July 14, 2015
Now that the new Wilson and Allain (2015) paper has redescribed Rebbachisaurus, we can use it to start thinking about some other specimens. Particularly helpful is this beautiful rotating animation of the best dorsal vertebra (here captured at the point of the rotation where we’ve viewing it in right anterolateral):
As I briefly discussed on Twitter, seeing this made me think of my baby, Xenoposeidon. Now that specimen, beautiful though it is, preserves only the lower one third of the vertebra. But there are some clear commonalities, and they’re clearer if you look at the animation.
Most obviously, there are laminae running up and down the anterior and posterior margins of the lateral face of Xeno’s neural arch, and those same laminae seem to exist in Rebbachisaurus. We didn’t name these laminae in the Xeno paper, but if they’re the same thing as in Rebbachisaurus, then they’re ACPLs and PCDL — anterior centroparapophyseal and posterior centodiapophyseal laminae.
If that’s right, then we misinterpreted the site of the parapophysis in Xenoposeidon. We (Taylor and Naish 2007) thought it was at the cross-shaped junction of laminae near the anterodorsalmost preserved part of the vertebra. In Rebbachisaurus, this cross exists, but it’s merely where the CPRL (centroprezygapophyseal lamina) intersects the ACPL.
But there’s more. In Xenoposeidon, the base of the CPRL (if that’s what it is) forms a “V” shape with an accessory lamina that proceeds posterodorsally from the same origin. (This is one of the features that’s apparent on the more damaged right side of Xeno as well as the nicer left side.) That lamina also seems to exist in Rebbachisaurus — but with the whole vertebra to consider, we can see that it’s not an accessory lamina, but a perfectly well-behaved CPOL (centropostzygapophseal lamina).
So if Xeno is indeed a rebbachisaurid, then the two branches of the “V” go to support the pre- and postzygs, and the laminae running up the anterior and posterior margins of the centrum support the parapophyses and diapophyses respectively. There are actually two crosses on each side of the neural arch: one at the intersection of CPRL and ACPL, the other at the intersection of CPOL and PCDL; but in the Xeno specimen, the posterior cross is lost, having been just above where the break occurs at the top of the neural arch.
Here’s what I mean:
In case it’s not clear, the grey lines are an (extremely crude) reconstruction, the blue lines label the important laminae, and the red circles highlight the two crosses.
Hmm. The more I look at this, the more convincing I find it.
But there’s more! The anterior aspect of the Rebbachisaurus vertebra also bears a notable resemblance to what we see in Xeno, with a pair or arched laminae forming a vaulted roof to the neural canal.
Jeff Wilson spotted the same thing in a sequence of comments on my tweets, saying:
That’s not a bad call—the infrazygapophyseal region of that vert is elongate, and there is a nice CPRF and those closely positioned TPRLs could mean that prz’s are close to one another or even conjoined. It’s tantalizing, but not much to go on. Would be nice to prep out CPRF & work out laminae on lat sfc.
Jeff is right that more preparation would help to figure this out.
Not that everything about the Rebbachisaurus dorsal is Xeno-ish. Most notably, the lateral foramen is nothing like that of Xeno, being an uninspiringly dull and simple oval rather than the much more elegant foramen-within-a-fossa arrangement that we see in Xeno. But there are other points of commonality, too, such as the flat stretch of bone above the fossa and the way the posterior margin of the neural arch reaches the posterior margin of the centrum.
All in all — while there is plenty of work yet to do — I am increasingly inclined to think that the evidence we currently have suggests Xenoposeidon is a rebbachisaurid. If that’s right, it would be quite an exciting result. It would be the earliest known rebbachisaur, and the only named one from the UK. (Mannion 2009 described, but did not name, a rebbachisaurid scapula from Wessex formation of the Wealden). Could Mannion’s scapula be Xenoposeidon? Unlikely, as it’s 10 million years more recent. But it could be a close relative.
- Mannion, Philip D. 2009. A rebbachisaurid sauropod from the Lower Cretaceous of the Isle of Wight, England. Cretaceous Research 30:521-526. doi:10.1016/j.cretres.2008.09.005
- Taylor, Michael P. and Darren Naish. 2007. An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England. Palaeontology 50(6):1547-1564. doi:10.1111/j.1475-4983.2007.00728.x
- Wilson, Jeffrey A., and Ronan Allain. 2015. Osteology of Rebbachisaurus garasbae Lavocat, 1954, a diplodocoid (Dinosauria, Sauropoda) from the early Late Cretaceous–aged Kem Kem beds of southeastern Morocco. Journal of Vertebrate Paleontology 35(4):e1000701. doi:10.1080/02724634.2014.1000701
Here at SV-POW! Towers, we’re keenly aware that some of our fans are just here for the hardcore sauropod vertebra action. These folks start to shift in their seats when we put up too many posts in a row on open access or rabbits or…okay, mostly just OA and bunnies. If that’s you – or, heck, even if it isn’t – your good day has come. Saddle up. Let’s ride.
When Brian Engh and I were at the new Natural History Museum of Utah recently, I spotted this cute little juvenile cervical in one of the display cases.
According to this sign, it’s UMNH 21054, and it was found by Frank DeCourten and prepared by Virginia Tidwell.
It shares a display case and a sign with what is probably an anterior dorsal, UMNH 21055.
Now, I don’t mean to brag (okay, maybe a little…) but the number of EKNApod* vertebrae is not large and the number of EKNApod vertebrae I’m not intimately familiar with hovers near zero. This thing was ringing bells – I knew I’d seen it before.
* Early Cretaceous North American sauropod
Here are few more views. Note the light-colored oblong spot on the top of the condyle in the image above – this may be a pneumatic foramen filled with matrix, or a spot where the cortical bone flaked away to reveal one of the internal pneumatic spaces. Also, check out the fragment of extraneous bone (probably cervical rib) stuck sideways across the top of the centrum, just behind the condyle, in the image immediately below. Both of these features will be important later.
The vert belongs to a juvenile sauropod because the neural arch is missing – it didn’t fuse to the centrum before the animal died. But it was a big baby; the centrum is maybe just a hair under 40 cm in length, meaning that a world-record giraffe might just maybe have a couple of cervicals of the same length. But basal titanosauriforms typically have 12-13 cervicals, not the whimpy 7 that almost all mammals must make do with, and all-stars like Euhelopus can have up to 17.
Also, this was not from the middle of the neck. No way. The parapophyses are huge, and the centrum is pretty stubby compared to Sauroposeidon or YPM 5294, the Sauroposeidonesque cervical from Unit VII of the Cloverly (pic here). My guess is we’re looking at something past the middle of the neck, where the cervicals start to get proportionally shorter (but sometimes max out in absolute length), maybe a C9 or C10. In Giraffatitan brancai HM SII/MB.R.2181, C10 has a centrum length of 100 cm and makes up about 12% of the 8.5-meter neck. Assuming similar proportions here, UMNH 21054 came from the roughly 3-meter neck of a sauropod about the size of a really big draft horse or a really small elephant.
But enough noodling about the animal’s size. I knew I’d seen this vert before, but where? Thank goodness for comprehensive signage – I knew the material had been discovered by Frank DeCourten and prepped by Virginia Tidwell. At one of the SVP meetings in Denver, at a reception at the Denver museum, Virginia had invited me into the prep lab to see some EKNApod material from the Long Walk Quarry in Utah. The Long Walk Quarry was Frank DeCourten’s baby – he wrote a couple of papers about it (e.g., DeCourten 1991) and included additional information in his book, Dinosaurs of Utah (1998; second edition in 2013). DeCourten had referred the material to Pleurocoelus because that’s what people did with EKNApods back in the 20th century, but I remembered seeing one cervical that, like Sauroposeidon and YPM 5294, was just too long to match any of the Pleurocoelus material. My ‘Museum Photos’ file has a subfolder titled ‘Denver 2004’ – was the mystery vert in there?
In short, yes. Here’s one of the photos I took back in 1994.
Here’s another, sans flash this time. Check out the white spot on top of the condyle, the bar of float bone stuck sideways across the centrum just behind the spot, and general pattern of breaks – it’s a perfect match for UMNH 21054. Also note the block number on the pink specimen label at the bottom of the image – LWQ8, for Long Walk Quarry.
Three mysteries remain. One, the signage says the vert is from Carbon County, Utah, but the Long Walk Quarry has always been described as being in Emery County. Just a typo, or is there a story there? Two, how much of the animal (or animals) was excavated and prepped? I saw other vertebrae, both larger and smaller, when I was in Denver back on ’04, and DeCourten figured still others that I haven’t yet seen personally. Finally, is anyone working on it? And if not…[cautiously raises hand].
For other posts on the NHMU public galleries, see:
- DeCourten, F.L. 1991. New data on Early Cretaceous dinosaurs from the Long Walk Quarry and tracksite, Emery County, Utah. In: T.C. Chidsey, Jr. (ed) Geology of East-Central Utah. Utah Geological Association Publication 19: 311-325.
- DeCourten, F.L. 1998. Dinosaurs of Utah. University of Utah Press, Salt Lake City, 208pp.
December 16, 2014
Right on the heels of Aquilops last week, my paper with John Foster on the new specimen of Haplocanthosaurus from Snowmass, Colorado, was just published in Volumina Jurassica. I’ll have more to say about it later, but right now I am up against a deadline on a big project and I need to go work on that. I’m only popping up here to note two quick things.
First, if you’re not familiar with Volumina Jurassica – and I wasn’t, before this project – it’s a free-to-access* journal that publishes papers on all aspects of the Jurassic. The current issue is specifically dedicated to the Jurassic formations of the American West. There’s a lot of interesting stuff in there, but of special interest to SV-POW! readers will be the paper by Cary Woodruff and John Foster on the legendary and possibly apocryphal Amphicoelias fragillimus.
* But not truly open access since the journal claims to retain exclusive rights to distribute the papers. That seems like a quaint affectation now that the internet is here, but whatever – at least they let anyone download the PDF for free, which is primarily what I care about.
Second, the figure resolution in the PDF of the Haplocanthosaurus paper is not stellar, so as is the case with almost all of our papers, the full-color, high-resolution figures are available at the paper’s page on the sidebar.
For our previous posts on Haplocanthosaurus, go here; for those on Amphicoelias, including Mike’s very popular, “How big was Amphicoelias fragillimus? I mean, really?”, go here.
- Foster, J.R., and Wedel, M.J. 2014. Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison Formation (Upper Jurassic) near Snowmass, Colorado. Volumina Jurassica 12(2): 197–210. DOI: 10.5604/17313708 .1130144
- Woodruff, D.C., and Foster, J.R. 2014. The fragile legacy of Amphicoelias fragillimus (Dinosauria: Sauropoda; Morrison Formation – latest Jurassic). Volumina Jurassica 12(2): 211–220. DOI: 10.5604/17313708 .1130144
July 16, 2014
I was at the Natural History Museum of Los Angeles County yesterday to do some research in the ornithology collection. After lunch I was working on this pelican skeleton and I thought, “Geez, there is just no way to do this thing justice with still photos. I should make a video.” Here it is. You’ll want to see it full-screen–this being my first time out making a video, I didn’t realize that I was holding the phone the wrong way for efficient viewing on other devices.
The specimen is LACM Ornithology 86262. I’m posting this video with the knowledge and kind permission of the ornithology collection staff.
For previous things in this vein, please see:
- There’s almost nothing but nothing there, Brachiosaurus edition
- There’s almost nothing but nothing there, Sauroposeidon edition
If you like it that stuff like this exists, please support your local natural history museum, especially the LACM, which has some really fantastic education and outreach programs.
June 27, 2014
In recent photo posts on the mounted Brachiosaurus skeleton and its bones in the ground, I’ve lamented that the Field Museum’s online photo archive is so unhelpful: for example, if it has a search facility, I’ve not been able to find it.
But the good news is that there’s a Field Museum Photo Archives tumblr. Its coverage is of course spotty, but it gives us at least some chance of finding useful brachiosaur images. Like this one of the sixth presacral vertebra (i.e. probably D7 in a column of 12 dorsals):
It’s instructive to compare that with Riggs’s (1904: plate LXXII) illustration of the same vertebra in the same aspect, in which he almost literally airbrushed out the jigsaw-puzzle complexity of the preserved bone surface:
More disturbing still, compare that old photograph with my own (terrible) 2005 photo of the same vertebra:
It looks very much as though the vertebra itself — not just Riggs’s illustration — has been “improved” since the older photo was taken exactly a century earlier in 1905. This is a constant problem when dealing with old fossils.
Here are three more interesting photos from the Tumblr. First, the Brachiosaurus fossils in the field:
This is evidently from later in the excavation process than the previous photo of this area, since much of the material is now jacketed. That’s the femur in front of shot, here seen in anteromedial view, with the top towards the right.
Next up, this photo purports to be “Thirteen men including Security Guard unloading dorsal vertebrae of type specimen Brachiosaurus fossil”:
But in fact it’s not Brachiosaurus — the neural spines are too tall and slender. I am pretty sure this is Riggs’s Apatosaurus — the rightmost dorsal has that distinctive notch on the dorsal aspect of the neural spine. And indeed, checking his monograph on that specimen (Riggs 1903: plate XLVI), I see that its dorsals were distorted in this way, and that the front-centre vert is a fine match for its D10.
Finally, there’s this one of the prep room:
On the far left, we have the still-jacketed Brachiosaurus femur; next to it stands Harold W. Menke, who discovered the fossil; and to his right is Elmer S. Riggs, who wrote the description.
Those are all the Brachiosaurus-related images I’ve been able to find on the tumblr. But do let me know if you find any others.
- Riggs, Elmer S. 1903. Structure and relationships of opisthocoelian dinosaurs. Part I: Apatosaurus Marsh. Field Columbian Museum, Geological Series 2:165-196.
- Riggs, Elmer S. 1904. Structure and relationships of opisthocoelian dinosaurs. Part II, the Brachiosauridae. Field Columbian Museum, Geological Series 2:229-247.
May 19, 2014
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: