Two nice pneumatic Allosaurus vertebrae

May 25, 2023

I spent last week bombing around Utah and western Colorado with Dave Hone, who was over from England to visit those states for the first time in his life. We did some fieldwork out at Brachiosaur Gulch and visited quite a few museums and quarries around the Dinosaur Diamond, in a sort of mini-recapitulation of my 2016 Sauropocalypse with Mike. It was a fun and rewarding trip and there will hopefully be more posts on it forthcoming, but for now I’m going to play against type and keep this as short and focused as I can.

The Prehistoric Museum in Price had added a fair number of new exhibits since Mike and I visited back in 2016, including this nice display on pneumaticity and respiration in birds and other dinos. I was quite taken with it because I’ve seen some nice examples of cut and polished sauropod vertebrae (like this one and this one), but I can’t remember ever having seen the same thing done to a theropod vertebra.

Near the end of Dave’s visit we hit the Natural History Museum of Utah in Salt Lake, and I spotted this cast of an Allosaurus dorsal vertebra in the gift shop. I thought it looked awfully familiar, and sure enough, it’s a slightly restored version of MWC 5818, which you may remember from this post. It’s an anterior dorsal of Allosaurus with the front of the centrum eroded away to show the internal chambers. The specimen is now available as a cast from Gaston Design, which is how it came to be in the NHMU gift shop.

I have a lot more I want to blog about, but I’m just digging out from having been out of town for most of the past two months. Further bulletins when I get the time and energy, I reckon.

Posted by Matt Wedel
Filed in Acrocanthosaurus, cervical, dorsal, everything's better cut in half, museums, Natural History Museum of Utah, pneumaticity, Price Prehistoric Museum, stinkin' theropods
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We were probably wrong about caudal pneumaticity in Ca13 of the Brontosaurus excelsus holotype YPM 1980

March 20, 2023

This is one of those posts where the title pretty much says it all, but here’s the detailed version.

Recap: the 2013 paper

In Matt’s and my 2013 paper Caudal pneumaticity and pneumatic hiatuses in the sauropod dinosaurs Giraffatitan and Apatosaurus (Wedel and Taylor 2013b), we wrote about the Brontosaurus excelsus holotype 1980:

Much more convincing, however, are two isolated lateral fossae: one on the left side of caudal 9, the other on the right side of caudal 13 (Figure 10). Both of these are much larger than the aforementioned foramina – about 6 cm across – and have distinct lips. There is absolutely no trace of similar fossae in any of the other caudals, so these fossae represent a bilateral pneumatic hiatus of at least seven vertebrae

And we illustrated the right side of Ca13 in our figure 10:

Wedel and Taylor (2013:figure 10). An isolated pneumatic fossa is present on the right side of caudal vertebra 13 in Apatosaurus excelsus holotype YPM 1980. The front of the vertebra and the fossa are reconstructed, but enough of the original fossil is visible to show that the feature is genuine.

Fast forward to 2023

The Yale Brontosaurus has been dismounted and sent to RCI in Canada for some long overdue TLC. It’s being re-prepared, and Brian Curtice has seen the material close up. The news from Brian is not good: I quote some of his emails. First, on 26 January:

The 1980 caudal 13 it isn’t pneumatic. That whole hole is plaster. The 2 verts in front of it have similar damage but on the opposite side. It looks like they were damaged during preservation, excavation, or preparation.

Then on 27 January:

Quick caudal pneumatic update: other than the fact 1980 has a large number of what I dub nutrient foramina there isn’t any shiny surfaces, no odd sculpting, fluting, etc. the bone is exquisite in these areas but will soon be painted black.

Later that day:

It was also exceptionally difficult to sometimes tell what was actual bone. Barbour [1890 — ed.] is spot on at what Marsh had done. The preparators sometimes couldn’t be sure without acetone and an air scribe… I did the best I could but my goodness it was tough and may have errors. Thus I stayed towards what I was positive on.

On 3 February, I wrote back to Brian asking:

My question about the “pneumatic fossa” in caudal 13 is: why did they sculpt it like that? It would have been the simplest thing in the world to give it a simple flat lateral aspect, like the other caudals, so what made them put the fossa in? One possible answer is that that’s what the bone was actually like, but smashed up, and they “repaired” it. I guess we are unlikely ever to know.

He replied the same day:

There are 3 caudals (11-13, pics attached) with similarly damaged bone, punky and smashed and “beat up”, with 11 and 12 having the damage on the left and ventral and 13 on the right. I suspect they were lying close to one another. I couldn’t tell if it was trampling, but it didn’t seem like it was from being hacked from the ground.
[…]
As to why they did it? I suspect because 13’s damage wasn’t as jagged, they could plaster over it easier? We’ll never know for sure.

Brian sent a photo of the re-prepared caudal 13, showing … well, see for yourself:

Truthfully, I don’t find this especially compelling. But that’s about the inadequacy of photos for this kind of work. My inclination is to trust Brian’s interpretation, while wondering how Matt and I were both fooled back in June 2012 when we visited YPM together and spent significant time gazing at this caudal.

So what now?

The good news for us is that this doesn’t really change any of our arguments or conclusion in the 2013 paper. We said that there is previously undocumented evidence of caudal pneumaticity in apatosaurines[1] — and there still is, in the other specimen we figured, FMNH P25112, in our figure 9. And the significant conclusion of the papers was the intermittent and unpredictable pneumatization along the tails of sauropods is compelling evidence for extensive “cryptic pneumaticity” — that is, for soft-tissue pneumatization alongside vertebrae that did not penetrate the bone. That conclusion is still good.

But still: one of the data-points we relied on in making that argument no longer looks solid, and it feels like the honest thing is to document that. It probably doesn’t warrant a follow-up paper or even an erratum. But it does warrant a blog-post, and this is it.

Thanks to Brian for bringing it to our attention!

Notes

[1]. In the paper we said “in Apatosaurus“, not “in apatosaurines”. But that was back when Apatosaurus was the only recognized apatosaurine, so it amounted t0 the same thing. If we were writing it in the post-Tschopp-et-al. world of today, we’d say “in apatosaurines”.

References

 

Posted by Mike Taylor
Filed in Brontosaurus, caudal, pneumaticity, Yale Peabody Museum
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How the Concrete Diplodocus paper came to be

February 23, 2023

Last time, I told you about my new paper, The Concrete Diplodocus of Vernal (Taylor et al. 2023), and finished up by saying this: “But Mike, you ask — how did you, a scientist, find yourself writing a history paper? It’s a good question, and one with a complicated answer. Tune in next time to find out!”

Paper 1

The truth is, I never set out to write a history paper. My goal was  very different: to belatedly write up my and Matt’s 2016 SVPCA presentation, How Big Did Barosaurus Get? (Taylor and Wedel 2016). In that talk, we discussed a half-prepared jacket at BYU that contains three Barosaurus cervicals which are significantly larger than those of the well-known specimen AMNH 6341. And we went on to note that the giant “Supersaurus” cervical BYU 9024 is morphologically indistinguishable from those of Barosaurus, even though it’s going on for twice the size.

That paper (codename: superbaro) is in progress, and I would estimate it’s about 40% done. But in that paper, I needed to write a brief section in the introduction about AMNH 6341, the keystone specimen for Barosaurus, from which all our perceptions of that animal derive. And it turned out that in that section I had a lot to say, to the point where …

Paper 2

It became apparent that this section needed to be pulled out and become its own paper on the AMNH Barosaurus. As I worked on this, trying to get to the bottom of the complicated history of the mounted cast in the museum’s atrium, I got a lot of help from Peter May of Research Casting International, and from AMNH alumni Lowell Dingus and Gene Gaffney, to the point where they have all been added as authors to the ongoing manuscript.

That paper (codename: baromount) is in progress, and I would estimate it’s about 80-90% done. But in that paper, I needed to write a section on the sources of the various elements that make up the cast — they are not all from AMNH 6341, which is pretty complete as sauropods go but still has a lot of gaps. It turned out, after some poking about, that significant parts of the skeleton were Diplodocus casts, and that they had been made from molds taken from a concrete cast in Vernal, Utah. I started to write up the background information on this, but quickly realised that there was a lot to say, and that it needed to be extracted out into its own paper.

Paper 3

Taylor et al (2023:figure 4). Assembly of the outdoor concrete Diplodocus at the Utah Field House in 1957. (A) In right posterolateral view. The sacrum and fused ilia having been mounted on the main support to begin the process, the hind limbs, last four dorsal vertebrae and first caudal vertebra have now been added. (B) In left anterodorsolateral view, probably taken from the roof of the museum. The mount is almost complete, with only the forelimbs, their girdles and the dorsal ribs yet to be attached. Note that, contra Untermann (1959, p. 367–368), the skull is already in place. Both images scanned by Aric Hansen for the J. Willard Marriott Digital Library, image IDs 1090660 and 1090647. Used by permission, Uintah County Library Regional History Center.

That paper, of course, became The Concrete Diplodocus of Vernal. As I was working on it, I found myself constantly consulting park manager Steve Sroka, and quickly realised that the manuscript had reached the stage of being co-authored. Later in the process, significant contributions from Ken Carpenter went beyond the point of pers. comms, and he was added as a third author. (This paper also received a lot of help from other people, and the acknowledgements are correspondingly extensive and effusive.)

So that is the origin story of yesterday’s paper. But there is another chapter in this story …

Paper 4

As I was writing the section of this paper about the original Carnegie Diplodocus, and in particular about the composition of the mounted skeleton from which the original molds were (mostly) made, it became apparent that this, too, was a long and complicated story. And even though that story has been told in detail multiple times (most notably by Nieuwland 2019), there was still plenty to be told. So this section needed to be pulled out of the CDoV paper (where only a brief summary remains) and become its own paper.

That paper (codename: carnegie) is in progress, and I would estimate it’s about 90-95% done. It, too, has acquired co-authors, including Ilja Nieuwland himself and three Carnegie staff members, but cannot be completed yet as I await an important contribution from an indisposed co-author. Still, it should not be too long before that one is submitted — to be followed by baromount, and then finally superbaro.

So what’s happened here is that a perfectly innocent morphological description paper, based on a conference abstract and a 15-minute talk, has mutated into four substantial papers (of which, admittedly, only one is published so far).

The moral of this story

One moral is that I evidently have very little idea what I am going to work on at any given point in my career. As I was putting together the sidebar page on the Concrete Diplodocus paper, I stumbled across another sidebar page titled Mike’s open projects, which I made in 2020. It lists eight projects that I was going to work on. Of those, one (What do we mean by “cranial” and “caudal” on a vertebra?, Taylor and Wedel 2022) is complete; one (the superbaro project) has advanced but been interrupted by its three offspring papers; and the other six have pretty much not advanced at all (though I do still plan to do them all). Meanwhile, I have done a ton of work on projects that weren’t even on my radar back then, including pneumatic variation (Taylor and Wedel 2021) and finally putting a stake through the heart of neck incompleteness (Taylor 2022).

That’s the bad moral. But there is also a good moral. This is a nice example of what Matt wrote about way back in 2011, for Tutorial 12: How to find problems to work on. Once you actually get started working on something — anything — it will tend to sprout buds. And those buds can easily — too easily, sometimes — become new projects of their own. There is no such thing as a linear programme of research, at least not in my experience. Just an endlessly ramifying tree of fascinating areas that beg to be worked on.

References

 

Posted by Mike Taylor
Filed in Diplodocus, history, mounts, roadside dinos, Utah Field House of Natural History
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Exciting news for people who like history, the state of Utah, or sauropods

February 22, 2023

… and I’m guessing that if you read this blog, you like at least one of these things.

Today sees the publication of a paper that I’m particularly pleased with, partly because it’s so far outside my usual area: The Concrete Diplodocus of Vernal — a Cultural Icon of Utah (Taylor et al. 2023). Let’s jump in by taking a look at the eponymous concrete Diplodocus:

Taylor et al. (2023:figure 5). The completed outdoor Diplodocus mount in a rare color photograph. Undated (but between 1957 and 1989). Scanned by Eileen Carr for the J. Willard Marriot Digital Library, image ID 415530. Used by permission, Uintah County Library Regional History Center.

(On of the things I love about this photo is that it has the same 1950s energy as the Carnegie Tyrannosaurus mount that I posted a while back.)

This paper tells the neglected story of how the Utah Field House museum in Vernal acquired the original Carnegie Diplodocus molds in 1957, after they had languished, unloved and overlooked, in their Pittsburgh basement for forty years; how they were used to cast a Diplodocus from actual concrete (one part cement to three parts aragonite, for those who care); how the molds then went on a series of adventures, never actually yielding another complete skeleton, before being lost or destroyed; how the concrete cast stood for 30 years before the harsh Utah weather degraded it past the point of safety; how it was then used to make a fresh set of molds, and replaced by a new lightweight cast taken from those molds; and how the molds were then used to create a new generation of Diplodocus casts.

It’s a long and fascinating story with lots of twists and turns that I necessarily omitted from that summary — which is why it runs to 27 pages in the lavishly illustrated PDF. I urge you to go and read it for yourself: we wrote it to be an engaging story, and I hope it’s a pretty easy read. (My wife found it interesting, and she once literally fell asleep while I was running a talk to solicit her feedback, so that’s really something.)

Taylor et al. (2023:figure 3). Field House Museum director G. Ernest Untermann (left), and his wife, Staff Scientist Billie Untermann (right), grouting the cast dorsal vertebrae of the Field House’s concrete Diplodocus. 24 January 1957. Scanned by Aric Hansen for the J. Willard Marriot Digital Library, image ID 1086940. Used by permission, Uintah County Library Regional History Center.

This paper was submitted on 2 November 2022, so it’s taken less than five months to go through peer review, editorial processes, typesetting with four(!) rounds of page proofs and online publication. This of course is how it should always be — it’s a bit stupid that I am drawing attention to this schedule like it’s something extraordinary, but the truth is that it is extraordinary. At any rate that makes it fifteen times faster than my long-delayed (mostly my fault) paper on neck incompleteness (Taylor 2022).

I got so deeply into this paper when I was lead-authoring it that the phrase “the Concrete Diplodocus of Vernal” really started to echo around in my head. That is why the paper ends by expressing this wish:

Our dearest hope for this paper is that it inspires someone to create a Dungeons and Dragons module in which the Concrete Diplodocus of Vernal is a quest artifact with magical powers.

But Mike, you ask — how did you, a scientist, find yourself writing a history paper? It’s a good question, and one with a complicated answer. Tune in next time to find out!

References

 

 

Posted by Mike Taylor
Filed in 100% totally real, Diplodocus, history, mounts, roadside dinos, Utah Field House of Natural History
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DIY dinosaurs: more dinosaur bone standees

January 25, 2023

Michelle Stocker with an apatosaur vertebra (left) and a titanosaur femur (right), both made from foam core board.

In the last post I showed the Brachiosaurus humerus standee I made last weekend, and I said that the idea had been “a gleam in my eye for a long time”. That’s true, but it got kicked into high gear late in 2021 when I got an email from a colleague, Dr. Michelle Stocker at Virginia Tech. She wanted to know if I had any images of big sauropod bones that she could print at life size and mount to foam core board, to demonstrate the size of big sauropods to the students in her Age of Dinosaurs course. We had a nice conversation, swapped some image files, and then I got busy with teaching and kinda lost the plot. I got back to Michelle a couple of days ago to tell her about my Brach standee, and she sent the above photo, which I’m posting here with her permission.

That’s OMNH 1670, a dorsal vertebra of the giant Oklahoma apatosaurine and a frequent guest here at SV-POW!, and MPEF-PV 3400/27, the right femur of the giant titanosaur Patogotitan, from Otero et al. (2020: fig. 8). (Incidentally, that femur is 236cm [7 feet, 9 inches] long, or 35cm longer than our brachiosaur humerus.) For this project Michelle vectorized the images so they wouldn’t look low-res, and she used 0.5-inch foam core board. She’s been using both standees in her Age of Dinosaurs class at VT (GEOS 1054) every fall semester, and she says they’re a lot of fun at outreach events. You can keep up with Michelle and the rest of the VT Paleobiology & Geobiology lab group at their research page, and follow them @VTechmeetsPaleo on Twitter.

Michelle’s standees are fully rad, and naturally I’m both jealous and desirous of making my own. I’ve been wanting a plywood version of OMNH 1670 forever. If I attempt a Patagotitan femur, I’ll probably follow Michelle’s lead and use foam core board instead of plywood — the plywood Brach humerus already gets heavy on a long trek from the house or the vehicle.

Speaking of, one thing to think about if you decide to go for a truly prodigious bone is how you’ll transport it. I can haul the Brach humerus standee in my Kia Sorento, but I have to fold down the middle seats and either angle it across the back standing on edge, or scoot the passenger seat all the way forward so I can lay it down flat. I could *maybe* get the Patagotitan femur in, but it would have to go across the tops of the passenger seats and it would probably rest against the windshield.

Thierra Nalley and me with tail vertebrae of Haplocanthosaurus (smol) and the giant Oklahoma apatosaur (ginormous), at the Tiny Titan exhibit opening.

As long as I’m talking about cool stuff other people have built, a formative forerunner of my project was the poster Alton Dooley made for the Western Science Center’s Tiny Titan exhibit, which features a Brontosaurus vertebra from Ostrom & McIntosh (1966) blown up to size of OMNH 1331, the largest centrum of the giant Oklahoma apatosaurine (or any known apatosaurine). I wouldn’t mind having one of those incarnated in plywood, either.

I’ll bet more things like this exist in the world. If you know of one — or better yet, if you’ve built one — I’d love to hear about it.

References

  • Alejandro Otero , José L. Carballido & Agustín Pérez Moreno. 2020. The appendicular osteology of Patagotitan mayorum (Dinosauria, Sauropoda). Journal of Vertebrate Paleontology, DOI: 10.1080/02724634.2020.1793158
  • Ostrom, John H., and John S. McIntosh. 1966. Marsh’s Dinosaurs. Yale University Press, New Haven and London. 388 pages including 65 absurdly beautiful plates.
Posted by Matt Wedel
Filed in caudal, diplodocids, DIY, DIY dinosaurs, dorsal, femur, Giant Oklahoma apatosaurine, gratuitous badassery, Haplocanthosaurus, Patagotitan, People we like, size, stinkin' appendicular elements, stinkin' mammals, stinkin' SV-POW!sketeers, titanosaur, Western Science Center
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Apatosaurus cervical ribs and the tyranny of 2D images

December 8, 2022

Some quick backstory: lots of sauropods have long, overlapping cervical ribs, like the ones shown here in Sauroposeidon (diagram from this old post):

These long cervical ribs are ossified tendons of ventral neck muscles, presumably longus colli ventralis. We know they’re ossified tendons because of their bone histology (Klein et al. 2012), and we suspect that they’re longus colli ventralis because those tendons look the same in birds, just less ossified, as in this rhea (same specimens as these even older posts: 1, 2):

Diplodocoids have apomorphically short cervical ribs, which never extend very far past the end of their respective centra and sometimes don’t overlap at all. Still, we assume the long ventral neck muscles were there, just without long ossified tendons. Which brings me to Apatosaurus, which has cervical ribs that are anteroposteriorly short but famously massive, extending very below and/or to the sides of the cervical centra — for a truly breathtaking example see this post. Here are C3 through C7 in CM 3018, the holotype of Apatosaurus lousiae (Gilmore 1936: plate 24):

At least for me, it’s hard to resist the temptation to mentally scoot those vertebrae together into articulation, and imagine that the very swoopy-looking and maybe even down-turned cervical ribs allowed the ventral tendon bundles to wrap around the bottom of each cervical rib protuberance, something like this:

But it’s just not so, because like all 2D images, Gilmore’s plate distorts 3D reality. If you get to see the mounted skeleton in person, it’s clear that the cervical ribs are all more or less in line, and none of them are pointed at the big protuberances, which stick way out ventrolaterally.

Here I’ve drawn in the likely trajectories of the longus colli ventralis tendons. My little red pathways don’t precisely match the cervical ribs as mounted, but there’s a lot of distortion and restoration going on. For example, comparing with Gilmore’s plate we can see that the cervical ribs of C5, which point downward compared to all the others, only do that because someone forced them to — the whole anterior portion of the rib, where the shaft would actually join to the capitulum and tuberculum, is reconstructed. Even if I’m a little off, it’s clear that the cervical ribs shafts point backward, they’re all more or less in two parallel lines, and none of them point down and out toward the ventrolateral processes. The photo contains a mountain of useful morphological information that you’d never get from the lateral views.

My takeaways from all this:

  1. If a person has only seen 2D images of a specimen, and especially if those 2D images have only been orthogonal views with no obliques, their little island of knowledge is surrounded by at least a sizeable lake of ignorance, if not a small ocean.
  2. That doesn’t mean that seeing specimens in person is the only antidote — 3D models and 3D prints are extremely useful, and for specimens that are difficult to manipulate because of their size or fragility, they may be more useful than seeing or handling the specimen, at least for some questions.
  3. For Apatosaurus specifically, those ventrolateral processes cry out for explanation. They’re fairly solid knobs of bone that stick way out past the ossified tendons of the ventral-most neck muscles. That’s a super-weird — and super-expensive — place to invest a bunch of bone if you’re not using it for something fairly important, especially in a lineage that had just spent the last 80-100 million years making their necks as light as possible.
  4. Pursuant to that last point, we’re now in — ugh-ouch-shame — our 8th year of BrontoSMASH!!, with still just the one conference presentation to show for it (Taylor et al. 2015). Prolly time we got moving on that again.

References

Posted by Matt Wedel
Filed in #Brontosmash, Apatosaurus, Carnegie Museum, cervical, cervical ribs, diplodocids, mounts, museums, necks, rhea, stinkin' theropods
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Here’s that ventral-view apatosaur cervical anaglyph you ordered

December 4, 2022

Just to wash our mouths out after all the theropod-related unpleasantness yesterday:

What we’re seeing here, in glorious 3D, is the 7th cervical vertebrae of BYU 1252-18531. This is an apatosaurine at the Brigham Young University Museum of Paleontology which the museum has catalogued as “Apatosaurus excelsus” (i.e. Brontosaurus excelsus), and which Tschopp et al. (2015) tentatively referred to Brontosaurus parvus, but which I suspect is most likely good old Apatosaurus louisae.

It’s in the rarely seen ventral view, which really emphasizes the ludicrously over-engineered cervical ribs. Get your 3D glasses on and marvel at how they come lunging out of the screen at you, like giant insects in a 1950s B-movie.

So beautiful.

Posted by Mike Taylor
Filed in Apatosaurus, BYU Museum of Paleontology, cervical, collections, ventral views
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Here’s that ornithopod-skeleton anaglyph you ordered

November 26, 2022

While I was thinking about Diplodocus atlas ribs, I was reminded of the ribs on the atlas of a diplodocine skull-and-three-cervicals exhibit that Matt and I saw at MOAL(*) back in the heady days of the Sauropocalypse.

And that reminded me that I have other pairs of photos from the MOAL visit, which I took with the intention of making anaglyphs. like the one I did of the diplodocine. So here is an anaglyph of a small bipedal ornithischian whose exact identity I evidently didn’t bother to write down:

Does anyone know what this is? Maybe Dryosaurus or something along those lines?

 

(*) When Matt and I visited this museum, it was known as the North American Museum of Ancient Life, or NAMAL for short. Since then, it’s dropped the “North American” and promoted the “of”, and it’s now the Museum Of Ancient Life, or MOAL for short. But we’re sticking with the existing category (see link below) for continuity with other things we’ve posted from there.

 

Posted by Mike Taylor
Filed in North American Museum of Ancient Life, public galleries, stinkin' ornithischians
7 Comments »

Putative atlantal ribs of Diplodocus

November 23, 2022

Last time, I showed you a photo of the head and neck of the London Diplodocus and asked what was wrong. Quite a few of you got it right (including Matt when we were chatting, but I asked him not to give it away by posting a comment). The 100 SV-POW! dollars, with their cash value of $0.00, go to Orribec, who was the first to reply that the atlas (cervical 1) is upside-down.

Here is again, from the other side:

The Natural History Museum’s Carnegie Diplodocus cast, skull and anterior cervical vertebrae in left lateral view. Photograph by Mike Taylor.

I noticed this — when it seems the people putting up the skeleton did not, unless this is a deliberate joke — because I happened to be particularly tuned into atlas ribs at the time. You can see what appears a tiny rib hanging below the atlas, but no neural arch above it projecting up and back to meet the prezygapophyses of the axis (cervical 2). In fact the “cervical rib” on this left side is the neural arch of the right side, rotated 180 degrees about the axis of the neck.

Here’s how this should look, from the Carnegie Museum’s own Diplodocus:

The Carnegie Museum’s Diplodocus mount, skull and anterior cervical vertebrae in left lateral view. Photograph by Matt Lamanna.

In this picture, the atlas seems to be pretty much fused onto the axis, as seen in Gilmore (1936: figure 6) which Matt helpfully reproduced in Tutorial 36.

(Digression 1: you might think that this atlas is the real thing, since the Carnegie’s mount is the one with the real CM 84/94/307 material in it. But no: the atlas does not belong to any of those, which all lack this element. It seems to be a sculpture, but we can’t figure out what it’s based on.)

(Digression 2: you might notice that the London and Carnegie skulls are rather different. That’s because the London cast still has the original skull supplied in 1907, which is a sculpture based on CM 622 (rear) and USNM 2673 (the rest), while the Carnegie’s mount at some point had its skull replaced by a cast of CM 11161 — though no-one knows when.)

(Digression 3: the diplodocine originally catalogued as CM 662, on which the rear of the skull was based, was named as the holotype of a new species Diplodocus hayi by Holland (1924), traded to the Cleveland Museum of Natural History in 1956 where it was numbered CMNH 10670, then traded on the Houston Museum of Natural History in 1963 where istbecame HMNS 175, mounted in  Houston in 1975, remounted between 2013 and 2015, and finally moved to its own new genus Galeamopus by Tschopp et al. 2015. Yes, this stuff gets complicated.)

In fact, it’s amazing how much stuff we actually don’t know about these classic specimens, including the source of the atlas for both the Carnegie mount and the various casts — which are not the same. If only there was a single definitive publication that gathered everything that is known about these mounts. Oh well, maybe some day.

Now everyone knows that all the Carnegie Diplodocus mounts around the world were cast from the same molds, and so they all have the same altas <SCREEEECH> wait what?

The Muséum National d’Histoire Naturelle’s Carnegie Diplodocus cast, posterior part of skull and anterior cervical vertebrae in left lateral view. Photograph by Vincent Reneleau.

Here we are in Paris, and the atlas has these two honking great ribs. I have not seen these in any other Carnegie Diplodocus. I know they’re absent from the Berlin cast (thanks to Daniela Schwarz), from the Vernal re-cast (personal observation) and of course from the London cast. I would welcome observations (or even better, photos) from anyone who’s in a position to look at the Vienna, Bologna, Moscow, La Plata, Madrid or Mexico City casts.

So where did these atlas ribs come from? As with so much of this, no-one really knows. It’s especially mysterious as the Paris mount is supposed to be completely unchanged since its initial mounting. But some clue to the origin of the ribs in this mount is found in Holland (1906:249–250):

Accompanying the elements of the atlas sent to the writer for study by the kindness of Professor Osborn  [i.e. AMNH 969] are two bones, undoubtedly cervical ribs. They are both bones belonging on the right side of the centra. They are reported to have been found at the same place at which the atlas was found. The writer is inclined to think that the larger of these two bones (Fig. 20), was probably the rib of the atlas and indeed it requires but little effort to see that it might very well have served such a function, and that the smaller bone (Fig. 21) was the rib of the axis. Were the stump of the rib which remains attached to the axis in the Carnegie Museum, and which Mr. Hatcher has figured, removed, this smaller rib might take its place and would undoubtedly articulate very neatly to the facet

In case you’re too lazy to go and look at Holland’s illustrations for yourself, here they are.

The atlas rib:

The axis rib:

Holland went on:

In case the view entertained by the writer is correct, the form of the atlas and the axis with their attached ribs would be as given in the accompanying sketch (Fig. 22) rather than as given in the figure which has been published by Mr. Hatcher. Such a location of these parts has in its favor the analogy of the crocodilian skeleton.

Here is that composite atlas/axis complex:

(This arrangement with closely appressed atlas and axis ribs should ring a bell for anyone who’s looked much at croc necks, as for example in Taylor and Wedel 2013:figure 19.)

The atlas ribs on the Paris mount look a decent match for the one illustrated by Holland (1906:figure 20), so it seems a reasonable guess that they were sculpted based on that element. But that only leaves us with two more mysteries:

  1. Why do we see these atlas ribs only on the Paris cast, not in the Carnegie original or any of the other casts (that I know of)?
  2. Why does this cast have atlas ribs based on one of Holland’s elements, but not axis ribs based on the other?

Anyone?

References

 

Posted by Mike Taylor
Filed in atlas-axis complex, cervical, cervical ribs, Diplodocus, Natural History museum, necks, public galleries, stinkin' heads
7 Comments »

What’s wrong with this picture? No, really: what’s wrong?

November 21, 2022

Last Saturday I was at a wedding at Holy Trinity Brompton, a London church that is conveniently located a ten-minute stroll from the Natural History Museum. As I am currently working on a history paper concerning the Carnegie Diplodocus, I persuaded my wife, my eldest son and his fiancée to join me for a quick scoot around the “Dippy Returns” exhibition.

Here is a photo that I took:

Something is wrong here — and I don’t just mean the NHM exhibition’s stygian lighting.

Who can tell me what it is? $100 in SV-POW! Dollars(*) awaits the first person to get it right in the comments.

 

(*) Cash value: $0.00.

Posted by Mike Taylor
Filed in atlas-axis complex, cervical, cervical ribs, Diplodocus, Natural History museum, necks, public galleries, short, stinkin' heads
17 Comments »
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