Aquilops skull, take 3

December 12, 2018

Nothing really new here, not like a new skull recon or anything. The original version I did for Farke et al. (2014) had the jaw articulated and closed. Then in 2017 I posted a version with the lower jaw disarticulated. Obviously what was needed was one with the lower jaw articulated and open. Now it exists, here. I mean, since I posted the separate parts last year people have had everything they needed to make their own, but it’s nice to have one already built, so here you go.

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The 1st Palaeontological Virtual Congress is underway now, and will run through December 15. Mike and I have two presentations up:

“What do we mean by the directions ‘cranial’ and ‘caudal’ on a vertebra?” by Mike and me, which consists of a video Mike made presenting a slide show that he put together. The presentation sums up our thinking following the series of vertebral orientation posts here earlier this summer and fall, which are all available here.

“Reconstructing an unusual specimen of Haplocanthosaurus using a blend of physical and digital techniques” by me and a gang of WesternU-based collaborators, including Jessie Atterholt and Thierra Nalley, both of whom you saw in our recent pig-hemisecting adventures. Almost everything I’ve written on this blog about Haplocanthosaurus in 2018 was part of the run-up to this presentation (except, somewhat ironically, the post about pneumaticity), which also includes quite a bit that I haven’t put on the blog yet. So even if you follow SV-POW!, the 1PVC slideshow should have plenty of stuff you haven’t seen yet.

IF you can see it–you have to be a registered 1PVC ‘attendee’ to log in to the site and see the presentations. So probably you are either already registered and this post is old news, or not registered and this post seems useless. Why would I bother telling you about stuff you can’t see?

The answer is that neither Mike or I intend for our work to disappear when 1PVC comes to an end on December 15. Both of us are planning to put our abstracts and slide decks up as PeerJ Preprints, which is our default move for conference presentations these days (e.g., this, this, and this). I believe Mike is also going to post his video to YouTube. So the work will not only live on after the congress is over, it will jump to a much broader audience. We’re looking forward to letting everyone see what we’ve been up to, and I’m sure we’ll have some more things to say here when that happens.

So, er, go see our stuff if you’re a 1PVC attendee, and if you’re not, hang in there, we’ll have that stuff out to you in a few days.

Here’s a frozen pig head being hemisected with a band saw.

The head in question, and the other bits we’ll get to later on in this post, both came from Jessie Atterholt’s Thanksgiving pig. As soon as Jessie knew she was cooking a pig for Thanksgiving, she had a plan for the head and the feet: cut ’em in half, skeletonize one half (like Mike did with his pig head), and plastinate the other. Jessie has her own plastination setup and you can see some of her work in her Instagram feed, here.

Here’s the freshly hemisected head. At one time or another, about four of us were involved in checking the alignment of the cut, with the intention of just missing the nasal septum (it can be easier to see some of the internal nasal anatomy if the septum’s all on one side). But we were all wrong–not only did the saw hit the nasal septum dead on, it hemisected the septum itself. Which I guess is the next-best possible outcome. The septum is the big expanse of white cartilage behind the nose and in front of the brain. You have one, too–it separates your left and right nasal cavities–but yours is a lot thinner.

Here’s the left half washed off and cleaned up a bit.

I was completely entranced by the little blood vessels inside the nasal septum, seen here as tiny traceries of red inside the blue-white cartilage. Also notice the frontal sinus above the septum and in front of the brain.

Here’s the right half in a postero-medial oblique view. Shown well here are the first two cervical vertebrae, plus part of the third, and the intervertebral joints. This was a young pig and the remains of growth plates are still visible between the different ossification centers of the vertebrae. If I get inspired (= if I get time) I might do a whole post on that.

It wasn’t my pig or my show, but Jessie made me a gift of two pig feet, and I got a little time on the saw. Here I’m using a plastic tool to push one of the pig’s hind feet through the saw.

We had been dithering over how best to prep the feet but the lure of the band saw proved irresistable: we hemisected all four. We’re planning to do half skeletonized/half plastinated preps for all of them, a forefoot and a hindfoot set for each of us.

Jessie and I were joined by two other WesternU anatomists, Thierra Nalley and Jeremiah Scott. Here Thierra is explaining to Jeremiah, who works on primate dentition and diet, that mammals have more parts than just teeth.

That’s a good segue to this video I shot, in which Thierra gives a quick tour of the hemisected pig head. All four of us have just come off of teaching human head and neck anatomy, so it was cool to see in another mammal the same structures we’ve just been dissecting in humans.

From 1:40 to 1:55 in the video Thierra and I are discussing the prenasal bone, something pigs have that we don’t. It’s the separate bone at the end of the snout in this mounted skeleton:

Darren discusses and illustrates the prenasal bone in this Tetrapod Zoology post.

Parting shots: many thanks to Ken Noriega and Tony Marino of WesternU’s College of Veterinary Medicine for their guidance, assistance, and expertise. Jessie covered this dissection as an Instagram story, here–I believe you have to be signed in to see it. Update: Jessie added a regular stream post, with lots of features labeled, here. I’ll probably have more to say about this pig and its bits in the future. Stay tuned!

For more hemisected heads and skulls, see:

We’ve posted a lot here about how crazy the cervical vertebrae of apatosaurines are (for example: 1, 2, 3), and especially the redonkulosity of their cervical ribs. But I think you will agree with me that this is still an arresting sight:

That’s MWC 1946, a mid-cervical from the Mygatt-Moore Quarry that was figured by Foster et al. (2018: fig. 18 A-B) and referred with the rest of the Mygatt-Moore apatosaur material to Apatosaurus cf. louisae (entirely correctly, in my view). This is a ventral view, with the condyle down by the scale bar.

Here’s the same thing cropped from the background to emphasize its unbelievableness:

and mirrored and restored a bit in GIMP to give a taste of its probable appearance in life (if you had an apatosaur, an x-ray machine, and a lot of confidence about not getting stepped on):

For obvious reasons, my nickname for this specimen is the Brontosmasher.

Keep in mind that the centrum was full of air in life, whereas the cervical ribs and the bony struts that support them are just huge slabs of bone. I strongly suspect that the volume of bone in the cervical ribs and their supporting struts is vastly more than in the centrum and neural arch. I will soon have the ability to test that hypothesis–I have this specimen on loan from Dinosaur Journey for CT scanning and 3D modeling. Watch this space.

Many thanks to Julia McHugh at Dinosaur Journey for access to the specimen and assistance during my frequent visits.

Reference

  • Foster, J.R., Hunt-Foster, R.K., Gorman, M.A., II, Trujillo, K.C., Suarez, C.A., McHugh, J.B., Peterson, J.E., Warnock, J.P., and Schoenstein, H.E. 2018. Paleontology, taphonomy, and sedimentology of the Mygatt-Moore Quarry, a large dinosaur bonebed in the Morrison Formation, western Colorado—implications for Upper Jurassic dinosaur preservation modes: Geology of the Intermountain West 5: 23–93.

Scholastica is a publishing platform that offers support for super-low-cost open-access journals such as Discrete Analysis, led by Tim Gowers. They’re putting together the first Academic-Led Publishing Day on 7 February next year, and as part of the build-up, they kindly invited me to do an interview for them, kicking off their Academic-Led Publishing From the Experts series.

I did tell them that I wasn’t qualified — “I am about as far from an expert as I could possibly be in the field of Academic-led publishing. I’ve never even been an academic editor for a journal, far less started one or run one. All I’ve ever done, really (beyond writing and peer-reviewing articles) is have opinions and write about them.” But they wanted to push ahead anyway, so I was happy to go along with it.

Here’s the interview: enjoy!

 

What it says on the tin. This is a specimen from the UCMP comparative collection.

I was just going to post this photo with zero commentary, but I can’t help myself. Note that on the two vertebrae in the middle, the crista transverso-obliqua (what in non-avian dinos would be the spinopostzygapophyseal lamina or SPOL) rises higher than either the neural spine apex or the epipophyses. That’s crazy. And it demonstrates something we also see in sauropods, which is that laminae are not merely the plates of bone left behind after pneumatization has scooped all of the unnecessary material out of a normal vertebra–sometimes they are additive structures, too.

If all of that sounded like gibberish, I can sympathize. I spent my first few months as a sauropodologist just learning the lingo (another thing I should blog about sometimes). Here’s a labeled version:

As long as I’m yapping, note the light shining through the honeycombed internal structure of these highly pneumatic vertebrae. For more on the ridiculous pneumaticity of pelican bones, see this post and this one. For more on the homology of bird and sauropod vertebrae, see Wedel and Sanders (2002), and for more on laminae as additive versus reductive structures, see the discussion on pages 210-212 of Wedel (2007).

References

 

Matt’s drawn my attention to a bizarre fact: despite 17 separate posts about Xenoposeidon on this blog (linked from here and here), we’ve never shown a decent scan of Lydekker’s (1893) original illustration of NHMUK PV R2095, the partial mid-to-posterior dorsal vertebra that since Taylor and Naish (2007) has been the holotype specimen of Xenoposeidon proneneukos — and since Taylor (2018) has been known to represent a rebbachisaurid.

Well, here it is at last!

That’s Xeno on the left, of course. On the right, we have one of the various Wealden titanosauriform dorsal vertebrae that were constantly getting referred back and forth between taxa in the late 1800s. I think it might be one of the NPMUK PR R90 vertebrae, perhaps the one that, for disambiguation purposes, I’ve informally named R90a.

Lydekker — or, more likely, an uncredited illustrator — did rather a good job on this, as we can see by juxtaposing the illustration with the now well-known left-lateral photo that’s launched a thousand blog-posts:

The main differences here seem to pertain to how Lydekker and I perceived “lateral”. I think he has the vertebra rotated slightly away from us, so that it’s leaning into the page, and that’s why the centrum appears slightly taller and the arch slightly less tall than in my photo. He seems to have a bit more matrix stuck on the front of the centrum — perhaps because slightly more prep has been done since 1893 — but, worryingly, slightly less bone around the cotyle. I think that can only be illustration error, since that bone is definitely there.

References