March 23, 2010
For various arcane reasons, the SV-POW!sketeers are all neck-deep in work, so the blog may actually become somewhat more of the APOD-style picture-n-paragraph thing we originally envisioned, and less of the TetZoo-style monograph-of-the-week thing it’s often leaned toward, at least for a while.
I like it when people decorate their papers with megapixels of vertebral goodness, so here are some caudal vertebrae of the African diplodocine Tornieria, from Remes (2006:fig. 5). Click through to see the figure at its massive native resolution. And check out that pneumaticity! Really, the only question about this image is whether you can settle for just using it as your desktop background, or if you need to print out a wall-sized poster for your bedroom. So the next time you see Kristian Remes, buy him a beer for doing solid work here, on the Humbolt sauropod remount, and on pretty much everything else (including this).
Remes, K. 2006. Revision of the Tendaguru sauropod Tornieria africana (Fraas) and its relevance for sauropod paleobiogeography. Journal of Vertebrate Paleontology 26 (3): 651–669.
October 13, 2009
UPDATE December 3, 2009
I screwed up, seriously. Tony Thulborn writes in a comment below to correct several gross errors I made in the original post. He’s right on every count. I have no defense, and I am terribly sorry, both to Tony and to everyone who ever has or ever will read this post.
He is correct that the paper in question (Thulborn et al 1994) does discuss track length, not diameter, so my ranting about that below is not just immoderate, it’s completely undeserved. I don’t know what I was thinking. I did reread the paper before I wrote the post, but I got the two switched in my mind, and I assigned blame where none existed. In particular, it was grossly unfair of me to tar Tony’s careful work with the same brush I used to lament the confused hodgepodge of measurements reported in the media (not by scientists) for the Plagne tracks.
I am also sorry that I criticized the 1994 paper and implied that the work was incomplete. I was way out of line.
I regard this post as the most serious mistake in my professional career. I want very badly to somehow unmake it. I am adding corrections to the post below and striking out but not erasing my mistakes; they will stand as a reminder of my fallibility and a warning against being so high-handed and unfair in the future.
I’m sorry. I beg forgiveness from Tony, from all of our readers, and from the broader vertebrate paleontology community. Please forgive me.
You might have seen a story last week about some huge sauropod tracks discovered in Upper Jurassic deposits from the Jura plateau in France, near the town of Plagne. According to the news reports, the tracks are the largest ever discovered. Well, let’s see.
The Guardian (from which I stole the image above) says the prints are “up to 2 metres (6ft 6 in) in diameter”, but ScienceDaily says “up to 1.5 m in total diameter”. Not sure how ‘total diameter’ is different from regular diameter, but that’s science reporting for you. The BBC clarifies that, “the depressions are about 1.5m (4.9ft) wide”, which might be the key here (see below), but then mysteriously continues, “corresponding to animals that were more than 25m long and weighed about 30 tonnes.” I find it rather unlikely that a pes track 1.5 m wide indicates an animal only as big as Giraffatitan (hence this post).
So there’s some uncertainty with respect to the diameter of the tracks–half a meter of uncertainty, to be precise. But sauropod pes tracks are usually longer than wide, and a print 1.5 m wide might actually be 2 m long.
Not incidentally, Thulborn (1994) described some big sauropod tracks from the Broome Sandstone in Australia, with pes prints up to 1.5 m. Although the photos of the tracks are not as clear as one might wish, they do appear to show digit impressions and are probably not underprints. [See Tony Thulborn's comment below regarding footprints vs underprints.]
I’ll feel a lot better about the Plagne tracks when the confusion about their dimensions is cleared up and when some evidence is presented that they also are not underprints. In any case, the only dimension with any orientation cited for the Plagne tracks is the 1.5 m width reported by the BBC, so we’ll go with that. So the Plagne tracks might only tie, but not beat, Thulborn’s tracks.
…Then again, Thulborn only said that the biggest tracks were up to 150 cm in diameter. What does that mean–length? Width? Are the tracks perfect circles? Does no one who works on giant sauropod tracks know how to report measurements? These questions will have to wait, because despite the passing of a decade and a half, the world’s (possibly second-) biggest footprints–from anything! ever!–have not yet merited a follow-up paper. [Absolutely wrong and unfair; please see the apology at top and Tony Thulborn's comment below.]
Nevertheless, for the remainder of this post we’ll accept that at least some sauropods were leaving pes prints a meter and a half wide. Naturally, it occurs to me to wonder how big those sauropods were. I don’t know of any studies that attempt to rigorously estimate the size of a sauropod from its tracks or vice versa, so in the finest tradition of the internet in general and blogging in particular, I’m going to wing it.
First we need some actual measurements of sauropod feet. When Mike and I were in Berlin last fall (gosh, almost a year ago!), we measured the feet (pedes) of the mounted Giraffatitan and Diplodocus for this very purpose. The Diplodocus feet were both 59 cm wide, and the Giraffatitan feet were 68 and 73 cm wide. The Diplodocus feet are trustworthy, the Giraffatitan bits less so. Unfortunately, the pes is the second part of the skeleton of Giraffatitan that is less well known than I would like (after the cervico-dorsal neural spines). The reconstructed feet look believable, but “believability” is hard to calibrate and probably a poor predictor of reality when working with sauropods.
One thing I won’t go into is that Giraffatitan (HM SII) probably massed more than twice what Diplodocus (CM 84/94) did, but on the other hand G. bore more of its weight on its forelimbs. It would be interesting to calculate whether the shifted center of mass would be enough to even out the pressure exerted by the hindfeet of the two animals; Don Henderson may have done this already.
Anyway, let’s say for the sake of argument that the hindfeet of the mounted Giraffatitan are sized about right. The next problem is figuring out how much soft tissue surrounded the bones. In other words, how much wider was the fleshy foot–deformed under load!–than the articulated pes skeleton? I am of two minds on this. On one hand, sauropods probaby had a big heel pad like that of elephants, and it seems reasonable that the heel pad plus the normal skin, fat, and muscle might have expanded the fleshy foot considerably beyond the edges of the bones. On the other hand, the pedal skeleton is widest across the distal ends of the phalanges, and in well-preserved tracks like the one below the fleshy foot is clearly not much wider than that (thanks, Brian, for the photo!).
Bear in mind that a liberal estimate of soft tissue will give a conservative estimate of the animal’s size, and vice versa. Looking at the AMNH track pictured above, it seems that the width added by soft tissue could possibly be as little as 5% of the width of the pes skeleton. Skewing hard in the opposite direction, an additional 20% or more does not seem unreasonable for other animals (keep in mind this would only be 10% on either side of the foot). Using those numbers, Diplodocus (CM 84/94) would have left tracks as narrow as 62 cm or as wide as 71 cm. For Giraffatitan (HM SII) I’ll use the wider of the two pes measurements, because the foot is expected to deform under load and the 73 cm wide foot looked just as believable as the 68 cm foot (for whatever that’s worth). Applying the same scale factors (1.05 and 1.20) yields a pes track width of 77-88 cm.
These numbers are like pieces of legislation, or sausages: the results are more pleasant to contemplate than the process that produced them. They’re ugly, and possibly wrong. But they give us someplace to start from in considering the possible sizes of the biggest sauropod trackmakers. Something with a hindfoot track 1.5 meters wide would be, using these numbers, conservatively more than twice as big as (2.11x) the mounted Carnegie Diplodocus or 170% the size of the mounted Berlin Giraffatitan. That’s right into Amphicoelias fragillimus/Bruhathkayosaurus territory. The diplo-Diplodocus would have been 150 feet long, and even assuming a very conservative 10 tons for Vanilla Dippy (14,000L x 0.7 kg/L = 9800 kg), would have had a mass of 94 metric tons (104 short tons). The monster Giraffatitan-like critter would have been “only” 130 feet long, but with a 14.5 meter neck and a mass of 113 metric tons (125 short tons; starting from a conservative 23 metric tons for HM SII).
Keep in mind that these are conservative estimates, for both the size of the trackmakers and the masses of the “known” critters. If we use the conservative soft tissue/liberal animal size numbers, the makers of the 1.5 meter tracks were 2.4 times as big as the mounted Diplodocus or almost twice as big as the mounted Giraffatitan, in which case masses in the blue whale range of 150-200 tons become not just probable but inevitable.
Going the other way, I can think of only a handful of ways that the “conservative” trackmaker estimates might still be too big:
First, the pes of Giraffatitan might have been bigger than reconstructed in the mounted skeleton. Looking at the photo above, I can image a pes 10% wider that wouldn’t do any violence to the “believability” of the mount. That would make the estimated track of HM SII 10% wider and the estimated size of the HM-SII-on-steroids correspondingly smaller. But that wouldn’t affect the scaled up Diplodocus estimate, and the feet of Giraffatitan would have to be a LOT bigger than reconstructed to avoid the reality of an animal at least half again as big as HM SII.
Second, the amount of soft tissue might have been greater than even the liberal soft tissue/conservative size estimate allows. But I think that piling on 20% more soft tissue than bone is already beyond what most well-preserved tracks would justify, so I’m not worried on that score. (What scares me more is the thought that the conservative estimates are too conservative, and the real trackmakers even bigger.)
Third, I suppose it is possible that sauropod feet scaled allometrically with size and that big sauropods left disproportionately big tracks. I’m also not worried about this. For one thing, when they’ve been measured sauropod appendicular elements tend to scale isometrically, and it would be weird if feet were the undiscovered exception. For another, the allometric oversizing of the feet would have to be pronounced to make much of a dent in the estimated size of the trackmakers. I find the idea of 100-ton sauropods more palatable than the idea of 70-ton sauropods with clown shoes.
Fourth, the meta-point, what if the Broome and Plagne tracks are underprints? [Please see Tony Thulborn's comment below regarding footprints and underprints.] I’ve seen some tracks-with-undertracks where the magnification of the apparent track size in the undertracks was just staggering. The Broom tracks have gotten one brief note and The Plagne tracks have not been formally described at all, so all of this noodling around about trackmaker size could go right out the window. Mind you, I don’t have any evidence that the either set are underprints, and at least for the Broome tracks the evidence seems to go the other way, I’m just trying to cover all possible bases.
So. Sauropods got big. As usual, we can’t tell exactly how big. Any one individual can leave many tracks but only one skeleton, so we might expect the track record to sample the gigapods more effectively than the skeletal record. Interestingly, the largest fragmentary skeletal remains (i.e., Amphicoelias and Bruhathkayosaurus, assuming they’re legit) and the largest tracks (i.e., Plagne and Broome) point to animals of roughly the same size.
It’s also weird that some of the biggest contenders in both categories have been so little published. I mean, if I had access to Bruhathkayosaurus or a track 1.5 m wide, you can bet that I’d be dropping everything else like a bad habit until I had the gigapod evidence properly written up. What gives? [The implication that the Broome tracks were not properly written up is both wrong and unfair; please see the apology at top.]
Finally, IF the biggest fragmentary gigapods and the biggest tracks are faithful indicators of body size, they suggest that gigapods were broadly distributed in space and time (and probably phylogeny). I wonder if these were representatives of giga-taxa, or just extremely large individuals of otherwise vanilla sauropods. Your thoughts are welcome.
Epilogue: What About Breviparopus?
It’s past time someone set the record straight about damn Breviparopus. The oft-quoted track length of 115 cm is (A) much smaller than either the Broome or Plagne tracks, and (B) the combined length of the manus and pes prints together; I know, I looked it up (Dutuit and Ouazzou 1980). Why anyone would report track “length” that way is beyond me, but what is more mysterious is why anyone was taken in by it, since the width of 50 cm (pathetic!) is usually quoted along with the 115 cm “length”, indicating an animal smaller than Vanilla Diplodocus (track length is much more likely than width to get distorted by foot motions during locomotion) [This part is wrong; see the update below.]. But people keep stumbling on crap (thanks, Guiness book!) about how at 157 feet long (determined how, exactly?) Breviparopus was possibly the largest critter to walk the planet. Puh-leeze. If there’s one fact that everyone ought to know about Breviparopus, it’s that it was smaller than the big mounted sauropods at museums worldwide. The only thing super-sized about it is the cloud of ignorance, confusion, and hype that clings to the name like cheap perfume. Here’s the Wikipedia article if you want to do some much-needed revising.
UPDATE (Nov 17 2009): The width of the Breviparopus pes tracks is 90 cm, not 50 cm. The story of the 50 cm number is typically convoluted. Many thanks to Nima Sassani for doing the detective work. Rather than steal his thunder, I’ll point you to his explanation here. Point A above is still valid: Breviparopus was dinky compared to the Broome and Plagne trackmakers.
You know I ain’t gonna raise the specter of a beast 1.7 times the size of HM SII without throwing in a photoshopped giant cervical. So here you go: me with C8 of Giraffatitan blown up to 170% (the vert, not me). Compare to unmodified original here.
- Dutuit, J.M., and A. Ouazzou. 1980. Découverte d’une piste de Dinosaure sauropode sur le site d’empreintes de Demnat (Haut-Atlas marocain). Mémoires de la Société Géologique de France, Nouvelle Série 139:95-102.
- Thulborn, R.A., T.Hamley and P.Foulkes. 1994. Preliminary report on sauropod dinosaur tracks in the Broome Sandstone (Lower Cretaceous) of Western Australia. Gaia 10:85-96.
After a completely barren 2008, this year is turning out to be a good one for me in terms of publications. Today sees the publication of Taylor (2009b), entitled Electronic publication of nomenclatural acts is inevitable, and will be accepted by the taxonomic community with or without the endorsement of the code — one of those papers where, if you’ve read the title, you can skip the rest of the paper. (Although on that score, my effort is knocked into a cocked hat by Hulke 1880.)
The message of the paper will be familiar to anyone who’s been following the Shiny Digital Future thread on this site; as indeed will parts of the text, as the paper is basically a more carefully worked and cohesive form of an argument that I’d previously spread across half a dozen blog posts, a similar number of emails on the ICZN mailing list and any number of comments on other people’s blogs. The sequence of section headings in the paper tells its own story:
And that conclusion reads as follows:
While we were looking the other way, the digital revolution has happened: everyone but the ICZN now accepts electronic publication. The Code is aﬀorded legitimacy by workers and journals only because it serves them; if we allow it to become anachronistic then they will desert it – or, at best, pick and choose, following only those provisions of the Code that suit them. Facing this reality, the Code has no realistic option but to change – to recognise electronic publishing as valid.
I have no detailed recommendations to make regarding the recently proposed amendments to the Code (ICZN, 2008). Instead I ask only this simple question: will the Code step up to the plate and regulate electronic publications as well as printed publications? Because this is the only question that remains open. Simply rejecting electronic publication is no longer a valid option.
Which I’m sure is familiar rhetoric to long-time SDF advocates, but which I hope will rattle a few cages in the more conservative ranks of specialist taxonomists. I think it’s a very promising sign that BZN, the official journal of the ICZN, is prepared to publish this kind of advocacy — they didn’t even ask me to tone down the language. I hope it indicates that in high places, they are sensing which way the wind is blowing.
Here’s a reminder of why electronic publishing is so desirable: figure 3 from Sereno et al.’s (2007) paper on the bizarre skull of the rebbachisaurid Nigersaurus:
Let me remind you that this was a paper about skulls — vertebrae were not even on the agenda. Yet click through the image (go on, you have to) and you will see them each presented in glorious high-resolution detail. That paper was of course published in the PLoS ONE — a journal that, because it is online only, can provide this quality of figure reproduction, which shames even the very best of printed journals. To see printed-on-paper figures this detailed and informative, you have to right back to Osborn and Mook (1921).
Which is why I recently decided to put my open-access money where my electronic-only mouth is, and submit the forthcoming Archbishop description to a PLoS journal. In response to a challenge from Andy Farke, I rather precipitately made a public commitment to do my level best to get that paper submitted this calendar year; and while that may not actually happen, having that goal out there can only help. Seeing that gorgeous quarry photo of Spinophorosaurus was what tipped me over the edge into wanting to use PLoS. My plan is to describe the living crap out of that bad boy, photograph every element from every direction and put the whole lot in the paper — make the paper as close as possible as a surrogate for the specimen itself. Only PLoS (to my knowledge) can do this.
(Of course, once you start wanting to include other kinds of information in your publications — videos, 3d models, etc. — then an electronic-only venue is literally your only option.)
I leave you with two photos of “Cervical P” of the Archbishop; commentary by Matt. These images are copyright the NHM since it’s their specimen.
- Hulke, J. W. 1880. Iguanodon Prestwichii, a new species from the Kimmeridge Clay, distinguished from I. Mantelli of the Wealden Formation in the S.E. of England and Isle of Wight by differences in the shape of the vertebral centra, by fewer than five sacral vertebrae, by the simpler character of its tooth-serrature, &c., founded on numerous fossil remains lately discovered at Cumnor, near Oxford. Quarterly Journal of the Geological Society 36:433-456. doi:10.1144/GSL.JGS.1880.036.01-04.36
- International Commission on Zoological Nomenclature. 2008. Proposed amendment of the International Code of Zoological Nomenclature to expand and refine methods of publication. Zootaxa 1908: 57-67, Bulletin of Zoological Nomenclature 65(4): 265-275 and various other places.
- Osborn, H. F. and C. 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. [HUGE download, but totally worth it.]
- Sereno, Paul C., Jeffrey A. Wilson, Lawrence M. Witmer, John A. Whitlock, Abdoulaye Maga, Oumarou Ide and Timothy A. Rowe. 2007. Structural Extremes in a Cretaceous Dinosaur. PLoS ONE 2 (11): e1230 (9 pages). doi:10.1371/journal.pone.0001230
- Taylor, Michael P. 2009. Electronic publication of nomenclatural acts is inevitable, and will be accepted by the taxonomic community with or without the endorsement of the Code. Bulletin of Zoological Nomenclature 66(3):205-214.
September 9, 2009
Today sees the publication of the new Journal of Vertebrate Paleontology, and with it my paper on the two best-known brachiosaurs and why they’re not congeneric (Taylor 2009). This of course is why I have been coyly referring to “Brachiosaurus” brancai in the last few months … I couldn’t bear to make the leap straight to saying Giraffatitan, a name that is going to take me a while to get used to.
But before we go lunging into the details, here is my skeletal reconstruction of Brachiosaurus proper, taken from the paper:
Those of you familiar with Greg Paul’s classic reconstruction of Giraffatitan brancai will immediately recognise that Real Brachiosaurus is rather differently proportioned, especially in having a longer torso and tail.
This paper has been in the works for some time, and while it was in review and then in press at JVP, it led a double life as Chapter 2 of my dissertation. (For most of its gestation period, the paper’s title was just “Brachiosaurus brancai is not Brachiosaurus“, and the folder where I keep all the project files is still called “bb-is-not-b”). In the end, I chickened out and went for a longer, more formal, title.
So why are the two species not congeneric? Well, it’s a long story, and you can read about the detail in the paper, but the bottom line is that virtually every bone that is known from both species differs in significant respects between them.
Of course, I am not the first to suggest that the African brachiosaurid that we know and love isn’t exactly Brachiosaurus. Credit for that goes to Greg Paul, who more than twenty years ago executed a then-new skeletal reconstruction of that species (the very same reconstruction that is now considered the classic), and in doing so noticed some differences between the American type species Brachiosaurus altithorax and the African referred species “Brachiosaurus” brancai (Paul 1988). Paul hedged his bets, though: rather than erect a new genus for the African animal, he proposed a subgenus Brachiosaurus (Giraffatitan), so that the full name of the species would become Brachiosaurus (Giraffatitan) brancai; and that of the type species would become Brachiosaurus (Brachiosaurus) altithorax. Unsurprisingly, this cumbersome nomenclatural scheme did not catch on, and I have not been able to locate a single subsequent reference to these subgenera in the literature.
That didn’t mean the idea was dead, though: three years later, George Olshevsky’s self-published mega-revision of dinosaur taxonomy proposed raising the name Giraffatitan to genus level (Olshevsky 1991). Although this genus became popular on the Internet (it cropped up, for example, in Mike Keesey’s much-lamented Dinosauricon web-site), it was almost completely ignored in the technical literature, and even Greg Paul himself subsequently seems to have reverted to using the name Brachiosaurus brancai (e.g. Paul 1994:246).
Why was the new name overlooked? Partly, I suspect, just because it’s so butt ugly — everyone knows and loves Brachiosaurus brancai, and the name itself has a definite poetry to it that Giraffatitan sorely lacks. But mostly it’s because Paul didn’t really make a case for the separation that he proposed — wrongly stating, for example, that “the caudals, scapula, coracoid, humerus, ilium, and femur of B. altithorax and B. brancai are very similar” (Paul 1988:7).
That’s how things stood a few years back when I started to take a serious interest in Migeod’s Tendaguru brachiosaurid, which lives in the basement of the Natural History Museum in London. It quickly started to seem to me that it wasn’t the same thing as what everyone means by Brachiosaurus, but to make sense of it all, I needed first to figure out what the Brachiosaurus actually does mean. That meant visiting the type material of both species, in Chicago and Berlin, and really looking closely.
Well, I don’t want to go on all day — apart from anything, England play Croatia in a World Cup qualifier in just over an hour — so I’ll just show you some of the the differences between the dorsal vertebrae of the two species. (You’ll have seen the caudals up above — I just threw them in to break up all that text).
Lots and lots of differences here — I will quote from the Systematic Paleontology section on the type species: “Postspinal lamina absent from dorsal vertebrae (character 130); distal ends of transverse processes of dorsal vertebrae transition smoothly onto dorsal surfaces of transverse processes (character 142); spinodiapophyseal and spinopostzygapophyseal laminae on middle and posterior dorsal vertebrae contact each other (character 146); posterior dorsal centra subcircular in cross-section (character 151); posterior dorsal neural spines progressively expand mediolaterally through most of their length (“petal” or “paddle” shaped) (character 155); mid-dorsals about one third longer than posterior dorsals (see Paul, 1988:7); middorsals only about 20% taller than posterior dorsals (see Paul, 1988:8); dorsal centra long (Janensch, 1950a:72) so that dorsal column is over twice humerus length (Paul, 1988:8); transverse processes of dorsal vertebrae oriented horizontally (Paul, 1988:8); dorsal neural spines oriented close to vertical in lateral view; dorsal neural spines triangular in lateral view, diminishing smoothly in anteroposterior width from wide base upwards; deep inverted triangular ligament rugosities on anterior and posterior faces of neural spines” …. *gasp*
So anyway: the upshot of all this is that “Brachiosaurus” brancai differs from Brachiosaurus altithorax more than, say, Barosaurus does from Diplodocus; and so it must be placed in its own genus … and that genus has to be Giraffatitan, because of the ICZN’s principle of priority. And THAT is why the very end of the paper — the last sentence of the Acknowledgements — reads:
Finally, I beg forgiveness from all brachiosaur lovers, that so beautiful an animal as “Brachiosaurus” brancai now has to be known by so inelegant a name as Giraffatitan.
Anyway, go and read the paper; full-resolution figures are freely available if you want to look more closely than the JVP’s PDF allows.
- Olshevsky, George. 1991. A Revision of the Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia. Mesozoic Meanderings #2 (1st printing): iv + 196 pp.
- Paul, Gregory S. 1988. The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, Giraffatitan, and a comparison of the world’s largest dinosaurs. Hunteria 2(3):1-14.
- Paul, Gregory S. 1994. Dinosaur reproduction in the fast lane: implications for size, success and extinction. pp. 244–255 in: K. Carpenter, K. F. Hirsch, and J. R. Horner (eds.), Dinosaur Eggs and Babies. Cambridge University Press, Cambridge.
- Taylor, Michael 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.
(And, yes, Randy, I know what your comment is going to say; go ahead and say it anyway, it’ll give me a chance to explain why your approach is wrong :-))
July 3, 2009
Big news today: Australia’s dinosaur fauna just got a little less depauperate. Hocknull et al. (2009) described three new saurischian dinosaurs in PLoS ONE, and two of them are sauropods! I’m just going to hit the highlights in this post. For all 51 pages of awesome, you can download the full paper for free.
Here are the new critters (Hocknull et al. 2009:fig. 40; oddly, the size of the scale bar is not given in the figure caption, but I assume it’s one meter). From top to bottom they are:
- Australovenator wintonensis, an allosauroid possibly close to Carcharodontosauridae;
- Wintonotitan wattsi, a basal titanosauriform;
- Diamantinasaurus matildae, a lithostrotian titanosaur.
The new taxa are from the late Early Cretaceous Winton Formation of eastern Australia. All three are represented by incomplete but diagnostic remains, and some of the material is really beautiful.
Here’s one of my favorite bits: the complete reconstructed manus of Diamantinasaurus (Hocknull et al. 2009:fig. 7). Sauropod forefeet were uniquely weird; for the full scoop read this. Note the thumb claw; if it’s legit–and the authors make a pretty good case that it is–then it’s unusual for a titanosaur, most of which are thought to lack hand claws and even manual phalanges.
Sadly no vertebrae were recovered with Diamantinasaurus, and those of Wintonotitan are not as pretty as the appendicular material. Still, they’re shards of excellence and they do carry some informative characters. Here are some dorsals and proximal caudals from Wintonotitan (Hocknull et al. 2009:fig. 13). You can see the partial rim of a pneumatic cavity on the dorsal in the upper left corner. According to the paper the sacrum was also pneumatic, which is to be expected in a titanosauriform.
There’s loads more to say about these critters and their implications for the evolution and biogeography of their respective clades, but tomorrow’s the 4th of July and I’ve got a barbeque to organize. Catch you on the flip side.
Hocknull SA, White MA, Tischler TR, Cook AG, Calleja ND, et al. (2009) New Mid-Cretaceous (Latest Albian) Dinosaurs from Winton, Queensland, Australia. PLoS ONE 4(7): e6190. doi:10.1371/journal.pone.0006190
May 20, 2009
Welcome to another episode of the ground-breaking and wonderful Sauropods of 2008 series. Yay! As I’m fond of pointing out, new dinosaurs do not only come from China, or South America: Europe continues to yield surprises. Tastavinsaurus sanzi Canudo et al., 2008 is from the Lower Cretaceous (Aptian) Xert Formation of Spain, and the holotype specimen is pretty good, including dorsal, sacral and caudal vertebrae, ribs, chevrons, and material from the pelvis and hindlimbs (we’ve previously mentioned it here, and figured some of it here). Evidently, only the hindquarters of the animal were preserved. But they’re in good shape, and preserve numerous unique characters: in fact 19 autapomorphies are identified, which is a pretty impressive number and indicates either that Tastavinsaurus was a highly disparate sauropod, or that the morphology of its close friends and relatives is but scrappily known (I have to say that the former possibility looks more likely).
Some of these autapomorphies are in the vertebrae. On the posterior surfaces of their neural spines, the antero-posteriorly short, opisthocoelous dorsal vertebrae sport two small accessory laminae that emerge from the base of a very wide, chunky looking postspinal process. Of more general interest (perhaps) is that the dorsal centra contain ‘big prismatic tubes linked together by slender walls [that exhibit] a honeycomb pattern in cross-section’ (Canudo et al. 2008, p. 713). The ‘honeycomb pattern’ sounds something like somphospondylous texture, but the authors note that the condition present in Tastavinsaurus is distinct, and perhaps represents a new type of pneumatic pattern. Frustratingly, they don’t illustrate the internal texture, so we’re left guessing.
The caudal vertebrae of Tastavinsaurus are not all that different from those of macronarians like Camarasaurus and Brachiosaurus: in the proximal caudals, the centra are wider than they are long, the proximal vertebrae have slightly procoelous centra, and the neural spines are ‘club-shaped’ [proximal caudal above from Canudo et al. (2008), fig. 7]. The more distal vertebrae – those from the 15th position onwards – are slightly amphicoelous. One weird little feature on the distal caudals is a small, centrally placed convexity on both the anterior and posterior articular faces of the centra (see pics below). As Canudo et al. (2008) note, Cedarosaurus and Pleurocoelus nanus both have this as well (Tidwell et al. 1999) [distal caudal below from Canudo et al. (2008), fig. 8].
The rest of Tastavinsaurus suggests that it would perhaps have superficially resembled a cross between Camarasaurus and Brachiosaurus. Its ilium looks like a dorsally stretched version of the ilium of Brachiosaurus and, indeed, in general character the specimen would appear to be a brachiosaur-grade titanosauriform. With pneumatic ribs, a lateral bulge on the femur, and caudal vertebrae that have anteriorly positioned neural arches, the rest of Tastavinsaurus agrees with this classification, and in their phylogenetic analysis, Canudo et al. (2008) found Tastavinsaurus to fall within Somphospondyli within Titanosauriformes, and within this clade to be the sister-taxon of Venenosaurus from Utah. If this is correct it weakens the proposal that six sacral vertebrae are a synapomorphy of Somphospondyli (Wilson & Sereno 1998), for Tastavinsaurus only has five.
Well, yet again I’ve done my best to concentrate on CAUDAL vertebrae, given that we have an obvious (and understandable) bias towards cervicals and dorsals. Someone has to speak up for tails. For previous instalments in the Sauropods of 2008 series please see the articles on Eomamenchisaurus, Dongyangosaurus, and Malarguesaurus.
Canudo, J. I., Royo-Torres, R. & Cuenca-Bescós, G. 2008. A new sauropod: Tastavinsaurus sanzi gen. et sp. nov. from the Early Cretaceous (Aptian) of Spain. Journal of Vertebrate Paleontology 28, 712-731.
Tidwell, V., Carpenter, K. & Brooks, W. 1999. New sauropod from the Lower Cretaceous of Utah, USA. Oryctos 2, 21-37.
Wilson, J. A. & Sereno, P. C. 1998. Early evolution and higher-level phylogeny of sauropod dinosaurs. Society of Vertebrate Paleontology Memoir 5, 68 pp.
April 12, 2009
Here’s another article in my ‘sauropods of 2008’ series. Previous entries have looked at Eomamenchisaurus and Dongyangosaurus, both of which are Asian. This time round we look at a new South American taxon: Malarguesaurus florenciae González Riga et al., 2008. In marked contrast to the majority of recent SV-POW! articles, this article really is going to be short!
While the majority of new South American sauropods are titanosaurs, Malarguesaurus is a basal titanosauriform. More specifically, González Riga et al. (2008) found it to be a non-titanosaurian somphospondylian, closer to titanosaurs that to Ligabuesaurus, Chubutisaurus or Euhelopus, and the sister-taxon to Phuwiangosaurus from Thailand. Some of these results might seem surprising, as Ligabuesaurus (itself only named in 2006) and Phuwiangosaurus have both previously been regarded as titanosaurs. However, note that González Riga et al. (2008) only found these taxa to be outside of Titanosauria because they employed a restricted, node-based version of Titanosauria that is less inclusive than the branch-based version used by some other authors. The node-based version is closer to the spirit of the name as originally employed by Bonaparte & Coria (1993). Anyway… Malarguesaurus is from an outcrop of the Turonian-Coniacian Portezuelo Formation that crops out in Mendoza Province, Argentina: it’s known from caudal vertebrae, limb bone fragments, ribs and chevrons [image below, from González Riga et al. (2008), shows proximal caudal vertebra in (A) anterior, (B) lateral and (C) posterior views. Scale bar = 50 mm].
Once upon a time it was thought that sauropod caudals were either platycoelous or amphiplatyan (as they are in brachiosaurs and camarasaurs), slightly procoelous (as they are in diplodocoids), or strongly procoelous (as they are in titanosaurs). Discoveries made over the past few decades have shown that things can be much more complicated than this, with some titanosaurs being opisthocoelous (Opisthocoelicaudia skarzynskii for one), and some possessing a combination of different articular types: in Rinconsaurus for example, the caudals are variously procoelous, amphicoelous, opisthocoelous and biconvex. Malarguesaurus also exhibits a combination of different articular types: its distal caudals are procoelous while those from elsewhere in the tail are procoelous-opisthoplatyan*. In fact, the authors regard this combination of caudal morphologies as diagnostic for the taxon: the vertically oriented neural spines on the proximal caudals, with their concave posterior borders, are also diagnostic (González Riga et al. 2008).
* These terms are all familiar, I’m sure. However, ‘procoelous-opisthoplatyan’ hasn’t been used much before, and might in fact be unique to this paper. In fact… the authors cite pers. comm. with a certain Mike P. Taylor for the invention of this term (Mike was a reviewer). It refers to a vertebra in which the anterior face is slightly concave while the posterior face is flat. Tidwell et al. (2001) referred to the same sort of morphology in the titanosauriforms Cedarosaurus and Venenosaurus, but termed it ‘procoelous/distoplatyan’.
Incidentally, the Malarguesaurus paper is another of those annoying pieces of literature that will prove problematical when it comes to citing the date of publication: the paper is dated 2009, but was actually published in 2008. I know it was definitely published in 2008 as I had a final, published version of the relevant journal issue in that year. So Malarguesaurus is a 2008 sauropod, not a 2009 one.
Bonaparte, J. F. & Coria, R. A. 1993. Un nuevo y gigantesco sauropodo titanosaurio de La Formacion Rio Limay (Albiano-Cenomaniano) de le provincia del Neuquen, Argentina. Ameghiniana 30, 271-282.
González Riga, B. J., Previtera, E. & Pirrone, C. A. 2008. Malarguesaurus florenciae gen. et sp. nov., a new titanosauriform (Dinosauria, Sauropoda) from the Upper Cretaceous of Mendoza, Argentina. Cretaceous Research 30, 135-149.
Tidwell, V., Carpenter, K. & Meyer, S. 2001. New titanosauriform (Sauropoda) from the Poison Strip Member of the Cedar Mountain Formation (Lower Cretaceous), Utah. In Tanke, D. H. & Carpenter, K. (eds) Mesozoic Vertebrate Life. Indiana University Press (Bloomington & Indianapolis), pp. 139-165.
March 31, 2009
Today saw the publication of the most startlingly dull paper I’ve ever been involved in (Upchurch et al. 2009) — and remember, I write this as co-author of a paper on the phylogenetic taxonomy of Diplodocoidea. Not only that, but one time when I was practising a conference talk with my wife Fiona as audience, she fell asleep actually while I was speaking. Actually asleep. And yet the new paper beats them all hands-down for boredom. If you don’t believe me, feast your eyes, gloat your soul, on the accursed ugliness of the very title of the new paper: “Case 3472: Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species.” What is it all about?
Well, take a look at the type material of Cetiosaurus:
Yes indeed — the most historically important of all sauropods is based on a set of non-diagnostic uninformative eroded partial mid-to-distal caudal centra. That is because this is the type material of the species which, for complex technical reasons, is the type species of the genus Cetiosaurus. We tend to ignore this fact because the material is clearly rubbish: the taxon C. medius is not valid. Sadly, however, the name C. medius is valid — nomenclaturally valid, even though it’s not taxonomically valid. But the International Code of Zoological Nomenclature (ICZN), which governs all zoological nomenclature, is purely a code of nomenclature, and does not take taxonomic considerations such as diagnosability into account. (It can’t, after all: how could the code contain rigorous rules that let you determine whether material is diagnostic, or whether a description is adequate?)
Anyway, the material of C. brevis, C. brachyurus, C. medius and C. longus, all published together (Owen 1842) is all pretty useless; but Phillips (1871) described in detail the much better material of a new species C. oxoniensis, and this is what everyone has meant by the name Cetiosaurus ever since. Upchurch and Martin (2003:215) even explicitly stated that they were provisionally using C. oxoniensis as the de facto type speces, pending a petition to the ICZN to overrule strict priority. And no wonder: the C. oxoniensis material really is way better. For example, check out this dorsal vertebra (which is by no means the best one — just one that I have a convenient photo of):
Today’s new paper is that long-promised petition: in it, we recount the nomenclatural history of the name Cetiosaurus and its species, explain with a big list of references that C. oxoniensis has been overwhemingly used historically and is overwhelmingly used today, and ask the Commission to legitimise this universal behaviour.
Will they do it? We actually don’t know, although I can’t think of any reason why they shouldn’t. The process now is that interested workers can send their comments, either in favour of or against our proposal, to the Executive Secretary of the ICZN (address at the end of the PDF), and these comments are weighed before a decision is returned. From my informal sampling of previous petitions, the process seems to take between one and two years. So we’re probably stuck in type-species limbo until 2011. Oh well — at least the main step has been taken.
So. I’m not exactly as excited about this paper as I was of Xenoposeidon — don’t worry, we won’t be launching a nine-post Cetiosaurus Type Species Redesignation Week — nor as pleased with it as I am with a certain in-press paper that all three of us SV-POW!sketeers are very much looking forward to because REDACTED. But it’s a dirty job that someone had to do.
- Owen, Richard. 1841. A description of a portion of the skeleton of the Cetiosaurus, a gigantic extinct saurian reptile occurring in the oolitic formations of different portions of England. Proceedings of the Geological Society of London 3: 457-462.
- Owen, Richard. 1842b. Report on British fossil reptiles, Part II. Reports of the British Association for the Advancement of Science 11: 60-204.
- Phillips, John. 1871. Geology of Oxford and the valley of the Thames. Clarendon Press, Oxford.
- Upchurch, Paul, and John Martin. 2003. The anatomy and taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England. Journal of Vertebrate Paleontology 23: 208-231.
- Upchurch, Paul, John Martin, and Michael P. Taylor. 2009. Case 3472: Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species. Bulletin of Zoological Nomenclature 66 (1): 51-55.
Update (3 April 2009)
Here’s that photograph of a leopard seal pulling the head right off a penguin you ordered:
Acknowledgement: I got this photo from http://img238.imageshack.us/img238/873/1627.jpg. Thanks to “Paul A.” (see comment below) I now know that it is the work of Paul Nicklen who has a stellar collection of photographs on his own site. This picture is entitled The Death Shake, and is the 10th of the 29 pictures in his leopard seal gallery.
Relevant Update (31 August 2010)
I should have noted this long ago, but back in July 2009 (more than a year ago!) Paul Barrett and Pete Galton both published comments in the BZN that were supportive of our petition.
Cetiosaurus, Pelorosaurus, Streptospondylus or maybe Iguanodon(?!) in bizarre Fused Chevrons scandal!
March 9, 2009
We have sometimes neglected tails on SV-POW!, in favour of the more obviously charismatic charms of presacral vertebrae, but every now and then you come across a caudal vertebra so bizarre that it just cries out to be blogged.
One such is this specimen, which may or may not be BMNH R 2144:
The reason I’m not sure whether this is BMNH R2144 is that I noticed this at the very last minute while visiting the NHM collections to see a different specimen, and just had time to take a couple of quick photos before kicking-out time. The label on the side of the vertebra has the unexplained number 2144 written on it, so I am guessing this is the specimen number, but I wouldn’t stake my life on it.
(By the way, both these photographs are copyright the NHM.)
The interesting thing about this vertebra is of course that that the chevrons are co-ossified with the centrum — an extremely rare condition in sauropods, in fact unique as far as I know. As we’ve shown here and here, among other places, the chevrons are usually separate bones from the vertebrae.
This vertebra caught my eye not only because it’s, well, weird, but also because I’d seen it a couple of times in published figures. It’s in Mantell’s (1850) description of Pelorosaurus, where it appears as figure 11 in plate XXIII, and is considered to belong to Pelorosaurus; and also in Owen (1859: plate V: figs. 3-4). Owen seems pretty confused about the identity of this element, and in this paper alone assigns it to Streptospondylus (p. 22), Iguanodon(!) (p. 25) and implicitly Cetiosaurus (p. 34). So what is it? Well, its provenance is vague in the extreme, so given that it’s not associated with any more diagnostic material, about the best we can say with any honesty is that it’s Sauropoda incertae sedis.
Let’s take a look at those old figures:
If you’re like me, your first thought was that Owen’s figures are simply mirror images of Mantell’s. I checked this out by Photoshopping the two sets of figures, flipping them horizontally, scaling and rotating as necessary, and found to my mild surprise that Owen’s figures are in fact redrawn, despite the startling resemblance they bear to Mantell’s. As it happens, the same is true with the Owen 1859 plate that is the humerus of Pelorosaurus figured by Mantell 1850, and in that case Owen’s figure is rather better than Mantell’s, so let’s give a bit of credit to Owen here. Most embarrassing for Mantell (not that he cares, having been dead for 157 years) is that Owen’s flipped images seem to be correct (at least, as best I can judge from the photographs I took) — looks like Mantell or his illustrator badgered this up.
So what is going on with these co-ossified chevrons? As is so often the case, we just don’t know. Some possibilities: this might be a pathology of an individual, caused either by injury or infection; it might be a natural ontogenetic character in very old individuals; or it might by a taxonomically significant character of a taxon we’ve not yet found — or one that we have found, but don’t yet recognise as being the same thing. It’s perfectly possible that this is a chevron of Xenoposeidon, for example, but until someone finds a nice complete specimen we’ll never know.
Not much is known about skeleton fusion in sauropods, and most of what’s in the literature is anecdote. That is set to change, I am pleased to say, as Matt is putting together a paper with his colleague Elizabeth Rega that will survey and interpret the various fusions known in sauropod vertebrae. I’m looking forward to seeing what they have to say about this vertebra.
- Brusatte, Stephen L., Roger B. J. Benson, and Stephen Hutt. 2008. The osteology of Neovenator salerii (Dinosauria: Theropoda) from the Wealden Group (Barremian) of the Isle of Wight. Monograph of the Palaeontographical Society 162 (631): 1-166.
- Calvo, Jorge O., Juan D. Porfiri, Claudio Veralli, Fernando Novas and Federico Poblete. 2004. Phylogenetic status of Megaraptor namunhuaiquii Novas based on a new specimen from Neuquen, Patagonia, Argentina. Ameghiniana 41 (4): 565-575.
- Mantell, Gideon Algernon. 1850. On the Pelorosaurus: an undescribed gigantic terrestrial reptile, whose remains are associated with those of the Iguanodon and other saurians in the strata of Tilgate Forest, in Sussex. Philosophical Transactions of the Royal Society of London 140: 379-390.
- Owen, R. 1859a. Monograph on the fossil Reptilia of the Wealden and Purbeck formations. Supplement no. II (pages 20-44 and plates V-XII): Crocodilia (Streptospondylus, &c.) [Wealden]. Palaeontographical Society, London.
Thanks to Mickey Mortimer for pointing out that this kind of centrum-chevron fusion is known in the theropod Megaraptor. Here is the relevant figure from Calvo et al.’s (2004) revision of that genus:
The strange thing is this comment in the text (p. 569): “Two articulated caudal vertebrae are preserved (figure 5), slightly laterally compressed. Their centra and the neural arches are firmly co-ossified, as well as their respective haemal arches [i.e. chevrons]. This fusion, not infrequent among dinosaurs, may be pathological.” Not infrequent? Is this going on all over the place and I’ve just never noticed it? Anyone have any more examples?
Here is that pair of fused Neovenator caudals with a co-ossified chevron, which Darren mentions in the comments below.
February 11, 2009
I had a new paper come out today. Unofficial supplementary info here, PDF here. I would have had all this ready to go sooner, but the paper came out sooner than I expected. In fact, I didn’t even know that it had been published until Andy Farke (aka the Open Source Paleontologist) wrote me for a PDF. Turnabout’s fair play, I suppose, because last year I congratulated Stuart Sumida on his Gerobatrachus paper before he knew it was out. I guess letting the authors find out through the grapevine that their stuff has been published is part of the “value added” that commercial journals provide. ;-)
Anyway, I’m happy the paper is out, finally. It’s the third chapter of my dissertation, but with teaching and traveling to Spain and such I didn’t get it submitted until last January. I had to forcibly bite my tongue during the Aerosteon saga last fall, when such a big deal was made about the absence of pneumatic hiatuses in non-avian dinosaurs. This despite the facts that there are several good reasons to expect pneumatic hiatuses to be rare, and that pneumatic hiatuses are not the Rosetta Stone or magic bullet for air sacs in saurischian dinosaurs. They’re more like the cinderblock that broke the camel’s back, given all the other evidence for air sacs.
In fact, the structure of the new paper is built around the idea that there are several tiers of evidence for bird-like air sacs in saurischians. Those tiers are:
- The presence of postcranial pneumaticity at all. Some of the first authors to get interested in the implications of pneumaticity for dinosaurs argued that pneumaticity probably implies an air sac system, and left it at that. Later workers have tended to denigrate this argument as overly simplistic–just because some of the postcranial skeleton is pneumatic does not mean that the animal’s air sac system was necessarily like that of birds–but it’s not actually a bad argument. We can imagine lots of ways to get air into the postcranial skeleton, but for tetrapods the only system that we have any evidence for is diverticula of a lung/air sac system like we see in birds.
- The distribution of pneumaticity in the skeletons of most saurischians and pterosaurs is diagnostic for specific air sacs, namely the cervical, clavicular, and abdominal air sacs that we see in birds. This is what Pat O’Connor and Leon Claessens established so firmly with their work on mapping parts of the respiratory system to skeletal domains in birds.
- The evolutionary patterns of pneumatization in sauropods and theropods parallel the development of pneumatization during ontogeny in birds. Or, more economically, ontogeny recapitulates phylogeny in this system. This is more evidence that the observed patterns of pneumaticity in the skeletons of birds and non-avian saurischians are produced by the same underlying process of diverticula developing from different air sacs in a highly conserved order–even if we don’t know why things evolved, and continue to develop, in the order that they do. And it’s better evidence, because it accounts for more observations (points 1 and 2 can be established from single specimens) and ties postcranial pneumaticity in all saurischians, living and extinct, into a more coherent picture.
- Pneumatic hiatuses are more evidence that the postcranial skeleton is pneumatized by diverticula from more than one part of the respiratory system. Not the only evidence–we already suspect this quite strongly based on points 2 and 3–but more evidence. It is possible that the diverticula of extinct animals behaved differently than those of all extant birds, and diverticula from a single source could conceivably pneumatize the whole vertebral column. Possible. Conceivably. How likely? Dunno–our n on this is either 1 (if you count all living birds as a batch) or several hundred (if you count each of the species that Pat O’Connor has dissected and injected). Pneumatic hiatuses offer another level of evidence, because they can potentially show that the patterns of pneumaticity in fossil taxa are inconsistent with pneumatization from a single point. That’s how they work in chickens, and that’s how they may work in non-avian dinosaurs, as long as diverticula don’t leapfrog over some bones without leaving any traces, or at least don’t do that very often.
For the record, I don’t think that pneumatic hiatuses are stronger evidence than point 3; if I was ranking the tiers based on importance I would put 3 at the top. Pneumatic hiatuses ended up being last in the paper because 1-3 were basically review material, and it made sense to group them together before the big bolus of description.
[UPDATE the next day: also, I just realized that those 4 are not the same as I used in the paper! In the paper I left out 1, advanced 2 and 3, and added a different number 3, which is pneumatization of the pelvic girdle and hindlimb. I tend to forget about that one because the evidence in sauropods is underwhelming so far. And arguably this is just another aspect of 2 (above), or if you like you can think of 5 tiers. They say consistency is the hobgoblin of small minds!]
The importance of pneumatic hiatuses remains to be seen; there might not be enough of them to tell us very much, or we might find that leapfrogging diverticula exist and are common (we’d then need a way to sort hiatuses caused by multiple sources of diverticula from those caused by leapfrogging diverticula). But they’re important to me, for a couple of reasons.
First, they’re probably one of the two or three best ideas that I’ve had in my life. When I realized that pneumatic hiatuses could potentially indicate pneumatization from multiple sources it really was like a light going on in my head. I walked around seeing stars all week.
I got the idea from this figure, from King (1957):
On the left King has drawn the vertebral columns of several chickens, and shaded in the pneumatic regions. Blocks of pneumatic verts separated by apneumatic gaps represent pneumatization from different sets of diverticula. I remember very vividly sitting in the Padian lab reading this paper and thinking, “if we found one of those in a dinosaur it would be the money.” Then I suddenly sat up straight, then stood up, then paced around the room a few times to burn off the discovery energy. I had a very profound need to tell someone. I don’t remember who I told, but it was probably Mike.
The other reason that pneumatic hiatuses are important to me: they are now one of those cool little cases that show that paleontology can be a predictive science. If you want to test a hypothesis in the experimental sciences you manipulate the conditions and see what happens. Historical sciences don’t usually give you that option. But you can play What If? As in, “If hypothesis A is true then we ought to see such-and-such evidence.” In 2003, I predicted that if sauropods had abdominal air sacs we ought to see pneumatic hiatuses once in a while. Finding the evidence that validated the prediction was almost as much of a rush as having the idea in the first place.
The owner of Sauropod Pneumatic Hiatus #1 is Haplocanthosaurus CM 879, which is a cool animal but fairly pathetic as sauropods go. In my dissertation/job talks I would show the above picture and joke that I could probably beat up that animal on a good day. I found out about the pneumatic hiatus by accident, when I was poring over Hatcher (1903). In one of the figures near the end of the paper, Hatcher shows the centra of the fourth and fifth sacral vertebrae. I noticed that sacral 4 had a pneumatic chamber of some sort but sacral 5 did not. Then a few minutes later I had gotten to the plates at the back of the paper, and saw what looked like a pneumatic chamber on the first caudal. Somewhere in the dank, beer-flooded grottoes of my skull, the neuron fired.
This is the figure I put together, using images from Hatcher (1903), for a Jurassic Foundation grant to go see the material in the Carnegie Museum in 2005. It worked; they came through with $1500 for that trip and a week at BYU the same fall (to my immense shame, although the Jurassic Foundation is credited for funding on the first page, I see that I forgot to thank them in the acknowledgments. Belatedly: thanks, you guys rock, I suck). The pneumatic cavities are labeled as foramina because that’s what they look like in the drawing, and not having seen them I didn’t know any better. In fact they are fossae, but they are deep, invasive fossae and their morphology is not consistent with anything other than pneumatic invasion. (Pneumatic invasion!? Flee for your lives!!) See the paper for all the excruciating details. Note that the sacrals have unfused neurocentral sutures, so the animal was not fully mature when it died (there is probably a whole post ahead just on the neurocentral weirdness in this animal).
So that’s the story, for now at least. There are more pneumatic hiatuses coming, but those papers are still in the pipe so I can say no more for now. I’m sure when they come out some alert blogger will notice and e-mail me for a PDF, and then you’ll get the news here.
The moral of the story is that you can make real progress by reading lots of old, obscure stuff. Support–and abuse–your local academic library!
- Hatcher JB. 1903. Osteology of Haplocanthosaurus, with a description of a new species, and remarks on the probable habits of the Sauropoda, and the age and origin of Atlantosaurus beds. Memoirs of the Carnegie Museum 2:1–72.
- King AS. 1957. The aerated bones of Gallus domesticus. Acta Anatomica 31:220–230.
- Wedel, M.J. 2009. Evidence for bird-like air sacs in saurischian dinosaurs. Journal of Experimental Zoology 311A.