Juvenile Tomistoma schlegelii, LACM Herpetology 166483, with me for scale. It wasn’t until I picked up the skull that I realized it was the same specimen I had looked at back when. I was looking at its neck in 2011, and its tail today, for reasons that will be revealed at the dramatically appropriate moment. I was only playing with the skull because it’s cute, an intricate little marvel of natural selection. Photos by Vanessa Graff (2011) and Jessie Atterholt (2018). Many thanks to collections manager Neftali Camacho for his hospitality and assistance both times!

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Just a quickie today. The 1st Palaeontological Virtual Congress is happening this December. Where? Everywhere! Well, everywhere with internet service. There is no physical place to go attend. Talks, posters, discussions, etc. will happen online. Consequently, registration is extremely affordable at a whopping 5 Euros. Circulars are here if you want to know more.

I’m “going”, probably to present on the Haplocanthosaurus project–which only occasionally dips into realspace anyway–with a bunch of the folks who made it happen.

A couple of things to note:

  • The abstract deadline has been pushed back from Sept. 20 to Oct. 8, so you’ve got a little time yet.
  • [UPDATE Sept. 17 – I shoulda waited a couple of days. The PayPal link is live and working. I know because I just used it.] Originally they were only accepting registration payments by bank transfer. I guess that’s a trivially easy thing in Europe to do from your smartphone. A lot of banks here in the States make you go to the bank in person, wait in line, see a teller, and fill out paperwork. Kind of a huge hassle for a measly 5 EUR. I brought this up with the organizing committee and they were already moving on getting a PayPal account set up to process registration payments. That should happen soon – I’ll update the post when it does.

So, er, see you there?

Here’s the story of my fascination with supramedullary airways over the last 20 years, and how Jessie Atterholt and I ended up working on them together, culminating with her talk at SVPCA last week. (Just here for the preprint link? Here you go.)

Müller (1908: fig. 12). Upper respiratory tract, trachea, and lungs in pink, air sacs and diverticula in blue. DSPM = diverticulum supramedullare.

Way back when I was working on my Master’s thesis at the University of Oklahoma and getting into pneumaticity for the first time, Kent Sanders found Müller (1908) and gave me a photocopy. This would have been the spring or summer of 1998, because we used some of Müller’s illustrations in our poster for SVP that year (Wedel and Sanders 1998). Müller’s description of pneumatic diverticula in the pigeon formed part of my intellectual bedrock, and I’ve referenced it a lot in my pneumaticity papers (complete list here).

One of the systems that Müller described is the diverticulum supramedullare, a.k.a. supramedullary diverticula, or, informally, supramedullary airways (SMAs). Traditionally these are defined as pneumatic diverticula that enter the neural canal and lie dorsal (supra) to the spinal cord (medulla), although O’Connor (2006) noted that in some cases the diverticula could completely envelop the spinal cord in a tube of air. I yapped about SMAs a bit in this post, and they’re flagged in almost every ostrich CT or dissection photo I’ve ever published, here on the blog or in a paper.

CT sections of a Giraffatitan cervical, with connections between the neural canal and pneumatic chambers in the spine highlighted in blue. Modified from Schwarz & Fritsch (2004: fig. 4).

Fast forward to 2006, when Daniela Schwarz and Guido Fritsch documented pneumatic foramina in the roof of the neural canal in cervical vertebrae of Giraffatitan. As far as I know, this was the first published demonstration of SMAs in a non-bird, or in any extinct animal. Lemme repeat that: Daniela Schwarz found these first!

OMNH 60718: too ugly for radio. This is an unfused neural arch in ventral view. Anterior is to the left. Neurocentral joint surfaces are drawn over with ladders; pneumatic foramina lie between them.

Shortly thereafter I independently found evidence of SMAs in a sauropod, in the form of multiple pneumatic foramina in the roof of the neural canal in an unfused neural arch of a basal titanosauriform (probably a brachiosaurid) from the Cloverly Formation of Montana. It’s a pretty roadkilled specimen and I was busy with other things so I didn’t get around to writing it up, but I didn’t forget about it, either (I rarely forget about stuff like this).

Then in 2013 I went to the Perot Museum in Dallas to see the giant Alamosaurus cervical series, and I also visited the off-site research facility where juvenile Alamosaurus from Big Bend is housed. When Ron Tykoski let me into the collections room, I was literally walking through the door for the first time when I exclaimed, “Holy crap!” I had spotted an unfused neural arch of a juvenile Alamosaurus on a shelf across the room, with complex pneumatic sculpting all over the roof of the neural canal.

Title slide for the 2014 SVPCA presentation.

The Big Bend and Cloverly specimens were the basis for my talk on SMAs at SVPCA in 2014, coauthored with Anthony Fiorillo, Des Maxwell, and Ron Tykoski. As prep for that talk, I visited the ornithology collections at the Natural History Museum of Los Angeles County, photographed a lot of bird vertebrae with foramina inside their neural canals, and shot this pelican video. That was four years ago – why no paper yet? It’s because I wanted one more piece of smoking-gun evidence: a CT scan of a bird that would show a direct communication between the SMAs and the air spaces inside a vertebra, through one or more foramina in the roof, wall, or floor of the neural canal.

A spectrum of pneumatic traces in the neural canals of birds, including complexes of large or small foramina, isolated foramina, and sculpting without foramina.

In 2017, Jessie Atterholt taught in our summer anatomy course at WesternU as an adjunct (her full-time employment was at the Webb Schools in Claremont, home of the Alf Museum). Jessie and I had been acquainted for a few years, but we’d never had the opportunity to really talk science. As we chatted between dissections, I learned that she had a huge warchest of CT scans of whole birds from her dissertation work at Berkeley (we’d missed each other by a few years). My antennae twitched: one nice thing about SMAs is that, being bounded by bone, they can’t collapse after death, unlike more peripheral diverticula. And air is jet black on CT scans, so SMAs are easy to spot even on comparatively low-res scans. All you need is one or two black pixels. I proposed a collaboration: we could use her CT scans to survey the presence and distribution of SMAs in as many birds as possible.

Vertebral diverticula in two sagittally-exploded cervical vertebrae of a turkey. Anterior is to the left, #5 is the SMA. Cover (1953: fig. 2). Yes, I know this is gross – if anyone has a cleaner scan, I’m interested.

You might think that such a survey would have been done ages ago, but it’s not the case. A few authors have mentioned supramedullary airways, and O’Connor (2006) gave a good description of some of the variation in SMAs in extant birds as a whole. But the only detailed accounts to illustrate the morphology and extent of the SMAs in a single species are Müller (1908) on the common pigeon and Cover (1953) on the domestic turkey. I’d seen what I suspected were traces of SMAs in the vertebrae of many, mostly large-bodied birds, and I’d seen them in CTs of ostriches and hummingbirds, and in ostriches and turkeys in dissection. But Jessie was offering the chance to see both the SMAs and their osteological traces in dozens of species from across the avian tree.

SMAs in a micro-CT of a female Anna’s hummingbird, Calypte anna. Scale bars are in mm.

Real life intervened: we were both so busy teaching last fall that we didn’t get rolling until just before the holidays. But the project gradually built up steam over the course of 2018. One story that will require more unpacking later: everything I’ve written on this blog about neural canals, Haplocanthosaurus, or CT scanning in 2018 is something serendipitously spun out of the SMA survey with Jessie. Expect a lot more Atterholt and Wedel joints in the near future – and one Atterholt et al. (minus Wedel) even sooner, that is going to be big news. Watch this space.

It didn’t hurt that in the meantime Jessie got a tenure-track job teaching human anatomy at WesternU, to run the same course she’d taught in as an adjunct last year, and started here at the beginning of June. By that time we had an abstract on our findings ready to go for this year’s SVP meeting. Alas, it was not to be: we were out in the field this summer when we learned that our abstract had been rejected. (I have no idea why; we’ve increased the taxonomic sampling of SMAs in extant birds by a factor of six or so, most of our important findings are in the abstract, and we mentioned the relevance to fossils. But whatever.)

We were bummed for a day, and then Jessie decided that she’d submit the abstract to SVPCA, only slightly chopped for length, and go to Manchester to present if it was accepted – which it was. Unfortunately I’d already made other plans for the fall, so I missed the fun. Fortunately the SVPCA talks were livestreamed, so last Friday at 1:30 in the morning I got to watch Jessie give the talk. I wish the talks had been recorded, because she knocked it out of the park.

Title slide for the 2018 SVPCA presentation.

And now everything we’re in a position to share is freely available at PeerJ. The SVPCA abstract is up as a PeerJ preprint (Atterholt and Wedel 2018), the longer, rejected SVP abstract is up as a supplementary file (because it has a crucial paragraph of results we had to cut to make the length requirement for SVPCA, and because why not), and our slideshow is up now, too. I say ‘our’ slideshow but it’s really Jessie’s – she built it and delivered it with minimal input from me, while I held down the sauropod side of our expanding empire of neural canal projects. She has the paper mostly written, too.

Oh, and we did get the smoking-gun images I wanted, of SMAs communicating with pneumatic spaces in the vertebrae via foramina in the neural canal. Often these foramina go up into the neural arch and spine, but in some cases – notably in pelicans and the occasional ratite – they go down into the centrum. So I now have no excuse for not getting back to the sauropod SMA paper (among many other things).

We’re making this all available because not only are we not afraid of getting scooped, we’re trying to get the word out. SMAs are phylogenetically widespread in birds and we know they were present in sauropods as well, so we should see some evidence of them in theropods and pterosaurs (because reasons). I made such a nuisance of myself at the recent Flugsaurier meeting, talking to everyone who would listen about SMAs, that Dave Hone went and found some pneumatic foramina in the neural canals of Pteranodon vertebrae during the conference – I suspect just to shut me up. That’ll be some kind of Hone-Atterholt-Wedel-and-some-others joint before long, too.

Anyway, point is, SMAs are cool, and you now have everything you need to go find them in more critters. Jessie and I are happy to collaborate if you’re interested – if nothing else, we have the background, lit review, and phylogenetic sampling down tight – but we don’t own SMAs, and we’ll be nothing but thrilled when your own reports start rolling in. Unexplored anatomical territory beckons, people. Let’s do this.

References

Imposter syndrome revisited

September 13, 2018

My wife Fiona is a musician and composer, and she’s giving a talk at this year’s TetZooCon on “Music for Wildlife Documentaries – A Composer’s Perspective”. (By the way, it looks like some tickets are still available: if you live near or in striking distance of London, you should definitely go! Get your tickets here.)

With less than four weeks to go, she’s starting to get nervous — to feel that she doesn’t know enough about wildlife to talk to the famously knowledgeable and attractive TetZooCon audience. In other words, it’s a classic case of our old friend imposter syndrome.

Wanting to reassure her about how common this is, I posted a Twitter poll:

Question for academics, including grad-students.
(Please RT for better coverage.)

Have you ever experienced Imposter Syndrome?
(And feel free to leave comments with more detail.)

Here are the results at the end of the 24-hour voting period:

Based on a sample of nearly 200 academics, just one in 25 claims not have experienced imposter syndrome; nearly two thirds feel it all the time.

The comments are worth reading, too. For example, Konrad Förstner responded:

Constantly. I would not be astonished if at some point a person from the administration knocks at my door and tells me that my work was just occupational therapy to keep me busy but that my healthcare insurance will not pay this any longer.

What does this mean? Only this: you are not alone. Outside of a tiny proportion of people, everyone else you know and work with sometimes feels that way. Most of them always feel that way. And yet, think about the work they do. It’s pretty good, isn’t it? Despite how they feel? From the outside, you can see that they’re not imposters.

Guess what? They can see that you‘re not an imposter, either.

Left lateral view

Have we ever posted decent photos of the Brachiosaurus altithorax caudals? Has anyone? I can’t remember either thing ever happening. When I need images of brachiosaur bits, including caudals, I usually go to Taylor (2009).

Taylor (2009: fig. 3)

Which is silly, not because Mike’s diagrams compiling old illustrations aren’t good – they definitely are – but because I’m sitting on a war chest of decent photos of the actual material. I am home sick with a sore throat today, and I can’t be arsed to (1) follow up on the “Down in Flames” post, (2) add anything thoughtful to the vertebral orientation discussion, or (3) crop or color-adjust these photos. You’re getting them just as they came out of my camera, from my trip to the Field Museum in 2012.

Here are the rest of the orthogonal views:

Right lateral view

 

Anterior view

 

Posterior view

 

Dorsal view of caudal 1

 

Dorsal view of caudal 2

And here’s a virtual walkaround using a series of oblique shots. Making a set like this is part of my standard practice now for important specimens during museum visits.

 

 

 

 

 

 

 

Now, I said up top that I wasn’t going to add anything thoughtful to the vertebral orientation discussion. I have thoughts on that, but I’m tired and hopped up on cold medicine and now ain’t the time. In lieu of blather, here are a couple of relevant photos.

 

I wanted to capture for my future self the pronounced non-orthogonality of the neural canal and centrum, so I rolled up a piece of paper and stuck it through the neural canal. I haven’t run the numbers, but in terms of “angle of the articular faces away from the neural canal”, these verts look like they’re right up there with my beloved Snowmass Haplocanthosaurus.

More on that next time, I reckon. In the meantime, all these photos are yours now (CC-BY, like everything on this site [that someone else hasn’t asserted copyright over]). Go have fun.

Reference

No time right now for me to dig into the interesting and important discussion on how we should orient vertebrae (here and here so far) – that will be coming soon. In the meantime, here’s something else.

As printed, in one of WesternU’s 3D printers.

Coming off the tray.

Cleaned up and in my hand. This is a 70% scale print, so a little smaller than the original, but all the important morphology is clear enough. For one thing, I can finally make sense of the dorsal views of the vertebra.

I have been astonished at how useful a 3D print can be as an aid to thought. The caudals of the Snowmass Haplocanthosaurus are among the smallest sauropod vertebrae I’ve spent a lot of time with, and they’re still heavy enough and fragile enough that I don’t just whip them out and twirl them around in my fingers. But I can do that with the 3D prints, and it really helps ram the morphology home in my brain. There are a thousand subtle things I might not otherwise have noticed if I hadn’t been able to turn those shapes over easily in my hand. Not to mention the other things you can do with prints, like physically sculpt on them without gooping up your fossils (we’re midway through step #8 from that post, BTW).

Anyway, back to Xeno. Mike reminded me that I have seen the actual specimen in person exactly once, very briefly during our 2005 visit to the NHM collections when I was over there for SVPCA. But it wasn’t Xeno yet, and we had other fish to fry, including a lot of pneumatic and possibly-pneumatic stuff for me to see and photograph for my dissertation. So I have to admit that it didn’t register. Being able to handle it now, so much that Mike has written about it snaps into focus. Not that his writing isn’t clear, there’s just a huge gulf between the best written description and holding a thing in your hands.

Why do I have this thing? Partly to educate myself, partly because it’s relevant to a current project, and partly because we may not be done with Xeno. Stay tuned.

Many thanks to Gary Wisser for setting up the print, and to Jeff Macalino for pulling it for me.

Thanks to everyone who’s engaged with yesterday’s apparently trivial question: what does it mean for a vertebra to be “horizontal”? I know Matt has plenty of thoughts to share on this, but before he does I want to clear up a couple of things.

This is not about life posture

First, and I really should have led with this: the present question has nothing to do with life posture. For example, Anna Krahl wrote on Twitter:

I personally find it more comprehensible if the measurements relate to something like eg. the body posture. This is due to my momentary biomech./functional work, where bone orientation somet is difficult to define.

I’m sympathetic to that, but we really need to avoid conflating two quite different issues here.

Taylor, Wedel and Naish (2009), Figure 1. Cape hare Lepus capensis RAM R2 in right lateral view, illustrating maximally extended pose and ONP: skull, cervical vertebrae 1-7 and dorsal vertebrae 1-2. Note the very weak dorsal deflection of the base of the neck in ONP, contrasting with the much stronger deflection illustrated in a live rabbit by Vidal et al. (1986: fig. 4). Scalebar 5 cm.

If there’s one thing we’ve learned in the last couple of decades, it’s that life posture for extinct animals is controversial — and that goes double for sauropod necks. Heck, even the neck posture of extant animals is terribly easy to misunderstand. We really can’t go changing what we mean by “horizontal” for a vertebra based on the currently prevalent hypothesis of habitual posture.

Also, note that the neck posture on the left of the image above is close to (but actually less extreme than) the habitual posture of rabbits and hares: and we certainly wouldn’t want to illustrate vertebrae as “horizontal” when they’re oriented directly upwards, or even slightly backwards!

Instead, we need to imagine the animal’s skeleton laid out with the whole vertebral column in a straight line — sort of like Ryder’s 1877 Camarasaurus, but with the tail also elevated to the same straight line.

Ryder’s 1877 reconstruction of Camarasaurus, the first ever made of any sauropod, modified from Osborn & Mook (1921, plate LXXXII).

Of course, life posture is more important, and more interesting, question than that of what constitutes “horizontal” for an individual vertebra — but it’s not the one we’re discussing right now.

In method C, both instances are identically oriented

I’m not sure how obvious this was, but I didn’t state it explicitly. In definition C (“same points at same height in consecutive vertebrae”), I wrote:

We use two identical instances of the vertebrae, articulate them together as well as we can, then so orient them that the two vertebrae are level

What I didn’t say is that the two identical instances of the vertebrae have to be identically oriented. Here’s why this is important. Consider that giraffe C7 that we looked at last time, with its keystoned centrum. if you just “articulate them together as well as we can” without that restriction, you end up with something like this:

Which is clearly no good: there’s no way to orient that such that for any given point on one instance, the corresponding point on the other is level with it. What you need instead is something like this:

In this version, I’ve done the best job I can of articulating the two instances in the same attitude, and arranged them such that they are level with each other — so that the attitude shown here is “horizontal” in sense C.

As it happens, this is also just about horizontal in sense B — the floor of the neural canal is presumably at the same height as the top of the centrum as it meets the neural arch.

But “horizontal” in sense A (posterior articular surface vertical) fails horribly for this vertebra:

To me, this image alone is solid evidence that Method A is just not good enough. Whatever we mean by “horizontal”, it’s not what this image shows.

References