Old drawings (of heads)

June 25, 2017

I was organizing my files in DropBox and I found a folder of old drawings I’d almost forgotten about. I drew this back in the late 90s. It was used on a t-shirt by the OU Zoology Department. I got the general idea of making a head out of animals, and the specific idea of using a butterfly wing for the ear, from Wayne Douglas Barlowe’s cover for the novel Wild Seed by Octavia Butler. The snake I stole from ancient Egypt. I think everything else is in there just because I thought it was cool. Note that inverts, fish, herps, birds, and mammals are all represented, with a good balance of aquatic, terrestrial, and volant forms. It looks awfully hippie-dippie from 20 years out, but heck, what doesn’t?

“Solitude” by Mathew Wedel. CC BY-NC 4.0.

Well, this, I suppose.

I drew this about the same time. I was reading The Gnostic Gospels by Elaine Pagels and lots of stuff about ancient monastic traditions and thinking that if the world is an illusion that must be penetrated, then the evidence of one’s senses can only mislead. Also, Vicki was working for the state medical examiner in Oklahoma City and they used wooden dowels to represent the paths of bullets when reconstructing the skulls of those killed by gunfire. So here’s the skull of a monk, with all of the lethal pathways of distraction and temptation clearly marked as such. At last he can contemplate the eternal mysteries in perfect solitude.

Obviously I didn’t get on board the world-is-an-illusion, sensation-is-bad train – skewed pretty hard in the opposite direction, in fact. Possibly because years earlier the Chessmen of Mars by Edgar Rice Burroughs had shown me that pursuing ‘pure’ intellectual and spiritual inquiry would ultimately lead one to a pathetic existence as a disembodied head living in a cave (high culture, meet low culture). Anyway, whatever interest I might have had in that philosophy I exorcised through this drawing. Stripped of any art-making-a-point baggage, I still think it’s pretty bitchin’. I should make t-shirts.

Actually, I probably will make t-shirts of this one if there’s any interest. Hence the CC BY-NC license I put on it, as opposed to the normal CC BY for almost everything else on this site. Look at me, boldly experimenting with new licenses.

This, obviously, is a lot more recent. I was collating all of my scanned drawings and I realized that I’d gone to the trouble of drawing the cranium and lower jaw of Aquilops separately, but I’d never posted the version from before I composited them back into articulation. It is very unlike me to do work and then hide it, so here it is.

It wasn’t until I the post mostly written that I realized that all three drawings are of heads, none of them are saurischians (although the first includes a saurischian, but not the cool kind), and two are stinkin’ mammals (and not the cool kind). I stand ready for your slings and arrows.

For previous posts on my drawings, see:

Hey sports fans! I met David Lindblad at Beer ‘N Bones at the Arizona Museum of Natural History last month, and he invited me to talk dinosaurs on his podcast. So I did (LINK). For two hours. Some of what I talk about will be familiar to long-time readers – dinosaur butt-brains and the Clash of the Dinosaurs saga, for example. But I also just sorta turned off my inhibitions and let all kinds of speculative twaddle come gushing out, including the specter of sauropod polyphyly, which I don’t believe but can’t stop thinking about. David was a gracious and long-suffering host and let me yap on at length. It is more or less the kind of conversation you could have with me in a pub, if you let me do most of the talking and didn’t want to hear about anything other than dinosaurs.

Is it any good? Beats me – I’m way too close to this one to make that call. Let me know in the comments.

Oh, I didn’t have any visuals that really fit the theme so I’m recycling this cool image of speculative sauropod display structures by Brian Engh. Go check out his blog and Patreon and YouTube channel.

I wanted to get my initial report on the Joni Mitchell conference out quickly. But since posting it, more thoughts have bubbled up through my mind. I’m thinking here mostly about how a humanities conference varies from a science one. Now of course this is only anecdote, nothing like a scientific survey: my sample size is one conference (for humanities) and only one field for science (vert palaeo, natch), so we should beware of generalising from these observations.

With that understood …

The Minerva Building of the University of Lincoln, where the main conference sessions took place.

The Minerva Building of the University of Lincoln, where the main conference sessions took place.

The Joni conference had mostly parallel sessions: a pair of panels early in the morning, then a pair in the later morning, then three simultaneous panels in the after-lunch session before dropping down to a single plenary session for the later afternoon. (My talk was in one of the three parallel panels, so less well attended than it might otherwise have been.) I don’t know how common this is in humanities conferences, but it’s never done at SVPCA or ProgPal. SVP, of course, does run parallel sessions — but then that is a very big meeting, with thousands of delegates.

I used the word “panel” in that description, which I’ve not come across in science conferences. It refers to one of a set of parallel sessions. The idea is that all the talks in a panel are on a somewhat related subject, and the panel ends with all the speakers coming back to the front together, for a discussion with the audience and among themselves. This is actually a really nice way to run things — much better than the very nominal Q&As at the end of SVPCA talks. It helps you to develop a sense of who people are, as well as digging deeper into the topics. My sense is that this is pretty typical of humanities conferences.

One less positive difference is that it seems far more acceptable in the humanities to read papers out loud from manuscripts. By no means everyone did this, but quite a few did, and it seemed to be thought normal. This did work out well for me in one respect, though. Because of the parallel panels, I missed a talk I would have liked to have heard, on using Joni’s music in therapeutic contexts. But when I later spoke to the author of that paper, she was able to give me a hardcopy of the talk. (I read it today.)

Did I say “Joni”? One aspect of this conference that corresponded pretty well with my prejudices was a sort of liberal guilt that popped up its head from time to time. Most of the speakers referred to our subject as “Joni” rather than “Mitchell”. In the round-table discussion at the end, someone suggested this implied an unwarranted level of intimacy, and indicated an unconscious sexism on the part of the participants. There was quite a bit of agreement with this, but I don’t buy it. I think we refer to Joni Mitchell as “Joni”, when we don’t refer to Paul Simon as “Paul” for two reasons: one practical, one fundamental. First, because Joni is a rare and distinctive name, whereas Paul could be Paul McCartney; and second because the high level of self-disclosure in Joni’s music creates the impression of intimacy. I don’t think it’s anything to do with her being female and Simon being male.

Similarly, there was some angst about cultural appropriation regarding Joni’s use of jazz idioms, and particularly about her appearance as a black man on the cover of Don Juan’s Reckless Daughter (1977):

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I can certainly see how that cover makes people uncomfortable in 2015, and I can easily imagine that it would have done even in the very different climate of 1977. On the other hand, it felt a bit strange to be part of a 100% white audience debating this. I’m not sure what conclusion would be appropriate, so I won’t attempt one.

Finally, the demographics of the conference were maybe the biggest surprise. I’m not good at noticing race, so I may have missed someone; but as far as I’m aware there was not a single non-caucasian face at the conference. And perhaps even more surprising, in a conference about a feminist icon[*], although the attendance was about 50-50 men and women, the programme was dominated by male speakers. From a quick scan of the programme, I make it 15 men to 7 women, so more than twice as many.

As with most of what I’ve said here, I have no idea what to make of this. I just offer it up as an observation, and I’ll be glad to know what others make of it all.


[*] Joni Mitchell has explicitly disowned the description “feminist” on more than one occasion; but as a woman who not only held her own in man’s world but by most judgements dominated it, she is certainly an admirable example of practical, if not dogmatic, feminism.

 

I got back this lunchtime from something a bit different in my academic career. I attended Court and Spark: an International Symposium on Joni Mitchell, hosted by the university of Lincoln and organised by Ruth Charnock.

court-and-spark-symposium-poster_v0-2

I went mostly because I love Joni Mitchell’s music. But also partly because, as a scientist, I have a necessarily skewed perspective on scholarship as a whole, and I want to see whether I could go some way to correcting that by immersing myself in the world of the humanities for a day.

My own talk was on “Musical progress and emotional stasis from Blue (1971) to Hejira (1976)”. I’ve posted the abstract and the slides on my publications list, and you can get a broad sense of what was in it from this blog-post about Hejira which talks a lot about Blue. (The talk was inspired by that blog-post, but it had a lot of new material as well.) I plan to write it up as a paper when I get a moment.

I was up in session 3, after lunch, so I’d had a couple of sessions to get used to how things were done. As far as I can tell, it seemed to go over pretty well, and there was some good discussion afterwards.

So how does a humanities conference stack up against a science one?

They were much less different than I’d imagined they would be. The main difference is that talks are called “papers”. As in “Did you hear the paper about X?”, or “I gave a paper on Y”. There was perhaps a little more time dedicated to discussion than at SVP or SVPCA.

Because I didn’t know how to dress, I erred on the side of conservative. As a result, I was the only man in the building wearing a tie, and was consequently the most overdressed person present — something that has never happened to me before, and likely never will again. (I typically wear a tie two or three times a year.)

All in all I had a great time. I’m currently in the process of trying to get my eldest son to appreciate Joni (he’s more of a prog-metal fan, which I can respect); against that backdrop, it was great to be surrounded be people who get it, who know all the repertoire, and who recognise allusions dropped into conversation. Also: beers with fellow-travellers between the main conference and the Maka Maron interview event in the evening; wine reception afterwards; Chinese food after that; after-party when we couldn’t eat any more food. (It was nice being invited along to that, given that I’d never met any of the people before yesterday, and only even exchanged email with one of them.)

I’d had to get up 4:45 in the morning to drive up to Lincoln in time for the conference, so all in all it was a long day. But well worth doing.

I’d do it again in a heartbeat.

Kraatz et al 2015 Figure 1 - rabbit skull freak gallery

Meet some of my new friends: (A) Brachylagus idahoensis, (B) Lepus capensis, (C) Poelagus marjorita, (D) Pronolagus crassicaudatus, (E) Lepus americanus, (F) Oryctolagus cuniculus, (G) Nesolagus timminsi, (H) Bunolagus monticularis, and (I) Romerolagus diazi. Kraatz et al. (2015: fig. 1).

I have a new paper out today in PeerJ: “Ecological correlates to cranial morphology in leporids (Mammalia, Lagomorpha)”, with coauthors Brian Kraatz, Emma Sherratt, and Nick Bumacod. Get it free here.

I know, I know, I have fallen from grace. First Aquilops, now rabbits. And, and…skulls! I know what you’re thinking: that maybe I’m not just experimenting with the non-vertebrae of non-sauropods anymore – maybe I have an actual problem. But I don’t. I can quit anytime! You’ll see.

Actually rabbits are the freakiest of all mammals and their skulls are wicked cool. They have double incisors, with the second set right behind the first, hence the name Duplicidentata for rabbits and their close relatives. They have weird fenestrations in their maxillae (pretty much all taxa) and parietal and occipital bones (some more than others) – I’ll come back to that in a bit. And, as we discuss in our new paper, you can tell something about how a rabbit runs by looking at its skull. I thought it would be fun to relate how we figured that out, and why.

A long time ago in a graduate seminar far, far away…

1950: DuBrul, Laskin, and Moss

I met Brian Kraatz at Berkeley, where he and I were part of the cohort of students that came into the Integrative Biology Department in the fall of 2001 (faithful readers may remember Brian from his work tracking oliphaunts from, gosh, three years ago already). We took a lot of classes together, including a seminar by Marvalee Wake on evolutionary morphology. I’m pretty sure that seminar was the first time I’d actually read DuBrul and Laskin (1961), “Preadaptive potentialities of the mammalian skull: an experiment in growth and form”, or as I think of it, “How to turn a rat skull into a pika skull for fun and profit.”

Pikas (Ochotonidae) are the sister group to rabbits (Leporidae) and together these groups make up crown Lagomorpha. If you’re not familiar with pikas, Brian describes them as starting with bunny rabbits and then making them even cuter and cuddlier. Seriously, go do an image search for ‘pika’ and try not to die of cute overload.

Pikas are interesting because in many ways their skulls are intermediate between those of rodents, especially rats, and rabbits. This is maybe not surprising since rodents are the sister group to lagomorphs and are united with them in the clade Glires. E. Lloyd DuBrul was all over this rat-pika-rabbit thing back in the mid-twentieth century. Here’s an illustration from DuBrul (1950: plate 2; labels added by me):

Rattus Ochotona and Lepus skulls compared - DuBrul 1960 plate 2

So DuBrul knew from pikas and in particular he had the idea that you could maybe just tweak a rat skull – say, by knocking out the basicranial sutures in a baby rat to limit the growth of the skull base – and produce a gently domed skull like that of a pika. That’s what DuBrul and Laskin (1961) is all about. They did that experiment and here are their results (DuBrul and Laskin (1961: plate 3). Normal rat skull on the right, and dotted in the bottom diagram; experimental “pika-morph” rat skull on the left, and solidly outlined below.

Experimental skull doming in rats - DuBrul and Laskin 1961 plate 3

What’s going on here morphogenetically is that the facial skeleton is getting tilted down and away from the back end of the skull. DuBrul was hip to that, too – here’s a relevant image from his 1950 paper (plate 4; labels added by me):

Skull tilting in Rattus Ochotona and Lepus - DuBrul 1960 plate 4

The common reference point against which these skulls are registered is the cranial base (the floor of the braincase just forward of the foramen magnum). Again, the pika is a pretty good intermediate between the rat and a ‘normal’ rabbit, and the dang-near-dog-sized Flemish Giant rabbit takes the lagomorph face-tilting thing to its extreme. (‘Flemish Giant rabbit’ is another entertaining image search that I will leave you as homework.)

Turns out there’s another way you can get rat skulls with different geometries: you can cut off their legs and make them walk on two feet. In an experiment that you might have trouble getting past an Institutional Animal Care and Use Committee today, Moss (1961) lopped off the forefeet or hindfeet in two experimental batches of rats, to see what effect this would have on their skulls. I’ll let Moss speak for himself on this one (Moss, 1961: pp. 301-303, emphasis in the original):

Circumnatal amputation of the forelimbs has successfully produced what are in essence “bipedal rats,” i.e., rats whose habitual mode of kinetic and static posture is permanently altered. […] The animals never became bipedal in the exact sense; that is, they never walked erect on two limbs at all times. […] Nevertheless, bipedal posture and motion were more frequently observed than in controls. […]

Animals whose hind limbs were removed represented another picture. They most certainly did not walk about on their intact forelimbs. Neither did they seem able to use their hind limb stumps as satisfactory substitutes. Their gait was not uniform and seemed to consist in a series of short pushes or hops. The most noticeable thing about them was, among other things, apparent accentuation of their cervical vertebral curvature. The sum of these changes was an upward rotation of the skull.

He wasn’t kidding: when the two groups of bipedal rats grew up, their facial skeletons were tilted relative to the control group, but in different directions (Moss, 1961: fig 3; ‘fore’ and ‘hind’ refer to which limbs the animals had left to locomote with):

Skull deformation in bipedal rats - Moss 1961 fig 3

Brian and I read Moss back at Berkeley, too. In fact, we were minor Moss junkies. If you’re interested in how living forms come into being, you owe it to yourself to read Moss (1968), “A theoretical analysis of the functional matrix”.

The upshot of all of this is that although neither Brian nor I had done anything with our deep (and, okay, deeply weird) knowledge of how to experimentally jack up rat skulls by the time we graduated from Berkeley, we were also primed to be thinking about how skulls attain their shapes – especially the skulls of rodents and rabbits.

2009: American Museum of Natural History

I went to the AMNH in February, 2009, to visit Brian, who was on a postdoc there at the time, and to spend one day looking at sauropods with Mike, who was over from England for a conference. What Brian and I planned to work on was the fenestration of rabbit skulls, because I’m always interested in the strategic loss of bone from skeletal structures. We spent probably half a day talking about that, and I filled a whole page in my notebook with related noodlings:

AMNH rabbit skull sketch 1

But as the sketch on the right shows, it didn’t take us long to figure out that there was something even more interesting to do with rabbit skulls. Brian had a whole shedload of rabbit skulls from different taxa sitting on his desk, and we noticed pretty quickly that one of the primary ways they varied was in the tilt of the facial skeleton relative to the back of the skull. Here’s the very next page of my notes from that trip:

The skull up top belongs to Caprolagus, the Hispid hare, which I tend to think of as the “bulldozer hare”. Seriously, it looks like a tank. It doesn’t bound or even hop, it scrambles. Here, stare into the abyss:

Caprolagus from ARKive

That rabbit will cut you, man. And just look at how flat its skull is. Even in life Caprolagus looks more rodent-y than rabbit-y. Or, more precisely, more Ochotona-y.

At the the other extreme are taxa like Bunolagus and Pronolagus, which really push the “I’m going to cute you to death by dint of my incredible bunnosity” thing:

Bunolagus from ARKive

As Brian and I started going through skulls of as many extant rabbits as we could, we noticed that the flatter-skulled taxa, with less pronounced facial tilt, tended to be the stolid, foursquare scramblers like Caprolagus, whereas the speed demons tended to have more strongly tilted skulls. It also seemed like the latter group were achieving that pronounced facial tilt by changing the geometry of the occipital region of the skull. Look back up at the red quadrilaterals I drew on the Caprolagus and Bunolagus skulls in my notebook – those mark the basioccipital ventrally and the dorsal exposure of the supraoccipital. Perhaps unsurprisingly, supraoccipital length is not the whole story; it turns out that some face-tilters get that way by having longer or more strongly arched parietals, BUT it remains true that if you find a rabbit skull with a long dorsal exposure of the supraoccipital, it will also have pronounced facial tilt.

ANYWAY, by my last night in New York, Brian and I decided that the best way to attack this would be to go down to the basement and stay up most of the night drinking beer and measuring rabbit skulls. We then tried to correlate the various measurements and angles with information on the locomotor and burrowing habits of each species. That was a big job, and after a couple of years with little forward progress (to be fair, Brian was moving across the country and taking his first tenure-track job in this interval, and I was helping birth a sauropod) we brought in Brian’s graduate student, Nick Bumacod, to do most of it. Later on the three of us were forced to acknowledge that we knew enough statistics to get ourselves into trouble but not enough to get back out. Brian had taken a geometric morphometrics course for which Emma Sherratt was a TA, and he started bugging her for help with the stats. Emma has been involved in writing new software packages for R, and we realized that the paper would be a lot stronger if we just brought her on as an author and gave her free rein with the data. Along the way Brian and Nick were giving presentations on the project everywhere from the local Western Area Vert Paleo meeting to the World Lagomorph Conference in Vienna. I got my name on four abstracts along the way, which I think is record abstract-to-paper ratio for me (especially considering that 90% of my effort on the paper was invested in a single evening in 2009 over a couple of six-packs).

But enough navel-gazing, what did we find?

2015: Rabbit skulls reveal their mode of locomotion

Our results, which you can read for free, support the hunch that Brian and I had back in 2009: slow-moving rabbits that locomote by scrambling or scampering instead of hopping tend to have less facial tilt, and faster-moving saltatorial (hopping) and cursorial (leaping and bounding) rabbits have more facial tilt. Interestingly, facial tilt does not distinguish the saltators from the cursors. So the break here is between scrambling and any kind of hopping or leaping, but not between hoppers and leapers.

Kraatz et al 2015 fig 5a

Kraatz et al. (2015: fig. 5a)

Why would that be so? We don’t know for sure yet, but our top hypothesis is that if you’re moving fast, it pays to see the ground in front of you more clearly, and getting your nose down out of the way probably helps with that. This is pretty similar to the hypothesis that tyrannosaurs have pinched nasals for better binocular vision (Stevens, 2006). Rabbits are prey animals and probably can’t afford to point their eyes forward, and they may need wide nasal airways as air intakes while they’re sprinting. Tilting the nose down may be the next best thing.

Guinea pig and mara skulls - DuBrul 1960 plate 6

Some circumstantial support for this comes from the Caviidae, the family of South American rodents that includes guinea pigs, cavies, maras, and capybaras. Here’s another plate from DuBrul (1950: plate 6) contrasting the flatter skull of the guinea pig (Cavia porcellus, top) with the decidedly arched skull of the mara or Patagonian hare (Dolichotis magellanica, bottom). Compare the mara skull to the sectioned rabbit skull in the other DuBrul plate, above – there aren’t a lot of obvious characters to separate the two (beyond the lack of double incisors in the mara).

Mara photo from Wikipedia

Mara photo from Wikipedia

Despite being commonly referred to as ‘hares’ and looking a lot like short-eared rabbits, maras are rodents that evolved their rabbit-like form independently. The acquisition of pronounced facial tilt in two separate lineages of small fast-moving herbivorous mammals is further evidence for the influence of locomotor mode on skull form. Irritatingly, I think we neglected to mention the guinea pig : mara :: pika : rabbit correspondence in the paper. Oh well, it wasn’t our novel observation, and we did cite DuBrul (1950).

Kraatz et al 2015 Figure 4 - skull measurements

Relevant to the next paragraph: DILU is ‘diastema length upper’ and BLD is ‘bulla diameter’. Kraatz et al. (2015: fig. 4).

We found lots of other interesting things, too. The PCA plots we produced from our data separate the living rabbits in unexpected ways. The length of the diastema (the toothless portion of the upper jaw) and the diameter of the auditory bulla seem to be particularly important. Diastema length isn’t too hard to figure out – most of the face-tilters have long diastemas, and the flat-heads tend to have short ones. We have no idea what bulla diameter means yet. I mean, obviously something to do with hearing, but we don’t have any ecological variables in our analysis to address that because we didn’t see it coming. So there’s a chunk of new science waiting to be done there.

Speaking of new science, or at least a relatively new thing in science, we published the full peer-review history alongside the paper, just as Mike and I did back in 2013 and as Mike did with his stand-alone paper last December. More than 80% of PeerJ authors elect to publish the peer review histories for their papers. I can’t wait until it’s 100%. PeerJ reviews are citeable – each one gets a DOI and instructions on how to cite it – and I’m tired of having my effort as a peer reviewer used once and then thrown away forever.

If you’ve been reading this whole post with gritted teeth, wondering why we were using linear measurements instead of geometric morphometrics, chillax. Brian and Emma are on that. They’ve been CT scanning the skulls of as many extant rabbits as possible and plotting landmarks for 3D morphometrics – if you were at SVP last fall, you may have seen their talk (Kraatz and Sherratt, 2014). So stay tuned for what will soon be a new ongoing series, Rabbit Skulls: The Next Generation. (Update: pilot episode here.)

I probably won’t be on that voyage. I’ve had fun getting acquainted with a completely different part of the tree of life, but there are an awful lot of shards of excellence – busted-up sauropod vertebrae, that is – crying out for my attention, and I need to stop neglecting them. I’m done with rabbit skulls, I promise. I’m going clean. (Wish me luck!)

References

  • DuBrul, E. L. (1950). Posture, locomotion and the skull in Lagomorpha. American Journal of Anatomy, 87(2), 277-313.
  • DuBrul, E. L., & Laskin, D. M. (1961). Preadaptive potentialities of the mammalian skull: an experiment in growth and form. American Journal of Anatomy, 109(2), 117-132.
  • Kraatz, B., and Sherratt, E. (2014). Evolution, ecology, and modularity of the lagomorph skull. Journal of Vertebrate Paleontology, 35(3, Supplement), 162A.
  • Kraatz, B.P., Sherratt, E., Bumacod, N., and Wedel, M.J. 2015. Ecological correlates to cranial morphology in leporids (Mammalia, Lagomorpha). PeerJ3:e844.  https://dx.doi.org/10.7717/peerj.844
  • Moss, M. L. (1961). Rotation of the otic capsule in bipedal rats. American Journal of Physical Anthropology, 19(3), 301-307.
  • Moss, M. L. (1968). A theoretical analysis of the functional matrix. Acta Biotheoretica, 18(1), 195-202.
  • Stevens, K. A. (2006). Binocular vision in theropod dinosaurs. Journal of Vertebrate Paleontology, 26(2), 321-330.

How bigsmall was Aquilops?

December 12, 2014

Handling Aquilops by Brian Engh

Life restoration of Aquilops by Brian Engh (CC-BY).

If you’ve been reading around about Aquilops, you’ve probably seen it compared in size to a raven, a rabbit, or a cat. Where’d those comparisons come from? You’re about to find out.

Back in April I ran some numbers to get a rough idea of the size of Aquilops, both for my own interest and so we’d have some comparisons handy when the paper came out.

Archaeoceratops skeletal reconstruction by Scott Hartman. Copyright Scott Hartman, 2011, used here by permission.

Archaeoceratops skeletal reconstruction by Scott Hartman. Copyright Scott Hartman, 2011, used here by permission.

I started with the much more completely known Archaeoceratops. The measurements of Scott Hartman’s skeletal recon (shown above and on Scott’s website – thanks, Scott!) match the measurements of the Archaeo holotype given by Dodson and You (2003) almost perfectly. The total length of Archaeoceratops, including tail, is almost exactly one meter. Using graphic double integration, I got a volume of 8.88L total for a 1m Archaeoceratops. That would come down to 8.0L if the lungs occupied 10% of body volume, which is pretty standard for non-birds. So that’s about 17-18 lbs.

Archaeoceratops and Aquilops skulls to scale

Aquilops model by Garrett Stowe, photograph by Tom Luczycki, copyright and courtesy of the Sam Noble Oklahoma Museum of Natural History.

Archaeoceratops has a rostrum-jugal length of 145mm, compared to 84mm in Aquilops. Making the conservative assumption that Aquilops = Archaeoceratops*0.58, I got a body length of 60cm (about two feet), and volumes of 1.73 and 1.56 liters with and without lungs, or about 3.5 lbs in life. The internet informed me that the common raven, Corvus corax, has an adult length of 56-78 cm and a body mass of 0.7-2 kg. So, based on this admittedly tall and teetering tower of assumptions, handwaving, and wild guesses, Aquilops (the holotype individual, anyway) was about the size of a raven, in both length and mass. But ravens, although certainly well-known, are maybe a bit remote from the experience of a lot of people, so we wanted a comparison animal that more people would be familiar with. The estimated length and mass of the holotype individual of Aquilops also nicely overlap the species averages (60 cm, 1.4-2.7 kg) for the black-tailed jackrabbit, Lepus californicus, and they’re pretty close to lots of other rabbits as well, hence the comparison to bunnies.

Of course, ontogeny complicates things. Aquilops has some juvenile characters, like the big round orbit, but it doesn’t look like a hatchling. Our best guess is that it is neither a baby nor fully grown, but probably an older juvenile or young subadult. A full-grown Aquilops might have been somewhat larger, but almost certainly no larger than Archaeoceratops, and probably a meter or less in total length. So, about the size of a big housecat. That’s still pretty darned small for a non-avian dinosaur.

Although Aquilops represents everything I normally stand against – ornithischians, microvertebrates, heads – I confess that I have a sneaking affection for our wee beastie. Somebody’s just gotta make a little plush Aquilops, right? When and if that happens, you know where to find me.

References