November 21, 2016
The question of whether sauropod cervicals got longer through ontogeny came up in the comment thread on Mike’s “How horrifying was the neck of Barosaurus?” post, and rather than bury this as a comment, I’m promoting it to a post of its own.
The short answer is, yeah, in most sauropods, and maybe all, the cervical vertebrae did lengthen over ontogeny. This is obvious from looking at the vertebrae of very young (dog-sized) sauropods and comparing them to those of adults. If you want it quantified for two well-known taxa, fortunately that work was published 16 years ago – I ran the numbers for Apatosaurus and Camarasaurus to see if it was plausible for Sauroposeidon to be synonymous with Pleurocoelus, which was a real concern back in the late ’90s (the answer is a resounding ‘no’). From Wedel et al. (2000b: pp. 368-369):
Despite the inadequacies of the type material of Pleurocoelus, and the uncertainties involved with referred material, the genus can be distinguished from Brachiosaurus and Sauroposeidon, even considering ontogenetic variation. The cervical vertebrae of Pleurocoelus are uniformly short, with a maximum EI of only 2.4 in all of the Arundel material (Table 4). For a juvenile cervical of these proportions to develop into an elongate cervical comparable to those of Sauroposeidon, the length of the centrum would have to increase by more than 100% relative to its diameter. Comparisons to taxa whose ontogenetic development can be estimated suggest much more modest increases in length.
Carpenter & McIntosh (1994) described cervical vertebrae from juvenile individuals of Apatosaurus and Camarasaurus. Measurements and proportions of cervical vertebrae from adults and juveniles of each genus are given in Table 4. The vertebrae from juvenile specimens of Apatosaurus have an average EI 2.0. Vertebrae from adult specimens of Apatosaurus excelsus and A. louisae show an average EI of 2.7, with an upper limit of 3.3. If the juvenile vertebrae are typical for Apatosaurus, they suggest that Apatosaurus vertebrae lengthened by 35 to 65% relative to centrum diameter in the course of development.
The vertebrae from juvenile specimens of Camarasaurus have an average EI of 1.8 and a maximum of 2.3. The relatively long-necked Camarasaurus lewisi is represented by a single skeleton, whereas the shorter-necked C. grandis, C. lentus, and C. supremus are each represented by several specimens (McIntosh, Miller, et al. 1996), and it is likely that the juvenile individuals of Camarasaurus belong to one of the latter species. In AMNH 5761, referred to C. supremus, the average EI of the cervical vertebrae is 2.4, with a maximum of 3.5. These ratios represent an increase in length relative to diameter of 30 to 50% over the juvenile Camarasaurus.
If the ontogenetic changes in EI observed in Apatosaurus and Camarasaurus are typical for sauropods, then it is very unlikely that Pleurocoelus could have achieved the distinctive vertebral proportions of either Brachiosaurus or Sauroposeidon.
A few things about this:
- From what I’ve seen, the elongation of the individual vertebrae over ontogeny seems to be complete by the time sauropods are 1/2 to 2/3 of adult size. I get this from looking at mid-sized subadults like CM 555 and the hordes of similar individuals at BYU, the Museum of Western Colorado, and other places. So to get to the question posed in the comment thread on Mike’s giant Baro post – from what I’ve seen (anecdata), a giant, Supersaurus-class Barosaurus would not necessarily have a proportionally longer neck than AMNH 6341. It might have a proportionally longer neck, I just haven’t seen anything yet that strongly suggests that. More work needed.
- Juvenile sauropod cervicals are not only shorter than those of adults, they also have less complex pneumatic morphology. That was the point of the figure at the top of the post. But that very simple generalization is about all we know so far – this is an area that could use a LOT more work.
- I’ve complained before about papers mostly being remember for one thing, even if they say many things. This is the canonical example – no-one ever seems to remember the vertebrae-elongating-over-ontogeny stuff from Wedel et al. (2000b). Maybe that’s an argument for breaking up long, kitchen-sink papers into two or more separate publications?
October 27, 2016
Quick heads up: Mark Hallett and I are both at the Society of Vertebrate Paleontology meeting in Salt Lake City. Tomorrow afternoon (Friday, October 28) at 4:15 PM we’ll be signing copies of our book, The Sauropod Dinosaurs: Life in the Age of Giants. If you’d like to get a copy of the book, or to have your already-purchased copy signed, please come to the Johns Hopkins University Press booth in the exhibitor/poster area tomorrow afternoon. We’re both generally happy to sign books whenever and wherever, but if you’d like to catch us both at the same time, this is a good opportunity. We’re hoping to do another joint book signing in Los Angeles before long – more info on that when we get it arranged.
In the meantime, or if you’re not at SVP, or if you just like cool things, check out this rad claymation video of fighting apatosaurs, by YouTube user Fred the Dinosaurman. I love this. My favorite thing is that if you’re familiar with the previously-produced, static visual images of neck-fighting apatosaurs (links collected here), you’ll see a lot of those specific poses and moments recreated as transient poses in the video. This was published back in June, but I’d missed it – many thanks to Brian Engh for the heads up.
May 12, 2016
Things remain frantic on the Sauropocalypse tour. Today, we were back at the BYU Museum of Paleontology, working on four or five separate projects. Here’s Matt, photographing broken bone of the iconic Supersaurus cervical BYU 9024, while a pallet of Big Pink Apatosaur cervicals wait for attention in the background:
And here’s Mike, getting Jensen’s sculpture of the same vertebra down from storage to compare it to the original:
In Jensen’s (1985) original description of this vertebra – which he at first referred to Ultrasauros – the only relevant illustration he included was one of the model, so it was good to see this bit of history in the flesh (Jensen did include photos of the actual bone in later papers). We’ll show the two vertebrae, real and sculpted, side by side in a future post.
- Jensen, J. A. 1985. Three new sauropod dinosaurs from the Upper Jurassic of Colorado. Great Basin Naturalist 45, 697-709.
When I was back in Oklahoma in March, I met with Anne Weil to see some of the new Apatosaurus material she’s getting out of her Homestead Quarry. It’s nice material, but that’s a post for another day. Anne said something that really resonated with me, which was, “I love it when you guys post about vertebral morphology, because it helps me learn this stuff.” Okay, Anne, message received. This will begin to make things right.
I spent a week at BYU back in 2005, collecting data for my dissertation. One of the first things I had to do was teach myself how to identify the vertebrae of different sauropods, because BYU has just about all of the common Morrison taxa. These are the notes I made back then.
I always planned to do something with them – clean them up, get them into a more usable form. There are a lot of scribbly asides that are probably hard for others to read, and it would be more useful if I put the easily confused taxa next to each other – Barosaurus next to Brachiosaurus, for example. And I didn’t go into serial changes at all.
Still, hopefully someone will find these useful. If there are things I missed or got wrong, the comment thread is open. And if you want all four spreads in one convenient package, here’s a PDF: Wedel 2005 notes on Morrison sauropod cervicals
March 14, 2016
October 22, 2015
I’d hoped that we’d see a flood of BRONTOSMASH-themed artwork, but that’s not quite happened. We’ve seen a trickle, though, and that’s still exciting. Here are the ones I know about. If anyone knows of more, please let me know and I will update this post.
And in close-up:
Very elegant, and it’s nice to see an extension of our original hypothesis into other behaviours.
The next thing I saw was Mark Witton’s beautiful piece, described on his own site (in a post which coined the term BRONTOSMASH):
And in close-up:
I love the sense of bulk here — something of the elephant-seal extant analogue comes through — and the subdued colour scheme. Also, the Knight-style inclusion in the background of the individual in the swamp. (No, sauropods were not swamp-bound; but no doubt, like elephants, they spent at least some time in water.)
And finally (for now, at least) we have Matthew Inabinett’s piece, simply titled BRONTOSMASH:
I love the use of traditional materials here — yes, it still happens! — and I like the addition of the dorsal midline spike row to give us a full on TOBLERONE OF DOOM. (Also: the heads just look right. I wish I could do that. Maybe one day.)
Update (Monday 26 October)
Here is Oliver Demuth’s sketch, as pointed out by him in a comment.
Thanks, Oliver! Nice to see the ventral-on-dorsal combat style getting some love.
So that’s where we are, folks. Did I miss any? Is anyone working on new pieces on this theme? Post ’em in the comments!
September 30, 2015
Here’s the last post (at least for now) in the Fighting Apatosaur Art series — and we’re back to Brian Engh, who we started with.
Early in the process of putting together artwork to illustrate our apatosaur neck combat hypothesis, Brian tried out a whole bunch of outlandish concepts. Here are two that he showed us, but which were too speculative to push forward with. First, necks as big, floppy display structures:
As a piece of art, I really like this one: the boldness, the vivid contrasts, the alien quality of the animals. But as a palaeobiological hypothesis, it doesn’t really work: so much of the neck morphology in apatosaurs is to do with absorbing ventral forces that soft-tissue display structures down there don’t make a whole lot of sense.
Here’s the other one — which Brian titles “Apatosaur inflato-porcupine fish neck-bag”.
I particularly like the way the theropod being rolled around on the ground and repeatedly spiked. It’s no more than it deserves.
Does the idea of an inflatable neck make sense? I wouldn’t be at all surprised if there were sauropods that did something like this — plenty of extant animals inflate parts of their body for display purposes, after all — but I don’t think it would have been apatosaurs. Again, the characteristic features of the neck don’t seem well matched to this scenario.
Well, that’s all the apatosaur neck-combat art we have. If there’s to be a part 7 in this series, it will be made of artwork that you, dear readers, have contributed. Fire away!