Monthly Archives: December 2025

More raptors with their heads on backwards

Chet Gottfried got in touch after he read Yet more lying necks: Backwards Birds edition, nearly two months ago now, with some more of his photos. Here they are, with his permission:

Sharp-shinned hawk from behind, its neck twisted 280 degrees to its head is looking straight at us.

Cooper’s hawk front view, with the head facing away from us.

Bald eagle from behind, its neck twisted about 135 degrees so that it’s looking back over its left shoulder.

Merlin in left posteolateral view with its neck twisted about 135 degrees so its head, looking back over its left shoulder, is directly facing us.

What’s going on here? As I wrote the Chet, “Interesting that this degree of twisting is common in raptors. I would not have thought their lifestyle demanded it, but what do I know?” He replied:

Movement means detection, and whoever can stay still the best (whether hunter or prey) will be most successful. And a head turn is much less detectable than a whole body turn. Also, if perching depends on balance, the least one does to upset the balance is best.

I replied “Solid point. I think of raptors cruising the skies, but of course they also spend a lot of time perching, waiting and watching.” Chet’s response:

I would suspect that eagles and buteos (such as red-tailed hawks) hunt from the sky, whereas falcons and accipiters hunt every which way. I remember once seeing a blue jay land in a tree and intent on harassing a Cooper’s hawk that was perched perhaps 2 feet below. The hawk literally jumped up, turned, grabbed the jay in its talons, and flew off. And whereas I’m accustomed to seeing Cooper’s hawks flying or perched, I saw one hawk stalk on the ground from underneath a hedge.

And of course it’s true: animals with apparently similar morphology can have very different lifestyles. It’s worth remembering when we’re thinking how extinct animals lived. Anything that we say about sauropods as a whole — or ceratopsians, say, or hadrosaurus — is very unlikely to be true of all members of the group.

 

doi:10.59350/w2kdp-25k61

New paper: Hart et al. 2025 on neural canal ridges in crocs

The dawn of a new era: AMNH FR 34089, a caudal vertebra of the giant extinct croc Thecachampsa, backlit to show the neural canal ridges. This is not just my favorite specimen with NCRs, it’s one of my favorite images of any fossil ever. Photo by William Jude Hart.

New paper out:

Hart, W.J., Atterholt, J., and Wedel, M.J. 2025. First occurrences of neural canal ridges in Crocodylia. Acta Palaeontologica Polonica 70(4): 749–753.

This one started last autumn. On October 2, 2024, I got an email from William Jude Hart, then an undergraduate at Hofstra University. At the time he was preparing to present a poster at the upcoming 2024 SVP meeting, on a caudal vertebra of a large extinct croc, Thecachampsa. Thecachampsa was a tomistomine gavialoid, closely related to the extant False Gharial, Tomistoma, which in turn is a member of Gavialidae and therefore a lot less “false” than we used to think. Thecachampsa lived on the east coast of North America in the Miocene, and it was bigger and scarier than any croc alive today. William had seen Atterholt et al. (2024), my paper with Jessie and a gang of other folks on neural canal ridges (NCRs) in non-avian dinosaurs — which we interpreted as bony spinal cord supports, following Skutschas and Baleeva (2012; see this post and this one). He had noted similar structures in his Thecachampsa caudal, and he offered to send photos.

OMNH RE 0215, a third dorsal vertebra of an alligator in anterior view showing the bilobed neural canal. Also used in Atterholt et al. (2024: fig. 9).

I was interested to see photos of the Thecachampsa vert, but I was trying to moderate my excitement. A lot of crocs have bilobed neural canals, shaped like a snowman or a numeral 8, with a larger lower passage for the spinal cord and its associated meninges, and a smaller upper passage for the large supraspinal vein (a character shared with many birds — see Atterholt et al. 2025 and this post). The two passages are often divided by longitudinal bony ridges, and these can mimic bony spinal cord supports. Criteria exist to distinguish the two, as we discussed in Atterholt et al. (2024), but it’s not always super clear-cut. I wondered if the structures in the Thecachampsa vert would just be elaborate ridges between the neural and vascular compartments.

Thecachampsa caudal AMNH FR 34089, close-up of the right NCR. Photo by William Jude Hart.

As the photo at the top of the post demonstrates, I should have had more faith in William’s perspicacity as a morphologist. When he sent the photos, my jaw hit the floor. These are the thinnest, spikiest, least ambiguous bony spinal cord supports I’ve seen in any amniote, extinct or extant. They’re up there with the rose-thorn-esque bony spikes in tuna vertebrae (see photos in this post).

Close-up of the right NCR in AMNH FR 34089. The morphology here is complex — there is a longitudinal ridgeline for the NCR itself (red highlight), but it doesn’t extend vert far at all. More interesting to me is the subtle ridge running dorsoventrally on the lateral wall of the canal (blue highlights).

I’m pretty confident that these have nothing to do with separating the supraspinal vein from the spinal cord. For one thing, this Thecachampsa vert does not have a bilobed neural canal. On the contrary, rather than having a longitudinal ridge on the side of the canal, the Thecachampsa caudal has a very subtle transverse ridge running up each side of the canal — highlighted in blue in the photo above — on which the neural canal ridge sits like a fairly abrupt summit. The photos above are closeups of the right NCR, but the same is true on the left, as you can see in the photo at the top of the post. That morphology looks a lot more consistent with bony spinal cord supports than with physically demarcating the canal into upper and lower halves.

My favorite sauropod NCRs, in MWC 10613, a Diplodocus caudal from Bone Cabin Quarry in Wyoming. Nice sharp little ridges about midway along the canal, visible to the naked eye, in CT slices (left), and in a hemisectioned digital model (right).

Also, the Thecachampsa spikes are at about the midpoint of the neural canal, where we tended to find the NCRs in sauropods and other dinosaurs. That makes perfect sense if the bony spinal cord supports are remnants of embryonic myosepta, as hypothesized by Skutschas and Baleeva (2012; see this post for more discussion). The neural arch pedicles form within those myosepta, so if the bony spinal cord supports are also myoseptal remnants, they should be located near the craniocaudal midpoint of each neural arch pedicle, which is just another way of saying “about halfway down the neural canal”. Et voila, so they are, in both Thecachampsa and non-avian dinosaurs.

(Why not just check in extant crocs and see what soft tissues are tethered to these things? We’re working on that. Even if we’re wrong about NCRs being bony spinal cord supports, they’re bony somethings, presumably related to interesting soft tissues, and with anatomical and phylogenetic distributions that are very far from being fully mapped.)

Deinosuchus caudal WSC 285.8 in anterior view. The left NCR is the lower of the two prominences visible on the right side of the canal (the upper is taphonomic damage, the edge of a crack).

Armed with the knowledge that NCRs were present in crocs, I drove out to Hemet to visit the Western Science Center. Andrew McDonald has been digging in the Menefee Formation of New Mexico for years, unearthing cool critters like the tyrannosaur Dynamoterror, the armored Invictarx, the hadrosaur Ornatops (which you’ve seen here before), some turtles (McDonald and Wolfe 2018, McDonald et al. 2018, 2021, Adrian et al. 2025) — and, oh yeah, the gigantic and terrifying Cretaceous croc Deinosuchus (Mohler et al. 2021). Thanks to the kind offices of Andrew and Alton Dooley, a good friend and Haplocanthosaurus partner in crime, I got my mitts on the Menefee Deinosuchus caudals. Two of the three vertebrae that I examined had an NCR preserved on at least one side. The third vertebra, by far the most complete externally, ironically had the worst-preserved neural canal. But the others were enough.

We had all the ammo for this paper about a year ago. William had the original discovery, the nicer specimen, and everything he needed to publish on his own, but he kindly invited me to contribute. We put together — well, William put together, with about 95% of the work — a presentation for the 5th Palaeontological Virtual Congress this spring. We looped in Jessie Atterholt for the paper, and she made a lot of improvements. And here we are.

Where will these things turn up next? Maybe you will be the one to find out. Modified from Hart et al. (2025: fig. 1).

(Incidentally, I created the silhouettes for Figure 1 myself, mostly tracing public domain images but drawing a few on my own. Why not use PhyloPic? Partly my own cussed persnickettiness, and partly because properly crediting 17 people was going to be cumbersome in such a short paper. I should make the originals available for everyone else — watch this space.)

Why do we find NCRs in some taxa but not others? Some animals are prevented from developing them: sharks don’t have a way to ossify their ligament attachments, and the denticulate ligaments of mammals don’t anchor to bone (see this post for more). Also, I suspect that NCRs are like the ossified traces of most muscle, tendon, and ligament attachments, in that they can be present but are not always present, even when the muscle, tendon, or ligament is. But that’s just kicking the can down the road — why do we see prominent NCRs in certain groups, and in certain regions of the vertebral column? We advance a hypothesis in the new paper (p. 752):

NCRs are prevalent in clades with laterally undulating locomotion (e.g., Teleosti; Skutchas and Baleev 2012), tail-driven femur retraction (e.g., Dinosauria; Atterholt et al. 2024), or both (e.g., Urodela; Wake and Lawson 1972), and absent in clades that have more rigid torsos, an absence of tail-driven femur retraction, or both, such as Anura, Aves, and Mammalia (Fig. 1A). This apparent distribution is consistent with the hypothesis that NCRs anchor the spinal cord against lateral undulatory motion.

That’s our best guess right now, but a LOT of work remains to be done. We hint at three fronts in the paper:

1. Discovery

NCRs are turning up all over the place. When we published the first NCR paper last year, they were known in salamanders but not in other lissamphibians. Now they’ve been documented in caecilians, by Santos et al. (2025), which we were able to cite in the new paper. The pace of discovery is rapid, but there is a lot of ground not yet covered. At this point, the number of non-sauropod archosaurs with published NCRs is very small — one individual each of Thecachampsa, Deinosuchus, Allosaurus, Ceratosaurus, Stegosaurus, and an indeterminate hadrosaur — but very suggestive, because Archosauria is a big, diverse clade. Not to mention all the other vertebrates. Someone is going to the be the first to document NCRs in, gosh, all the other things. Tyrannosaurs, anyone?

In particular, you may be thinking that it’s all very well for NCRs to be present in these giant extinct crocs, but what about mortal extant crocs? Stay tuned — we’re working on that, with William leading the charge. He’s a grad student now, pursuing his Master’s at East Tennessee State, and I’m confident you’ll be hearing a lot more about his work in the future.

Thecachampsa caudal AMNH FR 34089 in ventral view. This vert is just shy of four inches long, which if you know crocs, is up in *gulp* territory.

2. Investigating soft tissues

We think the NCRs in crocs and dinos are bony spinal cord supports, but it would be very nice to have that confirmed via dissection. Also, where do the denticulate ligaments attach in vertebrae with bilobed neural canals? Could some of the longitudinal ridges in croc verts be doing double duty, dividing the vascular and neural compartments and anchoring denticulate ligaments at the same time? These are open questions, which are about one dead alligator away from being answered.

Also, as mentioned above, if the NCRs of crocs aren’t bony spinal cord supports, what the heck are they?

3. Biomechanical testing

Assuming NCRs are bony spinal cord supports, is lateral movement of the vertebral column the primary driver in their formation, just one factor among many, or a complete red herring? This is the kind of thing that could easily lend itself to logistically intensive approaches like 3D scanning and modeling, but might also get solved by just, like, pulling on things to see what happens (e.g., Baumel 1985).

Conclusion

If you want to get in on this, it’s a pretty straightforward gig: find some vertebrae, peer in the neural canals, document what you find, tell the world. If you don’t find NCRs you might find pneumatic cavities or blood vessel tracks or some totally new thing to add to the neural canal zoo. There are whole big clades of vertebrates about which we know basically nothing, neural-canal-wise, and opportunities for new discoveries abound — as our new paper shows. Come play.

References

 

doi:10.59350/tdtq9-kt434

SV-POW! is an AI-free zone

We’ve written plenty about the problems with what is now ubiquitously called “artificial intelligence”: see for example These new “artificial intelligence” programs don’t know what they’re talking about, Another day, another catastrophic “AI” failure, If you believe in “Artificial Intelligence”, take five minutes to ask it about stuff you know well, What LLMs are really saving you from.

And those are just the problems you get when you try to use LLMs (which is what people almost always mean when they say “AI”). Much more pervasive is the problem of ubiquitous machine-generated slop. Even when you don’t go looking for it, it’s everywhere, polluting discourse, diluting scholarship, perverting politics.

The fundamental problem is that, for the first time in history, it’s easier to “write” something than it is to read it. Given even a tiny proportion of bad actors, how could that possibly not result in a tsunami of slop?

So this is our pledge to you: we will never publish LLM-generated text on this blog, except for the purpose of critique (as in most of the posts linked above). As a constant reminder of this, we now have the No To AI logo at the top right of every page.

If you run a blog of your own, we invite you to join us in this AI-free pledge. You can use the same logo as us — it’s in the public domain and can be downloaded in various formats from WikiMedia.

 

doi:10.59350/gcsjc-2tj45

Book Week 2025, Day 8: Jurassic West, 2nd edition, by John Foster

Ha ha, I lied. Book Week will continue until morale improves.

Mike has made the point to me more than once that there are papers I could and probably should write, but haven’t, because they’re things that I just assume everyone else knows. I’m not alone here, it’s a very common human thing to subconsciously assume that basic, background knowledge for each of us is also basic, background knowledge for most everyone else (a.k.a. the “curse of knowledge”, which Mike has blogged about before) — even when stopping and interrogating that assumption would explode it almost immediately. Similarly, there are books I haven’t blogged about because they are so fundamental to my process that it’s hard to remember that not everyone in the world operates from the same fundamentals.

I’ve given quite a few public talks about dinosaurs, and in the past decade I’ve typically ended with shout-outs to four things: (1) this blog, (2) my book with Mark Hallett, (3) Brian Engh’s website and paleoart channel, and (4) John Foster’s Jurassic West. I realized, admittedly a bit belatedly, that it’s plain loony for people who see my talks to learn about JW, but not people who read this blog. So I’m patching that hole.

John Foster in the field near Brachiosaur Gulch. That big rock he’s standing in front of is a preserved stream bed in cross-section.

Here’s my plug for Jurassic West: it’s the closest you can get to carrying the Morrison Formation around in your backpack. I don’t mean a couple of little pieces, I mean the whole damn thing. John covers everything about the Morrison: geology, sedimentology and stratigraphy, paleoenvironments (yes, plural, the Morrison was diverse in every way), plants, inverts, dinosaurs, other vertebrates, history of study, notable quarries (well, really, all the quarries, if you count the incredible appendices), current research, prospects for the future, and, I assume but am too busy to check right now, about 57 other things I’ve forgotten to mention. And it’s well written! And lavishly illustrated! And nicely produced, on good heavy high-gloss paper between sturdy covers. Which is a good thing, because I use this freakin’ book so often that it doesn’t have a space on my bookshelf, it stands cover-out in front of all the lesser books, where I can grab it in less time than it took to type this clause. It’s ridden with me to and from Utah and Colorado more times than I can count. If I had a nickel for every time I’ve picked it up just to review which dinosaurs are known from which quarries, I could afford to buy you a copy.

The emotional truth of my relationship to this book.

If Jurassic West was all that John had produced, it would still be a towering achievement, and a humbling one for those of us who toil in its shadow. But he also has a totally separate research thread on Cambrian strata and their biotas, and a whole ‘nother book on that stuff, Cambrian Ocean World. And he continues to do fieldwork and museum research and publish papers on both the Morrison and the Cambrian (jeez, pick a lane, fella!). Oh, and he’s a husband and father with a wonderful family, including his rather accomplished spouse, ReBecca Hunt-Foster, Park Paleontologist at Dinosaur National Monument. I assume John either has a Time-Turner or he’s into some deep necromancy, and he’s too good of a friend and colleague for me to want to find out which.

If you like dinosaurs, the Morrison Formation, or just want a truly killer guide to take with you on your museum-and-dinosaur-quarry tour of the American West, this book is a must have. Very Morosaurus-brained of me not to have recommended it sooner. In my defense, it’s only because I assumed you already had a copy.

Now Book Week is over. Probably. Come back tomorrow and we’ll find out together.

 

doi:10.59350/zrpkz-6fx38

Book Week 2025, Day 7: Three favorites by Knut Schmidt-Nielsen

I have been a fanboy of prominent animal physiologist Knut Schmidt-Nielsen for a long time. I first encountered his papers back in the late 90s, working on my MS thesis at OU. I realized that vertebral pneumaticity in sauropods implied, among other things, that I had better get to reading about birds. Probably the first Schmidt-Nielsen paper I read was, “Temperature regulation and respiration in the ostrich” (1969). It’s still a good read, focused, concise, containing much that is useful and interesting for people who care about dinosaurs, and at least right now it’s freely available here.

I believe that Vic Hutchison at OU, himself a pretty legendary animal physiologist, was the first to put me onto Schmidt-Nielsen’s magisterial textbook, Animal Physiology: Adaptation and Environment. I was used to textbooks written by committee, often not by the people leading their respective fields, which did workmanlike duty introducing undergrads to fundamentals, and which serious researchers would soon outgrow. Schmidt-Nielsen’s Animal Physiology was different; it was written by one person, who at the time of its writing was one of the world leaders in animal physiology; it covered so much so well that it seemed to have transcended the category of things that could be outgrown; and most importantly, it was well-written. Really well-written, to the point of being readable for pleasure (if you like learning how animals work). And, I thought then and still think today, a model for good science communication. A copy of the 5th and final edition sits within arm’s reach of my desk, and if the house ever starts sliding into a sinkhole or I see zombies coming down the street, I’ll put it on the stack of things to run out with, between the sauropod monographs and Brown’s Composition of Scientific Words. If you want a taste of the ideas and the writing but don’t want to lug around a 600-page textbook, try How Animals Work, a slim volume based on a lecture series that covers a lot of the same ground in 124 pages.

So what is it about this animal physiologist that made him one of my scientific heroes? I envy people who communicate well, and I find Schmidt-Nielsen’s papers to be models of clarity at every level. Each paper tends to be about a single thing, something you could relay in one sentence. They have short, punchy titles. They’re readable.

I should say right here that the Schmidt-Nielsen style is not the Wedel style. I have friends whose offices are so uncluttered that they look like model rooms in an IKEA store. I have an office at work and another at home, and both of them look like habitable cabinets of curiosities at best, and like hoarder nightmares at worst. I have come to accept that I am a maximalist — in my physical-space-arranging, in my writing, and in my choice of study organisms — and that’s that. But I can admire the minimalist aesthetic, and learn from it. I may never craft anything as elegantly lean as a Schmidt-Nielsen paper, but maybe by studying his writing I can ensure that underneath all the asides and digressions and racing stripes and feathers, my papers will have airworthy frames.

It was that attitude of careful study that led me to pick up Schmidt-Nielsen’s autobiography, The Camel’s Nose. I learned that a lot of the qualities I’d been admiring were not accidental at all, but deliberately chosen and cultivated. Schmidt-Nielsen was born and raised in Norway. English was his adopted language, not his first, and he wrote in simple, direct sentences to reduce the opportunities for being misunderstood. He’d stayed active for so long because he was driven by simple curiosity, about how animals got on in the world. When the time came around for a new edition of Animal Physiology, he basically made that his project for a year or so. He’d gather all the top papers and latest research on each topic, distill what was interesting and important, and write. That’s why the book is so good: one of the world’s top physiologists, who strove for clear communication, basically shelved everything else for a year at a time to make sure he was caught up on the literature, and then wrote.

That level of pure commitment doesn’t sound like a recipe for work-life balance. I’m sure there are exceptions, but in my experience the most driven people are not usually the ones with happy home lives. In The Camel’s Nose, Knut Schmidt-Nielsen relates how his marriage to his spouse, fellow physiologist Bodil Mimi Schmidt-Nielsen (née Krogh — she was descended from physiological royalty on both sides), unraveled because they were both too driven, too close to the work, too competitive. Schmidt-Nielsen relays all this with a tinge of sadness, but otherwise in his typical style — directly, concisely, matter-of-factly. It would be interesting to know Bodil’s side of the story. The dissolution of their marriage was certainly not a career-ender for her — she went on to be a department chair at Case Western Reserve, a full-time researcher at Mount Desert Island Biological Laboratory, and the first woman president of the American Physiological Society. On one hand, having two people at the top of their field — at the top of the same field — in the same household sounds pretty relentlessly intense to me, like trying to force the north poles of two magnets together. On the other hand, Knut Schmidt-Nielsen seems to me to have been pretty relentlessly intense all by himself, and I wonder if anyone’s inherent north-pole-ness (in this metaphor, we all prolly have a little) could have survived near him without being pushed away. As with his writing style, I can look and learn without being tempted to emulate.

Confession time: I’ve never made it to the end of The Camel’s Nose. For me, the ratio of new insights into Schmidt-Nielsen’s process and his discoveries in the field, on one hand, compared to increasingly dense chunks of self-congratulation on the other, becomes unfavorable in the final chapters. I already admired him before I picked up the book; indeed, that’s why I picked it up in the first place. Reading about his honors, however well-deserved and however fairly relayed, doesn’t help me (except maybe as a What Not To Do for Future Matt, and sometimes Present Matt). Possibly in skipping the last couple of chapters I’ve missed some gold nugget of advice or perspective, but I doubt it. I came for insights into Schmidt-Nielsen’s process of research and writing, I got what I was after, and I still recommend the book on that basis. Like the rest of his works, it’s remarkably clear in both vision and execution, and it’s probably the most readable of all his books. If you make it to the end, I’d be curious to hear what I missed.

All of these books are old. How Animals Work was first published in 1972, Animal Physiology 5th ed. in 1997, and The Camel’s Nose in 1998. They’re all still relevant, readable, and worth learning from. Do what I did and find used copies.

That’s it for Book Week 2025. There are of course legions of deserving books that I didn’t cover — feel free to shout ’em out in the comments.

Reference

Schmidt-Nielsen, K., Kanwisher, J., Lasiewski, R.C., Cohn, J.E. and Bretz, W.L. 1969. Temperature regulation and respiration in the ostrich. The Condor 71(4):341-352.

 

doi:10.59350/jas4p-peq65