A sauropod on Mars

February 24, 2021

This is old news, for those who have been following NASA’s Perseverance rover since before it left Earth, and it’s also not my find–my friend, colleague, and sometime co-author Brian Kraatz send me a heads-up about it this morning.

NASA posted the image above a couple of days ago, in a post called “Mastcam-Z looks at its calibration target“. If you zoom in, you can just make out a tiny silhouette of a sauropod on the ring around the MarsDial (what we call a sundial on Mars).

Here’s a much clearer pre-launch image from the Planetary Society (link), which helped design the calibration targets. Starting at about 7:00 and going around clockwise, there’s an image of the inner Solar System, with the Sun, Mercury, Venus, Earth, and Mars, then DNA, bacteria, a fern, a sauropod, humans (same silhouettes as on the Pioneer probes), a retro-style rocket ship, and finally a motto, “Two worlds, one beginning”, which may be a sly nod to the hypothesis that life in the inner Solar System started on Mars and was later seeded to Earth on meteorites–or possibly vice versa.

What’s with all this bling? It’s all about calibrating the cameras on Perseverance. The MarsDial gives the position and angle of the sun, and the colored dots help calibrate the color output of the cameras. There are other calibration targets for other cameras on board Perseverance, as well as some other technological ‘Easter eggs’ from the folks who designed and built the rover–read more about them here (link).

Perseverance is up there to explore “the potential of Mars as a place for life” (source), both past and future. Its four science objectives are:

  1. Looking for Habitability: Identify past environments capable of supporting microbial life.
  2. Seeking Biosignatures: Seek signs of possible past microbial life in those habitable environments, particularly in special rocks known to preserve signs of life over time.
  3. Caching Samples: Collect core rock and “soil” samples and store them on the Martian surface. [For a future sample-return mission.–MJW]
  4. Preparing for Humans: Test oxygen production from the Martian atmosphere.

Personally, I have my fingers firmly crossed that Perseverance finds something like this sticking out of a Martian rock:

(That one is actually from Utah, not Mars–see this post.) I don’t see any other way that my particular skill set is going to contribute to the exploration of the Solar System, which I’d really like to do. So I’ll wait, and watch Perseverance send back pictures, and wait some more. Sigh.

Anyway, there’s at least one sauropod on Mars, and that will have to do (for now!).

Bonus: if you haven’t watched the video of the rocket skycrane delivering the car-sized Perseverance to the surface of Mars, you need to. And if you have watched it, who cares, watch it again:

Figure 3. BIBE 45854, articulated series of nine mid and posterior cervical vertebrae of a large, osteologically mature Alamosaurus sanjuanensis. Series is estimated to represent the sixth to fourteenth cervical vertebrae. A, composite photo-mosaic of the cervical series in right lateral view; identification of each vertebra indicated by C6 to C14, respectively. B, line drawing based on the photo-mosaic in A. C, line drawing in B with labels shown and vertebral fossae indicated by solid grey fill; cross-hatching represents broken bone surfaces and reconstructive material. Abbreviations: C, cervical vertebra; cdf, centrodiapophyseal fossa; clf, centrum lateral fossa; pocdf, postzygapophyseal centrodiapophyseal fossa; prcdf, prezygapophyseal centrodiapophyseal fossa; prcdf1, dorsal prezygapophyseal centrodiapophyseal fossa; prcdf2, ventral prezygapophyseal centrodiapophyseal fossa; sdf, spinodiapophyseal fossa; spof, spinopostzygapophyseal fossa; sprf, spinoprezygapophyseal fossa. (Tykoski and Fiorillo 2016)

Have you been reading Justin Tweet’s series, “Your Friends the Titanosaurs“, at his awesomely-named blog, Equatorial Minnesota? If not, get on it. He’s been running the series since June, 2018, so this notice is only somewhat grotesquely overdue. The latest installment, on Alamosaurus from Texas and Mexico, is phenomenal. I have never seen another summary or review that pulled together so much of the relevant literature and explained it all so well. Seriously, that blog post deserves to be a review paper; it could be submitted pretty much as-is, although it would be even better with his two other Alamosaurus posts integrated (this one, and this one). It’s great work, is what I’m saying, and it needs to be acknowledged.

In particular, I was struck by the note by Anonymous in 1941 on the discovery of a cervical vertebra 1.2 meters long. I’d never heard of that ref, and I’ve never seen that vert, but at 120cm it would be in the top 7 longest cervical vertebrae on the planet (see the latest version of the list in this post), narrowly beating out the 118-cm cervical of Puertasaurus. In fairness, the preserved cervical of Puertasaurus is probably a posterior one, and more anterior cervicals might have been longer. Then again, in the big Alamosaurus neck the longest verts are pretty darned posterior, so…we need more Puertasaurus.

EDIT a few hours later: Thanks to the kind offices of Justin Tweet, I’ve now seen Anonymous (1941), and the exact wording is, “A single vertebra, or neck joint bone, is three feet across, only two inches less than four feet long, and in its present fossilized state weighs 600 pounds.” ‘Two inches less than four feet long’ is 46 inches or a hair under 117cm, which puts the supposed giant cervical just behind Puertasaurus after all, but still firmly in the top 10. And depending on how one interprets the passage in Anonymous (1941), it might not have been any bigger than BIBE 45854–see this comment for details.

Big cervical showdown. From the top left: BYU 9024, originally referred to Supersaurus but more likely representing a giant Barosaurus (137cm); the single available cervical of Puertasaurus (118cm); a world-record giraffe neck (2.4m); Alamosaurus referred cervical series BIBE 45854, longest centra are ~81cm; Sauroposeidon holotype OMNH 53062, longest centrum is 125cm. This image makes it very clear that whatever Sauroposeidon was doing, it was a way different thing from Alamosaurus.

Crucially, the longest vertebrae in the BIBE 45854 series are about 80 or 81 cm long, which means that a 1.2-meter cervical would be half again as large. That is a pretty staggering thought, and that individual of Alamosaurus–assuming it was the same taxon as BIBE 45854, and not some other, longer-necked critter–would definitely be a contender for the largest sauropod of all time.

Illustrations here are of the big Alamosaurus cervical series from Big Bend, which was comprehensively described by Ron Tykoski and Tony Fiorillo in 2016, and which we have covered in these previous posts:

References

  • Anonymous. 1941. Find dinosaur neck bone nearly four feet long. The Science News-Letter 39(1):6–7.
  • Tykoski, R.S. and Fiorillo, A.R. 2016. An articulated cervical series of Alamosaurus sanjuanensis Gilmore, 1922 (Dinosauria, Sauropoda) from Texas: new perspective on the relationships of North America’s last giant sauropod. Journal of Systematic Palaeontology 15(5):339-364.

This is RAM 1619, a proximal caudal vertebra of an apatosaurine, in posterior view. It’s one of just a handful of sauropod specimens at the Raymond M. Alf Museum of Paleontology. It’s a donated specimen, which came with very little documentation. It was originally catalogued only to a very gross taxonomic level, but I had a crack at it on a collections visit in 2018, when I took these photos. I told Andy Farke and the other Alf folks right away, I just never got around to blogging about it until now.

Why do I think it’s an apatosaurine? A few reasons: 

  • it’s slightly procoelous, which is pretty common for diplodocids, whereas caudals of Haplocanthosaurus, Camarasaurus, and Brachiosaurus are all either amphicoelous or amphiplatyan;
  • it has big pneumatic fossae above the transverse processes, unlike Haplo, Cam, and Brachio, but it lacks big pneumatic fossae below the transverse processes, unlike Diplodocus and Barosaurus
  • and finally the clincher: the centrum is taller than wide, and broader dorsally than ventrally.

In the literature this centrum shape is described as ‘heart-shaped’ (e.g., Tschopp et al. 2015), and sometimes there is midline dorsal depression that really sells it. That feature isn’t present in this vert, but overall it’s still much closer to a heart-shape than the caudals of any non-apatosaurine in the Morrison. Hence the literal 11th-hour Valentine’s Day post (and yes, this will go up with a Feb. 15 date because SV-POW! runs on England time, but it’s still the 14th here in SoCal, at least for another minute or two).

RAM 1619 in postero-dorsal view.

Back to the pneumaticity. Occasionally an apatosaurine shows up with big lateral fossae ventral to the transverse processes–the mounted one at the Field Museum is a good example (see this post). And the big Oklahoma apatosaurine breaks the rules by having very pneumatic caudals–more on that in the future. But at least in the very proximal caudals of non-gigantic apatosaurines, it’s more common for there to be pneumatic fossae above the transverse processes, near the base of the neural arch. You can see that in caudal 3 of UWGM 15556/CM 563, a specimen of Brontosaurus parvus:

I don’t think I’d figured out this difference between above-the-transverse-process (supracostal, perhaps) and below-the-transverse-process (infracostal, let’s say) pneumatic fossae when Mike and I published our caudal pneumaticity paper back in 2013. I didn’t start thinking seriously about the dorsal vs ventral distribution of pneumatic features until sometime later (see this post). And I need to go check my notes and photos before I’ll feel comfortable calling supracostal fossae the apatosaurine norm. But I am certain that Diplodocus and Barosaurus have big pneumatic foramina on the lateral faces of their proximal caudals (see this post, for example), Haplocanthosaurus and brachiosaurids have infracostal fossae when they have any fossae at all in proximal caudals (distally the fossae edge up to the base of the neural arch in Giraffatitan), and to date there are no well-documented cases of caudal pneumaticity in Camarasaurus (if that seems like a hedge, sit tight and W4TP). 

RAM 1619 has asymmetric pneumatic fossae, which is pretty cool, and also pretty common, and we think we have a hypothesis to explain that now–see Mike’s and my new paper in Qeios.

And if I’m going to make my midnight deadline, even on Pacific Time, I’d best sign off. More cool stuff inbound real soon.

References

Taylor 2015: Figure 8. Cervical vertebrae 4 (left) and 6 (right) of Giraffatitan brancai lectotype MB.R.2180 (previously HMN SI), in posterior view. Note the dramatically different aspect ratios of their cotyles, indicating that extensive and unpredictable crushing has taken place. Photographs by author.

Here are cervicals 4 and 8 from MB.R.2180, the big mounted Giraffatitan in Berlin. Even though this is one of the better sauropod necks in the world, the vertebrae have enough taphonomic distortion that trying to determine what neutral, uncrushed shape they started from is not easy.

Wedel and Taylor 2013b: Figure 3. The caudal vertebrae of ostriches are highly pneumatic. This mid-caudal vertebra of an ostrich (Struthio camelus), LACM Bj342, is shown in dorsal view (top), anterior, left lateral, and posterior views (middle, left to right), and ventral view (bottom). The vertebra is approximately 5cm wide across the transverse processes. Note the pneumatic foramina on the dorsal, ventral, and lateral sides of the vertebra.

Here’s one of the free caudal vertebrae of an ostrich, Struthio camelus, LACM Ornithology Bj342. It’s a bit asymmetric–the two halves of the neural spine are aimed in slightly different directions, and one transverse process is angled just slightly differently than the other–but the asymmetry is pretty subtle and the rest of the vertebral column looks normal, so I don’t think this rises to the level of pathology. It looks like the kind of minor variation that is present in all kinds of animals, especially large-bodied ones.

This is a dorsal vertebra of a rhea, Rhea americana, LACM Ornithology 97479, in posteroventral view. Ink pen for scale. I took this photo to document the pneumatic foramina and related bone remodeling on the dorsal roof of the neural canal, but I’m showing it here because in technical terms this vert is horked. It’s not subtly asymmetric, it’s grossly so, with virtually every feature–the postzygapophyses, diapophyses, parapophyses, and even the posterior articular surface of the centrum–showing fairly pronounced differences from left to right.

That rhea dorsal looks pretty bad for dry bone from a recently-dead extant animal, but if it was from the Morrison Formation it would be phenomenal. If I found a sauropod vertebra that looked that good, I’d think, “Hey, this thing’s in pretty good shape! Only a little distorted.” The roughed-up surface of the right transverse process might give me pause, and I’d want to take a close look at those postzygs, but most of this asymmetry is consistent with what I’d expect from taphonomic distortion.

Which brings me to my titular question, which I am asking out of genuine ignorance and not in a rhetorical or leading way: can we tell these things apart? And if so, with what degree of confidence? I know there has been a lot of work on 3D retrodeformation over the past decade and a half at least, but I don’t know whether this specific question has been addressed.

Corollary question: up above I wrote, “It looks like the kind of minor variation that is present in all kinds of animals, especially large-bodied ones”. My anecdotal experience is that the vertebrae of large extant animals tend to be more asymmetric than those of small extant animals, but I don’t know if that’s a real biological phenomenon–bone is bone but big animals have larger forces working on their skeletons, and they typically live longer, giving the skeleton more time to respond to those forces–OR if the asymmetry is the same in large and small animals and it’s just easier to see in the big ones.

If either of those questions has been addressed, I’d be grateful for pointers in the comments, and thanks in advance. If one or both have not been addressed, I think they’re interesting but Mike and I have plenty of other things to be getting on with and we’re not planning to work on either one, hence the “Hey, you! Want a project?” tag.

References

Picture is unrelated. Seriously. I’m just allergic to posts with no visuals. Stand by for more random brachiosaurs.

Here’s something I’ve been meaning to post for a while, about my changing ideas about scholarly publishing. On one hand, it’s hard to believe now that the Academic Spring was almost a decade ago. On the other, it’s hard for me to accept that PeerJ will be only 8 years old next week–it has loomed so large in my thinking that it feels like it has been around much longer. The very first PeerJ Preprints went up on April 4, 2013, just about a month and a half after the first papers in PeerJ. At that time it felt like things were moving very quickly, and that the landscape of scholarly publishing might be totally different in just a few years. Looking back now, it’s disappointing how little has changed. Oh, sure, there are more OA options now — even more kinds of OA options, and things like PCI Paleo and Qeios feel genuinely envelope-pushing — but the big barrier-based publishers are still dug in like ticks, and very few journals have fled from those publishers to re-establish themselves elsewhere. APCs are ubiquitous now, and mostly unjustified and ruinously expensive. Honestly, the biggest changes in my practice are that I use preprint servers to make my conference talks available, and I use SciHub instead of interlibrary loan.

But I didn’t sit down to write this post so I could grumble about the system like an old hippie. I’ve learned some things in the past few years, about what actually works in scholarly publishing (at least for me), and about my preferences in some areas, which turn out to be not what I expected. I’ll focus on just two areas today, peer review, and preprints.

How I Stopped Worrying and Learned to Love Peer Review

Surprise #1: I’m not totally against peer review. I realize that the way it is implemented in many places is deeply flawed, and that it’s no guarantee of the quality of a paper, but I also recognize its value. This is not where I was 8 years ago; at the time, I was pretty much in agreement with Mike’s post from November, 2012, “Well, that about wraps it up for peer-review”. But then in 2014 I became an academic editor at PeerJ. And as I gained first-hand experience from the other side of the editorial desk, I realized a few things:

  • Editors have broad remits in terms of subject areas, and without the benefit of peer reviews by people who specialize in areas other than my own, I’m not fit to handle papers on topics other than Early Cretaceous North American sauropods, skeletal pneumaticity, and human lower extremity anatomy.
  • Even at PeerJ, which only judges papers based on scientific soundness, not on perceived importance, it can be hard to tell where the boundary is. I’ve had to reject a few manuscripts at PeerJ, and I would not have felt confident about doing that without the advice of peer reviewers. Even with no perceived importance criterion, there is definitely a lower bound on what counts as a publishable observation. If you find a mammoth toe bone in Nebraska, or a tyrannosaur tooth in Montana, there should probably be something more interesting to say about it, beyond the bare fact of its existence, if it’s going to be the subject of a whole paper.
  • In contentious fields, it can be valuable to get a diversity of opinions. And sometimes, frankly, I need to figure out if the author is a loony, or if it’s actually Reviewer #2 that’s off the rails. Although I think PeerJ generally attracts fairly serious authors, a handful of things that get submitted are just garbage. From what I hear, that’s the case at almost every journal. But it’s not always obvious what’s garbage, what’s unexciting but methodologically sound, and what’s seemingly daring but also methodologically sound. Feedback from reviewers helps me make those calls. Bottom line, I do think the community benefits from having pre-publication filters in place.
  • Finally, I think editors have a responsibility to help authors improve their work, and reviewers catch a lot of stuff that I would miss. And occasionally I catch something that the reviewers missed. We are collectively smarter and more helpful than any of us would be in isolation, and it’s hard to see that as anything other than a good thing.

The moral here probably boils down to, “white guy stops bloviating about Topic X when he gains actual experience”, which doesn’t look super-flattering for me, but that’s okay.

You may have noticed that my pro-peer-review comments are rather navel-gaze-ly focused on the needs of editors. But who needs editors? Why not chuck the whole system? Set up an outlet called Just Publish Everything, and let fly? My answer is that my time in the editorial trenches has convinced me that such a system will silt up with garbage papers, and as a researcher I already have a hard enough time keeping up with all of the emerging science that I need to. From both perspectives, I want there to be some kind of net to keep out the trash. It doesn’t have to be a tall net, or strung very tight, but I’d rather have something than nothing.

What would I change about peer review? Since it launched, PeerJ has let reviewers either review anonymously, or sign their reviews, and it has let authors decide whether or not to publish the reviews alongside the paper. Those were both pretty daring steps at the time, but if I could I’d turn both of those into mandates rather than options. Sunlight is the best disinfectant, and I think almost all of the abuses of the peer review system would evaporate if reviewers had to sign their reviews, and all reviews were published alongside the papers. There will always be a-holes in the world, and some of them are so pathological that they can’t rein in their bad behavior, but if the system forced them to do the bad stuff in the open, we’d all know who they are and we could avoid them.

Femur of Apatosaurus and right humerus Brachiosaurus altithorax holotype on wooden pedestal (exhibit) with labels and 6 foot ruler for scale, Geology specimen, Field Columbian Museum, 1905. (Photo by Charles Carpenter/Field Museum Library/Getty Images)

Quo Vadis, Preprints?

Maybe the advent of preprints was more drawn out than I know, but to me it felt like preprints went from being Not a Thing, Really, in 2012, to being ubiquitous in 2013. And, I thought at the time, possibly transformative. They felt like something genuinely new, and when Mike and I posted our Barosaurus preprint and got substantive, unsolicited review comments in just a day or two, that was pretty awesome. Which is why I did not expect…

Surprise #2: I don’t have much use for preprints, at least as they were originally intended. When I first confessed this to Mike, in a Gchat, he wrote, “You don’t have a distaste for preprints. You love them.” And if you just looked at the number of preprints I’ve created, you might get that impression. But the vast majority of my preprints are conference talks, and using a preprint server was just the simplest way to the get the abstract and the slide deck up where people could find them. In terms of preprints as early versions of papers that I expect to submit soon, only two really count, neither more recent than 2015. (I’m not counting Mike’s preprint of our vertebral orientation paper from 2019; he’s first author, and I didn’t mind that he posted a preprint, but neither is it something I’d have done if the manuscript was mine alone.)

My thoughts here are almost entirely shaped by what happened with our Barosaurus preprint. We put it up on PeerJ Preprints back in 2013, we got some useful feedback right away, and…we did nothing for a long time. Finally in 2016 we revised the manuscript and got it formally submitted. I think we both expected that since the preprint had already been “reviewed” by commenters, and we’d revised it accordingly, that formal peer review would be very smooth. It was not. And the upshot is that only now, in 2021, are we finally talking about dealing with those reviews and getting the manuscript resubmitted. We haven’t actually done this, mind, we’re just talking about planning to make a start on it. (Non-committal enough for ya?)

Why has it taken us so long to deal with this one paper? We’re certainly capable — the two of us got four papers out in 2013, each of them on a different topic and each of them substantial. So why can’t we climb Mount Barosaurus? I think a big part of it is that we know the world is not waiting for our results, because our results are already out in the world. We’re the only ones being hurt by our inaction — we’re denying ourselves the credit and the respect that go along with having a paper finally and formally published in a peer-reviewed journal. But we can comfort ourselves with the thought that if someone needs our observations to make progress on their own project, we’re not holding them up. Just having the preprint out there has stolen some of our motivation to the get the paper done and out, apparently enough to keep us from doing it at all.

Mike pointed out that according to Google Scholar, our Barosaurus preprint has been cited five times to date, once in its original version and four times in its revised version. But to me, the fact that the Baro manuscript has been cited five times is a fail. Because all of my peer-reviewed papers from 2014-2016, which have been out for less long, have been cited more. So I read that as people not wanting to cite it. And who can blame them? Even I thought it would be supplanted by the formally-published, peer-reviewed paper within a few weeks or months.

Mike then pointed me to his 2015 post, “Four different reasons to post preprints”, and asked how many of those arguments still worked for me now. Number 2 is good, posting material that would otherwise never see the light of day — it’s basically what I did when I put my dissertation on arXiv. Ditto for 4, which is posting conference presentations. I’m not moved by either 1 or 3. Number 3 is getting something out to the community as quickly as possible, just because you want to, and number 1 is getting feedback as quickly as possible. The reason that neither of those move me is that they’re solved to my satisfaction by existing peer-reviewed outlets. I don’t know of any journals that let reviewers take 2-4 months to review a paper anymore. I don’t know how much credit for the acceleration should go to PeerJ, which asks for reviews in 10 to 14 days, but surely some. And I don’t usually have a high enough opinion of my own work to think that the community will suffer if it takes a few months for a paper to come out through the traditional process.

(If it seems like I’m painting Mike as relentlessly pro-preprint, it’s not my intent. Rather, I’d dropped a surprising piece of news on him, and he was strategically probing to determine the contours of my new and unexpected stance. Then I left the conversation to come write this post while the ideas were all fresh in my head. I hope to find out what he thinks about this stuff in the comments, or ideally in a follow-up post.)

Back to task: at least for me, a preprint of a manuscript I’m going to submit anyway is a mechanism to get extra reviews I don’t want*, and to lull myself into feeling like the work is done when it’s not. I don’t anticipate that I will ever again put up a preprint for one of my own manuscripts if there’s a plausible path to traditional publication.

* That sounds awful. To people who have left helpful comments on my preprints: I’m grateful, sincerely. But not so grateful that I want to do the peer review process a second time for zero credit. I didn’t know that when I used to file preprints of manuscripts, but I know it now, and the easiest way for me to not make more work for both of us is to not file preprints of things I’m planning to submit somewhere anyway.

So much for my preprints; what about those of other people? Time for another not-super-flattering confession: I don’t read other people’s preprints. Heck, I don’t have time to keep up with the peer-reviewed literature, and I have always been convinced by Mike’s dictum, “The real value of peer-review is not as a mark of correctness, but of seriousness” (from this 2014 post). If other people want me to part with my precious time to engage with their work, they can darn well get it through peer review. And — boomerang thought — that attitude degrades my respect for my own preprint manuscripts. I wouldn’t pay attention to them if someone else had written them, so I don’t really expect anyone else to pay attention to the ones that I’ve posted. In fact, it’s extremely flattering that they get read and cited at all, because by my own criteria, they don’t deserve it.

I have to stress how surprising I find this conclusion, that I regard my own preprints as useless at best, and simultaneously extra-work-making and motivation-eroding at worst, for me, and insufficiently serious to be worthy of other people’s time, for everyone else. It’s certainly not where I expected to end up in the heady days of 2013. But back then I had opinions, and now I have experience, and that has made all the difference.

The comment thread is open. What do you think? Better still, what’s your experience?

My favorite t-shirt

February 1, 2021

If you’ve been around SV-POW! for long, you’ve seen me in this shirt:

“Retro Brontosaurus Dinosaur T-shirt” by Dinosaur Tees, modeled by Matt Wedel, cast right forelimb of Brachiosaurus for scale.

I found it on Amazon. Well, actually the first one I found was this rather dapper plesiosaur:

One of the things I like best about the recent movies in Legendary Pictures’ MonsterVerse — Godzilla (2014), Kong: Skull Island, Godzilla: King of the Monsters, and the upcoming Godzilla vs Kong — is Monarch, the shadowy organization tasked with finding and studying giant monsters. By the time of King of the Monsters, Monarch is basically SHIELD, with bases scattered around the globe and a giant flying carrier-aircraft, the USS Argo.

I prefer the scrappier, always-on-the-verge-of-being-shut-down Monarch from the 1973-set Kong: Skull Island. And, as you’ve probably guessed by now, I was instantly taken with that plesiosaur t-shirt because in my headcanon it was the official garb of Monarch’s Loch Ness division in the 1970s. I had to go with the sauropod version, though, for obvious reasons — maybe Monarch has a Mokele-mbembe division (not so far out since old M-M shows up as a dot on a map in King of the Monsters). 

I have zero stake in Dinosaur Tees, mind. I just dig their retro dinosaur shirts. Find them here.

And as for Monarch — at least in its early incarnation, as a ragtag group of underfunded folks from wildly differing backgrounds that goes to remote places to search for monsters — I flatter myself that I have a not-entirely-different job.

 

Xinjiangtitan when originally described, from Wu et al. (2013)

We’re way late to this party, but better late than never I guess. Wu et al. (2013) described Xinjiangtitan shanshanesis as a new mamenchisaurid from the Middle Jurassic of China. At the time of the initial description, all of the dorsal and sacral vertebrae had been uncovered, as well as a handful of the most posterior cervicals and most anterior caudals.

Xinjiangtitan revealed, from Zhang et al. (2018)

Jump a few years forward 2018, when Zhang et al. described the complete cervical series of Xinjiangtitan, based on further excavation of the holotype (they also changed some of the element identifications in the original description). It’s pretty insane: 

  • 18 cervical vertebrae, same as Mamenchisaurus youngi, and one less than M. hochuanensis, all discovered in articulation;
  • 10 of those vertebrae have centrum lengths of 1 meter or more;
  • the longest centrum, that of C12, is 123cm long;
  • the total lengths of the separate cervical vertebrae (not articulated) add up to about 15 meters;
  • even assuming that the condyles of the vertebrae were fully buried in the cotyles, the total length of articulated neck would still be 13.36 meters. 

Now, some caveating. Zhang et al. (2018) report two different lengths for most the cervicals: a maximum centrum length, which includes the anterior condyle, and a “minimum centrum length” without the anterior condyle. Reporting cervical lengths minus the condyle is fairly common–Janensch did it for what is now Giraffatitan (“ohne condylus”), McIntosh (2005) did it for the AMNH Barosaurus, Tschopp and Mateus (2017) did it for Galeamopus pabsti, and so on. In the freely available but as-yet-not-formally-published 4th chapter of my dissertation (Wedel 2007), I referred to the length without the condyle as the “functional length”, and I explicitly assumed that it was “the length that each vertebra contributes to the total neck length”. At the time I assumed that condyles were always fully buried in cotyles in life, because I didn’t know about camel necks (see Taylor and Wedel 2013b: fig. 21 and this post). 

Why am I bringing up all these minutiae? Because I’m really interested in the actual length of the neck of Xinjiangtitan in life, and that’s not so very straightforward to figure out. I’ll start with what Zhang et al. wrote, then proceed to their measurements, and then discuss their map.

At the start of the Description section, Zhang et al. (2018: p. 3) wrote:

In SSV12001, the cervical series is almost completely articulated and is exposed laterally (Figure 2). The long neck (at least 14.9 m) is well-preserved with a total of 18 cervical vertebrae. This measurement was estimated based on the maximum centrum length including the anterior condyles with the space for the cartilage assumed.

How much space is assumed for the cartilage? They don’t say, and it’s not clear, but one reading is that they just added up the total lengths of all the cervical centra and assumed that the cotyles were completely full of cartilage. Which is not so crazy as it might sound, since that’s exactly what happens in camels. But let’s see what their tables of measurements say.

Xinjiangtitan cervical vertebra measurements, from Zhang et al. (2018)

Table 1 gives the measurements of the atlas and axis, and Table 2 gives the measurements of all the remaining cervicals. Only “minimum centrum length”–without the condyle–is reported for cervicals 4 and 5, because C3-C5 were articulated as a unit, they haven’t been separated, and without CT scanning or further prep it’s going to be impossible to determine how long they were with the condyles. However, we can infer that the condyles of C4 and C5 are buried in the cotyles of C3 and C4 because (a) only the without-condyle lengths are reported, and (b) the condyles aren’t visible in the figures. File that away, it’s going to be important.

Adding up all of the max centrum lengths, including 165mm for the axis and 30mm for the atlas, per Table 1, I get a total of 14985mm, or 14.985 meters. Because Zhang et al. were so assiduous about their reporting–they really did Measure Their Damn Dinosaur–we can estimate pretty closely how much longer that total would be if it included the condyles of C4 and C5. Subtracting the min length from the max length, we find that the condyle is 70mm long in both C3 and C6, so it’s reasonable to assume the same for the vertebrae in the middle. Adding 140mm to the earlier total gets us up to 15125mm, or 15.125 meters. That’s assuming condyles end even with the rims of the cotyles, and cotyles are completely full of cartilage.

Xinjiangtitan cervicals, from Zhang et al. (2018: fig 3)

Adding up the all of the minimum centrum lengths, again including the axis and atlas, yields a total of 13360mm, or 13.36 meters. I think this smaller total is much more likely to be the actual length of the neck in life, for three reasons:

  1. As mentioned above, the condyles of C4 and C5 of this very specimen are actually buried in the cotyles of the preceding vertebrae. So we don’t need to add any space for cartilage to the summed minimum (without condyle) lengths–there certainly was cartilage between the surfaces of the condyles and cotyles, because that’s how intervertebral joints work, but there was not enough to push the condyles back outside the cotyles, unless we want to engage in some special pleading that C3-C5 were unnaturally smooshed together.
  2. Camels notwithstanding, having the condyles buried in the cotyles is pretty standard for articulated necks of big, long-necked sauropods. In the holotype specimens of Mamenchisaurus hochuanensis and Sauroposeidon, the condyles are not visible in lateral view, because they are completely buried in the cotyles of the preceding vertebrae–see the photos in this post and on this page to confirm that for yourself. In Giraffatitan, just the edges of the condyles are visible sticking out the backs of the cotyles in some of the posterior cervicals–see this post.
  3. The 13.36-meter neck is more consistent with the map of the specimen in the ground than either the 14.9-meter or 15.1-meter totals.

A little unpacking on that last point. Using the dorsal lengths from Wu et al. (2013: table 1)–and assuming that Zhang et al. are correct, and the D1 of Wu et al. is actually cervical 18, but D11 of Wu et al. is actually D10 and D11 together, so there are still 12 dorsals–I get a total length for the articulated dorsal column of 3355mm. Dividing 13360 by 3355 yields a cervical/dorsal ratio of 3.98. Using the screenshot of the map from Zhang et al. (2018: fig. 2), I measured 1505 pixels for the summed cervicals, 380 pixels for the summed dorsals, and 112 pixels for the scale bar. Assuming the scale bar is supposed to be 1 meter (and not 20 meters or 2.0 meters as it is labeled) yields a summed cervical length of 13.4 meters, a summed dorsal length of 3.39 meters, and a cervical/dorsal ratio of 3.96–all admirably close, off by no more than 4cm across 16+ meters, if the neck in the ground was articulated condyle-inside-cotyle. If we assume the map shows a 14.9-meter neck, then both the dorsal series and the scale bar are off by about 12%, which is unreasonable given the high precision of the map if the articulated neck corresponds to the summed minimum lengths.

Mounted skeleton of Omeisaurus tianfuensis: N E C C

Bonus observation #1: the holotype of Mamenchisaurus hochuanensis has a cervical/dorsal ratio of 3.52, but in Omeisaurus tianfuensis the same ratio is 4.09. So Xinjiangtitan is actually a little shorter-necked than Omeisaurus, at least compared to the length of the dorsal series.

Bonus observation #2: the 123-cm cervical of Xinjiangtitan is only the fifth-longest vertebra of anything to date:

  1. BYU 9024, possibly referable to Supersaurus or Barosaurus: 137cm
  2. Price River 2 titanosauriform: 129cm
  3. OMNH 53062, Sauroposeidon holotype: 125cm
  4. KLR1508-77-2, Ruyangosaurus giganteus referred specimen: 124cm
  5. SSV12001, Xinjiangtitan shanshanesis holotype: 123cm
  6. MPEF-PV 3400/3, Patagotitan holotype: 120cm (+?)
  7. MPM 10002, Puertasaurus holotype: 118cm

Getting pretty crowded there in the 120s, but then a big jump to BYU 9024. I’ll have more to say on that in a second.

Just to put a bow on this section, I’m pretty confident, based on all available measurements, taphonomic evidence, and the consilience between the measurements and the map, that the holotype individual of Xinjiantitan had a neck 13.36 meters (43 feet, 10 inches) long in life. 

That’s stunning.

By comparison, the second- and third-longest complete cervical series (of anything, ever, to date) belong to Mamenchisaurus hochuanensis, at 9.5 meters (Young and Zhao 1972, and confirmed by Mike in a basement in Slovenia), and Giraffatitan at 8.5 meters for MB.R.2181 (the larger XV2 specimen would have had a 9.6-meter neck).

Some other contenders, from Taylor and Wedel 2013a (fig 3)

There were things with longer necks, for sure, but none of those necks are complete (yet). Mamenchisaurus sinocanadorum is estimated to have had a neck about 12 meters long, based on the partial cervical series of the holotype. I know there are skeletal reconstructions out there with longer necks, and I will believe them as soon as the specimens they are based on are published. In the aforementioned dissertation chapter, I estimated 11.5 meters for the neck of Sauroposeidon, assuming a brachiosaurid-like cervical count of 13. Note that Mannion et al. (2013) recovered Sauroposeidon as a somphospondyl, and a cervical count of 15 or more as a synapomorphy of Somphospondyli. Adding a couple more 1.2-meter mid-cervicals would bring Sauroposeidon up to perhaps 14 meters. The longest cervicals of Patagotitan are in about the same size class, and we don’t know the cervical count in that monster, either.

BYU 9024, with the mounted (cast, composite) skeleton of Brachiosaurus altithorax and one Mike Taylor for scale

And of course, lurking out there in crazy neck-space is BYU 9024, the immense cervical originally referred to Supersaurus, but which more likely belongs to Barosaurus, and an ungodly huge one. That critter might–might–have had a 17-meter neck.

And I gotta say, in light of Xinjiangtitan, that no longer seems so unreasonable. Because Xinjiangtitan was a big sauropod but not a monster. The dorsal length of 3.3 meters and the femur length of 1.65 meters put it in roughly the same size category as the bigger individual of Jobaria (DL 3.2m, FL 1.8m) or the AMNH 5761 Camarasaurus supremus (DL 2.5m, FL 1.8m). Let’s imagine a Xinjiangtitan with a 2.4-meter femur, the size of Patagotitan or Argentinosaurus. Assuming isometric scaling, that individual would have a 2.4/1.65 = 1.45 x 13.36 = 19.4-meter neck. 

Do we really think such animals never existed?

Food for thought: the holotype individual of Xinjiangtitan was small enough to be buried as a complete skeleton. What about the individuals that were too big to bury in one shot?

Utterly unsurprising, but still nice to see: the highly pneumatic internal structure of the vertebrae of Xinjiangtitan, from Wu et al. (2013)

References

Can I really be the first one to have done this? Seems unlikely. Sing out in the comments if you’ve seen others.

Anyway, folks, here’s your new all-purpose scale silhouette. Useful fact: the standard metal folding chairs found from sea to shining sea are 29.25 inches tall, or 0.75 meters. Bernie might be in a plastic folding chair here, I dunno, I’m no expert. But folding chair seats are typically 16-17 inches off the ground, so it can’t be that far out.

Who will get Bernie into print first?

These are nice. Click through to empiggen.

I ripped them from Parker (1874), which appears to be a free download from JSTOR, here, and tweaked the colors just a bit.

If you are here for serious science, these guides to the abbreviations used in the plates will come in handy. I hacked the second one, below, to include the descriptions of the plates above, which are the last in the series, not the first.

EDIT: Nick Gardner pointed out that the copy of Parker (1874) at the Biodiversity Heritage Library is a slightly sharper scan, so if you’d prefer that version, it’s here.

Reference

Parker, W.K. 1874. On the structure and development of the skull in the pig (Sus scrofa). Philosophical Transactions of the Royal Society of London 164: 289-336.

 

Here’s how my pig skull turned out (prep post is here).

Verdict? I’m reasonably happy with it. As Mike wrote in the post that kicked off the “Things to Make and Do” series, “a pig skull is a serious piece of kit”. It’s big and substantial and it looks awesome sitting on the shelf. I learned a lot prepping it, and in particular I learned a couple of things that I will do differently next time:

  1. From now on I will cut the meat off first and grill only that, and not put the skull through the thermal stress of getting dry-cooked. Even with indirect heat, I think smoking the whole head did adversely affect the quality of the bone. The forehead and the rami of the mandibles in particular lost a little integrity. I painted the whole skull with a mix of 50% PVA (white glue, like Elmer’s) and 50% water, so it’s solid, but the surface bone is just slightly rough, I think because of degradation of the cortical bone.
  2. Before this I had only prepped small bones–small mammal and reptile skulls, vertebrae and long bones of domestic fowl, cannon bones and hooves of cattle. Stuff like that takes maybe an hour or two max to simmer, and to whiten, and that’s how I approached the pig skull. And it took forever, because I was doing short cycles, which meant doing a lot of them. I did a sheep skull this past holiday break, which I will post about soon, and I learned that the trick with bigger bones is just time. Simmer for 12 hours, not 2 hours, whiten for 2 or 3 nights, not just one. The sheep skull probably took more time from start to finish, but it was a lot less effort, because for much of that time it was just simmering, or soaking in dilute hydrogen peroxide.

With their deep lower jaws, pig skulls look rather lumpen in lateral view. But they look awesome in anterodorsal view, like dragon skulls. Here you can see that the prenasal bone is a little darker and less crisp than the other bones of the face. That’s because it was still ossifying from a big block of cartilage. I scraped off most of the cartilage, but not all, and what remained dried and hardened into an incredibly tough, translucent, slightly yellowish shell. 

I still have two pig heads on ice. I probably won’t do anything with either of them until I get some more time off, but I am looking forward to prepping another pig skull, in part to see how much better I can do the next time. But I’m still happy to have this one. To paraphrase another line from Mike’s old post, this is something that everyone ought to do.

Edit: here are some links about cooking pig heads and prepping skulls.