Four complete, articulated, extant sauropod skeletons — yes, really!

August 30, 2009

Well, not really really.


Appendicular skeleton of savannah monitor lizard Varanus exanthematicus, "Charlie", in dorsal view.

What we have here is of course the bones of all four feet of a lizard (plus the limb bones): “sauropod” means “lizard foot”, so lizard-foot skeletons are sauropod skeletons — right?

(Note that the hind limbs are arranged in a weird posture here, with the knees bent forward.  Also that the left pes is missing one digit — possibly IV — which was presumably lost some time ago and healed.)

These are the bones of “Charlie”, a mature savannah monitor lizard Varanus exanthematicus, estimated as fourteen or fifteen years old at the time of death.  I have his whole skeleton — cranial, axial and limb-girdles — in various states of preparation, and no doubt they will all appear here sooner or later.  I was fortunate enough to encounter Charlie in the reptile house of a local kids’ activity centre with the boys, and he was not in a good way.  Luckily, his keepers happened to come in as I was looking at him, we got talking, and I popped the question as tactfully as I could — would it be OK to take his body away when the sad day comes?

The sad day came, and I found a message on my answering machine.  For one reason and another, it was a couple of days before I was able to drive out and pick up his mortal remains, but it was a proud day when I brought him home:

Charlie in his glory

Savannah monitor lizard Varanus exanthematicus, "Charlie", recently expired, in left dorsolateral view. Scale bar for, uh, scale.

Charlie was a good-sized beast: 111 cm in length from snout to tail, and massing 3.4 kg.  I tell you, it was quite a challenge getting him into that pot that you see top right.

Charlie with Jonno

Savannah monitor lizard Varanus exanthematicus, "Charlie", recently expired, in right anterodorsolateral view. Juvenile Homo sapiens "Jonno Taylor" for scale.

To prepare Charlie for the pan, I had to remove his tail — much, much harder than I’d been prepared for, as it was so difficult to locate the sacrocaudal intervertebral joint — and gut him.  Unfortunately, by the time I opened him up, internal decomposition had set in, and he was not in a pleasant state:


Savannah monitor lizard Varanus exanthematicus, "Charlie", recently expired, in the unpopular right posteroventrolateral view.

(I have much more disgusting photos than this one, but it wouldn’t be tasteful to show them.)  Anyway, I abandoned my initial plan of dissecting the organs out, and basically just removed and discarded them.  I’ve actually had shamefully little experience with dead animals, so I don’t know how much the horrible state of Charlie’s guts is due to his final illness and how much to post-mortem decomposition.

Once I’d managed — just — to get him into the pot, Charlie was lightly simmered for a couple of hours (to Fiona’s delight), then dismembered, and the individual parts reboiled before I started picking the bones out of the various parts.  There’s more to say, but that will have to wait for another time.

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48 Responses to “Four complete, articulated, extant sauropod skeletons — yes, really!”

  1. Neil Says:

    Looking forward to the follow-up post(s). We have a 2 meter water monitor (V. salvator (“Spike”) sitting in our freezer — but no one has yet been up to the challenge…

  2. Mike Keesey Says:

    Is there a book or something that tells you how to do this?

  3. Nathan Myers Says:

    It was exactly for occasions like getting a mature varanus carcass into such a pot that the expression “believe you me” was coined.

  4. DDeden Says:

    Just a li’l “Wow!” at the SV POW! Would like to compare that to a marine iguana and small gharial and an ancient similar shaped dinosaur or three.

  5. Zach Miller Says:

    Neil, goddamnit, send it to me!

    My leopard gecko, you know, the one that’s (still) sick, just won’t freaking die. It’s gotten to the point now where it’s just annoying. I scrape gunk out of his eyelids every day and pull dried stuff out of his mouth and try to feed him every two or three days. He’s not eating. He hasn’t eaten in like three months. Any other lizard would have keeled over by now. On the one hand, it’s a amazing. On the other hand, it’s not like he’s getting better!!!

  6. Nima Says:

    Aw Schei3….

    and I was hoping like crazy that by sauropods you means “long neck” dinosaurs.

    Well, that lizard is indeed amazing to look at…. I’ve never done dissections myself (not interesting ones like a lizard anyway) so it’ll be cool to see what the end result is like.

    And Zach, I truly feel your pain. I’ve had lizards die on me in some pretty bad ways too, and nothing seemed to save them.

    Lol, stinkin’ every thing that’s not a sauropod!

  7. Mike Taylor Says:

    BTW., just to be clear — I didn’t set out to do an actual dissection here, just to extract the skeleton. (All being well, I will eventually mount the skeleton in a life pose.) So I didn’t for example, take any time over seeing where muscles attached. For my purposes, all that stuff just gunk to get off of the bones.

  8. Very cool, though sad. On the pig head preparation post I mentioned I was going to pick up an armadillo skeleton soon. Unfortunately, when I checked on it it was still in the “filled with white goop” stage of decomposition, so must sit below the Maryland soil for another year. I did extract the skull though, which is rather unique in its peg-like teeth and lack of obvious orbits.

  9. Heinrich Mallison Says:


    I wish I had known about this beforehand, just to make sure you do the measurements I really really need…. Did you by any chance measure the circumference of the tail base before you cut him up? Or did you take a picture in cranial view of the tail base (or caudal view of the hips) afterwards?

    PLEASE say you did!

  10. Mike Taylor Says:

    Hi, Heinrich; sorry, no, I didn’t take measurements apart from total length and mass — that’s what comes of only caring about osteology, I guess :-(

    I do have a photograph showing the tail-base, but it’s not very pleasant and you won’t find it easy to figure out the scale. Still, if it’s any use to you, you’re welcome:

  11. Heinrich Mallison Says:

    Ah, a pity!

    Thanks for the pic – no it is not nice, but informative ;)

    I am currently very interested in the ratio of total diameter (vertical and transverse) of the entire tail base versus the same measurements in the verts. Turns out 99% of all dino muscle reconstructions are, well, Sahel-zone style.


  12. Mike Taylor Says:

    I know little of this Sahel-zone of which you speak. Is it corn on the cob, or a shish kebab?

  13. Heinrich Mallison Says:

    well, the tails of crocs are shish-kebab: a lot of meat on a very thin stick. But dino tails are always drawn as corn on the cob (Carpenter et al. 2005, Arbour 2009). WHY?

    Arbour V.M. 2009: Estimating impact forces of tail club strikes by ankylosaurid dinosaurs. PLoS ONE 4(8): e6738. doi:10.1371/journal.pone.0006738

    Carpenter, K., Sander, F., McWhinney, L.A., & Wood, L. 2005: Evidence for predator-prey relationships. Examples for Allosaurus and Stegosaurus. Pp. 325-350 in Carpenter, K. (ed.): The Carnivorous Dinosaurs. Indiana University Press, Bloomington.

  14. Mike Taylor Says:

    Well, in the shish-kebab article I discussed some reasons why the amount of flesh stretched over sauropod bones might be expected to be proportionally less than in microvertebrates such as crocodiles. Have you observed a trend in the extant critters you’ve looked at? We all know that scaling is rarely isometric, and I would expect to find that bigger animals tend to have proportionally larger tail-base vertebrae than smaller (or, equivalently, to have proportionally less flesh encasing them). It would be cool if you could provide some actual data to confirm (or falsify!) my intuition.

  15. Heinrich Mallison Says:

    I fully agree with your reasoning for the neck. Same for the trunk. And, in those critters with air sacs of significant size in the anterior caudals, again the bones are ‘blown up’ out of proportion.

    but there are no air sacs, there is no PSP in stegosaurs. And from what I can see (with an N < 10, sadly), size does not have a large influence on proportions in the cross section. Gunga verbally confirmed this, but I have no idea how much data is backing this hunch of his.

    The best data I have is Ray Wilhite's wonderful alligator sections. These show clearly that in healthy alligators the flesh extends far beyond the bones, not only bulging, but also simply extending way beyond. In this repect Arbour's (2009) generous reconstruction is still under par – I get a doubling of muscle diamters for the alligator compared to a hypothetical 'bone-tip to bone-tip' version, while she only adds 43%.

    Do you have the alligator pics?

  16. Mike Taylor Says:

    No, I don’t have Ray’s alligator pictures — are they online?

    Interesting point about how non-pneumatic caudal vertebrae are not “inflated” to fill more of the flesh envelope, as pneumatic cervicals are. I’m not sure what to make of that — if tails, especially of diplodocids, really did carry proportionally much more flesh than necks, there would surely have been a balancing issue. It would be interesting to see a mockup of how you think it should be restored.

    I’d be very wary of extrapolating from alligators, though — not only because of the size difference but because ‘gators are tail-draggers, and so dealing with completely different sets of forces.

    Finally: I wonder whether caudal pneumatisation may have been more common and extensive than anyone’s yet realised: looking at the only published quantitative survey of pneumaticity (Wedel 2005: table 7.2), I see that of the 24 vertebral slices examined, only ONE is from a caudal vertebra — that of “Barosaurus” africanus figured by Janensch (1947:fig. 9), and that it has a fairly healthy ASP of 0.49.

    Plenty of food for thought!


    Janensch, W. 1947. Pneumatizitat bei Wirbeln von Sauropoden und anderen Saurischien. Plaeontographica, supplement 7:1-25.

    Wedel, Mathew J. 2005. Postcranial skeletal pneumaticity in sauropods and its implications for mass estimates. pp. 201-228 in Wilson, J. A., and Curry-Rogers, K. (eds.), The Sauropods: Evolution and Paleobiology. University of California Press, Berkeley.

  17. Heinrich Mallison Says:

    ah, yep, good point about the center of mass position…. which is why I ALWAYS used fat, massive tails ;) So my results are for huge tails, not the usual starved tails.

    I’d be very vary of saying ‘can’t compare, they are tail-draggers’. In fact, the vert morphology is highly similar with regards to the epaxial parts, and those are the parts that do the liftin’. And why should a dragger have MORE muscles than an animal that has to hold the tail up?
    I might go for smaller hypaxial stuff like ilio- and ischiocaudalis. After all, crocs undulate, dinos don’t. But the CFL must be bigger than in a croc, if anything.


    I will ask Ray if I can send you the pics.

  18. Mike Taylor Says:

    “Why should a dragger have MORE muscles than an animal that has to hold the tail up?”

    Or rather, ask: why shouldn’t an animal that has to hold the tail us have MORE bone than a dragger?

    What we need to do is study the actual osteology and musculature of a large extant animal with erect gait and a substantial tail that is held off the ground. Find one of those, and we’re in business. (Is there any such thing?)

  19. Darren Naish Says:

    Great discussion. I’m a little wary of relying heavily on crocodilians though, as they’re tail-propelled swimmers and hence surely have specialised tails that may be very different from those of terrestrial archosaurs. Indeed fossil crocs that are thought to have been more terrestrial than living ones seem to have had less tail musculature (shorter transverse processes etc.).

    Extant animal with erect gait and substantial tail held off the ground: pangolins.. but, being mammals, they have crappy tail musculature to begin with.

  20. Mike Taylor Says:

    Now all we need is a pangolin!

    We need to freeze that sucker solid, and cross-section its tail every 5 mm or so.

    Anyone have the specimen, the equipment and the inclination to do this? For the good of science?

  21. Heinrich Mallison Says:

    here’s why: because the dragging is not really important. When swimming, crocs must avoid significant torsion in the tail (only the tail tip does rotate a bit), and this means that epaxial musculature must be stroooooooong, methinks.

    But yes, ideally we’d need an extant example, and I know of exactly zero. ‘roos aren’t that bad, I guess, but still a far cry from a proper terrestrial archosaur giant.

  22. Heinrich Mallison Says:

    Darren, I suspect that the width of the transverse processes does not really correlate too well with soft tissue extent. And are the transverses really smaller, or is the other dimension bigger?

  23. Darren Naish Says:

    Hi Heinrich. Well, now you’re asking questions that would require a bit more than mere assertion :) Someone should go forth, collect measurements and study this stuff…

  24. Heinrich Mallison Says:

    ‘someone’ actually being me, in my spare time ;)

  25. David Marjanović Says:

    Would like to compare that to a marine iguana and small gharial and an ancient similar shaped dinosaur or three.

    There is no similar-shaped dinosaur, ancient or otherwise.

  26. Sarah Bickers Says:

    I await the Pangolin skeleton with eager anticipation- but wouldn’t a Komodo dragon be better?!

  27. Mike Taylor Says:

    A Komodo dragon would be awesome indeed — but very similar to the monitor lizard that I am already working, being a member of the same genus (Varanus). What I really want for my collection is a crocodilian. (And an eagle. And while I’m dreaming, I may as well have a brachiosaur or two.)

  28. Tor Bertin Says:

    My (admittedly small) campus Biology storage area has a fairly decent skull collection–especially of interest was a komodo dragon, Smilodon, crocodile, and hyena.

    Oh, and a platypus.

  29. Matt Wedel Says:

    if tails, especially of diplodocids, really did carry proportionally much more flesh than necks, there would surely have been a balancing issue.

    At the risk of misinterpreting you or precipitating a small war: I assume you mean that if diplodocids had heavy tails, they would have been out of balance with the neck and therefore harder to hold up.

    I have to confess that I have never gotten this idea of balancing the neck and tail. I can see how it would be important for a biped to balance over its two feet, but for a big quadruped with a relatively long torso, it seems unnecessary. Sauropod necks and tails were relatively small fractions of the total body mass–probably not more than 10% and maybe 15% respectively, even for fat-tailed diplodocids. That little mass can just be cantilevered off one end without worrying about balancing at the other end. Elephants and all other large-ish mammals are forced to do this with their heads, which in elephants at least really are about 10% of the body mass. Arguing that a sauropod tail had to be heavy (or light) to counterbalance the neck is akin to arguing that I can’t hold one arm out to the side without tipping over (it’s not exactly the same because the mass of the other arm is still hanging off the opposite shoulder).

    I suspect that this whole balancing idea crept into the popular imagination in David Norman’s Illustrated Encyclopedia of Dinosaurs–which I almost wore out as a kid and still adore, BTW. I don’t recall seeing any data or calculations behind it, and it has always just struck me as rather silly.

    If that’s not what you were talking about, then ignore this mini-rant. :-)

  30. Heinrich Mallison Says:

    Matt, I fully agree! Balance is important, and mass x moment arm of a tail is not insignificant – but since the COM may theoretically be placed as far posteriorly as 1 cm in front of the acetabulum (which makes an effective biped): who cares???? A fat tail shifts it backwards, so what? A tail heavy enough to shift it behind the acetabulum would have to weigh as much as the skull, neck, arms and entire body…… and there is no animal out there that looks like adding any reasonable amount of muscles to the tail skeleton takes us there.

    Now, granted, a far posterior COM position has its issues.
    1) rapid acceleration is a no-go. Instead of retracting the limb in relation to the body and speeding up, you actually end up retracting the limb and tilting up the body. Much present in my sauropod models, especially in diplodocids. Which dovetails nicely with rearing for feeding. :D
    2) lateral stability is difficult to maintain. After all, the amount of weight on the forelimbs is minimal, so they have very low friction on the ground. So anything that pushes the anterior body laterally is hard to counter. (Can you say ‘thumb claw’?)
    3) even worse, the resulting vector of hind limb retraction (connect acetabulum – COM) points anteromedially – if the COM is further back, the medial component becomes larger. And this increases lateral acceleration, aggrevation problem No. 2. OUCH!

    But then, who imagines a sauropod trying to outrun Usain Boilt? or out-turn a rabbit? I don’t. And the (weird) anteromedial rotation of the main glenoid axis in practically all non-avian dinosaurs may play into this: obviously, forward-backward motion (in relation to the line of travel) is not the sole important issue in the forelimb

  31. Mike Taylor Says:

    Matt, you have evidently changed your opinion dramatically since you and I looked at the NHM mount of the Carnegie Diplodocus cast and you said that you thought it looked so back-heavy as to be functionally more or less bipedal. If that was true then AND we’re now going to lard a bunch more gloop onto the tail, then, yes, balance is going to become an issue. Not for brachiosaurs, sure — in which case I guess we may as well ignore it — but if we’re going to extend our interest as far as diplodocids from time to time, then it’s an issue.

    Rather that keep blowing hot air at this point, one of us ought to sit down with GSP’s multi-view Diplodocus reconstructions and do the GDI. I am prepared to bet good sushi that plenty more than 15% of the mass of that animal is behind the acetabulum.

  32. Heinrich Mallison Says:

    Why use GSP’s often… erhm…. somewhat questionable stuff? I have my own Diplo, and the mass breaks down like this (PSP included):

    neck & skull 1075 kg
    body 8100 kg
    forelimbs 941 kg
    hindlimbs 2100 kg
    tail 2233 kg
    TOTAL 14449 kg

    OK, the amount of PSP is debatable, but overall the tail amounts to ~15% of the total mass – and THIS model had various people say ‘no way, the butt and tail are WAY to fat’.

  33. Matt Wedel Says:

    Matt, you have evidently changed your opinion dramatically since you and I looked at the NHM mount of the Carnegie Diplodocus cast and you said that you thought it looked so back-heavy as to be functionally more or less bipedal.

    Yes, I thought that then about diplodocids, and I still do. The COM is back by the acetabulum, and they only bore about 10% of their weight on their forelimbs. So it makes sense to think of them as being nearly bipedal, but with forelimbs that almost incidentally made contact with the ground.

    And you’re right that, given the above, larding up the tail introduces some balance issues–between the tail and the entire body anterior to the acetabulum, not between the tail and the neck. You still don’t need a long tail to balance a long neck or vice versa.

  34. Matt Wedel Says:

    …although having a long tail or a long neck would allow you to put a little mass on the end of a boom instead of using a bigger mass with a shorter lever arm. IF the animal was a biped. Which sauropods weren’t, at least most of the time.

  35. Nathan Myers Says:

    I guess that explains why geese have such long, massive tails.

  36. Matt Wedel Says:

    Right! Big (m)ass, short boom.

    What strikes me about diplodocids is that they evolved from more foursquare critters that probably looked a lot like Cetiosaurus and Jobaria. So their short forelimbs, huge back ends, and posteriorly-shifted centers of mass are all apomorphic. I have not heard of any good reasons why a lineage would do that other than rearing, and I haven’t thunk up any myself. It’s a big functional package that is sort of crying out for an explanation–we can’t just ignore it and hope it will go away. The idea that diplodocids might have evolutionarily shortened their forelimbs to put their heads near the ground is…(contemplates using a career-limiting adjective)…not well supported. You don’t see horses and wildebeests running around with apomorphically short forelimbs in order to graze, and they even have titchy little necks where short forelimbs might conceivably help.

  37. [...] 2009 This is part 3 of an emerging and occasional SV-POW! series: part 1 was the pig skull, and part 2 was the lizard feet (though not advertised as such because I couldn’t resist the sauropod pun). Bennett's [...]

  38. Graham King Says:

    Great meaty discussion, guys! (groan)

    Nathan Myers Says:

    September 5, 2009 at 12:32 am

    I guess that explains why geese have such long, massive tails.

    Funny! And worth saying.. But (as I know you well know!) geese like many birds have near(er)-horizontal thighs, that position their lower leg well forward relative to hip-joint.. and though backward slant of shin counters this, birds also have elongated feet that move their footprint (toeprint really) even further forward.
    Thus, for birds, the acetabulum is not the balance-point posed over a near-columnar thigh-shin-foot support that it probably was for sauropods.

    I tried to find a goose lateral skeletal view to illustrate my point but this kiwi will have to do. I borrowed it from a mutual friend ;-)

  39. William Miller Says:

    If diplodocids were near-bipedal in their weight distribution (80-90% on hind legs), as big as some got (Amphicoelias being the ultimate example, but Supersaurus was huge too), then it seems unlikely that weight was a limiting factor on sauropod size. If a 120 ton (is that the current estimate?) Amphicoelias was putting 100 tons on two legs, couldn’t Ultra-Brachiosaurus get away with an evenly distributed 200 tons?

  40. Mike Taylor Says:

    Interesting point, William. But remember, the only sauropods for which we have enough of the skeleton to be confident they were carrying most of the weight over the hips are weedy little things like a 15-tonne Diplodocus. My guess is that if we ever recover good, associated remains of bigger diplodocids, we’ll find that they were more foursquare. (The WDC supersaur is missing its forelimbs, so it’s no use to us here.)

  41. William Miller Says:

    Oh, OK.

    That makes more sense.

    I still want that complete Amphicoelias fragillimus skeleton to test that idea, though…

  42. [...] whose distal tails I do know something about is monitor lizards, thanks to my adventures with the corpse of “Charlie”.  And those caudals do maintain astonishingly detailed structure right to the end of the tail, [...]

  43. [...] the actual bones, so enjoy the hyoid while you can.  (I similarly lost all the hyoid junk from my monitor lizard.  Bummer.  I must remember to show you more of Charlie’s cleaned bones some [...]

  44. [...] is how very much this is something anyone can do.  Well, OK, I admit I was super-lucky to score the monitor lizard; but I got the pig’s head by walking into a butcher’s shop and saying “One of you finest [...]

  45. jd Says:

    im going to attempt to articulate my monitor, who passed peacefully after a long life, not sure what im doing but im determined to complete the task. i have done some reaserch but am lacking the “pointers” fromone with experience. i assume you are a very busy person if you might find the time please point me in the right direction thank you. jd flock

  46. Mike Taylor Says:

    Hi, jd. Sorry to hear about your monitor, but you are absolutely right to make use of his remains. I’m not sure what, specifically, we can tell you beyond what’s in the posts we’ve already made on this site — read through the Things to Make and Do section — but if you have particular questions we’ll be happy to help out if we can.

  47. […] the savannah monitor, Varanus exanthematicus (same species as Mike’s “sauropod” Charlie), and monitor lungs are sufficiently diverse in form to have been used as taxonomic characters […]

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