Back in 2005, I made this drawing of the scapula of what would become Brontomerus. By the time we actually got the manuscript together to submit, I completely forgot that it existed! Which is just as well–I like the color photos of the bones in the PDF better than line drawings. Also, I traced this from a photograph of the medial view of the scap that was also at a sort of wonky angle, so the ventral “step” in the scapular border is not apparent (see Taylor et al. 2011: fig. 8 to see what I’m talking about).

Still, good or not, this does illustrate the danger of letting projects drag on forever.

Anyone else have horror stories of completely forgetting about work you’d done? The comment field is open.

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After a couple of relatively hardcore posts on ilial osteology, we though it would be good to look at something lighter this time.  If you’re interested in dinosaurs, or indeed alive, you will hardly have been able to avoid seeing Francisco Gascó’s glorious life restoration of Brontomerus.  Here it is again, in case you’ve been in a coma:

As well as being Figure 12 of the paper (Taylor et al. 2011), it’s popped up absolutely everywhere in media coverage: among many others, it was used by the BBC, Guardian, Telegraph and Independent in the UK; by USA Today, Fox News and National Geographic in the USA; by Spiegel in Germany; and by SVT (the state-funded national TV station) in Sweden.  There’s no question that this image contributed hugely to selling the paper to the secular media.  It’s probably responsible for 80% of all the coverage our work got, and I’m confident that it’s going to quickly become one of those images that everyone recognises, like the tyrannosaur/styracosaur fight on the cover of The Dinosaur Heresies and indeed Charles Knight’s classic swamp-bound Brontosaurus.

So it was a huge win for us, and it’s worth looking at how it came about.

Back in 2004, Matt gave a talk at the SVP annual meeting, entitled Skeletal pneumaticity in saurischian dinosaurs and its implications for mass estimates.  The material in this talk became a chapter in the Wilson and Curry Rogers edited volume of sauropod papers (Wedel 2005).  Some time in 2006, Matt heard about the Paleonturology competition, which is all about making palaeontology accessible for teenagers, especially in Spain: anyone who’d had a paper published in 2005 was invited to submit it, and the judges would choose the one that seemed most amenable to being rewritten in a compelling way for non-specialists.  Matt’s 2005 paper won the 2006 competition, and the rewritten version of that paper was translated into Spanish and published in a very nice booklet which I am pleased to have a copy of (Wedel 2007).  In 2007, Matt was invited to the Fundación Dinópolis in Teruel, Spain, to receive his award, launch the booklet, and act as a judge for the 2007 competition.

The relevance of all this now finally becomes apparent: while in Teruel, Matt met Francisco “Paco” Gascó, and looked through some of his portfolio of palaeo-art — including, for example, this rearing Camarasaurus:

So Matt had Paco in mind as a promising palaeo-artist.  Then towards the end of May 2008, when we were readying the Brontomerus paper for submission (not to Acta Palaontologica Polonica — to a different journal, which didn’t take it) I wrote to Matt saying:

I’m attaching a tentative skeletal reconstruction that I did.  […]  Now I’m thinking: should we approach a palaeoartist to see if we can get a life restoration done in time for the launch?  The eponymous thunder thighs hardly make an impact in the skeleton, after all.

And Matt quickly replied suggesting that Paco could be the person to do it.  He sent a few samples, including the Camarasaurus above, and I was sold.   A couple of days later, Matt suggested the idea to Paco, he was up for it, and so we were all systems go.

At that time, Paco (who is now getting towards the back end of his Ph.D) was a humble recent graduate, which was great because it meant that Matt and I got to boss him about — something that he accepted with enormous good grace as we went through a sequence of some 44 images on the way to the pair that we ended up with.

By this time, Matt and I had already realised that we wanted the artwork to show kicking.  So we started out by asking Paco to mock up three very rough sketches of how he thought a Brontomerus-kicking-a-predator scene might be composed.  Here is one of the three — pretty representative:

Although this scenario is pretty sweet, it’s not really what we wanted as it shows Brontomerus kicking backwards like a horse, rather than forwards like a footballer.  (That’s a soccer player, for those of you in the USA.)  So Matt offered this concept sketch:

(It’s well worth clicking through and seeing the details.)

It’s interesting to see how much of the final image was already in place even in that very early sketch: the basic pose of the adult sauropod, the juvenile behind, the theropod getting its arse kicked — even if at this stage it was a juvenile Acrocanthosaurus rather than a mature Utahraptor.

With this reference in the back of his mind, Paco started work on a 3D model of the sauropod that would be the core of the composition.  He was quickly able to show us a first draft that had all the pieces in place to look convincing at least as a generalised sauropod:

Already at this stage, I was pushing for the uniquely Brontomerus-like aspects of the anatomy to be made more apparent, so I sent back this modified and uglified version of the image to give a sense of where we wanted to be heading:

(You might want to open this image and the previous one in two tabs and switch back and forth between them.)

The purpose of the modified version, of course, was to show how high the ilium would sit on the torso and how it brings forward the anterior margin of the leg muscles.  We wanted the thigh to be much more thundrous!  This was part of a merciless campaign of anatomical criticism of many, many aspects of the in-progress restoration — for example, the cross-sectional shape of the neck, which at this point had a crest on top and flat sides.  (You’ll notice that in the final version, the neck has the distinctive subtriangular cross-section that is produced by the ventrolateral excursion of the cervical ribs in sauropods.)

While that stream of refinement was going on, Paca was starting to skin the model.  Here’s the first version we saw that had skin texture:

Seeing this was an exciting moment in the progress of the project.  It was the first time that the artwork started to look like actual art, and the sauropod to look like an actual sauropod.  We knew then that we were on the way to somewhere good.

That feeling intensified the first time Paco showed us the complete cast of our little drama: mother, baby, and evil raptor, all skinned and showing rather fetching stripes which survived in more or less this form through to the final version:

By this stage, most of the anatomical problems are getting ironed out: the flat-sided shape of the neck has gone, replaced by a broader and wrinklier ventral aspect; and the ilium was higher on the torso, with the shape of the dorsal margin more closely reflecting that of the Brontomerus holotype ilium.

Note the care that Paco took with the juvenile: it’s not just a scaled-down copy of the adult, but proportioned subtly differently in a way that reflects what we know of sauropod ontogeny: the limbs grow isometrically, but the neck is positively allometric, so that Baby Bronto’s neck is noticably shorter in proportion.  At this stage, the baby is too big — more than half Mama’s size, whereas the sizes of the elements from the Hotel Mesa quarry suggested that he should be closer to a third of her size.

At the same time that Paco was working on the details of the models, we were all still batting around composition ideas, trying to find the best way to put our three actors together.  This version of Paco’s was similar in concept to Matt’s earlier sketch, but different in a lot of details: the baby is running away rather than sheltering, the theropod is rather bigger than before, and has morphed from an acrocanthosaur to a raptor; and it’s upside-down in an attempt to show that it’s not in control of the situation:

I wasn’t convinced by this version, because the theropod seems to have been spun 180 degrees on the spot as well as kicked upside-down: I felt that he needed to be in a posture that more naturally emerges from having been facing Mama when he was kicked, so I ‘shopped Paco’s sketch into this version:

As well as turning the baby around (something that didn’t really help). I flipped the raptor and tried, clumsily, to convey that Mama had broken its neck.  Of course, that didn’t really work, because the extension at the base of the neck is habitual for most tetrapods anyway, but it at least gave us a sense of the direction we wanted to go in.

OK, so back to the model.  Paco had sent us a simple lateral-view render of Mama alone, as well as the group shown above, so that we could more easily critique its anatomy in isolation.  Here is that simple render, followed by the vandalism I did on it to show changes that we still wanted.  (See what I mean about Paco being patient?)

As you can see  (and as you’ll see more clearly if you flip back and forth between the two images), I was asking for two changes.  The simpler was that I wanted to see the distinctive profile of the Brontomerus scapula showing through the skin.  The more interesting is in the profile of the tail.  It’s been shown in many sauropods that there is a distinctive upwards kink at the base of the tail, so that the dorsal profile of the body does not progress smoothly from hips to tail, and I wanted to see that in Brontomerus.  At the same time, the tail needed to have more flesh on it and the ischium should have been producing a visible bulge in the ventral margin behind the hips.

The next version addressed these points (though the scapula outline was not yet right):

But picky as I am I still wasn’t satisfied…

I made a few changes here — again, in a hacky way using the GIMP, with the result not in any way intended as in improvement in itself, but as a sketch of how the model could be improved.  I shifted the tail up a little, smoothed the dorsal profile so that there was no longer a sort of dip at the base of the tail, and smoothed out the rear margin of the top of the thigh, so that there was no longer a “buttock”, but a hint of caudofemoralis musculature connecting the tail-base with the thigh.

Once Paco had made the necessary changes to the model, the next render looked superb — and very recognisable as the basis of the now-ubiquitous final version:

At this point, work on the main model was essentially complete, and Matt and I were both really happy with the result.  For people who’ve spent as much time gazing at the Brontomerus ilium and scapula as we have, this is very obviously Brontomerus and not just a generic sauropod.  Now it was time to put the model together with the composition ideas we’d been playing with:

We went through several versions of this, mostly varying in the posture of the theropod, but this is the one that led to the final piece.  For the first time, we were all happy with Baby Bronto in this one, too: he’s about the right size, and has a sort of skittering look to him, as though he wants to be elsewhere but doesn’t want to leave Mama.  (Am I anthopomorphising?  Very well; I contain multitudes.)  It’s a bit too close to the adult, though, so we can’t quite see its shape.  This was fixed in the next version, which also contained a backdrop for the first time:

Now we’re really getting somewhere.  You’ll notice that the raptor’s head is bent further back this time, hopefully conveying that its neck is broken.  But because I was really keen on getting it across that the raptor is DOWN and it’s NOT getting up again, I once again vandalised Paco’s work, this time with buckets of blood:

What I wanted to convey was: if this raptor wasn’t already secondarily flightless, it is now.  Still, I admit that the amount of blood, and the vividness of its colour, are a little over the top.  So in the final version, Paco took some of the blood back out, and toned it down to a more realistic colour.  The other important difference is that the raptor was moved a bit closer to the sauropod — not because that’s necessarily a better composition, but because we expected newspapers and other media outlets to crop the image mercilessly, and we wanted to give them best chance of keeping all the key element in frame when they did.

And so we arrive at the final version, as it appeared in the paper:

The very last thing we did was ask Paco for a second render of the same scene, so that media outlets would have a choice of artwork and wouldn’t all need to use the exact same image.  That was doable because all three dinosaurs, with their skin-textures, were built as a 3D model, which can be viewed from any angle.  But producing a finished artwork from this is not trivial: once an angle is chosen and the animals rendered, there is still a lot of post-production work to be done in putting in the background, the blood, the dust and so on.  So we didn’t ask for a complete array of 128 of these — just the one addition.  After reviewing a few candidate exported renders, we settled on one from a more anterolateral perspective, and Paco worked his magic to yield this alternative take:

I hardly have words to tell you how much I love this.  Several times, looking at it, I’ve found myself laughing out loud at how comprehensively the theropod is getting owned.  It’s OVER for that would-be predator.  It’s DONE.  The only question is whether Mama is going to put it out of its misery by stomping it flat, or whether it’ll be left to bleed out.  Either way, it picked on the wrong victim for dinner.

Part of what I love so much about this is that Brontomerus looks like an animal, not like a monster.  It works anatomically, feels like something that lives and breathes … and, indeed, kicks.

Let me close by clearly stating that 99% of all the Awesome here is the work of Paco — a talented and hardworking guy, who made Matt’s vision come to life.  My own input was basically restricted to whining.  I hope we’ll be seeing this image for many years to come, and that plenty more of Paco’s pieces make it out into the wide world where they belong.

For more of Paco’s stuff, please see his blog, El Pakozoico (TARDIS alert!), and his deviantART page.

References

Let’s look a bit more closely at the holotype element of Brontomerus mcintoshi, which as we all remember is the juvenile left ilium OMNH 66430.  Much of what we’ve said about Brontomerus is based on the shape of that ilium, so it’s important to get right.  Several commentators have expressed skepticism about how we reconstructed, so I thought it would be worth taking the time to explain why we put it together we way we did.

First, let’s orient ourselves.  Here is the torso from the skeletal inventory that was Figure 1 of the paper (Taylor et al. 2011, natch).  In this version, I’ve highlighted the ilium in red.  We’re looking at the left side of the animal, so the main part of the bone is further forward than the hip socket, towards the animal’s head.

As you’ll see from the area that we left shaded grey, a chunk is missing from the middle of the ilium, where it was damaged in the field.  As the figure of the ilium in the paper shows clearly, what we actually saw in the OMNH collection was three chunks of bone: a big one consisting of the acetacular margin, pubic and ischiadic peduncles and most of the preacetabular blade; and two smaller fragments, each contributing part of the dorsal or posterior margin.

We spent a while in the OMNH collection playing with the three chunks to see how they best fit together.  In doing this with the actual bones, we were able to take account of their curvature in the third dimension, which our figure don’t show — although a dorsal-view photo gives some idea.

Anyway, we this is what we came up with:

(Sorry if that image is getting a bit overfamiliar, but it’s worth seeing again in the context of this post.)

You’ll remember from the Clearing the Air post that Jim Kirkland, who excavated the ilium, felt that we’d got the two smaller fragments in the wrong places relative to the main chunk, and also that a fourth fragment which we’d missed also belongs to the ilium.  He kindly sent a photo of how he’d reconstructed the ilium, and I used the arrangement of pieces in the photo as the basis for a “what if” alternative reconstruction.

So far, this is old news.  But what was maybe not quite clear in the post is how very similar the two reconstructions really are.  Let’s fix that: here they are side by side, with ours on the left and Jim’s on the right:

It seems pretty clear that even if Jim’s arrangement is correct (which Rich Cifelli  disputes), that doesn’t affect the reconstruction in any significant way.

But the real question is why we put in that dotted line — and why we put it where we did.  How do we know there wasn’t a normal-sized postacetabular lobe sticking out behind?  This is what Jamie Headden wanted to know in an email to me shortly after the paper come out.  With his kind permission, I reproduce the illustration that he prepared, showing (A) the reconstruction from the paper, and (B) how it might have been different:

The reason we rejected a reconstruction like the one in Jaime’s part B is explained (too) briefly in the paper (pp. 80-81):

The postacetabular lobe is reduced almost to the point of absence […]  The ischiadic peduncle is reduced to a very low ventral projection from almost the most posterior point of the ilium. The near absence of the ischiadic peduncle cannot be attributed to damage as the iliac articular surface is preserved. Immediately posterodorsal to this surface is a subtle notch between the peduncle and the very reduced postacetabular lobe. This notch and the areas either side of it are composed of finished bone, demonstrating that the great reduction of the postacetabular lobe, too, is a genuine osteological feature and not due to damage.

To my lasting annoyance, I didn’t take any posterior-view photos of the ilium back in 2007, so I can’t show you this finished bone as well as I’d like — this was back before I’d learned all my lessons on how to photograph bones.  But here is a close-up of the posterovental extremity of the ilium, again from Fig. 2, showing the notch: I have left the postacetacular lobe in colour, and desaturated the ischiadic peduncle — the notch is between them.

This next photograph of the ilium, again in lateral view, is lit rather differently from the one we used in the figure, so that you can see a distinct shadow lying along the valley between the ischiadic peduncle and what there is of the postacetabular blade.

Here’s one that shows the main chunk of the ilium in anteromedial view: from here, you can more easily see the the distinction between the ischial peduncle (which projects towards the camera) and the preserved, ventralmost, part of postacetacular blade, which is further back.

And one in posteroventral view: this is similar to our Fig. 2b, but from a slightly more posterior (and medial) perspective, so that you can more easily see the mediolaterally compressed posterior lobe sticking out behind the broader ischial peduncle at top right:

What all these photos unfortunately do not show is the finished nature of the bone on the posterior margin of the postacetacular blade — on that, you just have to take our word.

But the point is this: we have the whole of the ischiadic peduncle and the ventralmost part of the postacetacular blade — we know that the posteriormost preserved part of the main chunk of ilium is not part of the peduncle (so that the postacetabular blade is missing), but that this really is the blade itself.  And because the bone is not broken, we know that the trajectory of the posterior margin of the postacetabular blade was directed dorsally from the posterior point of the peduncle.

I hope that’s clear.  What I really should have done, of course, was take my own good advice and get photos from every angle — and, ideally, pairs that would have allowed me to show the relevant features as anaglyphs.

Anyway, all this shows that the shape of the ilium really was pretty much as we reconstructed it — and, most, importantly, that the bizarre proportions we reported in Table 4 are correct: preacetabular blade, measured parallel to the longest axis of the ilium equal to 55% of total length; postacetabular blade equal to 0%.

Exactly how strange is this almost non-existent postacetabular blade?  In the paper we described it as “remarkable”, but it’s not completely unprecedented.  Lehman and Coulson (2002:fig. 8) showed the left ilia of six somphospondylians:

As you can see, the Euhelopus zdanskyi and Saltasaurus loricatus ilia both lack postacetabular blades (although Powell 1992:fig. 18 suggests that the posterior portion of the Saltasaurus ilium may be broken).  Where Brontomerus is unique is in the combination of this postacetabular reduction with the enormous preacetabular blade.

All clear?  Good.

“But wait!”, I hear you cry.  “That ilium is juvenile!  How do you know that its strange shape is not a juvenile feature?”

Stay tuned!  All will be revealed.

References