UPDATE 19 May 2016
I belatedly realized that I caused some confusion in the original version of this post. This will hopefully sort things out:
The ventrolateral processes (1) are nothing new. As Ken Carpenter pointed out in a comment, Hatcher noted them back in 1901 in his monograph on Diplodocus carnegii. These are the features I describe below as being, “huge in Barosaurus, big in Diplodocus, small in Apatosaurus, and nonexistent in Haplocanthosaurus, Camarasaurus, and the brachiosaurids, at least from what I’ve seen.” To clarify: occasionally in camarasaurs and frequently in brachiosaurs you can trace a ridge along the ventrolateral margin of the centrum from the parapophysis to the cotyle. But these ridges are basically just the ‘corners’ of the centrum, leftover by the lateral and ventral waisting of the centrum – they do not project beyond the margin of the cotyle. In contrast, what I’ve been calling the ventrolateral flanges in diplodocids do project beyond the margins of the cotyle – they are additive structures, not just architectural leftovers. They also don’t vary much, other than to be more pronounced in more posterior cervicals.
The irregular ventral ridges (2) are a totally different thing. They’re on or near the sagittal midline of the centrum, usually restricted to the anteroposterior middle of the ventral centrum (so, about halfway between the condyle and the cotyle), and as my preferred term implies, highly variable among individuals and even among vertebrae in a series.
Hope that helps! (Original post starts below.)
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Back in 2005 I visited BYU while I was working on my dissertation. Back then I noted ventral ridges in a few diplodocine cervical vertebrae. (I hesitate to call such flimsy things ‘keels’.)
Up above is BYU 16918, a mid-to-posterior cervical vertebra of Diplodocus from the famous Dry Mesa Quarry. Here it is again in posterior view:
The things I have labeled VLF here are ventrolateral flanges, which are huge in Barosaurus, big in Diplodocus, small in Apatosaurus, and nonexistent in Haplocanthosaurus, Camarasaurus, and the brachiosaurids, at least from what I’ve seen. See this post for details. I know that the left VLF here looks like a second ridge, but the cotyle is broken off in such a way that we’re seeing the fossa just dorsal to the VLF margin. The ridge itself is skewed to the right, which could be natural or a result of taphonomy – as you can see from the photo at the top of the post, this vert has seen better days.
Here’s another Dry Mesa vert, BYU 11617, this time an anterior cervical of Barosaurus and in left lateral view:
Again in right lateral view – on this side you can see the fossa in the VLF more clearly:
And here’s the ventral view showing the ridge:
I noted these things in my notebook back when, filed them under, “Huh. How about that?” and went on with life.
Then last week Mike and I were at the North American Museum of Ancient Life in Lehi, Utah, and we saw this super-nice Barosaurus cervical on display in the prep lab (left ventro-lateral view). Check out the monster ventrolateral flanges, and the ridges between them at about mid-centrum.
Here’s another view, a more square-on ventral this time:
We owe a big thank you to Rick Hunter, who let us into the prep lab at the North American Museum of Ancient Life to see the Barosaurus material up close.
So what’s the deal with these ridges? I assume that they’re caused by pneumatic diverticula remodeling the ventral surface of the centrum. We know that such diverticula were down there because there are actual foramina on the ventral centrum in Supersaurus, many apatosaurines (Lovelace et al., 2008), many brachiosaurids, and probably loads of other things that haven’t been checked. Oddly enough, I’ve never seen the ridges in any of those other taxa. It seems that you get foramina or ridges, but not both. I have no idea what’s up with that – to paraphrase Neal Stephenson, Barosaurus cervicals are confections of air and marketing, and you’d think that if any sauropod would have straight-up foramina down there, it would be Barosaurus. But Barosaurus gets ridges and clunky old Apatosaurus gets foramina (sometimes, not all the time).
It’s a sick world, I tell you.
- Lovelace, D. M., Hartman, S. A., & Wahl, W. R. (2007). Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny. Arquivos do Museu Nacional, Rio de Janeiro 65(4):527-544.
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.
Not much to say this time – the pictures tell the story for now.
It was a pretty transcendental experience, as I imagine it must be for anyone who loves dinosaurs, or has a pulse.
A huge thank-you to Dan Chure, the Park Paleontologist for the Monument, who conveyed us safely up and down the Wall, taught us about the prehistory of the site and the human history of its excavation and conservation, held scale bars, moved backpacks, took photos, and generally seemed to be having just as much fun as we were. This has been a common theme on the trip – every single person we’ve interacted with at a museum or fossil site has been unfailingly welcoming and generous with their time and knowledge. Whatever challenges vert paleo faces, a lack of wonderful people is not one of them.
I was up there, too, for the second time in my life – that will be a post for another day. For now, just bask in the glory of Mike basking in the glory of a literally mind-numbing array of amazing fossils.
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 spend the morning with the baby, 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!
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
Several drinks later, they all die and somehow become skeletonised, and that’s how they all land up on a table in my office:
Top left: pieces of monitor lizard Varanus exanthematicus. Cervical vertebrae 1-7 on the piece of paper, femora visible above them, bits of feet below them. Awaiting reassembly. The whole skeleton is there.
Top right, on a plate on top of some lizard bits: skull, cervicals and feet of common pheasant Phasianus colchicus. The skull has come apart, and I can’t figure out how to reattach the quadrates. One of the feet is cleanly prepped out and waiting to be reassembled, while the other retains some skin for now.
Bottom left: skull and anterior cervicals of red fox Vulpes vulpes. Lots of teeth came out during the defleshing process, and will need to be carefully relocated and glued after the skull has finished drying out.
Bottom right: skull and anterior cervicals of European badger Meles meles. The skull is flat-out awesome, and by far my favourite among my mammal skulls. If tyrannosaurs were medium-sized fossorial mammals, they’d have badgers’ skulls for sure. A few teeth that came out have been glued into place; once the glue is dry, this skull is done.
October 27, 2015
When I separated my cat’s head from its body, the first five cervical vertebrae came with it. Never one to waste perfectly good cervicals, I prepped them as well as the skull. Here they are, nicely articulated. (Click through for high resolution.) Dorsal view at the top, then right lateral (actually, slightly dorsolateral) and ventral view at the bottom.
Or you may prefer the same image on a black background:
For those of us used to sauropod necks, where the atlas (C1) is a tiny, fragile ring, mammal atlases look bizarre, with their grotesque over-engineering and gigantic wings.