We’ve not done many picture-of-the-week posts here recently. Let’s change that! Here’s a lovely little specimen that we saw in BYU on the 2016 Sauropocalypse trip.

Wedel and Taylor (2013), Figure 7. BYU 12613, a posterior cervical of Diplodocus, in dorsal (top), left lateral (left), and posterior (right) views. It compares most favourably with C14 of D. carnegii CM 84/94 (Hatcher, 1901: plate 3) despite being only 42% as large, with a centrum length of 270 mm compared to 642 mm for C14 of D. carnegii.

(At least, this is catalogued as Diplodocus. Jaime Headden suggested, and Emanuel Tschopp corroborated, the idea that it’s more likely Kaatedocus.)

References

Wedel, Mathew J., and Michael P. Taylor. 2013a. Neural spine bifurcation in sauropod dinosaurs of the Morrison Formation: ontogenetic and phylogenetic implications. PalArch’s Journal of Vertebrate Palaeontology 10(1):1-34.

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If you don’t get to give a talk at a meeting, you get bumped down to a poster. That’s what’s happened to Matt, Darren and me at this year’s SVPCA, which is coming up next week. My poster is about a weird specimen that Matt and I have been informally calling “Biconcavoposeidon” (which I remind you is not a formal taxonomic name).

Here it is, for those of you who won’t be at the meeting (or who just want a preview):

But wait — there’s more. The poster is now also formally published (Taylor and Wedel 2017) as part of the PeerJ preprint containing the conference abstract. It has a DOI and everything. I’m happy enough about it that I’m now citing it in my CV.

Do scientific posters usually get published? Well, no. But why not? I can’t offhand think of a single example of a published poster, though there must be some out there. They are, after all, legitimate research artifacts, and typically contain more information than published abstracts. So I’m happy to violate that norm.

Folks: it’s 2017. Publish your posters.

References

  • Taylor, Michael P., and Mathew J. Wedel. 2017. A unique Morrison-Formation sauropod specimen with biconcave dorsal vertebrae. p. 78 in: Abstract Volume: The 65th Symposium on Vertebrate Palaeontology and Comparative Anatomy & The 26th Symposium on Palaeontological Preparation and Conservation. University of Birmingham: 12th–15th September 2017. 79 pp. PeerJ preprint 3144v2. doi:10.7287/peerj.preprints.3144v2/supp-1

 

Or, how a single lateral fossa becomes two foramina: through a finely graded series of intermediate forms. Darwin would approve. The ‘oblique lamina’ that separates the paired lateral foramina in C6 starts is absent in C2, but C3 through C5 show how it grows outward from the median septum. How do I know it grows outward, instead of being left behind during the pneumatization of the more posterior cervicals? Because with very few exceptions, all neosauropod cervicals start out with a single lateral fossa on each side, as illustrated in this post. But many of them end up with two or more foramina. Diplodocus is a nice example of this (from Hatcher 1901: plate 3):

I should clarify that the vertebrae above show that character transformation in this individual, at this point in its ontogeny. The vertebrae of CM 555 are about two-thirds the size of those of CM 3018, the holotype of A. louisae. In CM 3018, even C4 and C5 have completely divided lateral fossae, corresponding to the condition in C6 of CM 555.

As Mike and I discussed in our 2013 neural spine bifurcation paper, isolated sauropod cervicals require cautious interpretation because the morphology of the vertebrae changes so much along the series. The simple morphology of anterior cervicals reflects both earlier ontogenetic stages and more primitive character states. As Mike says, in sauropod necks, serial position recapitulates both ontogeny and phylogeny. So if you have a complete series, you can do something pretty cool: see the intermediate stages by which simple structures become complex.

If you’re thinking this might have something to do with my impending SVPCA poster, you’re right. Here’s the abstract.

For more on serially increasing complexity in sauropodomorph cervicals, see this post.

Lots of discussion online lately about unpaid peer reviews and whether this indicates a “degraded sense of community” in academia, improper commoditization of the unwritten responsibilities of academics, or a sign that we should rethink incentives in academia. (NB: that’s my galloping sound-bite-ization of those three posts, which you should go read in full.)

Part of this “reviewers don’t get paid” thing is good, because it indicates that academics broadly are waking up to how badly they’ve been had by commercial publishers. It’s part of that necessary anger that Scott Aaronson wrote about back when. But I can also understand why people are pushing back and saying, “Oh, if you don’t review you’re not supporting the academic community that (in part) makes your career possible. We should all pitch in and do the work.” Until recently, there was no way to separate those two strands: in doing peer reviews (and editing, etc.), one was both supporting the community as a good citizen, and also, unavoidably, helping commercial publishers line their pockets. But now that previously single path has bifurcated (no, not that way). Now it’s possible to be a good citizen for the community by editing and reviewing for OA journals, and stick it to the barrier-based publishers by not editing and reviewing for them (here’s how to politely decline, and see more discussion here).

Here’s how jacked the situation is: if you edit or review for a barrier-based publisher whose journals you also subscribe to or otherwise pay for, then in effect you are paying them for the privilege of reviewing. Put like that, it sounds insane. In any normal transaction, I give you X and you give me Y in return, because we’ve jointly agreed that these things are of roughly equal worth. In barrier-based publishing, academics give publishers (1) their papers, which publishers then exert copyright over, (2) their effort as editors and reviewers, and (3) their money, in subscriptions or other access fees, individually or collectively as institutions. And publishers sell the work back to us, retaining the copyright, and reap massive profits. There is no part of that sequence where academics – and indeed humanity at large – are getting the upside of the deal. The publishers are running the table on us, because for a long time, there were no other options. That’s not true anymore.

In his post on community, Zen Faulkes wrote, “I think people are refusing to do reviews in part because they don’t feel connected to the academic community.” Possibly. But maybe people are refusing to do reviews because they’re tired of being had. Has anyone done any work that would allow us to test those hypotheses? If so, I’d love to hear about it in the comments.

TL;DR: The separation of community goals and corporate profits shouldn’t be a fine theoretical point of discussion. It should be what we lead with. Yes, I will support the academic community. No, I won’t donate my time and effort to rapacious barrier-based publishers. It’s possible to achieve both of those things at once. And we should.

“Biconcavoposeidon”

August 15, 2017

Here is a fascinating sequence of five consecutive posterior dorsal vertebra — AMNH FARB 291 from the”Big Bone Room” at the AMNH:

AMNH FARB 291, five consecutive posterior dorsal vertebrae of a probably brachiosaurid sauropod, in right lateral view. The vertebrae are embedded in a plaster block, which has been desaturated in this image.

Matt and I first saw this specimen back in February 2009, when we were mostly there to look at Apatosarusminimus (and then again in 2012). As soon as our eyes lit on it, we couldn’t help but be captivated by its bizarre biconcave centra. We immediately started flippantly referring to it as “Biconcavoposeidon” — the ugliest name we could come up with — and in our subsequent discussions the name has stuck (often abbreviated to “BCP”).

  • Taxonomic note: for avoidance of doubt, “Biconcavoposeidon” is not and will never be a formal taxonomic name, only an informal specimen nickname. If at some future point we conclude that this specimen represents a new taxon, and name it, we will definitely not use the name “Biconcavoposeidon”. If you ever use the name, please do not set it in italics.

As you can see in this front view, the specimen is sheared: the upper part of the vertebrae have been displaced to their left (which is the right as we see it in this image):

AMNH FARB 291, most anterior of five consecutive posterior dorsal vertebrae of a probably brachiosaurid sauropod, in anterior view.

Apart from the shearing, though, and the truncation of the neural spines shortly above the transverse processes, the specimen is in pretty good nick. Crucially, it’s not been “restored” in plaster to conceal what is and is not real bone — unlike many specimens of that era. It came out of the Bone Cabin quarry in 1898, back when scientific information was routinely discarded in order to obtain a more beautiful-looking specimen.

This is the specimen that I’ll be presenting at SVPCA this year — though only as a poster, unfortunately: there’s no talk for me, Matt or Darren this year. We’ve posted our abstract (including the illustration above) to the nascent PeerJ collection for SVPCA 2017, and we’re looking forward to seeing more of the materials from that conference — abstracts, then manuscripts, then papers — appearing in the collection.

So far as we know, there’s no other sauropod specimen with biconcave posterior dorsal vertebrae. (And, no, Amphicoelias is not an exception, despite its name.) But have we missed any?

A bunch of stuff, loosely organized by theme.

Media

First up, I need to thank Brian Switek, who invited me to comment on Patagotitan for his piece at Smithsonian. I think he did a great job on that, arguably the best of any of the first-day major media outlet pieces. And it didn’t go unnoticed – his article was referenced at both the Washington Post and NPR (and possibly other outlets, those are the two I know of right now). I don’t think my quotes got around because they’re particularly eloquent, BTW, but rather because reporters tend to like point-counterpoint, and I was apparently the most visible counterpoint. They probably would have done the same if I’d been talking complete nonsense (which, to be fair, some people may think I was).

Paleobiology vs Records

The most commonly reproduced quote of mine is this one, originally from Brian’s piece:

I think it would be more accurate to say that Argentinosaurus, Puertasaurus and Patagotitan are so similar in size that it is impossible for now to say which one was the largest.

That may seem at odds with the, “Well, actually…[pushes glasses up nose]…Argentinosaurus was still biggest” tack I’ve taken both in my post yesterday and on Facebook. So let me elaborate a little.

There is a minor, boring point, which is that when I gave Brian that quote, I’d seen the Patagotitan paper, but not the Electronic Supplementary Materials (ESM), so I knew that Patagotitan was about the same size as the other two (and had known for a while), but I hadn’t had a chance to actually run the numbers.

The much more interesting point is that the size differences between Argentinosaurus, Puertasaurus, and Patagotitan are astonishingly small. The difference between a 2.5m femur and a 2.4m one is negligible, ditto for vertebrae with centra 59cm and 60cm in diameter. OMNH 1331, the biggest centrum bit from the giant Oklahoma apatosaur, had an intact max diameter of 49cm, making it 26% larger in linear terms than the next-largest apatosaur. The centra of these giant South American titanosaurs are more than 20% bigger yet than OMNH 1331, just in linear terms. That’s crazy.

It’s also crazy that these three in particular – Argentinosaurus, Puertasaurus, and Patagotitan – are so similar in size. Dinosaur developmental programs were ‘messy’ compared to those of mammals, both in having weird timings for things like onset of reproduction, and in varying a lot among closely related taxa. Furthermore, sauropod population dynamics should have been highly skewed toward juveniles and subadults. So is the near-equality in size among Argentinosaurus, Puertasaurus, and Patagotitan just a coincidence, or does it mean that something weird was going on? There’s really no third option. I mean, even if some kind of internal (biomechanical or physiological) or external (ecological, food or predation) constraint forced those three to the same adult body size, it’s weird then that we’re finding only or at least mostly near-max-size adults. (If the available specimens of these three aren’t near-max-size, then any hypothesis that they’re forced to the same size by constraints is out the window, and we’re back to coincidence.)

BUT

With all that said, the title of “world’s largest dinosaur” is not handed out for effort expended, number of specimens collected, skeletal completeness, ontogenetic speculation, or anything other than “the dinosaur with the largest measured elements”. And that is currently Argentinosaurus. So although for any kind of paleobiological consideration we can currently consider Argentinosaurus, Puertasaurus, and Patagotitan to all be about the same size – and Alamosaurus, Paralititan, Notocolossus, and probably others I’ve forgotten should be in this conversation – anyone wanting to dethrone Argentinosaurus needs to actually show up with bigger elements.

So, if you’re interested in paleobiology, it’s fascinating and frankly kind of unnerving that so many of these giant titanosaurs were within a hand-span of each other in terms of size. Patagotitan is one more on the pile – and, as I said yesterday, exciting because it’s so complete.

But if you want to know who holds the crown, it’s still Argentinosaurus.

Humeri

In a comment on the last post, Andrea Cau made an excellent point that I am just going to copy here entire:

Even Paralititan stromeri humerus is apparently larger than Patagotitan humerus (169 cm vs 167.5 cm). I know humerus length alone is bad proxy of body size, but at least this shows that even in that bone Patagotitan is just another big titanosaur among a well known gang of titans, not a supersized one.

That made me want to start a list of the longest sauropod humeri. Here goes – if I missed anyone or put down a figure incorrectly, I’m sure you’ll let me know in the comments.

  • Giraffatitan: 213cm
  • Brachiosaurus: 203cm
  • Ruyangosaurus: 190cm (estimated from 135cm partial)
  • Turiasaurus: 179cm
  • Notocolossus: 176cm
  • Paralititan: 169cm
  • Patagotitan: 167.5cm
  • Dreadnoughtus: 160cm
  • Futlognkosaurus: 156cm

Admittedly the Patagotitan humerus is from a paratype and not from the largest individual, but that is true for some others on the list, including Giraffatitan. And we have no humeri from Argentinosaurus, Puertasaurus, and some other giants.

Dorsal Vertebrae

A couple of further thoughts on how the dorsal vertebrae of Patagotitan compare to those of Argentinosaurus. First, now that I’ve had some time to think about it, I have a hard time seeing how the dorsal polygon method used by Carballido et al. in the Patagotitan paper has any biological meaning. In their example figure, the polygon around the Puertasaurus vertebra is mostly full of bone, and the one around Patagotitan has a lot of empty space. It’s easy to imagine an alternative metric, like “area of the minimum polygon actually filled by bone”, that would lead to a different ‘winner’. But that wouldn’t mean much, either.

Something that probably does have a real and important biomechanical meaning is the surface area of the articular face of the centrum, because that’s the area of bone that has to bear the compressive load, which is directly related to the animal’s mass. The biggest Patagotitan centrum is that of MPEF-PV 3400/5, which is at least a local maximum since has smaller centra both ahead and behind. The posterior face measures 59cm wide by 42.5cm tall. Abstracted as an ellipse, which may not be perfectly accurate, those measurements give a surface area of (pi)(29.5)(21.25)=1970 cm^2. For Argentinosaurus, the largest complete centrum has a posterior face measuring 60cm wide by 47cm tall (Bonaparte and Coria 1993: p. 5), giving an elliptical surface area of (pi)(30)(23.5)=2210 cm^2. (I’d use hi-res images of the centra to measure the actual surface areas if I could, but AFAIK those images either don’t exist or at least have not yet been made public, for either taxon.) So although the Argentinosaurus dorsal seems like it is only a bit bigger in linear terms, it’s 12% larger in surface area, and that might actually be a meaningful difference.

Cervical Vertebrae

One thing I haven’t commented on yet – Patagotitan is the newest member of the “world’s longest vertebrae” club. The longest Patagotitan cervical, MPEF-PV 3400/3, is listed in the ESM as having a centrum length of 120cm, but it’s also listed as incomplete. In the skeletal recon in the paper, the centrum is colored in as present, but the neural spine is missing. So is the centrum complete in terms of length? I don’t think it’s clear right now.

Anyway, here’s the current rundown of the longest cervical centra of sauropods (and therefore, the longest vertebrae among animals):

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

You may be surprised to see the Price River 2 cervical in there. It was reported in an SVP abstract a few years ago (I’ll dig up that ref and update this post), and Mike and I saw it last year on the Sauropocalypse. We measured the centrum at 129cm, making it just a bit longer than the longest centrum of Sauroposeidon, and therefore the second-longest vertebra of anything ever.

Aside – I’m probably getting a reputation as a big ole meanie when it comes to debunking “world’s largest dinosaur” claims. If I’m willing to take the lead in kicking my own dinosaur down the ladder, don’t expect me to be kind to yours. I follow where the numbers lead.

Now, here’s an interesting thing – now that Sauroposeidon is coming out as a basal titanosaur, rather than a brachiosaur, it might not have been a skinny freak. The 120cm cervical of Patagotitan makes the 125cm cervical of Sauroposeidon and the 129cm cervical from Price River 2 look even more tantalizing. Maybe it’s super-giant sauropods all the way down.

“But wait, Matt”, I hear you thinking. “Every news agency in the world is tripping over themselves declaring Patagotitan the biggest dinosaur of all time. Why are you going in the other direction?”

Because I’ve been through this a few times now. But mostly because I can friggin’ read.

Maximum dorsal centrum diameter in Argentinosaurus is 60cm (specimen MCF-PVPH-1, Bonaparte and Coria 1993). In Puertasaurus it is also 60cm (MPM 10002, Novas et al. 2005). In Patagotitan it is 59cm (MPEF-PV 3400/5, Carballido et al. 2017). (For more big centra, see this post.)

Femoral midshaft circumference is 118cm in an incomplete femur of Argentinosaurus estimated to be 2.5m long when complete (Mazzetta et al. 2004). A smaller Argentinosaurus femur is 2.25m long with a circumference of 111.4cm (Benson et al. 2014). The largest reported femur of Patagotitan, MPEF-PV 3399/44, is 2.38m long and has a circumference of either 101cm (as reported in the Electronic Supplementary Materials to Carballido et al 2017) or 110cm (as reported in the media in 2014*).

TL;DR: 60>59, and 118>111>110>101, and in both cases Argentinosaurus > Patagotitan, at least a little bit.

Now, Carballido et al (2017) estimated that Patagotitan was sliiiiightly more massive than Argentinosaurus and Puertasaurus by doing a sort of 2D minimum convex hull dorsal vertebra area thingy, which the Patagotitan vertebra “wins” because it has a taller neural spine than either Argentinosaurus or Puertasaurus, and slightly wider transverse processes than Argentinosaurus (138cm vs 128cm) – but way narrower transverse processes than Puertasaurus (138cm vs 168cm). But vertebrae with taller or wider sticky-out bits do not a more massive dinosaur make, otherwise Rebbachisaurus would outweigh Giraffatitan.

Now, in truth, it’s basically a three-way tie between Argentinosaurus, Puertasaurus, and Patagotitan. Given how little we have of the first two, and how large the error bars are on any legit size comparison, there is no real way to tell which of them was the longest or the most massive. Still, to get to the conclusion that Patagotitan was in any sense larger than Argentinosaurus you have to physically drag yourself over the following jaggedly awkward facts:

  1. The weight-bearing parts of the anterior dorsal vertebrae are larger in diameter in both Argentinosaurus and Puertasaurus than in Patagotitan. Very slightly, but still, Patagotitan is the smallest of the three.
  2. The femora of Argentinosaurus are fatter than those of Patagotitan, even at shorter length. The biggest femora of Argentinosaurus are longer, too.

So all of the measurements of body parts that have to do with supporting mass are still larger in Argentinosaurus than in Patagotitan.

Now, it is very cool that we now have a decent chunk of the skeleton of a super-giant titanosaur, instead of little bits and bobs. And it’s nice to know that the numbers reported in the media back in 2014 turned out to be accurate. But Patagotitan is not the “world’s largest dinosaur”. At best, it’s the third-largest contender among near equals.

Parting shot to all the science reporters who didn’t report the same numbers I did here: instead of getting hype-notized by assumption-laden estimates, how about doing an hour’s worth of research making the most obvious possible comparisons?

Almost immediate UPDATE: Okay, that parting shot wasn’t entirely fair. As far as I know, the measurements of Patagotitan were not available until the embargo lifted. Which is in itself odd – if someone claims to have the world’s largest dinosaur, but doesn’t put any measurements in the paper, doesn’t that make your antennae twitch? Either demand some measurements so you can make those obvious comparisons, or approach with extreme skepticism – especially if the “world’s largest dino” claim was pre-debunked three years ago!

* From this article in the Boston Globe:

Paleobiologist Paul Upchurch of University College London believes size estimates are more reliable when extrapolated from the circumference of bones.

He said this femur is a whopping 43.3 inches around, about the same as the Argentinosaurus’ thigh bone.

‘‘Whether or not the new animal really will be the largest sauropod we know remains to be seen,’’ said Upchurch, who was not involved in this discovery but has seen the bones first-hand.

Some prophetically appropriate caution from Paul Upchurch there, who has also lived through a few of these “biggest dinosaur ever” bubbles.

References