Yes, sauropod neck vertebrae got longer as the animals grew up
November 21, 2016
Fig. 14. Vertebrae of Pleurocoelus and other juvenile sauropods. in right lateral view. A-C. Cervical vertebrae. A. Pleurocoelus nanus (USNM 5678, redrawn fromLull1911b: pl. 15). B. Apatosaurus sp. (OMNH 1251, redrawn from Carpenter &McIntosh 1994: fig. 17.1). C. Camarasaurus sp. (CM 578, redrawn from Carpenter & McIntosh 1994: fig. 17.1). D-G. Dorsal vertebrae. D. Pleurocoelus nanus (USNM 4968, re- drawn from Lull 1911b: pl. 15). E. Eucamerotus foxi (BMNH R2524, redrawn from Blows 1995: fig. 2). F. Dorsal vertebra referred to Pleurocoelus sp. (UMNH VP900, redrawn from DeCourten 1991: fig. 6). G. Apatosaurus sp. (OMNH 1217, redrawn from Carpenter & McIntosh 1994: fig. 17.2). H-I. Sacral vertebrae. H. Pleurocoelus nanus (USNM 4946, redrawn from Lull 1911b: pl. 15). I. Camarasaurus sp. (CM 578, redrawn from Carpenter & McIntosh 1994: fig. 17.2). In general, vertebrae of juvenile sauropods are characterized by large pneumatic fossae, so this feature is not autapomorphic for Pleurocoelus and is not diagnostic at the genus, or even family, level. Scale bars are 10 cm. (Wedel et al. 2000b: fig. 14)
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.
C6 of Apatosaurus CM 555 – despite having an unfused neural arch and cervical ribs, the centrum proportions are about the same as in an adult.
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?
Reference
Matt’s adventures in the Camarasaurus pit
May 7, 2016
At the Prehistoric Museum in Price, Utah, our host Ken Carpenter invited us to jump right into the Camarasaurus pit and start pulling apart their beautiful specimen. We did. Here is Matt, looking as happy as I’ve ever seen him:
The pit is the central exhibit of the museum’s palaeontology hall. You can look down on its Jurassic scene from the balcony above:
Theres a very nice Stegosaurus and an Allosaurus in pursuit of some kind of ornithopod, but needless to say the star of the show is the dead Camarasaurus that lies on the ground, well associated but partially articulated.
It’s a beautifully undistorted specimen, and we were amazed and delighted when Ken not only gave us permission to hop over the barrier and get closer to it, but even to move the elements around to better measure and photograph them. We spent the morning with the skeleton, concentrating on four anterior cervicals, and could happily have spent much, much longer.
A shot across the room at ground level:
Further bulletins as and when we find time to post. Can’t write more now, we’re off to the big wall of awesome at Dinosaur National Monument!
SV-POW! endorses Triceratops
May 6, 2016
Today, we were at the BYU Museum of Paleontology, which is in a ridiculously scenic setting with snow-capped mountains on the horizon in almost every direction.
We got through a lot of good work in collections, and we’ll show you some photos from there in due course. But for today, here are a couple of pictures from the public galleries.
First, here in a single photo is definitive proof that the “Toroceratops hypothesis” is wrong:
Say what you want about ontegenetic trajectories, that huge and well ossified Triceratops is not a juvenile of anything.
Good, glad we got that sorted out.
Meanwhile, at the even better end of the gallery, here is a very nice — and very well lit — cast of the famous articulated juvenile Camarasaurus specimen CM 11338 described by Gilmore (1925):
Further bulletins as events warrant.
References
Gilmore, Charles W. 1925. A nearly complete articulated skeleton of
Camarasaurus, a saurischian dinosaur from the Dinosaur National
Monument, Utah. Memoirs of the Carnegie Museum 10:347-384.
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
Mike and I leave for the Sauropocalypse tomorrow. I’m hoping to post at least a few pretty pictures from the road, as I did for the Mid-Mesozoic Field Conference two years ago. Stand by…
SV-POW! on the road – Sauropocalypse 2016
April 30, 2016
Mounted Diplodocus at the Utah Field House of Natural History State Park Museum in Vernal.
I love Utah. I love how much of the state is given over to exposed Mesozoic rocks. I love driving through Utah, which has a strong baseline of beautiful scenery that is frequently punctuated by the absolutely mind-blowing (Arches, Bryce Canyon, Zion, Monument Valley…). I love doing fieldwork there, and I love the museums, of which there are many. It is not going too far to say that much of what I learned firsthand about sauropod morphology, I learned in Utah (the Carnegie Museum runs a close second on the dragging-Matt-out-of-ignorance scale).
Cast of the juvenile Camarasaurus CM 11338 at Dinosaur National Monument.
There is no easy way to say this so I’m just going to get it over with: Mike has never been to Utah.
I know, right?
But we’re going to fix that. Mike’s flying into Salt Lake City this Wednesday, May 4, and I’m driving up from SoCal to meet him. After that we’re going to spend the next 10 days driving around Utah and western Colorado hitting museums and dinosaur sites. We’re calling it the Sauropocalypse.
Mounted Barosaurus at the Natural History Museum of Utah in Salt Lake City.
Why am I telling you this, other than to inspire crippling jealousy?
First, Mike and I are giving a pair of public talks next Friday evening, May 6, at the USU-Eastern Prehistoric Museum in Price. The talks start at 7:00 and will probably run until 8:00 or shortly after, and there will be a reception with snacks afterward. Mike’s talk will be, “Why giraffes have such short necks”, and my own will be, “Why elephants are so small”.
Second, occasionally people leave comments to the effect of, “Hey, if you’re ever passing through X, give me a shout.” I haven’t kept track of all of those, so this is me doing the same thing in reverse. Here’s our itinerary as of right now:
May 4, Weds: MPT flies in. MJW drives up from Cali. Stay in SLC/Provo area.
May 5, Thurs: recon BYU collections in Provo. Stay in SLC/Provo area.
May 6, Fri: drive to Price, visit USU-Eastern Prehistoric Museum, give evening talks. Stay in Price.
May 7, Sat: drive to Vernal, visit DNM. Stay in Vernal.
May 8, Sun: visit Utah Field House, revisit DNM if needed, drive to Fruita.
May 9, Mon: visit Rabbit Valley camarasaur in AM, visit Dinosaur Journey museum in PM. Go on to Moab.
May 10, Tues: drive back to Provo, visit BYU collections.
May 11, Weds: BYU collections.
May 12, Thurs: drive to SLC to visit UMNH collections, stay for Utah Friends of Paleontology meeting that evening.
May 13, Fri: BYU collections.
May 14, Sat: visit North American Museum of Ancient Life. MPT flies home. MJW starts drive home.
We’re planning lots of time at BYU because we’ll need it, the quantity and quality of sauropod material they have there is ridiculous. As for the rest, some of those details may change on the fly but that’s the basic plan. Maybe we’ll see you out there.
On Monday we visited the Prehistoric Museum in Price, Utah, the Cleveland-Lloyed dinosaur quarry, and sites in the Mussentuchit member of the Cedar Mountain Formation. Many thanks to Marc Jones for the photos.
In 2010, the College of Eastern Utah became Utah State University – Eastern, and the CEU Prehistoric Museum in Price is now officially the USU Eastern Prehistoric Museum. The dinosaurs in the center of exhibit hall are being remounted. These include Allosaurus, Stegosaurus, Camptosaurus (mounted, toward top of photo), and Camarasaurus (dismounted, on floor). Most of the mounts are either real material or casts of real material from the nearby Cleveland-Lloyd quarry.
The museum has many other exhibits besides the one shown above. The paleo wing alone covers two floors, and upstairs there are great displays on Cretaceous dinosaurs from the area, including Jurassic and Cretaceous ankylosaurs, a ceratopsian, and numerous tracks.
After leaving Price we went to the Cleveland-Lloyd dinosaur quarry, which has produced over 20,000 separate elements, including the remains of something like 50-60 allosaurs. The smallest ones are hatchlings–several elements from literally cat-sized baby allosaurs are known from the quarry.
Mark Loewen (right) talked to us about how the quarry might have formed, and what it’s like to work there. On the left in the above photo you can see a bunch of disarticulated Allosaurus bones suspended above the floor on wires. These are placed to give an idea of the three-dimensional jumbling of the bones in the matrix. It is almost impossible to jacket one bone or even several without hitting others. I remember how that goes from working at the OMNH sauropod bonebed in the Cloverly–it’s almost impossible to avoid blowing through some bones just to get others out of the ground.
Here’s one of a handful of bones from the quarry with bite marks. This is the pelvis of a Camarasaurus, lying upside down, anterior toward the wall. The back end of the right ilium is heavily tooth-marked.
After Cleveland-Lloyd we stopped at a couple of sites in the Mussentuchit. I’m not going to blog about those because they are active sites that are still producing fossils. Unfortunately it is not uncommon for fossil localities on public land to be looted and vandalized by unscrupulous private collectors. I don’t want to give those a-holes any help, so I’ve deliberately not shown any photos of about half a dozen of the most interesting sites that we visited during the conference. It sucks to know cool things and not be able to tell people about them, but if I blab then I put those cool things at risk. Happily there is a lot of active research going on, including one or two projects that got hatched at this conference, so hopefully I will be able to tell some of these stories soon.
Instead, I will close this series (for now) with a shout-out to the people who convened and ran the field conference: Jim Kirkland (left) and ReBecca Hunt-Foster (middle). John Foster (right) also contributed a lot of time, energy, effort, and expertise.
Jim Kirkland is amazing. If you know him, you know that his heart is as big and outgoing as his booming voice. His knowledge of and enthusiasm for the mid-Mesozoic sites in western Colorado and eastern Utah have driven a lot of science over the past quarter century, and he shared that knowledge and enthusiasm compulsively on this trip. My head is so full of new stuff, it’s honestly hard to think. I wish I had a solid week to just digest everything I learned at the conference.
My highest praise and thanks go to ReBecca. Thanks to her hard work and organization, the whole field conference ran about as much like clockwork as something this complicated can–and when it didn’t run smoothly, like that flat tire on Saturday, she took charge and got us back on track. She was basically den mom to about 60 folks, from teenagers to retirees, from at least ten countries and four continents, and somehow she did it all with unflagging grace and good humor. The fact that she had her appendix out just two or three days before the start of the conference only cements my admiration for what she pulled off here.
I had a fantastic time. I hope they do another one.
Actually we had the Jurassic talks today, but I can’t show you any of the slides*, so instead you’re getting some brief, sauropod-centric highlighs from the museum.
* I had originally written that the technical content of the talks is embargoed, but that’s not true–as ReBecca Hunt-Foster pointed out in a comment, the conference guidebook with all of the abstracts is freely available online here.
Like this Camarasaurus that greets visitors at the entrance.
And this Apatosaurus ilium ischium with bite marks on the distal end, indicating that a big Morrison theropod literally ate the butt of this dead apatosaur. Gnaw, dude, just gnaw.
And the shrine to Elmer S. Riggs.
One of Elmer’s field assistants apparently napping next to the humerus of the Brachiosaurus alithorax holotype. This may be the earliest photographic evidence of someone “pulling a Jensen“.
Here’s the reconstructed forelimb of B. altithorax, with Cary Woodruff and me for scale. The humerus and coracoid (and maybe the sternal?) are cast from the B.a. holotype, the rest of the bits are either sculpted or filled in from Giraffatitan. The scap is very obviously Giraffatitan.
Cary took this photo of me playing with a fiberglass 100% original bone Apatosaurus femur upstairs in the museum office, and he totally passed up the opportunity to push me down the stairs afterward. I kid, I kid–actually Cary and I get along just fine. It’s no secret that we disagree about some things, but we do so respectfully. Each of us expects to be vindicated by better data in the future, but there’s no reason we can’t hang out and jaw about sauropods in the meantime.
Finally, in the museum gift shop (which is quite lovely), I found this:
You had one job, Nova. ONE JOB!
So, this is a grossly inadequate post that barely scratches the surface of the flarkjillion or so cool exhibits at the museum. I only got about halfway through the sauropods, fer cryin’ out loud. If you ever get a chance to come, do it–you won’t be disappointed.
You know the drill: lotsa pretty pix, not much yap.
Our first stop of the day was the Fruita Paleontological Area, which has a fanstastic diversity of Morrison animals, including the mammal Fruitafossor and the tiny ornithopod Fruitadens.
Plus it’s a pretty epic landscape, especially with the clouds and broken light we had this morning.
I found a bone! Several bits, actually, a few meters away from the Fruitadens type quarry. I’d like to think that this proximal femur might be Fruitadens, but I don’t know the diagnostic characters and haven’t had time to look them up. Anyone know how diagnostic this honorary shard of excellence might be?
After lunch, John Foster took us on a short hike to the quarry where Elmer Riggs got the back half of the Field Museum Apatosaurus. The front half came from a site in southern Utah, several decades later.
The locals brought Riggs out in the 1930s for the dedication of two monuments–this one at the Apatosaurus quarry, and another like it at the Brachiosaurus quarry some miles away. Tragically, both monuments have the names of the dinosaurs misspelled!
In the afternoon we visited the Mygatt-Moore Quarry and the Camarasaurus site in Rabbit Valley. Can you see the articulated Camarasaurus neck in this photo?
Here’s a hint: the neural arches of two posterior cervical vertebrae in transverse horizontal cross-section.
This Camarasaurus is apparently a permanent feature. If you’re wondering why no-one has excavated it, it’s because it’s buried in sandstone that is stupid-dense. The expenditure of time and resources just isn’t worth it, when right down the hill dinosaurs are pouring out of the much softer sediments of the Mygatt-Moore Quarry like water from a hydrant. This is the lesson I am learning about the Morrison: finding dinosaurs is easy. Finding dinosaurs you can get out of the ground and prepare–that’s something else.
Our last stop of the day was Gaston Design, where Rob Gaston showed us how he molds, casts, and mounts everything from tiny teeth to good-sized skeletons.
Like this Deinosuchus that is about to chomp on Jim Kirkland. Jim doesn’t look too worried.
Here’s a nice cast of a busted sauropod dorsal, probably from Apatosaurus or Diplodocus, showing the pneumatic internal structure. Compare to similar views of dorsals in this post and this one. This is actually one half of a matched set that includes both halves of the centrum. I left with one of those sets of my own, a few dollars poorer and a whole lot happier.
The end–for now.
The Sauroposeidon stuff is cribbed from this post. For the pros and cons of scale bars in figures, see the comment thread after this post. MYDD is, of course, a thing now.
Previous posts in this series.
Reference:
The full story on Morosaurus lentus
February 14, 2014
Last time, we took a very quick look at YPM 1910, a mounted skeleton that is the holotype of Camarasaurus (= “Morosaurus“) lentus, in the dinosaur hall of the Yale Peabody Museum.
Here’s the whole skeleton, in various views. Skip down to the bottom for the science; or just enjoy the derpiness. First, in anterior view:
Here’s a more informative right anterolateral view. As you can see, this little Camarasaurus is in every sense in the shadow of the the much more impressive Apatosaurus (= “Brontosaurus“) excelsus holotype, YPM 1980: click through for the full image:
And here’s the corresponding photo from Lull (1930: figure 1) (see below):
Camarasaurus lentus, holotype skeleton, oblique front view (Lull 1930: fig. 1)
It’s interesting to see such a familiar mount in such unfamiliar surroundings. Judging by the cabinets in the background, YPM 1910 was mounted in what’s now the dinosaur hall at Yale — i.e. it hasn’t moved since the photo was taken. But back then, Brontosaurus hadn’t been mounted, and Zallinger’s mural hadn’t been painted.
If you thought this animal looked dumb from the front, check out this left anterodorsolateral view, taken from the balcony above the hall. The foreshortening of the neck makes Cam look like a particularly dense puppy.
(Once more, click through for the full version of the photo, including the much more impressive Apatosaurus.)
Right lateral view, with Zallinger’s justly famous mural in the background. Note the Diplodocus-type double-beamed chevrons in the tail:
Here’s the justly under-rated posterior view:
And finally, Lull’s left posterolateral photo — taken from a position that can’t now be replicated, due to the inconveniently located Brontosaurus. (The Archelon in the background, which was previously featured on SV-POW!, has been moved to the end of the hall since Lull’s time.
Camarasaurus lentus, oblique rear view. Lull (1930: fig. 2)
How much of this skeleton is real? Happily, not the skull. We can only hope that the real thing wasn’t quite so troubling. But much of the rest of the skeleton is real bone. To quote Lull (1930:1-3):
In the Yale specimen the entire vertebral column is present from the second or third cervical to the tenth caudal with one or two later caudals. Of the limbs and their girdles there are present the left scapula, right coracoid, both humeri, the left radius and ulna, both ilia, the right pubis and left ischium, and both femora, tibiae and fibulae. One cervical rib is present but no thoracic ribs. The disarticulated sacrum lacked one rib from either side.
(How could Lull have been unsure whether the most anterior preserved cervical was the second or third? C2 in sauropods, as in most animals, is radically different from the subsequent cervicals. He does go on to say that only the centrum of the most anterior vertebra is preserved, but the axis has a distinct anterior central articulation.)
Lull is quite ready to criticise the mount, and notes in particular:
The cervical ribs in the Yale mount are not long enough by half, and the thoracic ribs may be somewhat heavy and their length a little short […] both carpus and tarsus are probably incorrect, as the elements in each instance are fewer than shown, there being no more than two at most. There is apparently no justification for the fore and aft extensions of the distal chevrons, as these were not preserved and the Osborn-Mook restoration was followed. […] A probable error lies in too great an allowance for cartilage between the [pelvic] elements, thus making the acetabulum seem rather large.
He also notes a scheme that sadly never came to pass:
[The holotype of Camarasaurus (= “Morosaurus“) robustus], a very perfect specimen, we intend to mount when the great Brontosaurus excelsus type is completed. The three sauropods, ranging in length from 21 to nearly 70 feet, should make a very impressive group.
They would have done! But in the end it fell to the Museum für Naturkunde Berlin to give us the world’s first three-sauropod combo (unless someone knows of an earlier one?)
Finally; the mounted Yale Camarasaurus also crops up in three of the plates of Ostrom and McIntosh (1966). Plate 60 depicts metacarpals I and II in all the cardinal views except for some reason posterior; plate 61 does the same for metacarpals III and IV); and plate 70 shows the right pubis in every aspect but anterior. Here it is:
Morosaurus lentus [Now referred to Camarasaurus lentus] Marsh (1889) YPM 1910 (holotype). Right pubis (reversed) in medial (1), posterior (2), lateral (3), proximal (4), and distal (5) views; transverse sections through blade (6) and shaft (7). (Ostrom and McIntosh 1966: plate 70)
And on that line, I’m out.
References
Ostrom, John H., and John S. McIntosh. 1966. Marsh’s Dinosaurs: the Collections from Como Bluff. Yale University Press, New Haven, CT. 388 pages including 65 positively scrumptious plates.
Sauropod Vertebra Picture of the Week 