Reconstructing the skull of Aquilops

December 11, 2014

As I mentioned in my first post on Aquilops, I drew the skull reconstructions that appear in figure 6 of the paper (Farke et al. 2014). I’m writing this post to explain that process.

We’ve blogged here before about the back-and-forth between paleontologists and artists when it comes to reconstructing and restoring extinct animals (example 1, example 2). Until now, I’ve always been the guy making suggestions about the art, and asking for changes. But for the Aquilops project, the shoe was on the other foot: Andy Farke was my ‘client’, and he had to coach me through drawing a basal ceratopsian skull – a subject that I was definitely not familiar with.

Aquilops skull - Farke et al 2014 figure 3

I started from the specimen, OMNH 34557, which is more complete than you might think at first glance. The skull is folded over about 2/3 of the way up the right orbit, so in lateral view it looks like the top of the orbit and the skull roof are missing. They’re actually present, just bent at such a sharp angle that they’re hard to see at the same time as the lateral side of the skull.

Archaeoceratops lateral

I also used a cast skull of Archaeoceratops as a reference – it’s clear from what we have of Aquilops that the two animals were pretty similar.

Aquilops skull lateral 1 - outline

I started with this pencil outline on a piece of tracing paper.

Aquilops skull lateral 2 - rough stipple

And then I went right ahead and stippled the whole thing, without showing it to Andy until I was done. Yes, that was dumb. Noe the lack of sutures in this version.

Aquilops skull lateral 3 - rough stipple marked up

I added sutures and sent it off to Andy, who sent it back with these suggested changes. At this point I realized my error: I had already spent about a day and a half putting ink on the page, and I’d have to either start all over, or do a lot of editing in GIMP. I picked the latter course, since there were plenty of areas that were salvageable.

Aquilops skull lateral 4 - redrawn bits

Next I did something that I’d never done before, which is to redraw parts of the image and then composite them with the original in GIMP. Here’s are the redrawn bits.

Aquilops skull lateral 5 - penultimate version

With those bits composited in, and a few more tweaks to sutures, we got to this version, which was included in the submitted manuscript.

Aquilops skull lateral 6 - beak curvature issue

Then we brought Brian Engh in to do the life restorations. When Brian takes on a project, he does his homework. If you’ve seen his post on painting Aquilops, you know that all of the ferns in the Cloverly scene are based on actual fossils from the Cloverly Formation. Brian came to Claremont this summer and he and Andy and I spent most of a day at the Alf Museum looking at the specimen and talking about possible layouts for the full-body life restorations. He took a bunch of photos of the specimen while he was there, and a day or two later he sent us this diagram. He’d chopped up his photos of the skull to produce his own undistorted version to guide his painting, and in doing so he’d noticed that I had the line of the upper jaw a bit off.

Aquilops skull lateral 7 - partly revised

That required another round of digital revisions to fix. It ended up being a lot more work than the earlier round of edits in GIMP, because so many features of the skull had to be adjusted. I ended up cutting my own skull recon into about 8 pieces and then stitching them back together one by one. Here’s what the image looked like about halfway through that process. The back of the skull, orbit, and beak are all fixed here, but the snout, cheek, and maxilla don’t yet fit together.

Aquilops skull lateral 8 - final published version

After a little more work, I got the whole thing back together, and this is the final version that appears in the paper. It is not perfect – the area in front of the orbit where the frontal, nasal, maxilla, and premaxilla come together is a bit dodgy, and I’m not totally happy with the postorbital. But eventually you have to stop revising and ship something, and this is what I shipped.

Aquilops dorsal recon lineup for SV-POW

I did the dorsal view after the submitted version of the lateral view was finished. It went a lot faster, for several reasons:

  • Most of the gross proportional issues were already sorted out from doing the lateral view first.
  • The bilateral symmetry didn’t cut down on the number of dots but it did cut the conceptual workload in half.
  • I did all my roughs in pencil and didn’t start inking until after we had almost all of the details hashed out.

I did have to revise the dorsal view after getting feedback from Brian about the lateral view, but that revision was pretty minor by comparison. I stretched the postorbital region and tinkered a bit with the face and the frill, and both of those steps required putting in some new dots, but it was still just one afternoon’s worth of work. Here’s the final dorsal recon:

Aquilops dorsal skull reconstruction - final published version

In addition to the Life Lessons already noted in this post, I learned (or rather relearned) this important principle: if you do a big drawing and then shrink it down to column width, fine errors – a shaky line here, an ugly dot there – get pushed down below the threshold of perception. But there’s a cost, too, which is that uneven stippling becomes more apparent. I was skipping back and forth a lot between 25% image scale to see where the problem areas were, and 200% to revise the lines and dots accordingly.

All in all, it was a fun project. It was my most ambitious technical illustration to date, I learned a ton about ceratopsian skulls, and it was nice to get to make at least one substantial contribution to the paper.

Now, here’s the take-away: this is my reconstruction, and both of those words are important. “Reconstruction” because it has a lot of extrapolation, inference, and sheer guesswork included. “My” because you’re getting just one possible take on this. You can download the 3D files for the cranium and play with them yourselves. I hope that other artists and scientists will use those tools to produce their own reconstructions, and I fully expect that those reconstructions will differ from mine. I look forward to seeing them, and learning from them.

For other posts about my stippled technical illustrations, see:

Reference

Farke, A.A., Maxwell, W.D., Cifelli, R.L., and Wedel, M.J. 2014. A ceratopsian dinosaur from the Lower Cretaceous of Western North America, and the biogeography of Neoceratopsia. PLoS ONE 9(12): e112055. doi:10.1371/journal.pone.0112055

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6 Responses to “Reconstructing the skull of Aquilops

  1. Mike Taylor Says:

    “Here’s the final dorsal recon.”

    That’s no dorsal recon. That’s a Star Destroyer.


  2. I did a stippled drawing of a skull I can’t show anyone yet. The process was a bit different from my normal method, which has been to draw an idealized composite from multiple specimens (being preferred to have more than one) where I seek to correct distortion and size variation.

    Instead, I corrected all of this by using the photographs of the material, all size sampled and edited so that they overlay perfectly. The process is a story in itself. I then drew the outline and major features into one full drawing, double checking to make sure the overlap is correct. And from there is when I got to work on the definition and tone. At this point, most of the proportions are correct, but it turned out I flubbed on some key elements, and I had to produce a whole new, second one, from the first. This one was lain over the first to find proportions/shaped, then corrected for those errors. In between these two, I had modified and made special inserts for mapping different bones to the skull (isolated bits and fragments to examine), and now that must be corrected. Work!

    Ultimately, with difficulties of preservation, you have to make some guesses. It’s a fine reconstruction, and a great addition to those other ones. It has better tone than the chinese papers’ versions, frankly, which is to be admired. I also like how you draw the jaw and skull separately, to be conjoined.

    I noticed you shaded in the antorbital fenestra, indicating the presence of a bony wall medial to it. Is this an implication of the bony box surrounding the antorbital diverticulum, which only has a medial hole because the bone is often preserved broken, or the palate? I notice that you had opportunity to shade in the medial bones of the skull, but chose not to (interorbital, braincase, etc.).

  3. paleomanuel Says:

    It’s a nice reconstruction, and the drawings are well done!
    All the digital edition pass unnoticed, which is an achievement after so many interventions.
    I always try to not make the final drawing until all people involved in the work gives the ok. I do line sketches and if necessary, make loose shadings on pencil or digitally with grays on a new layer to ease all the changes made during the discussion.
    Sometimes this part of the job feels an eternity, but following this sort of protocol I feel sure enough to make a faster final presentation, which will receive minor twerks that most of the times are easy to adjust.
    And yes: the print size of the drawing is really important and it is among my first questions to the authors.
    The reduction could help or destroy your drawing, so knowing how big or small it will be, let you adjust the size of your drawing and the amount of work you can put.

  4. Matt Wedel Says:

    Jaime wrote:

    I did a stippled drawing of a skull I can’t show anyone yet. The process was a bit different from my normal method…

    Sounds interesting. When you are able to show the world, I hope you do a whole blog post just on the process. I’d love to see it, and I’m sure I’m not alone.

    Thanks for the kind words about my recon–high praise, given your impressive skills in this area!

    I noticed you shaded in the antorbital fenestra, indicating the presence of a bony wall medial to it. Is this an implication of the bony box surrounding the antorbital diverticulum, which only has a medial hole because the bone is often preserved broken, or the palate? I notice that you had opportunity to shade in the medial bones of the skull, but chose not to (interorbital, braincase, etc.).

    I realize now that it probably looks a bit hit-and-miss in terms of what features or areas got shaded deep to the outer table of bone. There wasn’t a ton of thought behind it. You can see in the earliest version that I had the AOF open, and then Andy pointed out that you wouldn’t be able to see all the way through it in the intact skull, so I blacked it out. I didn’t feel comfortable putting in medial bones that would have required details, like the interorbital and braincase. I didn’t have great references for what they should look like, or enough experience with those bits to feel confident about inventing them. So there is room for improvement.

  5. Matt Wedel Says:

    Mike wrote:

    That’s no dorsal recon. That’s a Star Destroyer.

    Yeah, one thing you can see clearly in my series of dorsal recons is that the skull gets progressively more Star-Destroyer-y through the iterations. I was leery of making it too triangular at the beginning. I figured that maybe the roughly triangular shape of the skull was a sort of visual trap, which the actual skull would have only vaguely approximated. But many of Andy’s edits along the way had to do with filing off the bits that stuck out, and we ended up with basically an isosceles triangle. Andy has actually been to Mongolia and China and seen most of the other basal ceratopsian skulls in person, so when he said “frog”, I jumped.

    I’d drawn skulls before, but I’d never reconstructed one, and I was paranoid that it was going to look stupid or just turn out to be unworkable. But I’m happy to see that the 3D reconstructed skull that Garrett Stowe and Kyle Davies have been working on at OMNH (pictures on this page) is almost identical to my recon and really works as a 3D object. The version they have right now is filled with faux matrix, but I know they’re planning to completely detail out the inside of the skull, which will address Jaime’s point about the missing braincase. Kyle is a master at this kind of stuff – you’ll remember the baby Apatosaurus atlas-axis complex that he sculpted freehand (this post).


  6. […] From that same blog on how the reconstruction was made. […]


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