Belatedly … here’s DRAFT v4 of the checklist for new zoological genus and species names
January 20, 2026
Long-term readers will remember that waaay back in 2011, we started the process of putting together a checklist for people naming new zoological genera and species, distilling the relevant portions of the long and complex International Code of Zoological Nomenclature (ICZN). Across twelve days of intense discussion, we got as far as DRAFT v3 of the checklist, and then I … sort of forgot about it for fifteen years.
Six months into those fifteen fallow years, of course, the ICZN introduced the electronic publication amendment, which means that the checklist has spent twenty-nine 30ths of its life outdated in a critical respect. So now I am doing what I should have done fourteen and a half years ago, and finalizing the checklist.
So I present DRAFT v4 of the checklist, which quietly went up on the site last night. I’ve tweaked the wording here and there, and adjusted whitespace, but the only substantive change is in clause 2 of the Requirements section, on what constitutes published work. Here’s what it now says:
2. The work must either printed or electronic. A printed work must be produced in an edition containing numerous simultaneously obtainable identical and durable copies. Numerous copies that are not simultaneously obtainable (e.g., print on demand, paper reprints, etc.) do not constitute published works. For the purposes of priority, the Code defines the date of publication as the date on which the numerous identical durable copies were made simultaneously obtainable. [The Code does not specify how many copies must be printed, but 50 or more is typical.] An electronic work must be registered in ZooBank before publication, and must state the date of publication and contain evidence that registration has occurred. The ZooBank registration must specify an electronic archive intended to preserve the work, and the ISSN or ISBN associated with the work.
I welcome comments on this clause — especially regarding any factual errors that might have crept in, but also on infelicities in the wording. Please hop over to DRAFT v4 to comment. (Comments on this post are closed, to avoid splitting discussion across two places.)
Never name a new species of an existing dinosaur genus
January 16, 2026
I’m still making my way through Brian Curtice’s excellent and detailed post on Greg Paul’s (2025) recent erection of a new titanosaur genus (Curtice 2025), but I just want to comment on this one passing thought of Brian’s:
The species tells me where it was found if named by “Old Timers,” the genus almost can do that if named by “New Kids on the Block” as they almost never add species names to existing genera (recent tyrannosaur excepted :-)).
The new kids are right.
You should never[1] name a new species of an existing dinosaur genus. Here’s why. Suppose you have two genera, A and B, which are sister taxa in your phylogeny:
Genus A
/
\
Genus B
Now you discover a new specimen, X, which your phylogenetic analysis says is more closely related to Genus A than than to any other named genus:
Genus A
/
/\
/ Specimen X
\
\
\
Genus B
The smart play is to name it genus X. But suppose you say “Oh, but it’s really quite similar to genus A, it can’t be separated at the genus level”, and you instead name it as a new species, A. x. You go merrily on your way congratulating yourself on not being one of those filthy splitters, and all is well until someone else runs a different phylogenetic analysis with more characters, better taxon sampling, a better weighting algorithm, whatever. And it comes out like this:
Genus A
/
/
/
\ Specimen X
\/
\
Genus B
Now the new author has to say something like “The species x is hereby removed into the genus B yielding the new combination B. x.”
And now your taxon’s name has changed. That’s really bad. The whole purpose of a name is to be a fixed, permanent label that consistently refers to the same thing. But Linnaeus’s terrible mistake, the Linnean binomial, is a “name” that encodes a specific phylogenetic hypothesis, and which implodes when that hypothesis is considered false.
Naming a new species x of a genus A is a nomenclatural enshrining of your phylogenetic hypothethesis that specimen X is more closely related to the genoholotype of genus A than to that of any other genus. It’s a bet that has no upside if you turn out to be right, but makes you look like a dummy if you’re wrong. There is absolutely no need to make such a bet.
Names are for naming things. Phylogenetic analyses are for analysing things. Don’t confuse them. And don’t reify that confusion in nomenclature.,
Note 1. As so often when one writes “never”, we really mean “hardly ever”. I don’t discount the possibility that there may be some very special circumstances when a new species within an existing genus is warranted, but I bet that your example of such a very special circumstance doesn’t qualify.
References
- Curtice, Brian. 2025. Et Tu Ut Te (Titan)? Thoughts on Alamosaurus and more. Fossil Crates, 5. https://www.fossilcrates.com/blogs/news/alamosaurus
- Paul, Gregory S. 2025. Stratigraphic and anatomical evidence for multiple titanosaurid dinosaur taxa in the Late Cretaceous (Campanian-Maastrichtian) of southwestern North America. Geology of the Intermountain West 12:201-220., doi: 10.31711/giw.v12.pp201-220.
Stop it, birds, your necks are stupid
January 13, 2026
We’ve seen a lot of raptors with their heads turned 180 degrees recently. Jerry Harris dropped me a line to remind me that flamingos are also perverts when it comes to neck posture. Here are three of his photos:
All these photos show multiple individuals curving their necks through 180 degrees so they can rest them on their torsos. In fact, they go much further than 180 degrees, then curve back again: the individual on the right of the second photo, and the one on the left of the last photo. are both curling their necks 270 degrees to the right, then 90 degrees back to the left. That is of course a total of 360 degrees, which strongly suggests these bad boys can crank a full 360 if they want to. (In fact, it has to mean that, unless the necks are asymmetric, and I’ve never heard any suggestion of that.)
And more: this is not some kind of extreme behaviour that flamingos can attain in extremis. This is what they do to relax.
Note by the way that different flamingos are shown here curving their necks in different directions. For example, check out the two birds sitting in the foreground of the third photo. I wonder whether different individuals have different handedness, or whether each bird randomly curves one way, then next time the other. Or even if they alternate handedness for successive rests.
In some senses, what we’re seeing here from the flamingos is the most extreme neck posture we’ve seen in the present sequence of posts. But in another sense, this is much less impressive than the raptors. Flamingos have long cervicals, and they are bending their intervertebral joints laterally to achieve these postures. The raptors by contrast have craniocaudally short vertebrae, and they are twisting the joints to achieve their 180-degree turns. And that is what I find preposterous.
Some time soon, I must get around to posting the osteological implications.
Yet more raptors with their heads on backwards
January 8, 2026
Here are a couple more backwards-headed raptor photos, courtesy of ceratopsian palaeontologist and home-brewing consultant Andy Farke:
Here’s what he had to say about them:
Your recent post spurred me to snap these photos of a burrowing owl doing backwards head things. There are a few individuals at the Living Desert Zoo in Palm Desert, California….it’s a super cool enclosure, in which you can walk into an aviary habitat that has free-roaming burrowing owls, prairie dogs, a turkey vulture, and a few other cool North American critters.
(Even though the San Diego Zoo is most famous, I am of the firm opinion that both Living Desert and the Santa Barbara zoos are objectively better – they have an amazing variety of semi-obscure animals, large and naturalistic enclosures, cool up-close opportunities, and both mostly avoid having kiosks placed every three feet selling cheap plastic crap, which has always perplexed me about organizations that purportedly promote conservation).
At some point, I’m going to have to stop just posting photos of these weirdos, and start writing about what’s going on and how and why.
Three Four quotes about doing good work
January 4, 2026
None of these were intended by their creators to be about research; even Marie Curie’s line was about her education. But each of them touched a nerve for me. Also, since they’re not explicitly about research, you may find them applicable to other areas of life as well, whether you’re a researcher or not.
“One never notices what has been done; one can only see what remains to be done.”
– Marie Curie, quoted in “Madam Curie: A Biography by Eve Curie”, p. 116
Oh man, do I feel this. I’m proud of my output to date, but I don’t spend a lot of time enjoying the sensation of having written a bunch of papers. My feelings about my past work fall, to varying degrees for various papers, into three bins:
- thank goodness that’s done so I don’t have to do it again, because it was a lot of work;
- thank goodness that’s done so I can just cite it now, and get on with other things;
- eesh, I wish done that a bit better.
It’s not that I never look back fondly on what I’ve done. I just have some distance from it, like it was done by someone else. I joke about Past Matt and Future Matt, but they’re pretty constant and often useful mental constructs. And my own work, out of all the work in the world, has this unique character: I know for dead certain that the guy who did it knew less than I do now and was a less-experienced writer. Eventually that starts to rankle, no matter how good the paper was at the time.
There is a less healthy side to this, for me and for a lot of people that I know, where it becomes hard for us to own the good work that we’ve done — or take a healthy, deserved break — because we’re always in pursuit of the next thing. I don’t know what to do about that; I’m fortunate to have a partner who pushes me to own my accomplishments and take my breaks, but it’s a skill or a viewpoint I’m still working on cultivating in myself.
“The greater the artist, the greater the doubt; perfect confidence is granted to the less talented as a consolation prize.”
– Robert Hughes, “Art: Modernism’s patriarch”, Time magazine, June 10, 1996
For ‘artist’, I think you can sub in pretty much any other field of human endeavor, public or private, solo or group effort, transient or permanent: scientist, educator, athlete, writer, counselor, mystic, programmer, diarist, craftsperson, parent, engineer, explorer, hobbyist. To me it pairs perfectly with a quote from Paul Graham which was part of my email signature for many years: “The people I know who do great work think that they suck, but that everyone else sucks even more.”
Again, there is the potential for unhealthy self-doubt here, and an unwillingness to fairly acknowledge our growth and own our inner gold. As Oliver Burkeman wrote in “Meditations for Mortals”, if any of us met our inner critic at a party, we’d think that person was impossible rude, socially inept, and in some way fundamentally broken. But I like to focus on the positive aspect: each of us is a tree, making leaves in our chosen fields of endeavor, and since we tend to get better at that over time, it’s hard to deny the possibility — or inevitability — that we’ll make even better leaves in the future. Just as I know that Past Matt was less knowledgeable and a less-experienced writer than I am, I know that Future Matt will think of me the same way. Part of me thinks, can’t I skip over all of this laborious becoming and just be that guy? But the truth is, there’s no path to a more capable Future Matt that doesn’t lead through hard work; trying to duck the effort is only going to turn me into a Wall-E chair person.
“It’s hard to build momentum if you keep dividing your attention.”
– James Clear, 3-2-1 Newsletter, September 25, 2025
Hammer, nail, WHAM!! This quote crystallizes why 2025 was my year of saying no. Since 2021 I’d said yes to almost every single invitation to collaborate that came down the pike. I don’t have many regrets about that; it got me on a lot of cool projects and I made a lot of new friends along the way. But it also meant that I didn’t get much of my own work done and out. Since last January I’ve been keeping a list of the projects and invitations that I’ve turned down — not just papers but conferences, leadership positions, and so on — and it’s really clarified for me just how much I’ve been Balkanizing my attention. I can be fourth or fifth author on a dozen papers or lead author on one or two; having done a lot of the former, I’m now going to lean into attempting the latter (again — for the first half of my career, solo or lead-authored papers dominated my output). I’m sure there’s a healthy balance to be struck, but for now I’m trying to swing the pendulum back toward my own projects. (And for any collaborators I’ve turned down in the past year: thank you for letting me come play, I had a blast, I’m sorry for whatever delays I introduced, let’s collaborate again sometime when I’m better-adjusted. It’s not you, it’s most definitely me.)
– – – – – – – – – –
I wrote the first draft of this post a few months ago, and it sat in the drafts folder, waiting for me to find images to go with it. I definitely had images in mind when I wrote the draft, but whatever visual inspiration I had at the time seems to have permanently evaporated. Eventually I realized that it was silly to leave a perfectly good draft just sitting there because I couldn’t think of pictures to back up its rather philosophical points.
But was it “a perfectly good draft”? Coming back to it after some months, I couldn’t help but read it through the lens of another quote that I’d come across in the meantime, one which has been ringing in my head like an alarm:
“Most successful people are just a walking anxiety disorder harnessed for productivity.”
– Andrew Wilkinson, Twitter, April 26, 2021
I reread the draft with mounting skepticism, and a tinge of discomfort. I was tempted to either junk the whole thing, or edit it to match my new, enlightened perspective. But I think the more honest thing is to admit that enlightenment is a moving target, or perhaps an ocean I could never drink all of, and this post — in both its draft version, and the one you’re reading now — is just a cobblestone on my path.
It’s oddly and perhaps perversely navel-gazey to think about doing my work so that I can become a better version of myself. In my best moments, when I’m in flow and it feels like I am a conduit funneling the mysteries of the past into words and images in my research notebook, I’m not thinking of myself at all, but only about the things I’m studying. And when I stop for the occasional meal or bio-break, or at the end of the day, I’m positively tingly with the exhilaration of discovering new things. Thinking of myself — like I’m doing right now — is a symptom of being very far from the work. And maybe that’s the conclusion that I’ve been unwittingly building toward, through the whole protracted development of this post. The best and surest way to quiet that anxiety that runs like a barbed vine through most of this post is to stop worry about myself, and even stop worrying about the work, and simply do it. Not because it will make me better (although it might, if I can get out of my own way, and out of my own head), but because it’s my calling and my privilege to get to do it.
Do it yourself.
January 1, 2026
Do it yourself.
I don’t mean that as a descriptive phrase. It’s a complete sentence, in the imperative. Do it yourself. Pick up the pencil, pen, stylus, paintbrush, airbrush, mouse, keyboard, scissors, rolling pin, hammer, drill, wrench, saw, welding torch, sewing needle, instrument, guitar pick, pickaxe, shovel, dumbbell, jump rope, paddle, piton, hiking pole. Do that thing, your thing, the one you love, or the one you’ve been putting off, the one you’re afraid of, the one that you were told you couldn’t do, the one you’ve always dreamed of doing.
Don’t wait for things to be perfect. Perfect isn’t coming. The world isn’t going to be perfect, conditions won’t be perfect, you won’t be perfect. We don’t get perfect here. Every baby is a few hours away from a dirty diaper and every sunset is tinged with wildfire smoke and cow farts. We get the perfection of things found in the dirt. You have to go find them. Dig them up, dust them off, learn to see the perfection in them, let them be perfect for you.
Don’t wait for inspiration. Go find it. The only reliable map to inspiration is the one on your hands, written in graphite, ink, paint, talc, grease, plaster, soil, flour, sap, chalk, oil, clay, sawdust, or sweat, punctuated with paper cuts, blisters, callouses, scrapes, welts, torn nails, and skinned knuckles. The Muses value sacrifice. Get to work on your own, and maybe you’ll tempt them to show up. And maybe not – they’re fickle, half feral and a quarter trickster – but at least you’ll have been working.
Someone told you that you couldn’t do it, wouldn’t do it, don’t have what it takes? That it was too hard, too time-consuming, too important, too frivolous? Where are those words now? Gone. They vibrated in the air for a few seconds, bounced around inaudibly for a few seconds more, and then got diluted to nothingness in the random movement of air molecules. If you’re still hearing them, still carrying them, still worrying at them or worrying about them, let them go. Feed them into the furnace of your action, and watch them curl to ash.
No one knows what you’re capable of. Even you don’t know what you’re capable of. Not yet. Start running, and you can run a little farther every day. Start climbing, and you’ll build muscle on the way up. Start making, and the things you make will get better. Start learning, start teaching yourself, and become unstoppable. Push past the end of comfort, and you’ll find that your real limits are a lot farther out than you – or anyone else – suspected. If you find your limits at all, it will be out there. Get going.
Be a fox – omnivorous, clever, crafty, relentless. Find people who do the thing better than you can, yet, and learn from them. Your next teacher might be down the street, across the planet, or dead for millennia. Study their practice, their tools, their techniques. Hunt for new points of view and new angles of attack. Lots of animals sharpen their teeth against each other. Find someone who sharpens you – a mentor, a partner, an accountabilibuddy, a friendly rival. Can’t do the thing right now? Get ready. Hit the books, hit the gym, study the masters, make a plan. Build that sled now, so you’ll be ready when the snow falls.
Be humble. The universe is complex, life is complex, people are complex. You’re complex. But you’re also your own worst enemy. You can’t learn from someone you’ve decided has nothing to teach you. You won’t ask a question when you think you already know the answer. “Question everything” is only good advice if you apply it to your own certainties first. Hold your certainties loosely, but cherish good questions. Pamper them, like pandas. See if you can get them to breed.
Be proud. Own your inner gold. Maybe jogging makes you feel like you’re going to die – at least you’re out here jogging. Maybe all your drawings look flat – but you’re putting in the pencil miles to get better. Maybe you haven’t found a good ending for Chapter 4 – but Chapters 1-3 are in the rearview. Measure your success by the footstep, by the rep, the line of ink or the line of text, and not only at the finish line. Almost everything you might make or do is iterative. So iterate, and own your progress.
You can be proud of your thing. Not because it’s perfect, but because you did it. You invested in yourself, and became a person who can do that thing. Just remember that even better things are out there, waiting for you to sweat them into existence.
Don’t duck the struggle, or outsource it. Steer into it. The hard lifting, at the edge of your capacity, builds the most muscle. A lot of people won’t make their things. They’ll buy someone else’s, find something close enough, or do without. They’ll never find out how good it might have been, and how strong they might have become, if they’d done it themselves. Or they’ll prompt a machine, and it will grind up a bunch of other people’s things and feed it back to them, shoplifted ingredients puréed into baby food. In time those people may forget how to chew, if they ever learn at all. Their choice. Not yours. You’ll already be up in the foothills, maybe a little winded, but breathing clear air and climbing steadily.
The thing is not the point. It never was. You are the point. Just as you spend graphite to make drawings and flour to make cakes, you spend drawings and cakes and practice sessions, mornings in the classroom, afternoons in the garage, and evenings in the gym, to become someone who can draw or bake, run a 10k, play a concerto, give CPR, rebuild an engine, speak a new language, get an orchid to bloom, write a sonnet, climb an ice wall, let go of an old hurt, find a new passion. The things you make or do are just leaves. You are the tree. Making leaves is what you do. The next batch will be better, and making them will make you better.
Start now. Set an achievable goal, based on practice, not product. Celebrate showing up, especially if it helps you keep showing up. Go a little farther each time – one more push-up, one more paragraph, one more stitch, one more swing. Build momentum. Get some early wins on the board. Hold yourself accountable. Don’t expect perfection; expect the opposite. Stumbling and falling short doesn’t make you a failure, it makes you human. Useful failures are symptoms of trying. Keep trying. Get back up, and check the tape. Study the fall, learn from it, try not to let it happen the same way next time. Recognize the off-ramps that distract you, and barricade them. You are the original neural network – learn from your inputs.
The inner critic, the one that tells you to stop, you suck, you can’t do it, you’ll never get there, why even start – like any voice, it needs air. Take up your tool of choice, and you choke it. Use up all the oxygen when you practice, and leave the inner critic gasping on the floor. You may end up gasping on the floor, too. That’s okay. The critic thinks life is about staying down. You know it’s about getting back up. Prove it.
You’re thinking about your thing right now. It’s been taking shape in your mind the whole time you’ve been reading this. It’s out there, in the future, waiting for you to grab your tools, plant your feet, set your shoulders, and chisel it free. Don’t listen to the voice that’s telling you not to, the one that right this second wants you to switch to another window, check your socials, watch one more video. Close this window, close this device (even if you’ll need it again in 10 minutes to make your thing), get up, stretch, shake out the lethargy, get the blood flowing, get a drink of water. Look in the mirror – that person is your greatest resource, and the only one who can stop you. Show them who you choose to be. Go find your tools, go find your passion, go find your possibilities. Go now. Do it.
Do it yourself.
– – – – – – – – – – – – – – –
Many thanks to London Wedel and Jenny Adams for helpful edits. I got the term “pencil miles” from John Muir Laws.
Happy New Year from SV-POW!
More raptors with their heads on backwards
December 21, 2025
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.
New paper: Hart et al. 2025 on neural canal ridges in crocs
December 12, 2025
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:
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
- Adrian, B., Smith, H.F. and McDonald, A.T. 2025. A revised turtle assemblage from the Upper Cretaceous Menefee Formation (New Mexico, North America) with evolutionary and paleobiostratigraphic implications. PeerJ 13: e19340.
- Atterholt, J., Wedel, M.J., Tykoski, R., Fiorillo, A.R., Holwerda, F., Nalley, T.K., Lepore, T., and Yasmer, J. 2024. Neural canal ridges: a novel osteological correlate of postcranial neuroanatomy in dinosaurs. The Anatomical Record, 1-20. https://doi.org/10.1002/ar.25558
- Atterholt, Jessie; Burton, M. Grace; Wedel, Mathew J.; Benito, Juan; Fricano, Ellen; and Field, Daniel J. 2025. Osteological correlates of the respiratory and vascular systems in the neural canals of Mesozoic ornithurines Ichthyornis and Janavis. The Anatomical Record. http://doi.org/10.1002/ar.70070.
- Baumel, J.J. 1985. Suspensory ligaments of nerves: an adaptation for protection of the avian spinal cord. Anatomia, Histologia, Embryologia 14(1): 1-5.
- 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.
- McDonald, A.T. and Wolfe, D.G. 2018. A new nodosaurid ankylosaur (Dinosauria: Thyreophora) from the Upper Cretaceous Menefee Formation of New Mexico. PeerJ 6: e5435.
- McDonald, A.T., Wolfe, D.G. and Dooley Jr, A.C. 2018. A new tyrannosaurid (Dinosauria: Theropoda) from the Upper Cretaceous Menefee Formation of New Mexico. PeerJ 6: e5749.
- McDonald, A.T., Wolfe, D.G., Fowler, E.A.F. and Gates, T.A., 2021. A new brachylophosaurin (Dinosauria: Hadrosauridae) from the Upper Cretaceous Menefee Formation of New Mexico. PeerJ, 9, p.e11084.
- Mohler, B.F., McDonald, A.T. and Wolfe, D.G. 2021. First remains of the enormous alligatoroid Deinosuchus from the Upper Cretaceous Menefee formation, New Mexico. PeerJ 9: e11302.
- Santos, R.O., Wilkinson, M., and Zaher, H. 2025. An overview of the postcranial osteology of caecilians (Gymnophiona, Lissamphibia). The Anatomical Record, 1–26, https://doi.org/10.1002/ar.70000.
- Skutschas, P. P., & Baleeva, N. V. 2012. The spinal cord supports of vertebrae in the crown-group salamanders (Caudata, Urodela). Journal of Morphology 273(9): 1031–1041.
- Wake, D. B., & Lawson, R. 1973. Developmental and adult morphology of the vertebral column in the plethodontid salamander Eurycea bislineata, with comments on vertebral evolution in the Amphibia. Journal of Morphology 139(3): 251–299.
SV-POW! is an AI-free zone
December 11, 2025
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.
Book Week 2025, Day 8: Jurassic West, 2nd edition, by John Foster
December 4, 2025
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.
Sauropod Vertebra Picture of the Week 
