Here’s my face.

I went to the dentists’ office recently for a regular checkup and cleaning, and when my dentist learned that I taught human anatomy, he volunteered to send me a high-res copy of my panoramic x-ray. I couldn’t think of any plausible scenario wherein someone could use it for evil, and it has lots of cool stuff in it besides teeth, so decided to post it so I could yakk about it.

First things first: my teeth are in pretty good shape. I had to have my wisdom teeth (3rd molars) pulled back in 2009, and my upper 1st molar on the left has a root canal and a porcelain crown, which stands out bright white on the radiograph. Everyone else is present and looking good. If it’s been a while since you’ve covered this, the full human dentition consists of 2 incisors, 1 canine, 2 premolars, and 3 molars on each side, top and bottom, for a total of 32 teeth. Because I’ve had all four 3rd molars removed, I’m down to 28.

I could go on and on about the cool stuff in this image. Here are 12 things that stand out:

  1. The mandibular condyle, which is the articular end of the mandible that fits into the mandibular fossa, a shallow socket on the inferior surface of the temporal bone, to form the temporomandibular joint (TMJ). There’s an articular disk made of fibrocartilage inside the joint, which separates it into two fluid-filled spaces, one against the condyle and one against the fossa. This allows us to do all kinds of wacky stuff with our lower jaws besides simply opening and closing them, such as slide the jaw fore and aft or side to side. This is a strong contrast to most carnivores, which bite down hard and therefore need a jaw joint that works as a pure hinge. See this post for pictures and discussion of the jaw joint in a bear skull.
  2. The coronoid process of the mandible, which is a muscle attachment site. A few fibers of the masseter and buccinator muscles can encroach onto the coronoid process, but mostly it is buried in the temporalis, one of the primary jaw-closing muscles. Put your fingers on the side of your head a little above and in front of your ear and bite down. That muscle you feel bulging outward is the temporalis. Back in the 1960s, Melvin Moss (1968) discovered that if he removed the temporalis muscles from newborn rats, the coronoid processes would fail to develop. Moss’s ambition was to discover the quanta of anatomy, which in his view were “functional matrices” – finite sets of soft tissues related by development and function, which might contain “skeletal units” that grew because of the morphogenetic demands of the functional matrices. His tagline was, “Functional matrices evolve, skeletal units respond”. Not all of Moss’s ideas have aged well in light of what we now know about the genetic underpinnings of skeletal development, but he wasn’t completely wrong, either, and functional matrix theory is still an interesting and frequently productive way to think about the interrelationships of bones and soft tissues. For more horrifying/enlightening Moss experiments on baby rats, see this post.
  3. The mandibular angle, which is another muscle attachment. The medial pterygoid muscle attaches to the medial surface, and the masseter attaches laterally. You can feel this, too, by putting your fingers over your mandibular angle and biting down – that’s the masseter you feel bulging outward. Note that the angle flares downward and outward on either side of my jaw. This flaring of the angle tends to be more pronounced in males than in females, and it is one of many features that forensic anthropologists (like the one I belong to) take into account when attempting to determine biological sex from human skeletal remains. Like most sexually dimorphic features of the skeleton, this is a tendency along a spectrum of variation rather than a binary yes/no thing. There are women with flared jaw angles (Courtney Thorne-Smith, probably) and men with slender mandibles, so you wouldn’t want to sex a skeleton by that feature alone.
  4. The mandibular canal, a tubular channel through the mandible that houses the inferior alveolar artery, vein, and nerve. This neurovascular bundle provides innervation and blood supply to the tooth-bearing part of the mandible and to the teeth themselves, and emerges through the mental foramen to provide sensory innervation and blood supply to the chin.
  5. The upper surface of the hard palate, formed by the palatine process of the maxilla anteriorly and by the palatine bones posteriorly. The palate is the roof of the mouth and the floor of the nasal airways.
  6. The median septum of the nasal cavity, formed by cartilage anteriorly, the perpendicular plate of the ethmoid bone superiorly, and the vomer posteriorly and inferiorly.
  7. The blue lines are the inferior margins of my maxillary sinuses – air-filled spaces created when pneumatic diverticula of the nasal cavity hollow out the maxillae. You have these, too, as well as air spaces in your frontal, ethmoid, sphenoid, and temporal bones. It looks like many of the roots of my upper molars stick up into my maxillary sinuses. This is not an illusion, as shown below.
  8. When I had the root canal on my left upper 2nd molar, the endodontist filled the pulp cavities of the tooth roots with gutta-percha, a rigid natural latex made from the sap of the tree Palaquium gutta. Gutta-percha is bioinert, so it makes a good filling material (it was also used to insulate transoceanic telegraph cables), and it’s radiopaque, which allows endodontists to confirm that the cavities have been filled completely. The other teeth show the typical structure of a dense enamel crown, less dense dentine forming the bulk of the tooth, and radiolucent pulp cavities containing blood vessels and nerves.
  9. This is the rubber bit I gripped with my incisors to keep my teeth apart and my head motionless while the CT machine rotated around me to make the scan. Not that cool in a science sense, but I figured it deserved a label.
  10. Note that the roots of the canines go farther into the jaws than those of the other teeth. This is true for all four canines, it’s just easiest to see with this one. This is a pretty standard mammalian thing, for taxa that still have canines – they tend to be big and mechanically important, so they have deep roots. Even though our canines are absolutely and proportionally much smaller than those in the other great apes, we can still see traces of their earlier importance, like these deep roots.
  11. In places you can see the trabecular internal structure of my mandible clearly. As someone who geeks out pretty much anytime I get a look inside a bone, this tickled me.
  12. The remains of an alveolus or tooth socket. I had my 3rd molars out almost a decade ago, and by now the sockets will have mostly filled in with new trabecular bone. But you can still see the ghostly outline of at least this one – a sort of morphogenetic trace fossil buried inside my mandible. I assume that in another decade or two this will have disappeared through regular bone remodeling.

Here’s a closeup of my left upper 2nd premolar and first two (and only remaining) molars. The gutta-percha filling the pulp cavities of the three roots of the 1st molar is obvious. The disparity in root length is mostly illusory – this was an oblique shot and the two ‘short’ roots are foreshortened.

Here’s the same image with the roots of the 2nd molar traced in pink, and the inferior margin of the maxillary sinus traced in blue. It’s not that uncommon for upper molar roots to stick up into the maxillary sinuses. That was true of my 3rd molars as well, and when I had them taken out, the endodontist had to put stitches into my gums to close the holes. Otherwise I would have had open connections between my oral cavity and maxillary sinuses, which would have sucked and been dangerous. Nasal mucus in the maxillary sinuses could have drained into my mouth, and food I was chewing could have been forced up into the sinuses, where it would have decomposed and caused a truly vile sinus infection.

In a developmental sense, it’s not that the roots of the teeth grow upward into the sinuses, it’s that the sinuses grow downward, eroding the bone around the roots of the teeth. This happens well after the teeth are done forming – the sinuses continue to expand as long as the skull is growing, and they retain the potential to remodel the surrounding bone for as long as we live. Even in cases like mine where the roots of the molars stick up into the sinuses, the tooth roots are still covered by soft tissue, including branches of the superior alveolar artery, vein, and nerve that enter the pulp cavities of the tooth roots through foramina at their tips.

If you ask your dentist for copies of your own dental x-rays, you’ll probably get them. If you do, have fun exploring the weird territory inside your head.


  • Moss, M. L. (1968). A theoretical analysis of the functional matrix. Acta Biotheoretica, 18(1), 195-202.

This morning, I was invited to review a paper — one very relevant to my interests — for a non-open-access journal owned by one of the large commercial barrier-based publishers. This has happened to me several times now; and I declined, as I have done ever since 2011.

I know this path is not for everyone. But for anybody who feels similarly to how I do but can’t quite think what to say to the handling editor and corresponding author, here are the messages that I sent to both.

First, to the handling editor (who in this case also happened to be the Editor-in-Chief):


I’m writing to apologise for turning down your request that I review NAME OF PAPER. The reason is that I am wholly committed to the free availability of all scholarly research to everyone, and I cannot in good conscience give my time and expertise to a paper that is destined to end up behind PUBLISHER‘s paywall.

I know this can sound very self-righteous — I am sorry if it appears that way. I also recognise that there is serious collateral damage from limiting my reviewing efforts to open-access journals. My judgement is that, in the long term, that regrettable damage is a price worth paying, and I laid out my reasons a few years ago in this blog post:

I hope you will understand my reasons for pushing hard towards an open-access future for all our scholarship; and I even hope that you might reconsider the time you yourself dedicate to PUBLISHER‘s journal, and wonder whether it might be more fruitfully spent in helping an open-access palaeontology journal to improve its profile and reputation.

Yours, with best wishes,


Then, to the corresponding author, a similar message:


I was invited by JOURNAL to review your new manuscript NAME OF PAPER. I’m writing to apologise for turning down that request, and to explain why I did so.

The reason is that I am wholly committed to the free availability of all scholarly research to everyone, and I cannot in good conscience give my time and expertise to a paper that is destined to end up behind PUBLISHER‘s paywall.

I know this can sound very self-righteous — I am sorry if it appears that way. I also recognise that there is serious collateral damage from limiting my reviewing efforts to open-access journals. My judgement is that, in the long term, that regrettable damage is a price worth paying, and I laid out my reasons a few years ago in this blog post:

I hope you will understand my reasons for pushing hard towards an open-access future for all our scholarship; and I even hope that you might consider withdrawing your work from JOURNAL, and instead submitting to one of the many fine open-access journals in our field. (Examples: Palaeontologia Electronica, Acta Palaeontologica Polonica, PLOS ONE, PeerJ, PalArch’s Journal of Vertebrate Paleontology, Royal Society Open Science.)

Yours, with apologies for the inconvenience and my best wishes,


Anyone is welcome to use these messages as templates or inspiration if they are useful. Absolutely no rights reserved.

Cryptic Aquilops, by Brian Engh. Available as a poster print – see below.

One of the many nice things about getting to help name new taxa is that once you let them out into the world, other people can unleash their considerable talents on ‘your’ critters. Which means that every now and then, something cool pops up that you have a deep personal connection to. Things have been fairly quiet on the Aquilops front for a while, and all of a sudden I have news.

I’m still waiting for a plush Aquilops – c’mon, Homo sapiens, how has this not happened already? – but if you’d like a life-size Aquilops in bronze, sculptor James Herrmann has you covered. James got in touch with me last fall when the project was just in the planning stages. His timing was excellent – I’d just seen the presentation on camouflage in Psittacosaurus at SVPCA, and the paper by Vinther et al. was out a week or two later. I sent James some papers and photos of dead animals, he sent back photos of the work in progress, and now his Aquilops is done.

About the sculpture, James writes:

I am offering the sculpture for sale as a limited edition of 25.  The sculpture is life sized, it is approximately 60 lbs and is 33″L x 14”H x 11”W.  The price I am asking for it is $4500.  I am getting a slab of green soapstone for the base although it does display well without the stone so it will be bolted on from below and not epoxied. […] The gingko leaves and log part of the sculpture were made from molds taken from plants growing locally.

I dig it. If you’re interested in getting one, please visit his website,

Aquilops ’14. I was there, man. It was crazy. A Brian Engh joint.

Next item: back in 2014, Brian Engh created the public face of Aquilops with the wonderful graphic art he did for the paper and the press release. Now he’s gone back to the well and reimagined Aquilops, based in part on what we know of its paleoecology – that’s the image at the top of the post. He explains his new view of Aquilops in a thoughtful and wide-ranging video on his paleoart YouTube channel. (If you miss his rap videos set in the Daikaijucene, he also has a YouTube channel for music and monsters. And a blog. And a Patreon page. You get the picture.) You should also check out the two-part interview with Brian at the PLOS Paleo Community blog (part 1, part 2).

Here’s the aforementioned video:

Poster prints of Aquilops Classic and Next Gen can be purchased through Brian’s website,

Finally, a couple of older Aquilops-themed art things that I didn’t cover when they happened. Lead author Andy Farke is also an award-winning homebrewer and he concocted his Eagle Face Oatmeal Stout in honor of our little buddy. He has lots more beer-and-dinosaur crossover goodness on his brewing blog – check it out.

Last fall artist Natalie Metzger did a bunch of drawings of extant animals wearing the skulls of extinct animals for Inktober. In the very first batch was this awesome squirrel looking unexpectedly badass in an Aquilops skull. I don’t know what it means, but I would totally play that D&D campaign. Natalie has a bunch more cool stuff on her blog and Patreon page, and she’ll be at the Rose City Comic Con in Portland this September, so go say hi and buy her art.

Really finally, I am not on Twitter – trust me, I don’t need less of a filter between my occasional stupidity and the world – but for all the rest of you, keep an eye on #Aquilops and, if you’re a heartless jerk, #Aquilopsburrito.

Have more Aquilops stuff I haven’t covered but should? The comment field is open.


Upcoming book signings

April 19, 2017

Come gawk at this weirdo in public!

I’ll be signing copies of The Sauropod Dinosaurs: Life in the Age of Giants at regional events the next two weekends.

This this coming Saturday, April 22, I’ll be at the Inland Empire Science Festival, which will run from 10 AM to 4 PM at the Western Science Center in Hemet, California. There will be a ton of other special exhibits and activities, too. I don’t know all of them off the top of my head, but I know that Brian Engh will have the table next to mine, so come by and get two doses of awesome paleo art.

The following Friday, April 28, I’ll be at Beer N’ Bones 2017, which runs from 7-11 PM at the Arizona Museum of Natural History in Mesa, Arizona. In addition to signing books, I’ll also be in the “Speed Dating a Scientist” thing, where small groups of people get five minutes each at a table with a researcher, to ask whatever they want. Not just paleontologists, but scientists of all stripes. That said, I know of a couple of other local paleontologists who will also be there as guests – Andy Farke and Thierra Nalley. I was at Beer N’ Bones last year and it was a blast. As you might suspect from the name, it is 21-and-over only.

I’ll have books for sale – at a healthy discount – at both events. Hopefully I’ll see you out there.

I was fortunate to get to visit some pretty cool places last year, and to photograph some awesome critters, many of which I had never seen so well before. Here are the best of the lot.

In March I went out to Black Mesa with my mentor, Rich Cifelli, and a Native Explorers crew led by Kent Smith. Rich and I saw this pronghorn on the way in, and I got the shot by holding my phone up to Rich’s binoculars.

Later that same day, I caught these pronghorns crossing the highway in front of us. You can tell from the glare and splotches that I was shooting through the windshield. It was that or no shot.

A few days later, we got absurdly lucky. Everyone was driving back to base at the end of the day, with Rich’s truck at the end of the train. This herd of bighorn sheep picked that time to jump a fence and run across the road, right in front of Rich’s truck. Everyone else missed it, they were too far ahead. The bighorns crossed the road in front of our caravan again a couple of days later, and Kent Smith and Jeff Hargrave got some good photos of their own.

I like this landing-and-recovery sequence, illustrated by four different individuals.

Check out the two at the edge of the road, running in step.

A final wide shot. Thank goodness for burst mode shooting. These are all cropped iPhone photos, by the way.

Then in June I got to go with my son’s 5th grade field trip group to Santa Cruz Island in Channel Islands National Park, where we camped for three days and two nights. The dwarf island foxes were always around.

I think people have actually been good about not feeding them because they don’t beg. Neither are they afraid of humans. They treated us as non-threatening and inedible chunks of ambulatory matter. This one was startled by something in the bush and decided that running past me was the lesser of two evils. It might have been another fox, we saw and heard several get into tussles.

Another burst mode catch was this raven on the beach.

Here’s a crop. Not bad, sez me. For a shot of a stinkin’ theropod.

And here’s my favorite shot of that trip, and my second-favorite of the entire year. On the boat ride out to the island, a pod of dolphins came and surfed our bow wake. They did this for quite a while, and everyone who wanted to was able to cycle through the front of the boat and get close-up shots. I’d seen dolphins from shore before, when we lived in NorCal, but I’d never gotten to see them up close from the water. This is yet another burst-mode catch, taken just as this dolphin was breaking the water and before most of the bubbles coming out of its blowhole had popped.

I’m going to use my son’s standing as a tetrapod to sneak this in: sunset at Dead Horse Point, near Moab, Utah. That’s the Colorado River down there, 2000 feet below the clifftops. If you’re ever in that neck of the woods, this is the place to come see the sun set. Trust me on this.

Back in 2012, in response to the Cost Of Knowledge declaration, Elsevier made all articles in “primary math journals” free to read, distribute and adapt after a four-year rolling window. Today, as David Roberts points out, it seems they have silently withdrawn some of those rights. In particular, the “free” articles can no longer be redistributed or adapted — which, for example, prevents their use in teaching or in Wikipedia articles.

We don’t know when this changed. It just did, quietly, at some point after the Cost of Knowledge anger had died down, when no-one was watching them carefully. So here, once more, Elsevier prove that they are bad actors who simply cannot be trusted.

There is a broader and more important point here: we simply can’t build a meaningfully open scholarly infrastructure that is dependent on the whims of corporations. It can’t be done.

Whatever corporations like Elsevier give us one day, they can and will take away another day. They can’t help themselves. It’s in their nature. And, really, it’s unreasonable of us to expect anything different from a corporation whose reason for existing is to enrich its shareholders.

So to have a genuinely open scholarly infrastructure, there is no real alternative to building it ourselves, within the scholarly community. It’s worse that useless to sit around waiting for likes of Elsevier to gift us the infrastructure we need. It’s not in their interests.

So once more, folks: there’s no need for us to be hostile to Elsevier et al. Just walk away. Do not deal with them. They are not on your side. They never have been, and they never will be. They will give just enough ground to defuse anger when it threatens their bottom line; that’s all. Then they will take the ground back when it suits them.

Note. This post is based on a series of tweets.

It’s baffled me for years that there is no open graph of scholarly citations — a set of machine-readable statements that (for example) Taylor et al. 2009 cites Stevens and Parrish 1999, which cites Alexander 1985 and Hatcher 1901.

With such a graph, you would be able to answer question like “what subsequent publications have cited my 2005 paper but not my 2007 paper?” and of course “Has paper X been rebutted in print, or do I need to do it?”

At a more basic level, it’s ridiculous that every one of us maintains our own citation database for our own work. It makes no sense that there isn’t a single, global, universally accessible citation database which all of us can draw from for our bibliographies.

Today we welcome the Initiative for Open Citations (I4OC), which is going to fix that. I’m delighted that someone is stepping up to the plate. It’s been a critical missing piece of scholarly infrastructure.

As far as I can see, I4OC is starting out by encouraging publishers to sign up for CrossRef’s existing Cited-by service. This is a great way to capture citation information going forward; but I hope they also have plans for back-filling the last few centuries’ citations. There are a lot of ways this could be done, but one would be crowdsourcing contributions. They have good people involved, so I’m optimistic that they’ll get on this.

By the way, this kind of thing — machine-readable data — is one area where preprints genuinely lose out compared to publisher-mediated versions of articles. Publishers on the whole don’t do nearly enough to earn their very high fees, but one very real contribution they do make is the process that is still, for historical reasons, known as “typesetting” — transforming a human-readable manuscript into a machine-readable one from which useful data can be extracted. I wonder whether preprint repositories of the future will have ways to match this function?