Supersaurus vs Brachiosaurus - BYU 9024 and FMNH P25107

This was inspired by an email Mike sent a couple of days ago:

Remind yourself of the awesomeness of Giraffatitan:
http://svpow.files.wordpress.com/2008/11/mike-by-jango-elbow.jpeg

Now think of this. Its neck is 8.5m long. Knock of one measly meter — for example, by removing one vertebra from the middle of the neck — and you have 7.5 m.

Supersaurus’s neck was probably TWICE that long.

Holy poo.

I replied that I was indeed freaked out, and that it had given me an idea for a post, which you are now reading. I didn’t have a Giraffatitan that was sufficiently distortion-free, so I used my old trusty Brachiosaurus. The vertebra you see there next to Mike and next to the neck of Brachiosaurus is BYU 9024, the longest vertebra that has ever been found from anything, ever.

Regarding the neck length of Supersaurus, and how BYU 9024 came to be referred to Supersaurus, here’s the relevant chunk of my dissertation (Wedel 2007: pp. 208-209):

Supersaurus is without question the longest-necked animal with preserved cervical material. Jim Jensen recovered a single cervical vertebra of Supersaurus from Dry Mesa Quarry in western Colorado. The vertebra, BYU 9024, was originally referred to “Ultrasauros”. Later, both the cervical and the holotype dorsal of “Ultrasauros” were shown to belong to a diplodocid, and they were separately referred to Supersaurus by Jensen (1987) and Curtice et al. (1996), respectively.

BYU 9024 has a centrum length of 1378 mm, and a functional length of 1203 mm (Figure 4-3). At 1400 mm, the longest vertebra of Sauroposeidon is marginally longer in total length [see this post for a visual comparison]. However, that length includes the prezygapophyses, which overhang the condyle, and which are missing from BYU 9024. The centrum length of the largest Sauroposeidon vertebra is about 1250 mm, and the functional length is 1190 mm. BYU 9024 therefore has the largest centrum length and functional length of any vertebra that has ever been discovered for any animal. Furthermore, the Supersaurus vertebra is much larger than the Sauroposeidon vertebrae in diameter, and it is a much more massive element overall.

Neck length estimates for Supersaurus vary depending on the taxon chosen for comparison and the serial position assumed for BYU 9024. The vertebra shares many similarities with Barosaurus that are not found in other diplodocines, including a proportionally long centrum, dual posterior centrodiapophyseal laminae, a low neural spine, and ventrolateral flanges that connect to the parapophyses (and thus might be considered posterior centroparapophyseal laminae, similar to those of Sauroposeidon). The neural spine of BYU 9024 is very low and only very slightly bifurcated at its apex. In these characters, it is most similar to C9 of Barosaurus. However, theproportions of the centrum of BYU 9024 are more similar to those of C14 of Barosaurus, which is the longest vertebra of the neck in AMNH 6341. BYU 9024 is 1.6 times as long as C14 of AMNH 6341 and 1.9 times as long as C9. If it was built like that of Barosaurus, the neck of Supersaurus was at least 13.7 meters (44.8 feet) long, and may have been as long as 16.2 meters (53.2 feet).

Based on new material from Wyoming, Lovelace et al. (2005 [published as Lovelace et al. 2008]) noted potential synapomorphies shared by Supersaurus and Apatosaurus. BYU 9024 does not closely resemble any of the cervical vertebrae of Apatosaurus. Instead of trying to assign its serial position based on morphology, I conservatively assume that it is the longest vertebra in the series if it is from an Apatosaurus-like neck. At 2.7 times longer than C11 of CM 3018, BYU 9024 implies an Apatosaurus-like neck about 13.3 meters
(43.6 feet) long.

Supersaurus vs Diplodocus BYU 9024 and USNM 10865 - Gilmore 1932 pl 6

Bonus comparo: BYU 9024 vs USNM 10865, the mounted Diplodocus longus at the Smithsonian, modified from Gilmore 1932 (plate 6). For this I scaled BYU 9024 against the 1.6-meter femur of this specimen.

If you’d like to gaze upon BYU 9024 without distraction, or put it into a composite of your own, here you go:

Supersaurus cervical BYU 9024

References

 

OLYMPUS DIGITAL CAMERA

Now considered a junior synonym of Supersaurus, on very solid grounds.

Incidentally, unlike the neural spines of most non-titanosaurian sauropods, the neural spine of this vertebra is not simply a set of intersecting plates of bone. It is hollow and has a central chamber, presumably pneumatic. Evidence:

OLYMPUS DIGITAL CAMERA

I need to be sleeping, not blogging, so here are just the highlights, with no touch-ups and minimal commentary.

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I don’t know what these real street signs were doing sitting on the ground when I walked to the museum this morning, but it was a good omen for the conference.

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Home base for this part of the conference. We head to Green River, Utah, on Friday for the Early Cretaceous half.

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I had never seen this on exhibit. This is not the Brachiosaurus scapulocoracoid formerly referred to “Ultrasauros”, this is the other big scap from Dry Mesa, from the giant diplodocid Supersaurus.

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Seems legit.

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This is not Dinosaur Baptist Church–it is a cathedral of an entirely different order.

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And that order is Sauropoda.

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The sauropod bones are entombed in a matrix consisting of super-hard sandstone and non-sauropod bits.

I got about 150 photos of the Wall, but only because I ran out of time. You probably already know what I’m going to attempt with them. (If not, here’s a hint.)

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Jim Kirkland (center left) literally walked us through the Morrison and Cedar Mountain Formations at this set of exposures north of the visitor center. The reddish stuff on the lower left is Morrison, and after that it’s CMF all the way up this ridge and next two behind it.

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A cast of Diplodocus carnegii at the Utah Field House of Natural History State Park Museum, signalling that we’ve come to end of this tail–er, tale.

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Further updates as time and opportunity allow. If you tweet about the conference, please use #MMFC14!

Wedel and Taylor 2013 bifurcation Figure 4 - classes of bifurcation

Figure 4. Cervical vertebrae of Camarasaurus supremus AMNH 5761 cervical series 1 in anterior view, showing different degrees of bifurcation of the neural spine. Modified from Osborn & Mook (1921: plate 67).

Today sees the publication of my big paper with Mike on neural spine bifurcation, which has been in the works since last April. It’s a free download here, and as usual we put the hi-res figures and other supporting info on a sidebar page.

Navel-gazing about the publication process

This paper is a departure for us, for several reasons.

For one thing, it’s a beast: a little over 13,000 words, not counting tables, figure captions, and the bibliography. I was all geared up to talk about how it’s my longest paper after the second Sauroposeidon paper (Wedel et al. 2000), but that’s not true. It’s my longest paper, period (13192 vs 12526 words), and the one with the most figures (25 vs 22).

It’s the first time we’ve written the paper in the open, on the blog, and then repackaged it for submission to a journal. I have several things to say about that. First, it was more work than I expected. It turns out that I definitely do have at least two “voices” as a writer, and the informal voice I used for the initial run of blog posts (linked here) was not going to cut it for formal publication. So although there is very little new material in the paper that was not in the blog posts, a lot of the prose is new because I had to rewrite almost the whole thing.

I have mixed feelings about this. On one hand, last May kinda sucked, because just about every minute that wasn’t spent eclipse chasing was spent rewriting the paper. On the other hand, as Mike has repeatedly pointed out to me, it was a pretty fast way to generate a big paper quickly, even with the rewriting. It was just over two months from the first post in the destined-to-become-a-paper series on April 5, to submission on June 14 (not June 24 as it says on the last page of the PDF), and if you leave out the 10 days in late May that I was galavanting around Arizona, the actual time spent working on the paper was a bit under two months. It would be nice to be that productive all the time (it helped that we were basically mining everything from previously published work; truly novel work usually needs more time to get up and going).

Wedel and Taylor 2013 bifurcation Figure 18 - Barosaurus and Supersaurus cervicals

Figure 18. Middle cervical vertebrae of Barosaurus AMNH 6341 (top) and Supersaurus BYU 9024 (bottom) in left lateral view, scaled to the same centrum length. The actual centrum lengths are 850 mm and 1380 mm, respectively. BYU 9024 is the longest single vertebra of any known animal.

You may fairly wonder why, if almost all the content was already available on the blog, we went to the trouble of publishing it in a journal. Especially in light of sentiments like this. For my part, it’s down to two things. First, to paraphrase C.S. Lewis, what I wrote in that post was a yell, not a thought. I never intended to stop publishing in journals, I was just frustrated that traditional journals do so many stupid things that actually hurt science, like rejecting papers because of anticipated sexiness or for other BS reasons, not publishing peer reviews, etc. Happily, now there are better options.

Second, although in a sane world the quality of an argument or hypothesis would matter more than its mode of distribution, that’s not the world we live in. We’re happy enough to cite blog posts, etc. (they’re better than pers. comms., at least), but not everyone is, and the minimum bound of What Counts is controlled by people at the other end of the Overton window. So, bottom line, people are at least theoretically free to ignore stuff that is only published on blogs or other informal venues (DML, forums, etc.). If you want to force someone to engage with your ideas, you have to publish them in journals (for now). So we did.

Finally, ever since Darren’s azhdarchids-were-storks post got turned into a paper, it has bothered me that there is an icon for “Blogging on Peer-Reviewed Research” (from ResearchBlogging.org), but not one (that I know of) for “Blogging Into Peer-Reviewed Research”. If you have some graphic design chops and 10 minutes to kill, you could do the world a favor by creating one.

Hey, you! Want a project?

One of the few things in the paper that is not in any of the blog posts is the table summarizing the skeletal fusions in a bunch of famous sauropod specimens, to show how little consistency there is:

Wedel and Taylor 2013 NSB Table 1 - sauropod skeletal fusions

(Yes, we know that table legends typically go above, not below; this is just how they roll at PJVP.)

I want this to not get overlooked just because it’s in a long paper on neural spine bifurcation; as far as I’m concerned, it’s the most important part of the paper. I didn’t know that these potential ontogenetic indicators were all mutually contradictory across taxa before I started this project. Not only is the order of skeletal fusions inconsistent among taxa, but it might also be inconsistent among individuals or populations, or at least that’s what the variation among the different specimens of Apatosaurus suggests.

This problem cries out for more attention. As we say at the end of the paper:

To some extent the field of sauropod paleobiology suffers from ‘monograph tunnel vision’, in which our knowledge of most taxa is derived from a handful of specimens described decades ago (e.g. Diplodocus carnegii CM 84/94). Recent work by McIntosh (2005), Upchurch et al. (2005), and Harris (2006a, b, c, 2007) is a welcome antidote to this malady, but several of the taxa discussed herein are represented by many more specimens that have not been adequately described or assessed. A comprehensive program to document skeletal fusions and body size in all known specimens of, say, Camarasaurus, or Diplodocus, could be undertaken for relatively little cost (other than travel expenses, and even these could be offset through collaboration) and would add immeasurably to our knowledge of sauropod ontogeny.

So if you’re looking for a project on sauropod paleobiology and you can get around to a bunch of museums*, here’s work that needs doing. Also, you’ll probably make lots of other publishable observations along the way.

* The more the better, but for Morrison taxa I would say minimally: Yale, AMNH, Carnegie, Cleveland Museum of Natural History, Field Museum, Dinosaur National Monument, BYU, University of Utah, and University of Wyoming, plus Smithsonian, University of Kansas, OMNH, Denver Museum, Wyoming Dinosaur Center, and a few others if you can swing it. Oh, and Diplodocus hayi down in Houston. Check John Foster’s and Jack McIntosh’s publications for lists of specimens–there are a LOT more out there than most people are familiar with.

References

supersaurus-vs-giraffe

At the top: our old friend BYU 9024 — the cervical vertebra that’s part of the Supersaurus vivianae holotype. At the bottom, C2 (the longest cervical) of Giraffa camelopardalis angolensis FMNH 34426.

The Supersaurus vertebra is 138 cm long. We don’t know which cervical it is, but there’s no reason to think it’s the longest. The giraffe vertebra is 31 cm long. Not only is the Supersaurus vertebra four times as long as that of the giraffe, it’s one of more than twice as many cervicals as the giraffe has.

Did we cheat by using an unusually small giraffe? Not really. When we articulated all seven cervicals as best we could, the sequence measured 171 cm, which is a fairly healthy 71% of the 2.4 m neck of the world-record giraffe. It’s not a monster, but it’s a decent-sized adult.

Bottom line, giraffes are just lame.

If you found the hypothetical Amphicoelias fragillimus cervical in a recent post a bit too much to swallow, I won’t blame you. But how big do we know Morrison diplodocoid cervicals got?

The longest centrum of any specimen of anything, anywhere, is that of the cervical vertebra BYU 9024 that’s part of the Supersaurus vivianae holotype. It’s 138 cm long, which means that composited at scale with an MTSRSU, it looks like this:

latin-love-god-with-supersaurus

This is not hypothetical. It’s an actual fossil.

(Just for the record: C8 of the Sauroposeidon holotype OMNH 53062 is slightly longer overall, at 140 cm. But that includes overhanging prezygapophyses. Its centrum is “only” 125 cm long.)

In the recent post on OMNH 1670, a dorsal vertebra of a giant Apatosaurus from the Oklahoma panhandle, I half-promised to post the only published figure of this vertebra, from Stovall (1938: fig. 3.3). So here it is:

And in the second comment on that post, I promised a sketch from one of my notebooks, showing how much of the vertebra is reconstructed. Here’s a scan of the relevant page from my notebook. Reconstructed areas of the vert are shaded (confusingly, using strokes going in opposite directions on the spine and centrum, and the dark shaded areas on the front of the transverse processes are pneumatic cavities), and measurements are given in mm.

Next item: is this really a fifth dorsal vertebra?

Apatosaurus louisae CM 3018 D4 and D5, in anterior (top), left lateral, and posterior views, from Gilmore (1936: plate 25).

Here are D4 and D5 of A. louisae CM 3018. They sort of bracket OMNH 1670 in terms of morphology. D4 has a broader spine, and D5 has a narrower one. The spine of D5 lacks the slight racquet-shaped expansion seen in OMNH 1670, but the overall proportions of the spine are more similar. On the other hand, the transverse processes of D4 taper a bit in anterior and posterior view, as in OMNH 1670, and unlike the transverse processes of D5 with their more parallel dorsal and ventral margins. But honestly, neither of these verts is a very good match (and the ones on either side, D3 and D6, are even worse).

Apatosaurus parvus UWGM 15556 (formerly A. excelsus CM 563) D4 (left) and D3 (right) in anterior (top), right lateral, and posterior views, from Gilmore (1936: plate 32).

Here are D3 and D4 of A. parvus UWGM 15556. D3 is clearly a poor match as well–it is really striking how much the vertebral morphology changes through the anterior dorsals in most sauropods, and Apatosaurus is no exception. D3 looks like a dorsal in lateral view, but in anterior or posterior view it could almost pass for a posterior cervical. If I was going to use the term “cervicodorsal”, indicating one of the vertebrae from the neck/trunk transition, I would apply it as far back as D3, but not to D4. That thing is all dorsal.

And it’s a very interesting dorsal from the perspective of identifying OMNH 1670. It has fairly short, tapering transverse processes. The neural spine is a bit shorter and broader, but it has a similar racquet-shaped distal expansion. I’m particularly intrigued by the pneumatic fossae inscribed into the anterior surface of the neural spine–in Gilmore’s plate they make a broken V shapen, like so \ / (or maybe devil eyes). Now, OMNH 1670 doesn’t have devil eyes on its spine, but it does have a couple of somewhat similar pneumatic fossae cut into the spine just below the distal racquet–perhaps a serially modified iteration of the same pair of fossae as in the A. parvus D4. It’s a right sod that D5 from this animal has its spine blown off–but it still has its transverse processes, and they are short and tapering as in OMNH 1670.

Apatosaurus sp. FMNH P25112, dorsal vertebrae 1-10 and sacrals 1 and 2, Riggs (1903: plate 46)

Here are all the dorsals and the first couple sacrals of FMNH P25112, which was originally described as A. excelsus but in the specimen-level analysis of Upchurch et al. 2005) comes out as the sister taxon to the A. ajax/A. parvus/A. excelsus clade. Note the striking similarity of the D5 here with D4 of the A. parvus specimen in Gilmore’s plate (until the careful phylogenetic work up Upchurch et al. 2005, that A. parvus specimen, once CM 563 and now UWGM 15556, was considered to represent A. excelsus as well). But  also notice the striking similarity of D6 to OMNH 1670. It’s not quite a dead ringer–the transverse processes are longer and have weird bent-down “wingtips” (XB-70 Valkyrie, anyone?)–but it’s pretty darned close, especially in the shape of the neural spine.

So what does this all mean? First, that trying to specify the exact serial position of an isolated vertebra is nigh on to impossible, unless it’s something that is one-of-a-kind like an axis. Second, after doing all these comparos I think it’s unlikely that OMNH 1670 is a D4–those are a bit too squat across the board–but it could plausibly be either a D5 or a D6. Third, I’m really happy that it doesn’t seem to match any particular specimen better than all the rest. What I don’t want to happen is for someone to see that this vertebra looks especially like specimen X and therefore decide that it must represent species Y. As I said in the comments of the previous post, what this Oklahoma Apatosaurus material needs is for someone to spend some quality time seeing, measuring, and photographing all of it and then doing a phylogenetic analysis. That sounds like an ambitious master’s thesis or the core of a dissertation, and I hope an OU grad student takes it on someday.

If you were intrigued by my suggestion that the big Oklahoma Apatosaurus rivalled Supersaurus in size, and wanted to see a technical comparison of the two, I am happy to report that Scott Hartman has done the work for you. Here’s one of his beautiful Apatosaurus skeletal reconstructions, scaled to the size of OMNH 1670, next to his Supersaurus silhouette. This is just a small teaser–go check out his post on the subject for a larger version and some interesting (and funny) thoughts on how the two animals compare.

References

  • Gilmore, C.W. 1936. Osteology of Apatosaurus with special reference to specimens in the Carnegie Museum. Memoirs of the Carnegie Museum 11:175-300.
  • Riggs, E.S. 1903. Structure and relationships of opisthocoelian dinosaurs, part I: Apatosaurus Marsh. Field Columbian Museum Publications, Geological Series 2(4): 165–196.
  • Stovall, J.W. 1938. The Morrison of Oklahoma and its dinosaurs. Journal of Geology 46:583-600.
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