A new book is out from Cambridge University Press, Dental Cementum in Anthropology, edited by Stephan Naji, William Rendu, and Lionel Gourichon. Although human teeth are not my area of expertise, I ended up coauthoring the twelfth chapter of the book, “Tooth cementum annulations method for determining age at death using modern deciduous human teeth: challenges and lessons learned”. Of all of my publications, this one is the hardest to write about. In part that’s because our original project failed, for various reasons that we document in the chapter, and the final publication is mostly a catalog of things not to do. But more importantly, it’s because Vicki Wedel, the lead author and my spouse of nearly 25 years, passed away unexpectedly last May.
I haven’t written here about Vicki’s passing because I’ve never been sure what to say. Other than two memorial ceremonies last year and a handful of Facebook posts in the month or so after, I haven’t talked about it in public at all. I hoped that I’d know what to say by the time that the book chapter was published, but here we are, and words still feel like grotesquely inadequate tools with which to sketch the horrifying suddenness and totality of the loss. I thought that time would dull the edge of grief, but it doesn’t hurt any less 10 months after, it just hurts less often. I haven’t become numb to any of the obvious triggers, I’ve just gotten good at side-stepping them. All that means is that it’s a cruel surprise when, at unpredictable and frequent intervals, grief sidles up and slips a dagger between my ribs.
Vicki and I met in high school, when we were both 16. We dated for five years, and got married when we were 21. Professionally, she was always ahead of me: she earned her bachelor’s degree first, and her master’s, and her doctorate; presented at a conference before I did, and traveled internationally, and published a journal article, and a book; got a tenure-track job first, and mentored a graduate student first. Far from being resentful, I was emboldened by her successes in every one of those arenas, and grateful for her example and her encouragement. She passed on May 15, 2021, three weeks short of our 25th wedding anniversary, and five months before our 30th anniversary as a couple.
As a forensic anthropologist, Vicki was frequently asked how she wanted to die. Her standard answer was that she wanted to go quietly in her sleep, at home, in clean clothes; to be found almost immediately by family; and to be conveyed rapidly to a funeral home. The timing was nothing that any of us had imagined or hoped for, but in the actual event she got everything she had wanted, and that is no small comfort. She went out at the apex of her personal and professional development, with no decline and no suffering, which is something that most of us will not get.
Vicki and I daydreamed of coauthoring papers together, and we always figured we’d get around to it eventually, although we both expected that any joint publications would be on dinosaur bone histology (she was the hard-tissue histologist, I would have supplied the dinosaurs). In the actual event, she was working on a project to determine age at death of human adolescents by counting cementum bands in deciduous teeth (‘baby teeth’), and she hit a wall transmuting the results into a discussion. I volunteered to help with that, and pretty soon I’d gotten sucked into being genuinely interested in the problem that she was up against.
The development and loss of deciduous teeth restrict cementochronology to the interval in which the root apex is complete. (Wedel et al. 2022: fig. 12.1)
I’ve written here before about the method of counting dental cementum bands, which are laid down annually, to determine age and season at death (this post). Vicki wanted to know if that method, which she’d used successfully on permanent teeth, would work on deciduous teeth. That turns out to be a surprisingly tricky problem, for several reasons. One of the foremost reasons is sampling. Human deciduous teeth have three fates:
- Most deciduous teeth complete development normally, which means that the roots are resorbed and the teeth fall out. The resorption of the root destroys the cementum bands, so there’s nothing to study.
- Some deciduous teeth are retained in the jaw instead of being resorbed, and usually these retained teeth are pulled by dentists when it becomes clear that they are not going to fall out on their own. Practically by definition, these retained teeth do not represent the typical course of development — not great when you’re trying to validate a method on ‘normal’ samples.
- Tragically, some deciduous teeth stop developing because they belong to people who die as children or adolescents. For reasons of privacy and respect for grieving loved ones these teeth are rarely used in research, and they don’t represent a controlled sample anyway. The remains of children from archaeological sites have the additional problem that there’s often no good independent line of evidence for age at death, which makes them useless for a validation study.
As we put it in the chapter, “normal, healthy deciduous teeth are unlikely to be extracted, and extracted deciduous teeth are therefore unlikely to be normal”.
We did have some deciduous teeth, culled from a sample of more than 1000 teeth collected by dentists at Creighton University in Omaha, Nebraska, and sent to Vicki by her collaborator, Ken Hermsen, who coauthored the chapter with us. Unfortunately, the methods that had worked so well for Vicki on adult teeth broke down when applied to deciduous teeth, in multiple ways that left us scratching our heads and chasing phantoms. I won’t go through the whole litany of failures here — it’s too depressing, and I already coauthored a whole chapter about it. Suffice it to say that peer review worked in this case, when an anonymous reviewer caught and called attention to our errors. We were ready to shelve the chapter, but lead editor Stephan Naji encouraged us to not let all our effort go to waste. About all we could do in the remaining time was catalog the stuff we’d done wrong, so…that’s the paper. It’s very much an ‘eating our vegetables’ affair, but hopefully it will steer future researchers away from the reefs that our original study foundered on. I’m grateful to Stephan for the opportunity to publish — not least because it would be my last chance to collaborate with my partner — and for the lovely words about Vicki that he wrote in the dedication of the book.
It is supremely bittersweet that Vicki and I finally got to coauthor something, only for it to come out when she’s no longer around to see it. It also hit me with unexpected force that with the publication of this book, Vicki’s scientific legacy is almost complete (there is one more collaboration, with folks other than me, that will hopefully still get published). Like many things related to her passing, those thoughts don’t point anywhere. There’s no neat resolution, no bow to tie things up with. Sometimes things just stop, awkwardly and before their time, and there’s nothing to do but go on.
Reference
Wedel†, V., Hermsen, K., & Wedel, M. 2022. Tooth cementum annulations method for determining age at death using modern deciduous human teeth: challenges and lessons learned. pp. 215-225 in Naji, S., Rendu, W., and Gourichon, L. (eds.), Dental Cementum in Anthropology. Cambridge University Press, Cambridge, UK. doi:10.1017/9781108569507.014
New special issue out today: “Boots and burlap: papers in honor of Richard L. Cifelli”
March 31, 2022
Today sees the publication of a special issue of Acta Palaeontologica Polonica in honor of my mentor, Rich Cifelli, who took me under his wing when I was in high school and advised me in my undergraduate and Master’s thesis research. Fellow Cifelli lab alums and guest editors Brian Davis and Brooke Haiar and I were fortunate to get a great set of papers from Rich’s friends and colleagues around the globe. The papers reflect the diversity of Rich’s own interests and those of the students he’s mentored, covering everything from trilobites and salamanders to Miocene ungulates and screenwashing techniques, with the lion’s share of the works dealing with Rich’s favorite topic, early mammals. I’m particularly pleased to have a contribution from another of my mentors in the volume: Kevin Padian’s thoughtful paper on the function of tyrannosaur forelimbs.
A whole cabal of former Cifelli students hatched the idea of the festschrift back in April of 2020, before Rich retired in the fall of that year, and before we knew just how much the pandemic would impact our lives and professional productivity. We originally hoped to have the volume out last summer, but…you’ve been on Earth for the past two years, same as the rest of us, so you know how that went. It’s finally done and out, and we couldn’t be happier.
Rich in the Morrison Formation of eastern Utah, in June of 2017. Photo by Brian Davis, from the preface to the special issue.
As icing on the cake, this morning Brian Davis lured Rich into a Zoom meeting that was ostensibly to talk about research, but actually was a sort of virtual surprise party with Brooke and me. The three of us got to watch in real time as Rich opened the link to the somehow-against-all-odds-still-secret special issue. It might be the first time in 31 years that I’ve seen Rich, with his quicksilver wit and infinite store of puns and quips, actually speechless. (For something less than a minute, I think. But still!)
Many thanks to all who contributed. Thanks also to the editors at APP, who were enthusiastically in support of the festschrift from the moment we proposed it, and who worked hard to bring the special issue to fruition. A big, heartfelt thank you to Brooke Haiar and especially Brian Davis for keeping the project moving forward and taking on more of the work than anticipated when life events kept me out of the game for most of last year. Like everything in APP, this special issue is open access, free to the world, so go read up on all kinds of weird and wonderful things. Here’s the link.
Rich at Stovall’s Quarry 5 at Black Mesa in the Oklahoma Panhandle, in March of 2016. Photo by Matt Wedel.
Finally, to Rich: thank you, for taking on an enthusiastic but untrained high school student all those years ago; for teaching me what it means to be professional, by instruction and by example; for launching my career (including the timely application of boot to backside a few times!); and for continuing to be a sounding board, colleague, coauthor, and above all a friend. I’ve always been proud to be your student, and I always will be.
Morphological variation in paramedullary airways; yellow = spinal cord, green = diverticula. The spectrum of variation is discretized into four groups: i, branches of intertransverse diverticula contact spinal cord at intervertebral joints; ii, branches of intertransverse diverticula extend partially into the vertebral canal, but remain discontinuous; iii, paramedullary diverticula form sets of tubes that are continuous through vertebral canals of at least two consecutive vertebrae; iv, continuous paramedullary diverticula anastomose with supravertebral diverticula. Each variant is depicted diagrammatically (A, dorsal view; B, E, H, & K, transverse view) and shown in two CT scans; images in each column correspond to the same morphology. Morphology i: C, cormorant; D, scrub jay. Morphology ii: F, bushtit; G, common murre. Morphology iii: I, red-tailed hawk; J, black-crowned night heron. Morphology iv: L, M, pelican. (Atterholt and Wedel 2022: figure 5)
New paper out:
Quick aside, which will soon be of historical interest only: so far, only the accepted-but-unformatted manuscript is available, with the final, fully-formatted ‘version of record’ due along at some point in the future. We’re not sure when that will be — could be next week, could be months from now — which is why I’m following my standard procedure and yapping about the new paper now. This has paid off in the past, when papers that were only available in accepted ms form were read and cited before the final version was published. UPDATE on April 9: the formatted version of record is out now, as an open-access article with a CC-BY license, and I swapped it for the ‘accepted ms’ version in the links above and at the end of this post.
This paper has had a weirdly drawn-out gestation. Jessie and I hatched the idea of it way back in 2017, when we were teaching in the summer anatomy course together. I learned that Jessie had a big war chest of CTs of dead birds, and I’d been obsessed with supramedullary diverticula in birds and sauropods for some time already (e.g., an SVPCA talk: Wedel et al. 2014). There were detailed published descriptions of the supramedullary diverticula in a handful of species — namely chickens, turkeys, and pigeons — but no broad survey of those diverticula across living birds. Jessie had the CT scans to do that big survey, which we got rolling on right away. She presented our preliminary results at SVPCA in 2018 (Atterholt and Wedel 2018), and by rights the paper should have been along shortly thereafter. More on that in a sec.
One thing that may seem odd: we use the term ‘paramedullary diverticula’ instead of the more familiar and established ‘supramedullary diverticula’. That’s because these diverticula are not always dorsal to the spinal cord; sometimes they’re lateral, sometimes they’re ventral, and sometimes they completely surround the spinal cord, like an inflated cuff. So we decided that the term ‘paramedullary’, or ‘next to the spinal cord’, was more accurate than ‘supramedullary’, or ‘above the spinal cord’, for describing this class of diverticula.
Observed variation in the shape, arrangement, and orientation of paramedullary diverticula relative to the spinal cord; yellow = spinal cord, green = diverticula. A, paired diverticula dorsal to spinal cord in an ostrich. B, paired diverticula lateral to spinal cord in a bushtit. C, paired diverticula ventral to spinal cord in a violet turaco. D, three diverticula dorsal to spinal cord in an ostrich. E, four diverticula dorsal to spinal cord in an eclectus parrot. F, single, c-shaped diverticulum dorsal to spinal cord in an ostrich. G, diverticula completely surrounding spinal cord and pneumatizing vertebra in a violet turaco. H, no paramedullary diverticula present in a Pacific loon. I, diverticula completely surrounding spinal cord in a pelican. (Atterholt and Wedel 2022: figure 6)
I will have more to say about the science in other posts, and you can get the scientific backstory in this post and this one and the abstracts cited above and linked below. The rest of this post is mostly about me, so if you stick around, buckle up for some advanced navel-gazing.
There’s no one reason why this paper didn’t come out sooner. In short, I hit a wall. We went through a curriculum change at work, and suddenly the annual schedule that I’d relied on for a decade was completely upended. I had some unexpected challenges in my personal life. But the biggest problem was that my attitude toward research and writing had changed, for the worse.
When I was fresh out of grad school I had this kinda snotty attitude that my research was MINE, and wherever I was teaching was just, like, a paycheck, man, but they don’t own me, or my research. And as my teaching and committee responsibilities ramped up I still felt like research and writing was something I did for myself, and that my mission was to steal however many hours I could away from the “day-job work” to get done the things that I really wanted to do. Like a guerilla insurgency. In retrospect, it was a pretty good attitude for getting stuff done.
But somewhere along the way, I stopped thinking about research as something that belonged to me, something that I did for myself, and started thinking about it as part of my job. (This also maybe is not so flattering in what it reveals about how I think, or at least thought, about my job.) Instead of using my research time as a source of energy and a wellspring of satisfaction and positivity, I starting thinking of it only as a sink. And it happened so insidiously that I didn’t even realize it. My productivity plummeted, and I didn’t understand why. I was restless and depressed, and I didn’t understand that either. At the level of my superficial thoughts I still wanted to get research done, but my subconscious was turned off to it, so I just spun my wheels.
Then the pandemic hit. I’d always been a pretty optimistic, upbeat person, but I found myself just staring off into space franticizing about all the horrible things going on in the world, or staying up too late doom-scrolling the news. I slept too little, and poorly, and by the end of 2020 I felt worn down to a nub.
Osteological evidence of paramedullary diverticula. A, pocked texturing inside the vertebral canal of a pelican (LACM 86262). B, pneumatic foramen on the roof of the vertebral canal of an albatross (Phoebastria nigripes, LACM 115139). C, pneumatic foramina in the floor of the vertebral canal of an ostrich (Struthio camelus, LACM 116205). D, deep pneumatic fossae in the roof of the vertebral canal of an Eastern moa (Emeus sp., LACM unnumbered). (Atterholt and Wedel 2022: figure 7)
Then a series of positive things happened:
- I received a long, heartfelt email from Jessie (fittingly!), asking after me and laying out a plan for getting the paper done and out. It was the kick I needed to look inside and start picking myself apart, to figure out what the heck was going on. Much of this post is cribbed from my reply to her.
- I got a little break from lecturing in the spring of 2021, and that gave me the space to get a couple of things finished and submitted — the pneumatic variation paper with Mike in January (Taylor and Wedel 2021), and the Haplocanthosaurus neural canal paper, which was submitted even earlier in January, although it came out much later (Wedel et al. 2021; more on that publication delay in a future post).
- Finally, I had young, energetic coauthors who were moving projects forward that required modest levels of effort from me, but which paid off with highly visible publications that I’m proud to be an author on, including the saltasaur pneumaticity paper (Aureliano et al. 2021) and the ‘Sauro-Throat’ paper (Woodruff et al. 2022).
It’s impossible to overstate how energizing it was to get new things done and out, and how much it helped to have collaborators who were putting wins on the board even when I was otherwise occupied. One of those collaborators was Jessie, who just kept pushing this thing forward — and, sometimes, pushing me forward — until it was done. So the paper you can read today is a testament not only to her acumen as a morphologist, but also to her tenacity as a scholar, and as a friend.
The part of the paper I’m happiest about is the “Conclusions and Directions for Future Research”, which points the way toward a LOT of further studies that need to be done, both on extant birds and on fossil archosaurs, ranging from bone histology to functional morphology to macroevolution. As we wrote in the concluding sentence of the paper, “We hope that this study serves as a foundation and an enticement for further studies of this most unusual anatomical system, in both extinct and extant archosaurs.”
I can’t wait to see what comes next.
References
- Atterholt, J., and Wedel, M. 2018. A CT-based survey of supramedullary diverticula in extant birds. 66th Symposium on Vertebrate Palaeontology and Comparative Anatomy, Programme and Abstracts, p. 30.
- Atterholt, Jessie, and Wedel, Mathew J. 2022. A computed tomography-based survey of paramedullary diverticula in extant Aves. The Anatomical Record, 1– 22. https://doi.org/10.1002/ar.24923
- Aureliano, Tito, Aline M. Ghilardi, Bruno A. Navarro, Marcelo A. Fernandes, Fresia Ricardi-Branco, & Mathew J. Wedel. 2021. Exquisite air sac histological traces in a hyperpneumatized nanoid sauropod dinosaur from South America. Scientific Reports 11: 24207.
- Taylor, Michael P., and Mathew J. Wedel. 2021. Why is vertebral pneumaticity in sauropod dinosaurs so variable? Qeios 1G6J3Q. doi:10.32388/1G6J3Q.5
- Wedel, M.J., Fiorillo, A., Maxwell, D., and Tykoski, R. 2014. Pneumatic diverticula associated with the spinal cord in birds, sauropod dinosaurs, and other ornithodiran archosaurs. 62nd Symposium on Vertebrate Palaeontology and Comparative Anatomy, Meeting Proceedings, p. 60.
- Wedel, Mathew; Atterholt, Jessie; Dooley, Jr., Alton C.; Farooq, Saad; Macalino, Jeff; Nalley, Thierra K.; Wisser, Gary; and Yasmer, John. 2021. Expanded neural canals in the caudal vertebrae of a specimen of Haplocanthosaurus. Academia Letters, Article 911, 10pp. DOI: 10.20935/AL911
- Woodruff, D. Cary, Wolff, Ewan D.S., Wedel, Mathew J., Dennison, Sophie, and Witmer, Lawrence M. 2022. The first occurrence of an avian-style respiratory infection in a non-avian dinosaur. Scientific Reports 12, 1954. https://doi.org/10.1038/s41598-022-05761-3
What my life is like right now
March 11, 2022
I made this for my own amusement, and thought you guys may as well get to benefit from it, too.
Melstrom et al. (2016:figure 4). Pectoral vertebrae of a juvenile specimen of Barosaurus sp. (DINO 2921) from the Upper Jurassic Morrison Formation of Utah, U.S.A., in right lateral view (red-cyan anaglyph made from stereopair).
Enjoy!
References
- Melstrom, Keegan M., Michael D. D’Emic, Daniel Chure and Jeffrey A. Wilson. 2016. A juvenile sauropod dinosaur from the Late Jurassic of Utah, U.S.A., presents further evidence of an avian style air-sac system. Journal of Vertebrate Paleontology 36(4):e1111898. doi:10.1080/02724634.2016.1111898
Things to Make and Do, part 31: redneck CT-scan
March 3, 2022
For reasons that would be otiose, at this moment, to rehearse, I recently found myself in need of a hemisected turkey cervical. Happily, I own five skeletonised turkey necks, so it was with me the work of a moment to select a candidate. But now what? How to hemisect it? We have discussed plenty of hemisected things here at SV-POW!, but they tend to have been produced using heavy machinery such as a band saw: something that I singularly lack.
SPOILER: I found a way. Here is a domestic turkey Meleagris gallopavo domesticus, 9th cervical vertebra, hemisected, in right medial view. Read on to discover the extremely high-tech approach that yielded this prize. It’s propped up on some kind of turkey bone to help me get a good medial perspective, I am thinking maybe the pygostyle?
One idea was to use an angle-grinder: not to cut down the midline of the vertebra — it would be much too blunt and powerful for a small, delicate vertebra — but to use as a sanding surface, locking the grinder in place and holding the vertebra up against the spinning plate. That might work well, assuming I could find a way to secure the angle grinder safely, but as it happened my need for a hemisected vertebra came up during a power cut. (Thanks, Storm Eunice!)
So I did it the way the Amish do their vertebral hemisections: by hand, simply by rubbing the vertebra against a sheet of sandpaper:
CT scanning: the Amish method.
This is not as laborious as you might think. I used a single sheet of medium-grade sandpaper, and it took maybe 15–20 minutes. And I just rubbed back and forth while exerting downward pressure. Initially I worked my way only through the prezygapophyseal ramus, which is the part of the turkey cervical that extends the furthest laterally. Once I was satisfied that the plane between eroded prezyg and the intact postzyg was parasagittal, I just kept the vertebra parallel to the sandpaper and kept rubbing. (Sorry I didn’t think to get a photo at this stage.)
One thing that took me by surprise is that there was so very much bone dust. I mean, I am an idiot that this surprised me, since the whole purpose of this exercise was to reduce one half of this vertebra to bone dust. But the lesson to be learned here is to do it on the easily-cleaned bathroom floor — not on the desk next to the computer keyboard and above a carpet. Learn from my mistakes, folks!
Anyway, after some work on the prezyg/postzyg pair, here’s how the vertebra was looking:
You can see straight away that the prezyg ramus, postzyg ramus and parapophyseal ramus are extensively pneumatized, honeycombed with small, irregular air-spaces. In this image it looks like the region of bone between the pre- and postzygs is much more solid, but this is an illusion: what we’re seeing here is a section through the cortical bone of the neural arch, cut parallel to the surface. Let this be a warning not to over-interpret individual slices of CT-scans!
Once we get a little deeper, we see that the whole wall of the neural arch — and indeed the centrum and the neural spine — is honeycombed, just like the zyg rami:
Now we have another area of what I’m going to call Phantom Apneumaticity: the posterior part of the centrum looks like solid bone, apart from a few pneumatic spaces in the posteroventral extremity. Again, this is an illusion.
Here’s the next place I stopped:
Here, the Phantom Apneumaticity is even more striking: seeing just this as a CT slice could easily mislead someone into thinking that almost the whole of the posteroventral part of the centrum is solid bone. But again, it’s just that we’re very close to the surface of the bone, and seeing a slice parallel to that surface.
This last image also shows an important point of technique: there is a low convex ridge running across the phantom apneumatic area from the top of the cotyle to the base of the centrum. This is where I had changed the angle I was holding the vertebra at, so I accidentally sanded the posteroventral part of the vertebra more than the rest. I found that it was important during this process to keep checking the angles, and to adjust: making sure I wasn’t sanding more from the front than the back, or from the top than the bottom, or leaving a ridge like this.
Also in this last photo you can see that I was just beginning to break through into the neural canal: the anterior part of it is now exposed, between the anterior part of the neural spine and the anterior articular surface. At this stage I sighted along from in front to get a sense of how much further I had to go:
Domestic turkey Meleagris gallopavo domesticus, 9th cervical vertebra, most of right side removed, in anterior view with dorsal to the right. Propped up on the coracoid of a different, larger, turkey.
Quite a way, I guess. Here it is rotated and cropped, so you can more easily recognise it:
Domestic turkey Meleagris gallopavo domesticus, 9th cervical vertebra, most of right side removed, in anterior view. You can see that the neural canal is still mostly intact.
More sanding was required. I sanded some more.
You’ve already seen the final result up at the top of the page, but here is a cleaned-up version of that image, oriented according to Definition 3 of Taylor and Wedel (2019):
Domestic turkey Meleagris gallopavo domesticus, 9th cervical vertebra, hemisected, in right medial view.
And if that isn’t beautiful, what is?
The exciting thing is, anyone can make one of these. Matt’s already explained how to extract and clean up bird vertebrae and given you some ideas of what to do with them. Prepare out some turkey vertebrae and get going with the sandpaper!
I leave you with one more image: the hemisected vertebra in anterior view, oriented with dorsal to the top, and mirrored so it make up a complete vertebra once more. Enjoy!
References
Sauropod Vertebra Picture of the Week 