoration of Vancleavea for the New Mexico Museum of Natural History’s “Dawn of the Dinosaurs” Triassic gallery.

  5. #5 shiva
    November 28, 2009

    Cpuntdown to Vancleavea becoming the next Tanystropheus for sea serpent enthusiasts playing phylogenetic roulette… 3… 2… 1…

  6. #6 shiva
    November 28, 2009

    Seriously thought: this *is* weird. And possibly more like a “sea serpent” (in all but size) than any other known fossil reptile i can think of. Anyone know if it would have undulated up and down or sideways?

  7. #7 Bill
    November 28, 2009

    The illustration makes it look like it is undulating up and down but surely it must have been side to side – besides, look at that laterally flattened tail

  8. #8 Matt Celeskey
    November 28, 2009

    [from Darren: sorry, delayed by spam-filter]

    Couple quick addenda to Alex’s comment –

    First up, congratulations on getting this critter in the literature!

    Link to the HMNH post with the pictures of Phil Bircheff’s sculpture.

    Mary Sundstrom ended up doing the illustration for the NMMNH Triassic gallery – that can be seen here.

  9. #9 Jerzy
    November 28, 2009

    It looks like something which crawled into anuses of sauropods and eaten them from inside. :]

  10. #10 David Marjanović
    November 28, 2009

    The illustration correctly depicts side-to-side undulation, but doesn’t have enough shadow on it to make that clear enough.

  11. #11 220mya
    November 28, 2009


    Your statement that “it hasn’t previously been possible to determine [Vancleavea’s] affinities” is incorrect. Parker and Barton (2008) (who you cite) demonstrated quite clearly that it was a basal archosauriform.

  12. #12 Mark Evans
    November 28, 2009

    My bizarrometer just went off the scale.
    The skull looks like an archosaur trying to be Simosaurus.

  13. #13 J.S. Lopes
    November 28, 2009

    It look’s like a Chinese Dragon… was it aquatic?

  14. #14 Allen Hazen
    November 28, 2009

    “The Amniotes’ answer to Crassigyrinus” is what came to my mind.

  15. #15 Darren Naish
    November 28, 2009

    Randy (comment 10) writes…

    Your statement that “it hasn’t previously been possible to determine [Vancleavea’s] affinities” is incorrect. Parker and Barton (2008) (who you cite) demonstrated quite clearly that it was a basal archosauriform.

    Oops, sorry: when I first wrote the ‘hasn’t previously been possible’ comment, the only pre-2009 work I referred to was Long & Murry (1995). Thanks for correction, will now go and edit the text.

  16. #16 Rob Jase
    November 28, 2009

    Yes, it would have been perfect in the roll of Nessie in that film done in the ’30’s that hypothesized that Nessie was a giant newt.

    Any affinities with modern lines?

  17. #17 Zach Miller
    November 28, 2009

    That sucker’s kind of insane. Can’t wait to read the paper, maybe do my own reconstruction…

  18. #18 Brian Beatty
    November 28, 2009

    that is so cool, go Sterling!
    But, considering its general appearance, I would have named it Manda. Please, tell me someone else gets the idea…

  19. #19 Monado
    November 28, 2009

    Snakelike swimming motions and carnivorous with vicious mating fights? It looks as if it could nose into cavities and snap things up, rather than chasing fish. Maybe a little ambushing of smaller critters come to drink? Possibly it slapped things with that tail, too.

  20. #20 220mya
    November 28, 2009

    Brian (comment 18):

    Vancleavea was not named by Sterling et al. (2009), but by Long & Murry (1995). At that time, there was very little idea what the animal even looked like.

  21. #21 neil
    November 28, 2009

    (I think Neil Kelley patented the term ‘hellasaurs’)

    So good to know that, even if I bomb my oral exams this week, I will at least have made a significant contribution to the field…

    I used to think Vancleavea was really cool, now that she’s getting so popular I’m not so sure, once the Wikipedia page shows up I’m over it.

  22. #22 Jason S.
    November 29, 2009

    I first read about Vancleavea in the book “Dawn of the Dinosaurs” a couple years, but it was only a paragraph-long description. I thought it would be a bit more like a swimming pangolin (considering the large osteoderms) but nevertheless it’s fantastic to see what this peculiar animal might have looked like in the flesh. Thanks for posting this.

  23. #23 Bill Parker
    November 29, 2009

    Vancleavea is definitely a strange beast, but the holotype specimen has a bizarre history as well. It was collected in the 1960s by a park ranger at Petrified Forest National Park named Phillip Van Cleave (hence the name). The holotype consists mainly of vertebral centra, limb and girdle fragments, and a few fragmentary osteoderms mixed with phytosaur teeth. Long and Murry (1995) were the first to realize that this specimen was unique; however, they had no freakin idea what it was (they assigned it to Neodiapsida incertae sedis). Unfortunately the holotype specimen never made it back to the Petrified Forest after this study and was missing when I showed up at the park in 2001. Later that year I found it in a collection of mystery specimens at the Museum of Northern Arizona. I remember joking “Wow..here’s the missing holotype of Vancleavea campi, I’ll bet people have been beating down the door for this piece of #$%&@!”. Unknown to me at that moment, both Alex Downs at Ghost Ranch and Adrian Hunt (then at Mesalands) both had specimens they thought belonged to this taxon. Within a few years I had collected a few better specimens as well. Amazing how a fragmentary specimen that was ignored for over 30 years and barely assignable when first described, has suddenly become so important. The holotype specimen gives no hint whatsoever to the bizarre nature of this critter!

  24. #24 Steve P
    November 29, 2009

    If anyone’s interested, the original paper by Long & Murry (1995) is available for free download through the NMMNH’s website:


    …as are a whole lot of other awesome papers.

  25. #25 Sordes
    November 29, 2009

    The tail looks really extremely weird, much more like those of a fish than those of any tetrapod. But I ask me if it is 100% for sure that the osteoderms supported some kind of skin covered fin or if it could also be possible that they were similar to the serrated ridges on the tails of crocodylians.

  26. #26 David Marjanović
    November 29, 2009

    I like the Simosaurus and Crassigyrinus comparisons.

  27. #27 Sordes
    November 29, 2009

    There is also a really wonderful model reconstruction of Vancleavea:

  28. #28 Jorge Velez-Juarbe
    November 29, 2009

    Hi Darren, thanks for bringing this to our attention. The use of osteoderms to increase the height of the tail is very interesting! It shows another path taken by tetrapods in their way to adapt to a life in water. That is so cool!!

  29. #29 Nathan Myers
    November 30, 2009

    For the pig-ignorant among us, what is so odd about this, besides the caudal osteoderms? Is the skull peculiar somehow?

    I picture these things sliding down mudbanks for fun.

  30. #30 Darren Naish
    November 30, 2009

    Nathan: I’d say that Vancleavea is really surprising for two main reasons.

    — Firstly, it possesses a very odd combination of features: short, well ossified skull, small/’reduced’ limbs, and complex covering of osteoderms. As Nesbitt et al. (2009) note, this combination of features ‘is unparalleled within Reptilia’ (outside of fiction, ha ha).

    — Secondly, Vancleavea is highly divergent compared to other basal archosauriforms (proterosuchids, erythrosuchians, proterochampsids, Euparkeria). These are all rather long-snouted animals with terrestrial adaptations, and yet short-snouted, semi-aquatic Vancleavea is nested among them. While non-archosaurian archosauriforms were mostly gone by the Late Triassic, Vancleavea was a late survivor, and in fact the latest-surviving non-archosaurian archosauriform we know of.

  31. #31 Darren Naish
    November 30, 2009

    ps – I am not so keen on the comparisons with Simosaurus (see comment 26 and others). Simosaurus had a broad, flattened snout (suggesting that it might have been a suction-feeder: use the search box for more, I’m sure I’ve covered this previously), whereas Vancleavea‘s snout is deep and narrow. Ergo, the two are not much alike. As for Crassigyrinus, it’s snout also looks broader and blunter than that of Vancleavea and I’d imagine that it (= Crassigyrinus) was an aquatic lunge-feeder. Reminder: Crassigyrinus has been covered on Tet Zoo before.

  32. #32 David Peters
    December 4, 2009

    One of the reasons why Vancleavea campi does not have an antorbital fenestra and upper temporal fenestrae is because it is not an archosauriform. It is a askeptosaurid thalattosaur and a sister taxon to the short-snouted Miodentosaurus. [Links below]


  33. #33 David Marjanović
    December 5, 2009

    Unconvincing so far, based on the very links you provide, as I just posted to the DML. Vancleavea lacks supratemporals, has a closed ventral temporal arch, lacks the pineal foramen, and so on and so forth…

  34. #34 David Peters
    January 3, 2010

    Look again, David. Push the two parietals together and you’re left with a pineal foramen. The entire back half of the skull has been misidentified. There is no quadratojugal. The novel bone between the eyes is the ascending process of the premaxilla. Please compare to Miodentosaurus. It is the suite of characters that counts, not just a few apomorphies, especially misidentified apomorphies.

New comments have been disabled.