Tetrapod Zoology

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Helveticosaurus zollingeri is an unusual and poorly known diapsid from the Middle Triassic rocks of Monte san Giorgio, Switzerland. First described in 1955, it was initially identified as a primitive placodont and regarded as the only representative of the basal placodont group Helveticosauroidea. But this isn’t correct and Helveticosaurus lacks the features unique to both Placodontia and to Sauropterygia (Rieppel 1989).

Helveticosaurus was long-bodied and it had a long, flexible tail and – like mesosaurs, claudiosaurs, thalattosaurs and hupehsuchians – it was probably an axial undulatory swimmer. However, its pectoral girdle was robust, and in its forelimbs it exhibited several features commonly seen in secondarily aquatic tetrapods (SATs) that use their limbs as paddles or wings. Helveticosaurus therefore seems to have combined axial undulatory swimming with a rowing or flying motion of the forelimbs. It may therefore have exhibited an extremely unusual style of swimming. In marked contrast to that of most marine reptiles, the skull of Helveticosaurus is short and box-like, and it’s not immediately clear what it was doing with this skull, or what it was feeding on. Its long caniniform teeth show that was most likely a predator, but – as to what it was preying on – we have no idea.

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Helveticosaurus is the only known member of its lineage and it doesn’t possess any obvious close relatives (although a pelvis from the Lower Triassic of Spitsbergen might represent a close relative: see the comments below). It does however exhibit several features unique to archosauromorphs and it probably fitted somewhere into this diapsid clade, though exactly where we don’t really know (I’d like to know if John Merck’s thesis included information on it).

Incidentally, I tried googling Helveticosaurus. The screen-capture included above shows the results. Virtually everything traces back to stuff I’ve done (including the astrapothere and tapir stuff). How embarrassing – is no-one else interested? You might think that you’ve never seen a photo of Helveticosaurus. However, if you own Mike Benton’s The Reign of the Reptiles (Kingfisher Books, 1990), there’s an excellent colour photo of the only known specimen on p. 114… unfortunately it’s labelled as ‘the nothosaur Ceresiosaurus‘, so most people have missed it. The life restoration shown above was originally posted here and there have been a few requests for further info. The text you’ve just read was recycled from a talk script (the talk was this one), so was one of those ‘post something quickly with minimum effort’ articles.

Refs – -

Rieppel, O. 1989. Helveticosaurus zollingeri Peyer (Reptilia, Diapsida): skeletal paedomorphosis; functional anatomy and systematic affinities. Palaeontographica A 208, 123-152.

Comments

  1. #1 David Marjanovi?
    September 13, 2008

    It does however exhibit several features unique to archosauromorphs

    Oho!

    Anyway, I’m supposed to review the placodonts for my thesis, so I’ll have to check the beast out in person.

    How embarassing – is no-one else interested?

    On some animals there is a curse. Take Doswellia. Or the chroniosuchians. Or the “lindholmemydids”…

  2. #2 Nemo Ramjet
    September 13, 2008

    Actually, there IS a painting of Doswellia, done by me and John Conway, on the following link:

    http://jconway.deviantart.com/art/Doswellia-44209696

  3. #3 mr_subjunctive
    September 13, 2008

    Damn. I knew Helvetica was an old font, but I had no idea. . . .

  4. #4 Mike from Ottawa
    September 13, 2008

    Here’s another TetZoo post that has me spending 1bout ten times as long looking up stuff in the post and the comments as it did to read the post and comments. That’s a compliment to both Darren and the commenters.

    Doswellia is a weird thing (Paleos has lots of info) indeed, kind of cute in an ugly sort of way. But, apart from being some kind of turtle, what is a lindholmemydid and what is there about them that makes it odd they’re not better known?

    And, Darren, it’s not at all unusual that when one googles images of some odd tetrapods, they end up tracing back here or to your flickr. I regularly find myself doing that coming from some other and then see your materials come up.

  5. #5 David Marjanovi?
    September 13, 2008

    Doswellia is a weird thing (Paleos has lots of info)

    It has the entirety of information that exists on the animal save apparently for an unpublished thesis or something.

    kind of cute in an ugly sort of way.

    :-D

    But, apart from being some kind of turtle, what is a lindholmemydid

    See? Nobody knows. Could be stem-cryptodires or stem-testudinoids or who knows what. Could be paraphyletic. Asia, Cretaceous and maybe Paleogene (I forgot). They just haven’t been put into any cladistic analysis ever, like the chroniosuchians.

  6. #6 Lars Dietz
    September 13, 2008

    The original description of Doswellia is online here:
    http://tinyurl.com/6qsslk

  7. #7 William Miller
    September 13, 2008

    What a bizarre creature. It does look like a placodont, sort of … but that head looks creepy. Sharp predatory teeth, small boxy head… weird. The jaws aren’t snoutlike like a crocodilian or barracuda, or broad like a shark or bass; I wonder how it fed? Piercing and holding relatively small prey with its mouth? Were its teeth serrated enough to be used for ripping chunks off a large animal?

  8. #8 Mark Lees
    September 13, 2008

    The head of that reconstruction does seem odd – my first thought was that it had been drawn with gill slits!

  9. #9 djlactin
    September 13, 2008

    as for eating habits, i call ‘marine iguana’ kind of thing. just because of the resemblance.

  10. #10 DDeden
    September 13, 2008

    Yeah, reminds me of the marine iguana, scraping algae (or benthics like octopus?) off rocks, then scooting to the shore for a breath and a sunny warm-up and a sneeze to expel salts. It really doesn’t look all that aquatic, for a marine reptile.

  11. #11 Zach Miller
    September 13, 2008

    Actually, quite a few of my drawings show up on Google Image Search, as long as you know what to look for. My Silesaurus skull reconstruction is up there, so are a few of my Effigia restorations. I believe the Hupehsuchus drawing I did for Neil shows up, too.

    As for Helveticosaurus, it looks like another marine hellasaur that Neil will never get around blogging about! :-D

  12. #12 Bill Parker
    September 14, 2008

    Rumor has it that a redecription of Doswellia is in press. The original article by Weems (1980) really isn’t too bad (description wise), it is just that the figures are rather poor.

  13. #13 Zach Miller
    September 14, 2008

    That Doswellia link doesn’t work…

  14. #14 Lars Dietz
    September 14, 2008

    “That Doswellia link doesn’t work…”

    I just tried it, it still works for me. No idea why it doesn’t work for you. It’s on Google Books, so if you search for Doswellia there, you should get it.

  15. #15 David Marjanovi?
    September 14, 2008

    The link works for me. I wonder if the skull roof and the cheek are really articulated…

  16. #16 Quietman
    September 15, 2008

    There is a recent paper on Grippia Longirostris where it is compared to Helveticosaurus (as a possible reletive?) which is available as a downloadable PDF (free, open access).

  17. #17 Darren Naish
    September 15, 2008

    There is a recent paper on Grippia Longirostris where it is compared to Helveticosaurus (as a possible reletive?) which is available as a downloadable PDF (free, open access).

    Hmm. I can only think you’re referring to…

    Motani, R. 2000. Skull of Grippia longirostris: no contradiction with a diapsid affinity for the Ichthyopterygia. Palaeontology 43, 1-14.

    Motani suggested that the pelvis SVT 203 (from the Lower Triassic of Spitsbergen) – referred to Grippia by Mazin (1981) – might represent a relative of Helveticosaurus. He was not implying that Helveticosaurus might be a grippidian. Is this the paper you were referring to, or another one? (if the latter, it’s news to me). Thanks!

    Ref – -

    Mazin, J.-M. 1981. Grippia longirostris Wiman, 1929, un Ichthyopterygia primitif du Trias inférieur du Spitsberg. Bull. Mus. Natn. Hist. Nat., Paris, 4e sér. 3, 317-340.

  18. #18 Quietman
    September 15, 2008

    Darren
    That is the paper and if you read the paper (not the abstract however) He compares the skull and suggests an affinity which would (if correct) place both in the clade Eoichthyosauria (see his diagnostics). What is your take on this?

  19. #19 Quietman
    September 15, 2008

    Sorry, I said skull but meant pelvis.

  20. #20 Darren Naish
    September 15, 2008

    Many thanks for the clarification Ed – but you have misunderstood, Motani says that the pelvis SVT 203 has (1) been wrongly referred to Grippia and does not belong to that taxon, and (2) is most similar to the pelvis of Helveticosaurus and may represent a close relative. He does not say that Helveticosaurus and Grippia might be close relatives. The key section is at the top of p. 7.

  21. #21 Quietman
    September 15, 2008

    You are right, I missed that. Is there a full downloadable description of Helveticosaurus that you are aware of? The file at the german site can’t be printed (or at least I don’t know how to). I would like to compare it to some descriptions at Palaeos.com

  22. #22 Thomas R. Holtz, Jr.
    September 15, 2008

    Yes, Helvictosaurus was in Merck’s dissertation, and it does come out as an archosauromoph. John’s in Australia now (lucky bastard, leaving me to teach three different classes solo this week, grumble, grumble…) so I will wait for him to come back to find out if it is okay for me to say more about where it fell.

  23. #23 David Marjanovi?
    September 15, 2008

    Helvictosaurus

    Hel-ve-ti-co-saurus.

    if it is okay for me to say more about where it fell.

    If it is, I’d be interested in his whole thesis to, if not use it for my own, at least compare the results to my own one day… has a manuscript been submitted?

  24. #24 Quietman
    September 15, 2008

    Darren
    Well if not the order Prolacertiformes then it must be a new order. The Archosauromorpha / Prolacertiformes description was the closest I could find to what little description I could discern. It’s going to drive me crazy now.

  25. #25 William Miller
    September 15, 2008

    I’d be interested to know what it’s related to too … that picture looks stranger every time I look at it.

  26. #26 Nathan Myers
    September 16, 2008

    The footprint of the Naish cohort’s oeuvre on Google Images is no smaller than tyrannosaurical.

  27. #27 DDeden
    September 16, 2008

    Comparing the marine iguana again, I’ve read that the large males head butt or nudge each other in some way for dominance, might that have been done by Helveticosaurus zollingeri? Are the facial and cranial bones fragile or robust?

  28. #28 Thomas R. Holtz, Jr.
    September 16, 2008

    David,

    Was typing too fast before: no offense to the little Swiss critter…

    You can contact John at jmerck at umd dot edu; he’s out of the country for a while. As for a publishable version: much as I’ve tried to get him to work on an update, he’s had to spend far too much of the last several years in committees and bureaucratic stuff. So no manuscript has been submitted yet. As it is more then 10 years old new, he’ll have revise it (including Senter’s stuff, various new critters, update the phylogenetic techniques, etc.) and send it of to ZJLS or JSP or some other journal that allows lengthy articles. Good illustrations in there, too, so it’s a shame they are just sitting around not getting looked at.

  29. #29 David Marjanovi?
    September 16, 2008

    Thanks a lot. I had no idea it was that old, though… do you know how big the matrix is?

  30. #30 Thomas R. Holtz, Jr.
    September 17, 2008

    David,

    In his 1997 dissertation there were three outgroups, 81 OTUs, and 473 characters. He added & rescored taxa and characters for the version that was presented as an SVP poster a few years ago, but I can’t remember the details for that matrix size.

  31. #31 David Marjanovi?
    September 17, 2008

    version that was presented as an SVP poster a few years ago

    Oh, so it is the thing I have heard of. Great. The matrix has a very nice size; I’ll ask Merck.

  32. #32 Benjamin Chandler
    September 19, 2008

    If you’re looking for pictures of the critter, I believe Doug Henderson did a piece featuring Helveticosaurus in the new “Dawn of the Dinosaurs”.

  33. #33 Michael P. Morales
    October 5, 2008

    Thank you! I knew that photo couldn’t be of Ceresiosaurus in The Reign of the Reptiles book, but I couldn’t figure out what it could be. I guessed it might have been Helveticosaurus since that was one of the only animals from Monte San Giorgio I hadn’t seen an illustration of. And now you’ve confirmed it. Its nice to have a better idea of what this thing actually looked like.

  34. #34 David Peters
    February 17, 2010

    Basal placodont, derived from Claudiosaurus, not far from basal sauropterygia and basal thalattosauria including Vancleavea. Hope this helps.

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