Caudal pneumaticity in saltasaurines. Cerda et al. (2012: fig. 1).

Earlier this month I was amazed to see the new paper by Cerda et al. (2012), “Extreme postcranial pneumaticity in sauropod dinosaurs from South America.” The title is dramatic, but the paper delivers the promised extremeness in spades. Almost every figure in the paper is a gobsmacker, starting with Figure 1, which shows pneumatic foramina and cavities in the middle and even distal caudals of Rocasaurus, Neuquensaurus, and Saltasaurus. This is most welcome. Since the 1990s there have been reports of saltasaurs with “spongy bone” in their tail vertebrae, but it hasn’t been clear until now whether that “spongy bone” meant pneumatic air cells or just normal marrow-filled trabecular bone. The answer is air cells, loads of ‘em, way farther down the tail than I expected.

Caudal pneumaticity in diplodocines. Top, transverse cross-section through an anterior caudal of Tornieria, from Janensch (1947: fig. 9). Bottom, caudals of Diplodocus, from Osborn (1899: fig. 13).

Here’s why this is awesome. Lateral fossae occur in the proximal caudals of lots of neosauropods, maybe most, but only a few taxa go in for really invasive caudal pneumaticity with big internal chambers. In fact, the only other sauropod clade with such extensive pneumaticity so far down the tail are the diplodocines, including Diplodocus, Barosaurus, and Tornieria. But they do things differently, with BIG, “pleurocoel”-type foramina on the lateral surfaces of the centra, leading to BIG–but simple–camerae inside, and vertebral cross-sections that look like I-beams. In contrast, the saltasaurines have numerous small foramina on the centrum and neural arch that lead to complexes of small pneumatic camellae, giving their vertebrae honeycomb cross-sections. So caudal pneumaticity in diplodocines and saltsaurines is convergent in its presence and extent but clade-specific in its development. Pneumaticity doesn’t get much cooler than that.

Pneumatic ilia in saltasaurines. Cerda et al. (2012: fig. 3).

But it does get a little cooler. Because the stuff in the rest of the paper is even more mind-blowing. Cerda et al. (2012) go on to describe and illustrate–compellingly, with photos–pneumatic cavities in the ilia, scapulae, and coracoids of saltasaurines. And, crucially, these cavities are connected to the outside by pneumatic foramina. This is important. Chambers have been reported in the ilia of several sauropods, mostly somphospondyls but also in the diplodocoid Amazonsaurus. But it hasn’t been clear until now whether those chambers connected to the outside. No patent foramen, no pneumaticity. It seemed unlikely that these sauropods had big marrow-filled vacuities in their ilia–as far as I know, all of the non-pneumatic ilia out there in Tetrapoda are filled with trabecular bone, and big open marrow spaces only occur in the long bones of the limbs. And, as I noted in my 2009 paper, the phylogenetic distribution of iliac chambers is consistent with pneumaticity, in that the chambers are only found in those sauropods that already have sacral pneumaticity (showing that pneumatic diverticula were already loose in their rear ends). But it’s nice to have confirmation.

So, the pneumatic ilia in Rocasaurus, Neuquensaurus, and Saltasaurus are cool because they suggest that all the other big chambers in sauropod ilia were pneumatic as well. And for those of you keeping score at home, that’s another parallel acquisition in Diplodocoidea and Somphospondyli (given the apparent absence of iliac chambers in Camarasaurus and the brachiosaurids, although maybe we should bust open a few brachiosaur ilia just to be sure*).

* I kid, I kid.**

** Seriously, though, if you “drop” one and find some chambers, call me!

Pectoral pneumaticity in saltasaurines. Cerda et al. (2012: fig. 2).

But that’s not all. The possibility of pneumatic ilia has been floating around for a while now, and most of us who were aware of the iliac chambers in sauropods probably assumed that eventually someone would find the specimens that would show that they were pneumatic. At least, that was my assumption, and as far as I know no-one ever floated an alternative hypothesis to explain the chambers. But I certainly did not expect pneumaticity in the shoulder girdle. And yet there they are: chambers with associated foramina in the scap and coracoid of Saltasaurus and in the coracoid of Neuquensaurus. Wacky. And extremely important, because this is the first evidence that sauropods had clavicular air sacs like those of theropods and pterosaurs. So either all three clades evolved a shedload of air sacs independently, or the basic layout of the avian respiratory system was already present in the ancestral ornithodiran. I know where I’d put my money.

There’s loads more interesting stuff to talk about, like the fact that the ultra-pneumatic saltasaurines are among the smallest sauropods, or the way that fossae and camerae are evolutionary antecedent to camellae in the vertebrae of sauropods, so maybe we should start looking for fossae and camerae in the girdle bones of other sauropods, or further macroevolutionary parallels in the evolution of pneumaticity in pterosaurs, sauropods, and theropods. Each one of those things could be a blog post or maybe a whole dissertation. But my mind is already thoroughly blown. I’m going to go lie down for a while. Congratulations to Cerda et al. on what is probably the most important paper ever written on sauropod pneumaticity.

References

• Cerda, I.A., Salgado, L., and Powell, J.E. 2012. Extreme postcranial pneumaticity in sauropod dinosaurs from South America. Palaeontologische Zeitschrift. DOI 10.1007/s12542-012-0140-6
• Janensch, W. 1947. Pneumatizitat bei Wirbeln von Sauropoden und anderen Saurischien. Palaeontographica, Supplement 7, 3:1–25.
• Osborn, H. F. 1899. A skeleton of Diplodocus. Memoirs of the American Museum of Natural History 1:191–214.

This is the Brontosaurus that I grew up with:

It’s by Kenyon Shannon, found on page 14 of The How And Why Wonder Book of Dinosaurs (Geis 1960). I call it Brontosaurus rather than Apatosaurus because this outdated rendition is forever tied to the outdated name in my mind.

It would be terribly easy to pick holes in this representation — the completely wrong head, the bizarre croc-like eyes, the incorrect attitude of the head, the tubular shape and much too thin profile of the neck, the full set of manual unguals and so on. But the part that’s most shocking to me is just how darned fat it is.

Even given that Apatosaurus was among the most robustly build of sauropods — certainly the most robust diplodocoid — how wrong is that super-fat forearm? Here, for comparison, is an Apatosaurus humerus:

Right humerus of Apatosaurus ajax NSMT-PV 20375 in (left to right) anterior, medial, lateral and posterior views, and (top to bottom) proximal and distal views. From Upchurch er al. (2005:fig. 5)

And here is the lower arm:

Right forearm of Apatosaurus ajax NSMT-PV 20375. A: “anterior” (more like anterolateral) view with ulna to left, radius to right; B: “posterior” (more like posteomedial) view with radius to left, ulna to right; C; proximal view; D: distal view.

Put them together and you can get some impression of the proportions of the complete forelimb:

In short: it’s a solidly build animal; but the Shannon depiction that we started with is not merely solid, it’s what we refer to as “a lardy bloater”. Just say no.

References

• Geis, Darlene. 1960. The How and Why Wonder Book of Dinosaurs. Price Stern Sloan, Los Angeles. 48 pages. ISBN: 0-8431-4250-2.
• Upchurch, Paul, Yukimitsu Tomida, and Paul M. Barrett.  2005.  A new specimen of Apatosaurus ajax (Sauropoda: Diplodocidae) from the Morrison Formation (Upper Jurassic) of Wyoming, USA.  National Science Museum Monographs No. 26.  Tokyo.  ISSN 1342-9574.

In a comment on the previous post, Steve P. asked whether “Apatosaurus” minimus might not be a Apatosaurus specimen after all — particularly, an Apatosaurus ajax individual resembling NSMT-PV 20375, the one in the National Science Museum, Tokyo, that Upchurch et al. (2005) so lavishly monographed.

Initially, I dismissed this idea out of hand, because the “Apatosaurus” minimus sacrum-pelvis complex is so very different to that of the “Brontosaurus” illustrated by Hatcher (1903: fig. 4), as seen in an earlier post. But on going back to the Upchurch et al. monograph I realised that their sacrum-ilium complex is very different from Hatcher’s. Here it is, cleaned up from scans and re-composed in the same format as the Camarasaurus and “Apatosaurus” minimus from last time, for easy comparison.

Sacrum and fused ilia of Apatosaurus ajax NSMT-PV 20375. Top row: dorsal view with anterior to left. Middle row, left to right: anterior, right lateral (reversed), posterior. Bottom row: ventral view with anterior to left. Modified from Upchurch et al. (2005: plate 4 and text-figure 9).

Here’s Hatcher’s “Brontosaurus” illustration (from his plate 4) again:

I’m not sure what to make of this. The Tokyo Apatosaurus seems to be intermediate in some respects between Hatcher’s specimen and “Apatosaurus” minimus.

One important difference is that the neural spines are much taller in Hatcher’s illustration than in the Tokyo Apatosaurus. Could that be ontogenetic? (IIRC the Tokyo individual is subadult). Or are they in fact different species? Or is it just individual variation?

I don’t know. Anyone?

References

• Hatcher, J.B. 1903. Osteology of Haplocanthosaurus with description of a new species, and remarks on the probable habits of the Sauropoda and the age and origin of the Atlantosaurus beds; additional remarks on Diplodocus. Memoirs of the Carnegie Museum 2:1-75.
• Upchurch, Paul, Yukimitsu Tomida, and Paul M. Barrett. 2005. A new specimen of Apatosaurus ajax (Sauropoda: Diplodocidae) from the Morrison Formation (Upper Jurassic) of Wyoming, USA. National Science Museum Monographs No.26. Tokyo.

Upchurch et al. (2005)

We’re off to Oxford next week for SVPCA, so things may be quiet around here for a few days. Catch you on the flip side.

Another blast from the past:

Like the recent Compsognathus, this is a card from the “Flesh” card-game that was printed across several progs (issues) of the comic 2000 AD in 1977. This one is from the back cover of Prog 10. (Click through the picture for the whole back cover.)

What’s interesting about this one is how very flagrant a rip-off it is of Rudolph Zallinger’s 1960 painting of Brontosaurus being attacked by Allosaurus:

I know this painting best from Dinosaurs and other Prehistoric Reptiles, a 1966 book that I had as a boy, and which I believe is the same thing as the Giant Golden Book of Dinosaurs. Here is a high-resolution scan of my copy of that book, pages 24-25. (Click through for 5472 by 3669 version.)

And while I’m here, I may as well throw in my scan of the “Brachiosaurus” (i.e. Giraffatitan)on pages 20-21. (Click through for 5431 by 3162 version.)

I will leave it to others to point out which other classic piece of sauropod art this one plagiarises.

A few months ago, Matt and Darren saw a picture someone had done of an Apatosaurus with huge neck-flaps. Since they, they’ve tried to find it again but without success. Then, happily, I stumbled across it in this All Yesterdays review, so here it is:

Unfortunately, I can’t tell you much about it. I know it’s the work of Emiliano Troco, but I’ve not been able to find his web-site, nor a description of the piece, nor a version in a decent resolution. So all we have to go on at the moment is this thumbnail. If you know more, please leave a comment!

Is it credible? Who’s to say? The one thing we know for certain about Apatosaurus is that it had truly crazy cervical vertebrae, unlike those of any other animal. In our recent arXiv paper, we wrote:

It is difficult to see the benefit in Apatosaurus excelsus of cervical ribs held so far below the centrum – an arrangement that seems to make little sense from any mechanical perspective, and may have to be written off as an inexplicable consequence of sexual selection or species recognition.

It certainly seems to have been doing something weird with its neck. It’s no obvious why big flaps like these would require honking great cervicals ribs to hang down from, but maybe it was swinging them around or something?

[We've featured bizarrely ornamented sauropods here before, notably Brian Engh's pouch-throated Sauroposeidon.]

Because it’s doing a hell of an impression of one, if not. It’s got the huge cervical rib loops (wings), bifurcated neural spine (top fins), and even a condyle on the front of the centrum (cockpit pod). About all it’s missing are the zygapophyses and the cervical ribs themselves.

Some actual Apatosaurus cervicals for comparison, from previous posts:

Apatosaurus ajax NSMT-PV 20375, cervical vertebrae 3, 6 and 7 in anterior and posterior views. Modified from Upchurch et al. (2005: plate 2)

Apatosaurus parvus CM 563/UWGM 15556 cervicals 7, 5, 4 and 3 in anterior and right lateral views, from Gilmore (1936:pl. 31)

Various Apatosaurus cervicals–see Wedel and Sanders (2002) for specimen numbers and sources.

And of course Mike’s magisterial work photographing the Apatosaurus ajax holotype YPM 1860 cervical:

More on the Umbaran Starfighter here.

For other Star Wars/paleontology crossovers, please see:

The sauropods of Star Wars

The sauropods of Star Wars: Special Edition

and–mostly as shameless self-promotion since the paleo link is pretty tenuous:

Tales of the Flaming Vagabond

References

• Gilmore, C.W. 1936. Osteology of Apatosaurus with special reference to specimens in the Carnegie Museum. Memoirs of the Carnegie Museum 11:175-300.
• Upchurch, P., Tomida, Y., and Barrett, P.M. 2005. A new specimen of Apatosaurus ajax (Sauropoda: Diplodocidae) from the Morrison Formation (Upper Jurassic) of Wyoming, USA. National Science Museum Monographs No. 26. Tokyo. ISSN 1342-9574.
• Wedel, M.J., and Sanders, R.K. 2002. Osteological correlates of cervical musculature in Aves and Sauropoda (Dinosauria: Saurischia), with comments on the cervical ribs of Apatosaurus. PaleoBios 22(3):1-6.

Yesterday, Matt showed you this starship from the Star Wars universe:

And asked whether it’s based on a cervical vertebra of Apatosaurus.

Absolutely it is. It can’t be just a coincidence. Matt showed a lot of useful orthogonal views of various Apatosaurus cervicals in the last post, but here’s a a nice informative oblique view which is similar (though not identical) to that of the Umbaran ship:

Apatosaurus ajax holotype YPM 1860, cervical vertebra of unspecified position but probably from around the middle of the neck, in left anterolateral view. This is the same vertebra that appears in the last three photos in Matt’s post.

(Because the vertebra photo was taken from higher up than the starfighter image, the condyle/cockpit appears lower on the vertebra. That is basically an effect of perspective rather than a difference in proportions.)

The questions for me are twofold: which Apatosaurus vertebra is it based on, and who did it?

What vertebra is it based on?

In some ways, the cervical that it most resembles is this classic: C?8 of the Apatosaurus excelsus holotype YPM 1980:

This one resembles the starfighter in the very deep cervical rob loops — deep even for Apatosaurus — and in the small, high condyle. It also resembled the ship in the absence of neural-spine metapophyses (due to breakage, not taxonomically significant variation, alas). The result of their absence is that the “upper wings” (i.e. postzygapophyseal rami) are swept up, out and back, as in the ship.

But in other respects it’s very different — notably the very elongate prezyg rami (an effect exaggerated by the breakage) and the more or less parallel trajectories of the top and bottom margins of the loop.

Another candidate would be the one that appears in the top left part of figure 7 (“the freak gallery”) from our recent neck-anatomy paper on arXiv:

This on is rather bulky for a model for the ship, but does have a less wrong shape of the cervical rib loops. And the damage that blew off both the prezygs and the metapophyses leaves the isolated “wings” on the top, just as in the ship.

I think the best model I can find for the starfighter is probably C8 of the Apatosaurus louisae holotype CM 3018, which Gilmore illustrated beautifully in his 1936 monograph but which unfortunately I only have as this bad scan:

It has good, deep cervical-rib loops; a definite bend from the fairly lateral upper part to the more ventrally inclined lateral part; a high, fairly small condyle; and a definite bulges where the parapophysis fuses with the cervical ribs, corresponding to the weapons pods of the starfighter.

And yet, and yet …

I can’t shake the feeling that I’ve seen another Apatosaurus vertebra somewhere that is a more or less perfect fit for the ship. But I can’t remember where I saw it. Come to that, I can’t think what specimen it could be from, if not one of those that Matt and I have shown in these posts.

Anyone?

Whose work is it?

The other mystery is — whose work is this design, and where did he or she get the shape from? In a comment on the last post, I said to Matt that “one can hardly help but suspect that Jarrod did it on your instruction”. (Jarrod is an old friend of Matt’s who works in digital effects for film and TV.) But  Matt insists it’s none of his doing — and I must say that if it had been in any way his work, he would have been shouting about it long before now.

So how did it happen?

Anyone know?

Just sayin’:

vs.

(From here.)

A couple of days ago, a paper by Tschopp and Mateus (2012) described and named a new diplodocine from the Morrison Formation, Kaatedocus siberi, based on a beautifully preserved specimen consisting of a complete skull and the first fourteen cervical vertebrae.

Unfortunately, the authors chose to publish their work in the Journal of Systematic Palaeontology, a paywalled journal, which means that most of you reading this will be unable to read the actual paper — at least, not unless you care enough to pay £27 for the privilege.

So you’ll just have to take my word for it when I tell you that it’s a fine, detailed piece of work, weighing in at 36 pages. It features lavish illustrations of the skull, but we won’t trouble you with those. The vertebrae are illustrated rather less comprehensively, though still better than in most papers:

Tschopp and Matteus (2012: figure 9). A, Photograph and B, drawings of the mid-cervical vertebrae of the holotype of Kaatedocus siberi (SMA 0004). Photograph in lateral view and to scale, CV 8 shown in the drawings is indicated by an asterisk. Drawings of CV 8 (B) in dorsal (1), lateral (2), ventral (3), posterior (4) and anterior (5) views. Scale bars = 4 cm.

It should be immediately apparent from these lateral views that the vertebra are rather Diplodocus-like. But the hot news is that there is a great raft of free supplementary information, including full five-orthogonal-view photos of all fourteen vertebrae!

Here is just one of them, C6, in glorious high resolution (click through for the full awesome):

Now, folks, that is how to illustrate a sauropod in 2012! The goal of a good descriptive paper is to be the closest thing possible to a proxy for the specimen itself, and you just can’t do that if you don’t illustrate every element from multiple directions. By getting this so spectacularly right, Tschopp and Matteus have made their paper the best illustrated sauropod descriptions for 91 years. (Yes, I am talking about Osborn and Mook 1921.)

It’s just a shame that all the awe-inspiring illustrations are tucked away in supplementary information rather than in the paper itself. Had the paper been published in a PLOS journal, for example, all the goodness could have been in one place, and it would all have been open access.

Is Kaatedocus valid?

There’s a bit of a fashion these days for drive-by synonymisation of dinosaurs, and sure enough no sooner had Brian Switek written about Kaatedocus for his new National Geographic blog than comments started cropping up arguing (or in some cases just stating) that Kaatedocus is merely Barosaurus.

It’s not. I spent a lot of time with true Barosaurus cervicals at Yale this summer, and those of Kaatedocus are nothing like them. Here is Tschopp and Mateus’s supplementary figure of C14:

And here is a posterior vertebra — possibly also C14 — of the Barosaurus holotype YPM 429, in dorsal and right lateral views:

Even allowing for a certain amount of post-mortem distortion and “creative” restoration, it should be immediately apparent that (A) Barosaurus is much weirder than most people realise, and (B) Kaatedocus ain’t it.

There may be more of a case to be made that Kaatedocus is Diplodocus — but that’s the point: it there’s a case, then it needs to be actually made, which means a point-by-point response to the diagnostic characters proposed by the authors in their careful, detailed study based on months of work with the actual specimens.

There seems to be an idea abroad at the moment that it’s somehow more conservative or sober or scientific to assume everything is a ontogenomorph of everything else — possibly catalysed by the Horner lab’s ongoing “Toroceratops” initiative and subsequent cavalier treatment of Morrison sauropods — maybe even by the Amphidocobrontowaassea paper. Folks, there is no intrinsic merit in assuming less diversity. Historically, the Victorian sauropod palaeontologists of England did at least as much taxonomic damage by assumptions of synonymy (everything’s Cetiosaurus or Ornithopsis — whatever that is) as they did by raising new taxa. The thing to do is find the hypothesis best supported by evidence, not presupposing that either splitting or lumping is a priori the more virtuous course.

Sermon ends.

Morrison sauropod diversity

As we’ve pointed out a few times in our published work, sauropod diversity in the Kimmeridgian-Tithonian in general, and in the Morrison Formation in particular, was off-the-scale crazy. There’s good evidence for at least a dozen sauropod genera in the Morrison, and more than fifteen species. Kaatedocus extends this record yet further, giving us a picture of an amazing ecosystem positively abundant with numerous species of giant animals bigger than anything alive on land today.

Sometimes you’ll hear people use this observation as a working-backwards piece of evidence that Morrison sauropods are oversplit. Nuh-uh. We have to assess taxonomy on its own grounds, then see what it tells us about ecosystem. As Dave Hone’s new paper affirms (among many others), Mesozoic ecosystem were not like modern ones. We have to resist the insidious temptation to assume that what we would have seen in the Late Jurassic is somehow analogous to what we see today on the Serengeti.

Hutton’s (or Lyell’s) idea that “the present is the key to the past” may be helpful in geology. But despite its roots as a branch of the discipline, the palaeontology we do today is not geology. When we’re thinking about ancient ecosystems, we’re talking about palaeobiology, and in that field the idea that the present is the key to the past is at best unhelpful, at worst positively misleading.

Sermon ends.

But isn’t the Kaatedocus holotype privately owned?

You’ve had two sermons already, I’m sure we can all agree that’s plenty for one blog post. I will return to this subject in a subsequent post.

Sermon doesn’t even get started.

References

Osborn, Henry Fairfield, and Charles C. Mook. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3:247-387, and plates LX-LXXXV.

Tschopp, Emanuel, and Octávio Mateus. 2012. The skull and neck of a new flagellicaudatan sauropod from the Morrison Formation and its implication for the evolution and ontogeny of diplodocid dinosaurs. Journal of Systematic Palaeontology. doi:10.1080/14772019.2012.746589

We’ve gotten a few complaints this year about how much time we’ve spent talking about open access instead of dinosaurs. Brian Engh is in the more-dinosaurs faction, but he doesn’t just whinge about our non-dino coverage, he does something about it. He writes:

here’s the deal:

when sv-pow becomes more discussion about human things and less discussion about ancient monsters i bombard your email with whatever crappy unfinished dino-drawings i got lying around. you have my permission to do with these as you wish, however if they end up on SV-POW i will be happy and feel i’m doing my part to combat humans.

Awesome.

Happy new year, sauropod fans. Enjoy this rearing Dicraeosaurus courtesy of Brian.

A few weeks ago, we were considering the bizarre Umbaran Starfighter from The Clone Wars, and its extraordinary similarity to an Apatosaurus cervical:

In a comment, Kyle Hartshorn suggested:

The Clone Wars “Plan of Dissent” episode concept art gallery features some conceptart of the starfighter, with the artist initials “RGC”. I believe that’s Russell G. Chong, one of the show’s art designers. You can find his contact information at his website.

He might not be the one who came up with the design–that art looks too polished to be an early concept—but he would probably know who did.

Nice detective work.

Here’s some of that concept art:

I found an email address for Chong, and wrote to him:

Hi, Russell. Matt Wedel and I are palaeontologists, specialising in the neck skeletons of sauropod dinosaurs. Matt noticed that the Umbaran Starfighter seems to be closely modelled on an Apatosaurus vertebra — see these two blog posts.

We’re trying to figure out whether this is deliberate as it appears, or just a crazy coincidence. One of our commenters believes the design might be yours — can you comment?

Russell was on vacation for a while, but wrote back a couple of days ago. I quote his message with permission:

Hey Mike,

I’ve been away on vacation and I just found this email.

That’s pretty trippy that the vertebrate looks so similar.

It’s also pretty trippy that palaeontologists are watching clone wars.

I did have the final design for this ship but I didn’t do the original ‘inspirational’ sketch. George often goes thru a book of older sketches from the movies and randomly picks stuffout for us to ‘fix’ or ‘cleanup’. My input was to give it more extreme character so I sharpened some edges and made the fins more pronounced, figured out how to land it, design a working cockpit, and then gave it final color. I don’t know who did the original but I don’t recall any notation saying they based it on the Aptosaurus vertebra so I have to say, yes, it’s coincidental.

Similarities are really odd!

Russell also gave me a lead on where I might look for the original designer. I’ll follow that up, and report back in a later post.

The last time we reported on the Apatosaurus cervical-shaped Umbaran Starfight from The Clone Wars, we’d heard from the concept artist Russell G. Chong, who had done the final design on the startfighter, and who told that he wasn’t aware of a sauropod original to the design.

But Russell was not the original designer. He put me onto David Hobbins, who had generated the original rough design that he’d honed. I wrote to David early in January to find out more:

Date: 4 January 2013 22:57
From: Mike Taylor <mike@indexdata.com>
To: David Hobbins
Subject: Is the Umbaran Starfighter from Clone Wars inspired by an Apatosaurus vertebra?

Hi, David. You don’t know me, but I was put onto you by Russell G. Chong. Matt Wedel and I are palaeontologists, specialising in the neck skeletons of sauropod dinosaurs. Matt noticed that the Umbaran Starfighter seems to be closely modelled on an Apatosaurus vertebra – see these four blog posts [1, 2, 3, 4] (You don’t need to read them all, the first one gives the flavour.)

We’re trying to figure out whether this is deliberate as it appears, or just a crazy coincidence. The design was finished by Russell, but he wasn’t its originator, and thinks you might be the man — or know who was.

Can you comment?

David wrote back a few days ago. Here is his message (reproduced with permission):

Date: 16 January 2013 15:58
From: David Hobbins
To: Mike Taylor <mike@indexdata.com>
Subject: Re: Is the Umbaran Starfighter from Clone Wars inspired by an Apatosaurus vertebra?

Hi Mike,

I read the blog posts — interesting commentary! I remember the original design perfectly, and you are absolutely right, I was inspired by the skeletal forms of dinosaur bones. It’s pretty cool that you were able to discern that!

I’ve looked for the original photo I took of the vertebra, but it seems to be lost in the archives. I can’t confirm that it was of an Apatosaurus vertebra exactly, but it’s quite possible. I was at the California Academy of Sciences in San Francisco and took a number of photos that day.

Nature renders complex and beautiful designs; I often find myself drawn to studying organic forms and patterns as inspiration in my vehicle designs.

And he clarified in a subsequent message:

Date: 16 January 2013 20:51
From: David Hobbins
To: Mike Taylor <mike@indexdata.com>
Subject: Re: Is the Umbaran Starfighter from Clone Wars inspired by an Apatosaurus vertebra?

The bone was presented as a single vertebra on public display. I’m uncertain that the collection will be the same now. I took the photo back in 2007 just before the California Academy of Sciences moved into their present location in Golden Gate Park. I’m sure there have been a lot of changes since.

I will continue the search for the original photo. Will let you know right away if I find anything.

So this is great news! Matt’s initial hypothesis is confirmed from the horse’s mouth. All we need to wrap this investigation up is a photo of the original exhibit.

Does anyone out there have a photo of an isolated Apatosaurus vertebra that was on exhibit at the California Academy of Sciences in San Francisco before it moved to Golden Gate Park? Or does anyone know someone who works at CAoS that we could talk to?

Update (later the same day)

This discovery has been covered at sci-fi fan site io9!

The rest of the posts in what we’re calling the Umbaran Starfighter Saga:

• Was the Umbaran Starfighter from Clone Wars inspired by an Apatosaurus vertebra? (Dec. 13, 2012)
• Heck, yes, the Umbaran Starfighter from Clone Wars was inspired by an Apatosaurus vertebra (Dec. 15, 2012)
• Umbaran Starfighter vs. Apatosaurus cervical, round 3 (Dec. 16, 2012)
• Umbaran Starfighter update (Jan. 4, 2013)

Here are cervical vertebrae 2-15 of Diplodocus carnegii in right lateral view, from Hatcher (1901: plate 3). Click to embiggen, and then just gaze in wonder for a while.

Wouldn’t that look smashing, printed, framed, and hanging on the wall?

I wonder if I will ever stop finding new interesting things to think about in this image. I doubt it.

(For a bit o’ fair-and-balanced, remember that this neck may not be complete, and that some of the neural spines are sculptures.)

Thanks to Mike for the scan.

Reference

Hatcher, John Bell. 1901. Diplodocus (Marsh): its osteology, taxonomy, and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1:1-63.

Apatosaurus lousiae 1/12 scale skeleton in left antero-lateral view, modelled by Phil Platt, assembled and photographed by Brant Bassam. Image courtesy of BrantWorks.com.

Today our paper on sauropod neck anatomy is formally published in PeerJ.

There’s not much new to say about the paper, since we posted it to arXiv last year and told the world about it then (post 1, post 2, post 3). Although a lot more attractive in form, this version is almost identical in content, modulo some changes requested by the PeerJ reviewers, and some changes to the figures to make sure every part of every figure was CC BY or otherwise in the public domain. Many thanks to everyone who gave us permission to use their images, especially Scott Hartman, who is rapidly getting to be the go-to person for this sort of thing just by doing good work and being a nice guy.

The big news, of course, is not the paper but the outlet. We’re excited about PeerJ because it promises to be a game-changer, for lots of reasons. Mike has a nice article in the Guardian today about the thing that is getting the most attention, which is the cost to publish. I blogged about it last fall, when I bought the max bling lifetime membership–for about one-tenth of the OA publication fee for a single article from one of the big barrier-based publishers.

Apatosaurus lousiae 1/12 scale skeleton in left lateral view, modelled by Phil Platt, assembled and photographed by Brant Bassam. Image courtesy of BrantWorks.com.

Then there’s turnaround time: for our paper, a mere 72 days, including both submission day (Dec. 3) and publication day (Feb. 12). My fastest turnaround before this was 73 days for my sauropod nerve paper, but that was from submission to posting of the accepted manuscript, not publication of the final version of record. Prior to that I’d had a couple of papers published within six months of submission, but that was definitely the exception rather than the rule. And sadly, I’ve had several situations now where a paper  languished in peer review for six months.

And that brings me to peer review–the real “peer” in PeerJ. When you sign up a lifetime membership, you agree to review one paper a year for them to keep your membership active. Certainly not a crushing amount of work, especially since I’ve been averaging 5 or 6 reviews a year for much less congenial outlets.

I’ve seen this from both sides now, since I was tapped to review a manuscript for PeerJ back in December. The first thing I liked is that they asked for the review back within 10 days. That’s just about right. I can see a thorough review taking three days (not working straight through, obviously, but taking time to carefully read, digest, look stuff up, and compose the review), and a busy academic maybe needing a week to find that kind of time. If one is too busy to get it done within 10 days, better to just be honest, say that, and decline the review. There is certainly no reason to let reviewers have manuscripts for four to six weeks, let alone the three to four months that was standard when I got into this business.

Apatosaurus lousiae 1/12 scale skeleton in dorsal view, modelled by Phil Platt, assembled and photographed by Brant Bassam. Image courtesy of BrantWorks.com.

The second thing I liked is that they gave me the option to sign the review (which is almost always implicitly present, whether reviewers take advantage of it or not), and they gave the authors of the manuscript the option to publish my review alongside the paper. I love that. It means that, for the first time ever*, maybe the time and effort I put into the review will not disappear without a trace after I send it off. (It is astonishingly wasteful that we write these detailed technical critiques and then consign them to never be seen by any but a handful of people.) And it had a salutary effect on my reviewing. I always strive to be thoughtful and constructive in my reviews, but the knowledge that this review might be published for the world to see made me a lot more careful, both in what I said and how I said it. Hopefully, the authors I reviewed for will opt to publish my review, so you will be able to judge for yourself whether I succeeded–I’ll keep you posted on that.

* There are a bare handful of other outlets that publish reviews alongside papers, but I’ve never been tapped to review for them, so this was my first experience with a peer review that might be published.

Naturally Mike and I took the maximum openness option and had our reviews and all the rest of the paper trail published alongside our paper, and I intend to do this every time from here on out. As far as I’m concerned, the benefits of open peer review massively outweigh those from anonymous peer review. There will always be a few jackasses in the world, and if openness itself doesn’t force better behavior out of them, at least they’ll be easier to identify and route around in an open world. Anyway, to see our reviews, expand ‘Author and article information’ at the top of this page, and click the link in the green box that says, “The authors have chosen to make the review history of this article public.”

One happy result of this will manifest in just a few weeks. Bunny-wrangler and sometime elephant-tracker Brian Kraatz and I co-teach a research capstone course for the MS students at WesternU, and one of the things we cover is peer review. Last year I had to dig up a couple of my reviews that were sufficiently old and anonymous that no harm could come from sharing them with the students, but even so, they only got half the story, because I no longer had the manuscripts and couldn’t have shared them if I had. This year I’ll be able to point the students at PeerJ and say, “Go look. There’s the back-and-forth. That’s how we do this. Now you know.”

Science, process and product alike, out in the open, freely available to the world: that’s why I’m proud to be a member of PeerJ.

(And I haven’t even mentioned the preprint server, or all the thought the PeerJ team put into the graphic design of the papers themselves, or how responsive the production team was in helping us get the finished product just right, or….)

Apatosaurus lousiae 1/12 scale skeleton in left postero-lateral view, modelled by Phil Platt, assembled and photographed by Brant Bassam. Image courtesy of BrantWorks.com.

The pictures in this post have nothing to do with our paper, other than showing off one of the beautiful products of the factors we discuss therein. The images are all borrowed from Brant Bassam’s amazing BrantWorks, which we will definitely be discussing more in the future. Explicit permission to reproduce the images with credit can be found on this page. Thanks, Brant!

In our PeerJ neck-anatomy paper, we speculated on how long individual cervical vertebrae might have grown. Here is the relevant section:

Mere isometric scaling would of course suffice for larger animals to have longer necks, but Parrish (2006, p. 213) found a stronger result: that neck length is positively allometric with respect to body size in sauropods, varying with torso length to the power 1.35. This suggests that the necks of super-giant sauropods may have been even longer than imagined: Carpenter (2006, p. 133) estimated the neck length of the apocryphal giant Amphicoelias fragillimus Cope, 1878 as 16.75 m, 2.21 times the length of 7.5 m used for Diplodocus, but if Parrish’s allometric curve pertained then the true value would have been 2.21^1.35 = 2.92 times as long as the neck of Diplodocus, or 21.9 m; and the longest single vertebra would have been 187 cm long.

Now this speculation is shot through with uncertainty. As we’ve discussed before, at length, all estimates of Amphicoelias fragillimus length and mass are wildly speculative; and Parrish’s allometry result was extrapolated from an unconvincingly small data set. But still, these numbers are probably the best we can do with what we have.

In Diplodocus carnegii, C14 is the longest individual vertebra at 642 mm long (Hatcher 1901, p. 38). The Amphicoelias:Diplodocus size ratio of 2.21 from Carpenter and the neck allometry constant of 1.35 from Parrish suggest that the corresponding vertebra in the big boy would have been 2.92 times as long as that 642 mm, hence the 187 cm that we reported.

So what does a 187-cm long cervical vertebra look like? Scaling up from the Diplodocus carnegii C14 in Hatcher (1901: plate III) and using my good self as a scalebar, here it is:

I find that just a little bit frightening. In more ways than one.

References

• Carpenter, Kenneth. 2006 Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus (Cope, 1878). New Mexico Museum of Natural History and Science Bulletin 36:131.
• Cope, Edward D. 1878. Geology and paleontology: a new species of Amphicoelias. The American Naturalist 12:563.
• Hatcher, Jonathan B. 1901. Diplodocus (Marsh): its osteology, taxonomy and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1:1-63 and plates I-XIII.
• Parrish, J. Michael. 2006. The origins of high browsing and the effects of phylogeny and scaling on neck length in sauropodomorphs. pp 201-224 in: Amniote paleobiology, University of Chicago Press, Chicago.

If you found the hypothetical Amphicoelias fragillimus cervical in a recent post a bit too much to swallow, I won’t blame you. But how big do we know Morrison diplodocoid cervicals got?

The longest centrum of any specimen of anything, anywhere, is that of the cervical vertebra BYU 9024 that’s part of the Supersaurus vivianae holotype. It’s 138 cm long, which means that composited at scale with an MTSRSU, it looks like this:

This is not hypothetical. It’s an actual fossil.

(Just for the record: C8 of the Sauroposeidon holotype OMNH 53062 is slightly longer overall, at 140 cm. But that includes overhanging prezygapophyses. Its centrum is “only” 125 cm long.)

Well, this is rad. And adorable. Brian Switek, whom we adore, commissioned a fuzzy juvenile sauropod from Niroot, whom we adore, for his (Brian’s) upcoming book, My Beloved Brontosaurus, which I am gearing up to adore. And here is the result, which I adore, borrowed with permission from Love in the Time of Chasmosaurs.

There is much to like here. Here’s my rundown:

• Small forefeet that are the correct shape: good. Maybe too small, given that young animals often have big feet. But better too small than too big, given how often people screw this up.
• Pronounced forelimb-hindlimb disparity: win.
• Fat neck: pretty good.

In fact, let me interrupt the flow of praise here to put in Brant Bassam’s dorsal view of his mounted Phil Platt model Apatosaurus skeleton. I’ve been meaning to post about this for a while now and haven’t gotten to it, so now’s a good time: just look at how friggin’ FAT that neck is, and how it blends in with the body, and how the tail gets a lot skinnier a lot quicker (and, yeah, caudofemoralis, but not that much).  Now, go look at a bunch of life restorations of Apatosaurus–drawings, paintings, sculptures, toys, whatever–and see how many people get this wrong, by giving Apatosaurus a too-skinny neck. The answer is, damn near everyone.

Apatosaurus lousiae 1/12 scale skeleton in dorsal view, modelled by Phil Platt, assembled and photographed by Brant Bassam. Image courtesy of BrantWorks.com.

Okay, back to Niroot’s baby:

• Proportionally shorter neck and tail because it’s a juvenile: win.
• Neck wrinkles possibly corresponding to vertebrae: okay, just this once.
• Greenish fuzz possibly functioning as camouflage: We-ell…

Yes, it’s true that all of the known sauropod skin impressions show scales, not fuzz. But. We don’t have anything like full-body coverage. And I suspect that there is a collection bias against fuzzy skin impressions. Scaly skin impressions are probably easier to recognize than 3D feathery skin impressions (as opposed to feathers preserved flat as at Liaoning and Solnhofen) because the latter probably just look like wavy patterns on rock, and who is looking for feather impressions when swinging a pickaxe at a sauropod’s back end? And how many sauropods get buried in circumstances delicate enough to preserve dinofuzz anyway? Also, some kind of fuzz is probably primitive for Ornithodira, and scales do not necessarily indicate that feathers were absent because owl legs. So is this speculative? Yes. Is it out of the question? I think not. In the spirit of Mythbusters, I’m calling it ‘plausible’.

Oh, one more thing: Niroot posted this in honor of Brian Switek’s birthday. Happy birthday, Brian! (You owe me a book!)

From Jensen (1987, page 604):

“In 1985 I found the proximal third of an extremely large sauropod femur (Figs. 8A, 12A) in a uranium miner’s front yard in southern Utah.  The head of this femur is 1.67 m (5’6″) in circumference and was collected from the Recapture Creek Member of the the Morrison Formation in Utah near the Arizona border.  It is the largest bone I have ever seen.”

Jensen included not one but two figures of this immense shard of excellence. Here they are:

Jensen 1987, Figure 8

Jensen 1987, Figure 12

The specimen was heavily reconstructed, as you can see from the big wodge of unusually smooth and light-colored material in the photo. So we can’t put much stock in that part of the specimen.

Unfortunately, the only measurement of the specimen that Jensen gives in the paper is that circumference; there are no straight-line linear measurements, and the figures both have the dreaded scale bars. Why dreaded? Check this out:

As you can see, when the scale bars are set to the same size, the bones are way off (the scale bar in the drawing is 50 cm). This is not an uncommon problem. I make the Fig 8 version 30% bigger in max mediolateral width of the entire proximal end, and still 17% bigger in minimum diameter across the femoral head, as measured from the slight notch on the dorsal surface (on the right in this view).

Can we figure out which is more accurate based  on the internal evidence of the paper? For starters, the Fig 12 version is a drawing (1), that does not match the outline from the photo (2), and the hand-drawn scale bar (3) does not actually coincide with any landmarks (4), and that’s plenty of reasons for me not to trust it.

What about that circumference Jensen mentioned? Unfortunately, he didn’t say exactly where he took it, just that the head of the femur had a circumference of 1.67 meters. Is that for the entire proximal end, or for the anatomical head that fits in the acetabulum, er wot? I’m afraid the one measurement given in the paper is no help in determining which of the figures is more accurately scaled.

The obvious thing to do would be to see if this bone is in the BYU collections, and just measure the damn thing. More on that at the end of the post.

In the meantime, Jensen said that the shape of the Recapture Creek femur was most similar to the femur of Alamosaurus, or to that of Brachiosaurus among Morrison taxa, and he referred it to Brachiosauridae. So how does this thing–in either version–compare with the complete femur of FMNH P25107, the holotype of Brachiosaurus altithorax?

The Recapture Creek femur fragment compared to the complete femur of the Brachiosaurus altithorax holotype FMNH P25107

The first thing to notice is that the drawn outline from Figure 12 is a much better match for the Brachiosaurus altithorax femur–enough so that I wonder if Jensen drew it from the Recapture Creek specimen, or just traced the B.a. proximal femur and scaled it accordingly (or maybe not accordingly, since the scale bars don’t match).

But let’s get down to business: how long would the complete femur have been?

Using the scale bar in the photograph from Figure 8 (on the left in above image), I get a total femur length of 2.36 meters. Which is long, but only 7.7% longer than the 2.19-meter femur of FMNH P25107, and therefore only 25% more massive. So, 35 tonnes to Mike’s 28-tonne B.a., or maybe 45 tonnes to a more liberal 36-tonne B.a. Big, yeah, but not world-shattering.

Using the scale bar in the drawing from Figure 12 (on the right in the above image)–which, remember, is 50 cm, not 1 meter–I get a total femur length of about 1.9 meters, which is considerably smaller than the B.a. holotype. That is very much at odds with Jensen’s description of it as “the largest bone I have ever seen”, and given that we have many reasons for not trusting the scale bar in the drawing, it is tempting to just throw it out as erroneous.

So it would seem that unless Jensen got both scale bars too big, the Recapture Creek brachiosaur was at most only a shade bigger than the holotype specimen of Brachiosaurus altithorax.

But wait–is the Recapture Creek brachiosaur a brachiosaur at all? Jensen didn’t list any characters that pushed him toward a brachiosaurid ID, and I don’t know of any proximal femur characters preserved in the specimen that would separate Brachiosaurus from, say, Camarasaurus. And in fact a camarasaur ID has a lot to recommend it, in that Camarasaurus femora have very offset heads (the ball- or cylinder-like articular surface at the top end sticks out a big more to engage with the hip socket–see Figure 12 up near the top of the post), moreso than in many other Morrison sauropods, and that would make them better matches for the Recapture Creek femur photo. Here’s what the comparo looks like:

The Recapture Creek femur fragment compared with a complete femur of Camarasaurus.

I make that a 2.07-meter femur using the photo on the left, and a 1.66-meter femur using the drawing on the right. The one decent femur in the AMNH 5761 Camarasaurus supremus collection is 1.8 meters long, so these results are surprisingly similar to those for the B. althithorax comparison–the drawing gives a femur length shorter than the largest known specimens, and the photo gives a length only slightly longer. A camarasaur with a 2.07 meter femur would be 15% larger than the AMNH C. supremus in linear terms, and  assuming isometric scaling, 1.5 times as massive–maybe 38 tonnes to AMNH 5761′s estimated 25. A big sauropod to be sure, but not as big as the largest apatosaurs, and not nearly as big as the largest titanosaurs.

I have always been surprised that the Recapture Creek femur frag has attracted so little attention, given that “Dinosaur Jim” himself called it the biggest bone he had ever seen. But it appears that the lack of attention is justified–whether it was a brachiosaur or a camarasaur, and using the most liberal estimates the scale bars allow, it simply wasn’t that big.

Update about half an hour later: Okay, maybe I was a little harsh here. IF the photo scale bar is right, the Recapture Creek femur might still represent the largest and most massive macronarian from the Morrison Formation (Edit: only if it’s a brachiosaur and not a camarasaur; see this comment), which is something. I suppose I was particularly underwhelmed because I was expecting something up in OMNH 1670-to-Argentinosaurus territory, and so far, this ain’t it. I’ll be interested to see what the actual measurements say (read on).

The Moral of This Story

So, if it wasn’t that big after all, and if no-one has made a stink about it being big before now, why go to all this trouble? Well, mostly just to satisfy my own curiosity. If there was a truly gigantic brachiosaur from the Morrison, it would be relevant to my interests, and it was past time I crunched the numbers to find out.

But along the way something occurred to me: this should be a cautionary tale for anyone who gets all wound up about the possible max size of Amphicoelias fragillimus. As with A. fragillimus, for the Recapture Creek critter we have part of one bone, and at least for this exercise I was working only from published illustrations with scale bars. And as with A. fragillimus, the choice of a reference taxon is not obvious, and the size estimates are all over the place, and some of them just aren’t that big.

It always amuses me when A. fragillimus comes up and people (well, trolls) accuse us of being big ole’ wet blankets that just don’t want to believe in 200-tonne sauropods. It amuses me because it’s wrong on so many levels. Believe me, when we have our sauropod fanboy hats on, we most definitely do want to believe in 200-tonne sauropods. That would rock. But when we put our scientist hats on, wanting and belief go right out the window. We have to take a cold, hard look at the data, and especially at its limitations.

Oh, the other moral is to go buy a tape measure, and use it. Sheesh!

Coda

As I said above, the obvious thing to do would be to just track down the bone and measure it. It does still exist, it’s in the BYU collections, and Brooks Britt has kindly offered to send along some measurements when he gets time. So we should have some real answers before long (and here they are). But I wanted to work through this example without them, to illustrate how much uncertainty creeps in when trying to estimate the size of a big sauropod from published images of a single partial bone.

Reference

Jensen, J.A. 1987. What I did on my holidaysNew brachiosaur material from the Late Jurassic of Utah and Colorado. Great Basin Naturalist 47(4): 592-608.

Brachiosaurus sp. BYU 12866 c5? in left lateral view with CT slices, some corrected for distortion.

Last Tuesday Mike popped up in Gchat to ask me about sauropod neck masses.  We started throwing around some numbers, derived from volumetric estimates and some off-the-cuff guessing. Rather than tell you more about it, I should just paste our conversation, minimally edited for clarity and with a few hopefully helpful links thrown in.

BYU 12613, a posterior cervical probably referable to Diplodocus, in dorsal (top), left lateral (left), and posterior (right) views. It most closely resembles C14 of D. carnegii CM 84/94 (Hatcher 1901: plate 3) despite being less than half as large, with a centrum length of 270 mm compared to 642 mm for C14 of D. carnegii. From Wedel and Taylor (in press).

* R. McNeill Alexander (1985, 1989) did estimate the mass of the neck of Diplodocus, based on the old Invicta model and assuming a specific gravity of 1.0. Which was a start, and waaay better than no estimate at all. Still, let’s pretend that Mike meant “tried based on the actual fossils and what we know now about pneumaticity”.

The stuff about putting everything off until April is in there because we have a March 31 deadline to get a couple of major manuscripts submitted for an edited thingy. And we’ve made a pact to put off all other sciencing until we get those babies in. But I want to blog about this now, so I am.

Another thing Mike and I have been talking a lot about lately is the relation between blogging and paper-writing. The mode we’ve seen most often is to blog about something and then repurpose or rewrite the blog posts as a paper. Darren paved the way on this (at least in our scientific circle–people we don’t know probably did it earlier), with “Why azhdarchids were giant storks“, which became Witton and Naish (2008). Then last year our string of posts (starting here) on neural spine bifurcation in Morrison sauropods became the guts–and most of the muscles and skin, too–of our in-press paper on the same topic.

But there’s another way, which is to blog parts of the science as you’re doing them, which is what Mike was doing with Tutorial 20–that’s a piece of one of our papers due on March 31.

Along the way, we’ve talked about John Hawks’ model of using his blog as a place to keep his notes. We could, and should, do more of that, instead of mostly keeping our science out of the public eye until it’s ready to deploy (which I will always favor for certain projects, such as anything containing formal taxonomic acts).

And I’ve been thinking that maybe it’s time for me–for us–to take a step that others have already taken, and do the obvious thing. Which is not to write a series of blog posts and then decide later to turn it into a paper (I wasn’t certain that I’d be writing a paper on neural spine bifurcation until I had written the second post in that series), but to write the paper as a series of blog posts, deliberately and from the outset, and get community feedback along the way. And I think that the sauropod neck mass project is perfect for that.

Don’t expect this to become the most common topic of our posts, or even a frequent one. We still have to get those manuscripts done by the end of March, and we have no shortage of other projects waiting in the wings. And we’ll still post on goofy stuff, and on open access, and on sauropod stuff that has nothing to do with this–probably on that stuff a lot more often than on this. But every now and then there will be a post in this series, possibly written in my discretionary blogging time, that will hopefully move the paper along incrementally.

• Alexander, R.M. 1985. Mechanics of posture and gait of some large dinosaurs. Zoological Journal of the Linnean Society, 83(1): 1-25.
• Alexander, R.M. 1989. Dynamics of Dinosaurs and Other Extinct Giants. Columbia University Press.
• Hutchinson, J.R., Bates, K.T., Molnar, J., Allen, V., and Makovicky, P.J. 2011. A computational analysis of limb and body dimensions in Tyrannosaurus rex with implications for locomotion, ontogeny, and growth. PLoS ONE 6(10): e26037. doi:10.1371/journal.pone.0026037
• Taylor, M.P. 2009. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). Journal of Vertebrate Paleontology 29(3):787-806.
• Wedel, M.J., and Taylor, M.P. In press. Neural spine bifurcation in sauropod dinosaurs of the Morrison Formation: ontogenetic and phylogenetic implications. PalArch’s Journal of Vertebrate Paleontology.
• Witton, M.P., and Naish, D. 2008. A reappraisal of azhdarchid pterosaur functional morphology and paleoecology. PLoS ONE 3(5): e2271. doi:10.1371/journal.pone.0002271