Scaled restoration of the giant titanosaur Puertasaurus by Nima Sassani, from the Art Evolved Sauropod Gallery

Get on over to Art Evolved and scope out the sauroponderous Sauropod Gallery. It’s brobdingnaginormous. I don’t want to seem biased, but there’s a lot of hot brachiosaurian action on display. I’m happy to say that the other clades are not ignored–diplodocids, dicraeosaurids, titanosaurs, mamenchisaurids, basal eusauropods, and even a basal sauropodomorph are all in the mix.

Normally my brachiosaurcentricity would lead me to steal one of the numerous brachiosaur images–perhaps the awesome parade of brachiosaurs that includes both Sauroposeidon and the Archbishop (!!)–BUT my laziness led me to choose another piece by the same artist, Nima Sassani. That would be the Puertasaurus reconstruction shown at top, which includes vertebrae and thus fulfills our titular mandate. That means I can stop writing now and get back to gawking. Go do likewise.

…oh, and don’t forget to stop by Dracovenator and congratulate Adam Yates on his new critter, Aardonyx. You’ll be hearing more about Aardonyx here at SV-POW! in the hopefully not-too-distant future. I can say no more for now…

I’m following up immediately on my last post because I am having so much fun with my wallaby carcass.  As you’ll recall, I was lucky enough to score a subadult male wallaby from a local farm park.  Today, we’re going to look at its feet.

Wallabies are macropods; together with their close relatives the kangaroos and Wallaroos, they make up the genus Macropus, literally “bigfoot”.  So wallabies got there long before cryptic North American anthropoids.  And indeed their feet are big.  Here are those feet, in dorsal view, from before I started doing unspeakable things to my specimen:

Bennett's wallaby, hind feet in dorsal view

From here they look pretty weird, but it’s only when we go round the back that we really see how odd they are.  Same feet in ventral view:

Bennett's wallaby, hind feet in ventral view

There are (at least) three things to notice here: first just that the feet are very long; second, the thick, scaly pad that runs all the way up to the heel; and third, the bizarre arrangement of toes.  At first glance, it seems that there is one main toe and a smaller one each side, but if you look more closely you’ll see that the medial “toe” is really two tiny toes closely appressed, so that they function as a single toe.  This condition is known as syndactyly, Darren tells me.  Also from Darren: it’s digit I that is missing in macropods, so the tiny-toe pair are digits II and III, the main toe is IV and the lateral one is V.

(By the way, seeing my patio in these photos reminds me of something I forgot to mention in the previous post: it’s surprisingly difficult to wash wallaby blood off paving slabs.  Remember that, kids, it’ll be on the test.)

Regular readers will remember from last time that I planned to prepare the skull and left fore- and hindlimbs by simmering and dissection, and let nature deal with the rest of the elements.  You’ve already seen the skull, so here goes with that foot.

After an initial simmer, I was able to skin the left pes, so here it is at that stage, in medial view:

Bennett's Wallaby, left pes in medial view, skinned and simmered

From this angle, you can clearly see the absurdly thin second metatarsal (MT II) that supports the innermost of those two tiny digits.  MT III is just as long and thin, but is fused proximally to the much larger MT IV, as we shall see below.  The simmering has resulted in the more distal phalanges breaking away from their more proximal brethren, and being pulled downwards and beneath them.  This is most apparent with the tiny digits, whose supporting phalanges are clearly visible poking out above the claws.  So the large lump of what looks like cartilage at top right is actually phalanx IV-I, with IV-II and IV-III (the ungual) beneath it.  Also note the significant amount of resilient tissue below the metatarsals.  I’ve cut most of it away, but you can get a good idea from the bits that are still attached distally.

Here is the metatarsus in ventral view after I had removed the phalanges:

Bennett's Wallaby, metatarsus in ventral view, skinned and simmered

Here you can clearly see the syndactyly (in those two closely appressed thin metatarsals II and III at the top of the picture) and the very sculpted distal ends of the  larger metatarsals IV and V.

Now let’s skip straight to to the completed stripped-down pes, now in dorsal view:

Bennett's wallaby, left pes in dorsal view, disarticulated and cleaned skeleton; ungual sheaths removed from bony cores.

It’s interesting that the phalangeal formula is so uniform: 0-3-3-3-3.  That is, all four digits have two normal phalanges and an ungual.  But the differences in proportions between them are quite something.

This is our first look at the tarsals — those seven bones on the left of the picture, before we get to the metatarsals.  The three big ones fit together very nicely.  At the back you see the calcaneum, where the achilles tendon attaches; next is the astragalus, which sits on top of the calcaneum and where the distal end of the tibia articulates. Next up is a bone whose name I don’t know, being pretty darned ignorant of ankles — might it be the cuboid?  Anyway, even after cleaning and cartilage-removal , this articulates very nicely indeed with both the calcaneum and MT IV.

Medial to these (i.e. below them in the picture) are four much smaller tarsal bones whose identity I can’t even guess at.  It’s not clear to me how they articulate with the big tarsals — they were all pretty solidly embedded in cartilage and gloop and I fear that they’re not going to fit neatly whatever I do.  Hints will be welcome.

One big surprise was the small bones between the metatarsals and their corresponding phalanges: one each at the ends of MT II and MT III, and two each at the ends of MT IV and MT V.  Because the proximal phalanges articulate so nicely with their metatarsals, it’s clear that these small bones were not positioned between them in life, but rather floated above them — rather as your kneecap, or patella, floats above your femur-tibia joint.  They are sesamoids.  Does anyone know whether this sesamoid formula of 0-1-1-2-2 is common?  Seems a bit weird to me.

Finally, I leave you with the entire left hindlimb: foot as in the previous picture, surmounted by the tibia and fibula, then by the femur, all in anterior view.  Just to the left of the femur-tibia joint is a small bone which I assume is the patella.

Bennett's wallaby, disarticulated left hind limb in dorsal view

Special bonus wallaby limb: over there on the right is the left forelimb.  As you can see, I’ve done the easy part (scapula, humerus, ulna and radius) but I still have to dissect out the bones from the wrist and hand — a picky, tedious job that to be frank I am not looking forward to.  The feet are much more exciting than the hands.

That’s all for today.  On Sunday evening I am off to London to spend a whole week in the company of the Archbishop.  The plan is to spend Monday to Wednesday taking final publication-quality photos (I finally have a proper tripod) and digging out field photos and suchlike from the museum archives, then take Cervical U to be CT-scanned at the Royal Veterinary College, courtesy of theropod hindlimb mechanics guru John Hutchinson.  Friday is emergency backup in case something crops up to delay the scanning, and also gives me a chance to retake any photos that didn’t come out as required.  The plan is that this visit should give me everything I need (pictures, measurements, observations, historical documents) to finish up the long-overdue Archbishop description.  Fingers crossed.

I leave you with a puzzle.  This is the jacket that I have designated “Lump Z”:

Brachiosauridae indet. BMNH R5937, "The Archbishop". Unidentified elements "Lump Z". Image copyright the NHM, since it's their material.

Can anyone offer a guess as to what this is, and which way up it should be?  It’s a jacket that was opened years ago — before I was involved with the specimen — but never fully prepared.  Matt and I have discussed it a little, but I don’t want to prejudice anyone with our guesswork, so I leave the floor open.  What is it?

SV-POW! Dollars are at stake!



This is part 3 of an emerging and occasional SV-POW! series: part 1 was the pig skull, and part 2 was the lizard feet (though not advertised as such because I couldn’t resist the sauropod pun).

Bennett's wallaby, right lateral view

Today, we’re going to be taking a wallaby apart.  Specifically, a Bennett’s wallaby, the larger of the two subspecies of the red-necked wallaby Macropus rufogriseus.  I was delighted (though of course also saddened) to get a call on Saturday afternoon from the very same mini-zoo that had given me Charlie the monitor — Dick Whittington Farm Park in Longhope, Gloucestershire.  They have a small group of seven wallabies sharing a paddock with goats, and one had died — most likely from being butted by one of the goats, although there were no external signs of injury.

This is going to be the largest animal I’ve prepared the skeleton out of — I measured it at 123 cm from snout to tail and 10.5 kg total weight, which compares with 75 cm and 12 kg for the badger, 100 cm and 5.2 kg for the fox and 111 cm and 3.4 kg for the monitor.  Yes, the badger was heavier, but the awkward shape of the wallaby makes it all-round “bigger” and harder to deal with.  Both the badger and the fox would, just, fit into large plastic toy-boxes which I buried and will exhume after a suitable time has passed, but that wasn’t going to work for the wallaby.  I needed to take that baby apart:

Bennett's wallaby, right ventrolateral view into guts

I was pleasantly surprised at what good condition the guts were in (compared with the horrible state of Charlie innards) — nice and fresh.  If I’d had time, I’d have attempted to learn something from a proper dissection, but as I was pushed for time (trying to get this done in my lunch break) I had to push on.  I discarded the guts and started to carve up the remainder.

Bennett's wallaby in posteroventral view. right leg removed; Homo sapiens for scale

The knife is a Norwegian fisherman’s knife — very sharp, and short enough to be easy to wield.  It’s perfect for dismembering a carcass this size, even though previously I’ve only used it for slicing sushi rolls.  It was a Christmas present from my employer, Index Data, a few years ago.

My plan was to carefully divide the animal into seven portions (head, torso, tail and four legs), remove as much skin and muscle as I could without risking damage to the bone, and to process the parts separately.

Bennett's wallaby, in kit form, mostly dorsal view but with the head and torso in left lateral. WARNING: GRAPHIC CONTENT

After some thought, I decided to prepare the skull and the left fore- and hind-limb by boiling, and to bury the rest in the box.  Here are the relevant divisions:

Bennet's wallaby not looking at all healthy. Top: torso, tail and right fore- and hindlimbs, awaiting burial. Bottom left: head, left fore- and hindlimbs, awaiting cooking. Bottom right: bag full of discarded soft-tissue

Then I put the pot through an hour’s simmering, peeled the skin off the skull and feet, and removed what meat I could; then I simmered a second time and removed more meat.  By this stage, I was able to remove the three most anterior cervicals, which had been attached to the back of the skull — but they are still so covered with attached flesh that they’re not much use yet.  Here’s how the simmered material is looking:

Bennett's wallaby: skull, anterior cervical vertebrae and left hind-limb long bones

And here is the skull as it looks now, after a little more flesh-picking (but not nearly enough):

Bennett's wallaby, partially prepared skull in right lateral view

I think that it (and the other boiled bones pictures above) would benefit from a third simmer-and-pick session before I put them out somewhere for invertebrates to deal with.  While that’s going on, I’ll prep out the foot and the forelimb, which have also been boiled twice but phalanges are a right nasty piece of work.

And then I have to decide what to do with my big yellow box that has the rest of the bits in.  Plan A is still burying, but it is kind of tempting to simmer these parts, too, and get the whole thing completed much more quickly.

On the other hand, now is not a good time for such an effort: I will be away from home all week on a mission of utmost importance, and of great relevance to this blog.  Details to follow!

Finally, I leave you with your weekly sauropod-vertebra goodness!

Giraffatitan brancai paralectotype HMN SI, cervical vertebrae 2 and 3 in right lateral view, attempting to do DinoMorph

Figure 3 from Schwarz-Wings et al. 2009. A is Diplodocus, B-D are Giraffatitan.

Earlier this month Daniela Schwarz-Wings and colleagues published the first finite element analysis (FEA) of sauropod vertebrae (Schwarz-Wings et al. 2009). Above is one of the figures showing some of their results. Following standard convention, stresses are shown on a gradient with cooler colors indicating lower stresses and hotter colors indicating higher stresses. I’m not going to dwell on the on the nuts-n-bolts of FEA in general or of this study in particular. Instead, I want to talk about how sauropod vertebrae are built.

CT cross sections of BYU 12866, a mid-cervical of Brachiosaurus sp.

In cross-section, sauropod vertebrae often have thick bone at the outer edges of the laminae and in the walls and especially the floor of the centrum, as shown in this Brachiosaurus cervical. The bone everywhere else is pretty thin. If you hit one of these vertebrae with some magical forumula that would dissolve away all the bone thinner than, say, 1 cm, all that would be left would be the various apophyses, the outer margins of the laminae connecting them, and probably the bottom half of the centrum. It would be like the outline of a vertebra constructed from tent poles, or tinkertoys.

This is weird because most pneumatic sauropod vertebrae have at least something approaching an I-beam shape in cross-section. You might think that the median septum would be mechanically important, but it’s usually very thin, sometimes perforated (see Hatcher’s [1901] Diplodocus cervicals, for example), and often asymmetrically deviated to one side or the other. Not what you would expect for a piece of bone that was doing any work.

And indeed, Schwarz-Wings et al. (2009) found that:

Comparative stresses are distributed evenly around the vertebrae and mainly on the bone cortex. Peak stresses occur only at points where the tendons and muscles are inserting because the insertion areas used were small resulting in extreme localized stresses. The interior of both vertebrae is nearly stress free. Almost no stresses occur around the cavities and in their bony walls (figure 3).

This reminds me not of I-beams but of the long bones of the limbs of terrestrial vertebrates. There’s a reason why you’ve got a big honkin’ marrow cavity running through the middle of your femur: the stresses are being borne by the walls of the bone. It makes sense that vertebrae would function similarly, especially sauropod cervicals which sometimes approximate limb bones in their proportions.

So how about that median septum? Why aren’t sauropod vertebrae just hollow tubes? My guess–and it is a guess–is that they got as close to being hollow tubes as their evolutionary and developmental origins allowed. The pneumatic diverticula invaded the centra from either side and pushed in lateral-to-medial, and I think the median septum is just the wimpy little bit of bone left in between the two sets of diverticula when they almost meet up in the middle.

Even if that’s correct, there’s another mystery: why don’t the diverticula just go ahead and erode away the median septum? I can think of two possible reasons. One is that, for reasons I don’t know and I’m not sure if anyone else does either, pneumatic diverticula are good at getting into bones but pretty lousy at getting back out. There are comparatively few cases of diverticula inside bones making foramina to get out into the  surrounding tissue. It does happen–in humans, the mastoid air cells sometimes bust out and make subcutaneous pneumatocoels, basically bubbles of air under the skin (Anorbe et al. 2000)–but it seems to be rare. Maybe median septa fall under the same inscrutable rule.

(Incidentally, this makes the perforate laminae in Giraffatitan all the weirder.)

Another, more mundane possibility is that the median septa (and other oddly thin bits of bone) are not never loaded, just infrequently loaded. Not enough to make them straight, thick, or normal-lookin’, but enough to make sure they don’t get resorbed entirely.

Sauropod vertebrae are just loaded with these growth-and-form-related mysteries. Kudos to Schwarz-Wings et al. for pushing us a little farther down the road toward solving them.

References

• Anorbe, E., Aisa, P. and Saenz de Ormijana, J. 2000. Spontaneous pneumatocele and pneumocephalus associated with mastoid hyperpneumatization. European Journal of Radiology 36:158–160. [abstract only for free]
• Hatcher, J.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.
• Schwarz-Wings, D., Meyer, C.A., Frey, E., Manz-Steiner, H.-R., and Schumacher, R. 2009. Mechanical implications of pneumatic neck vertebrae in sauropod dinosaurs. Proceedings of the Royal Society B. doi: 10.1098/rspb.2009.1275

At the 2007 SVP meeting in Austin, Texas, I noticed that the suffix “-ass” was ubiquitiously used as a modifier: where an Englishman such as myself might say “This beer is very expensive”, a Texan would say “That is one expensive-ass beer” — and the disease seemed to spread by osmosis through the delegates, so that by my last day in Austin is was seemingly impossible to hear an adjective without the “-ass” suffix.

All of which is by way of introducing the fact that Futalognkosaurus really was a big-ass sauropod, as this photo of its sacrum (with articulated ilia) shows:

Articulated pelvis (sacrum and ilia) of Futalognkosaurus, in ventral view. Juan Porfiri (175 cm high) for scale. Photo by kind permission of Jorge Calvo.

A version of this photograph (in black and white and with the background chopped out) appeared in Ferdinand Novas’s recent book (Novas 2009) and attracted some discussion on the Dinosaur Mailing List.

Although in the past, we have complained about the lack of measurements in the two papers describing Futulognkosaurus (Calvo et al. 2007, 2008), this photo demonstrates a lower bound on its size: we know that it was, at least, Darned Big.  (I would attempt to calculate some measurements from this photo using Porfiri as my scale-bar, but we all know how variable human proportions are, so it’s probably better to refrain.)  The great news here is that, as explained by Ruben Juarez Valieri in a comment on an earlier article, a third article is on the way that will contain all the measurements we want.

Anyway, here are some more of Calvo’s awesome Futalognkosaurus photos, all used with grateful permission:

Median or posterior cervical vertebra of Futalognkosaurus in right anterolateral view; Juan Porfiri (175 cm) for scale. Photo by kind permission of Jorge Calvo.

(That is an insanely tall cervical.)

Articulated dorsal vertebrae of Futalognkosaurus in ?ventral view. And there is Juan Porfiri again, still 175 cm tall. Photo by kind permission of Jorge Calvo.

How on Earth did they get that jacket out the ground and back to the museum?!

And finally — if you’ll forgive the flagrant appendicularity:

Right ischium and pubis of Futalognkosaurus in ventrolateral view. Where's Juan? Photo by kind permission of Jorge Calvo.

And now for something completely different:

Open Access Week

I’m pleased to say that this week (October 19-23) is Open Access Week.  Get over to the site for statistics about the rise of open access.  Particularly impressive is a sequence of institutions that are introducing open-access mandates, i.e. requiring that all research produced by its staff is made freely available to the world.  We’re on the way!

References

• Calvo, J.O., Porfiri, J.D., Gonzalez-Riga, B.J., and Kellner, A.W.A. 2007. A new Cretaceous terrestrial ecosystem from Gondwana with the description of a new sauropod dinosaur. Anais da Academia Brasileira de Ciencias 79(3):529-541.
• Calvo, J.O., Porfiri, J.D., Gonzalez-Riga, B.J., and Kellner, A.W.A. 2008. Anatomy of Futalognkosaurus dukei Calvo, Porfiri, Gonzalez-Riga & Kellner, 2007 (Dinosauria, Titanosauridae) from the Neuquen Group (Late Cretaceous), Patagonia, Argentina. Arquivos do Museu Nacional, Rio de Janeiro 65(4):511-526.
• Novas, F. 2009. The Age of Dinosaurs in South America. Indiana University Press (Life of the Past series). 480 pages.

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.

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.

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.

How Big?

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.

Mike measuring Giraffatitan's naughty bits. Check out the hindfeet. Also note the sauropod vertebrae in the background--titular obligation fulfilled!

Too Big?

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? 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.

Conclusions

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?

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). 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.

Parting Shot

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.

References

• 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.

One of the most bizarre of sauropods – and arguably one of the most bizarre of dinosaurs – is the Patagonian dicraeosaurid diplodocoid Amargasaurus cazaui Salgado & Bonaparte, 1991. Here’s a picture of a replica specimen, provided by Nizar Ibrahim. You’ll note that this skeleton has been posed with an extended cranio-cervical junction, and a slightly extended cervico-dorsal junction: virtually the opposite of what you’d expect in ‘normal’ posture (Taylor et al. 2009).

Thanks to its appearance in virtually every post-1991 book on dinosaurs, Amargasaurus is a relatively familiar animal these days, which is sort of a shame: we’ve somehow forgotten how frikkin’ weird it is. We’ve looked at Amargasaurus on SV-POW! before: in this article we drew attention to the fact that its dorsals are pretty interesting too, and as usual with sauropods we could write whole essays on all manner of its vertebral osteology. Perhaps, in time, we will.

However, let’s be honest and note that it’s those ridiculous cervical spines that keep us awake at night. What the hell did the animal do with these structures, and exactly what did it look like when alive? Early reconstructions (most notably Brian Franczak’s drawing from 1992 (see Hecht 1992)) all went with the idea of two paired sails, running in parallel along the length of the neck. All artists thereafter followed suit. Until 1994, when Greg Paul noted that the circular cross-sections of the spines and tapering tips might suggest that the paired neural spines instead protruded from the neck as horn-covered spikes (Paul 1994). Greg also suggested that having paired sails along the neck might be a really bad idea as it could restrict neck mobility, but this idea never made much sense as the tissue between the spines would presumably be flexible and hence not such a problem (the circular cross-section is not really a problem either, since other animals that are thought to have had skin sails, like Dimetrodon, also have rounded neural spines). Since 1994 few opinions have been expressed on this subject, but those that have have sided with Greg in noting that spines are more likely than sails (Salgado 1999).

At SVP Bristol last month, your favourite blog authors spent many happy hours discussing sauropods and their vertebrae. And, inevitably, the subject of Amargasaurus and its weird cervical spines came up. Fact is, sails AND spines are both equally stupid, and the idea of independent neck spines is particularly stupid because animals just don’t ever have their neural spines poking out beyond the musculature and skin of the neck. Right?

Wrong. Hardly known and rarely mentioned is that the last four (or so) cervical neural spines and first three thoracic spines of the Potto Perodicticus potto (a peculiar African strepsirrhine primate, closely related to the Asian lorises) protrude from the skin of the neck and shoulders, have sharply pointed tips, and are usually stated to serve a defensive function [potto skeleton above provided by Mo Hassan]. The spines don’t protrude as naked bone (though this was claimed by Ivan Sanderson), but are covered with skin and some hair, and form a series of tubercles in the live animal. When threatened, a potto is supposed to hide its head and point those protruding neck spines towards the danger, sometimes even butting the predator or aggressor with the spines. Other functions have been suggested for the spines, but a defensive function remains most popular and in the absence of any special knowledge I’ll go with the majority.

At left, Potto with flexed neck, showing its cervical and thoracic spines. From Walker (1970). At right, Amargasaurus as reconstructed by Salgado (1999). Salgado imagined this to be the animal's normal posture: an idea that we find somewhat unlikely (see Taylor et al. 2009).

You might wonder, quite reasonably, whether the anatomy of a small arboreal modern primate has any bearing whatsoever on the soft-tissue morphology of a Cretaceous sauropod (even a ‘small’ one). The point is, however, that neural spines can protrude from the neck after all (albeit sheathed in skin and other tissue), and hence there is at least some precedent for this sort of thing. All that’s needed now is for someone to study the histology and microscopic surface texture of those protruding potto spines and see if there are any correlates for their protruding nature (so far as I can tell this hasn’t been done). Then go look at Amargasaurus. There’s clearly a paper in this, please report back and include me on the authorship, thanks.

References

• Hecht, J. 1992. Dollars for dinosaurs. New Scientist 136 (1845), 50.
• Paul, G. S. 1994. Dinosaur art & restoration notes: dicraeosaurs. The Dinosaur Report Summer 1994, 8.
• Salgado, L. 1999. The macroevolution of the Diplodocimorpha (Dinosauria; Sauropoda): a developmental model. Ameghiniana 36, 203-216.
• Taylor, M. P., Wedel, M. J. & Naish, D. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54, 213-220.
• Walker, A. 1970. Nuchal adaptations in Perodicticus potto. Primates 11, 135-144.

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:

Sereno et al. (2007:fig. 3): Nigersaurus taqueti, including photographs of cervical, dorsal and caudal vertebrae in left lateral view.

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.

Unnamed brachiosaurid NHM R5937, "The Archbishop", Cervical P in right lateral view.

Unnamed brachiosaurid NHM R5937, "The Archbishop", Cervical P in left lateral view.

References

• 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.

I made brachiosaur sand-sculptures.

Brachiosaurid in hypothetical sleep posture, left anteroventrolateral view. Juvenile Homo sapiens (Daniel Taylor) for scale.

(And yes, it’s that Daniel Taylor, the author of Taylor 2005 — a copy of which apparently hangs on the wall of the Padian Lab.)

But wait!  Is the brachiosaur truly asleep, as it seems, or is it actually the victim of a mighty hunter?

Brachiosaurid in hypothetical death pose, left posteroventrolateral view. Mighty hunter (Michael P. Taylor) for scale. Note bemused bystander in middle distance.

No, it turns out it was just asleep after all; and I joined it.

Brachiosaurid in hypothetical sleep pose after all, left posteroventrolateral view. Brachiosaur's new best friend for scale.

… and finally: your obligatory sauropod-vertebra shot:

Cast of Mamenchisaurus hochuanensis holotype CCG V 20401, in right lateral view. Need I draw your attention to the truly absurd neck? This cast is owned by the Homogea Museum in Trzic, Slovenia, and was on loan in the car-park of the Geological Museum in Copenhagen.

References

• Taylor, Daniel J.  2005.  Sauropods of the Mesozoic Era.  Journal of Dinosaurs 1(1):1-2.

Just checking: no-one’s bored of brachiosaurs yet, are they?

Thought not.  Right, then, here we go!

Greg Paul’s (1988) study of the two “Brachiosaurus” species — the paper that proposed the subgenus Giraffatitan for the African species — noted that the trunk is proportionally longer in Brachiosaurus than in Giraffatitan due to the greater length of its dorsal centra. Paul (p. 7) stated that the difference is “25%-30%” on the basis of his figure 2.

Having seen the dorsal vertebrae of the type specimens of both species, my gut reaction was that the difference was nowhere near this great, so I recalculated it for myself (Taylor 2009:table 3).  Dorsal column length is the sum of the “functional length” of the centra of the dorsal vertebrae, where functional length is the length of the centrum not counting the condyle (which of course is nestled in the preceding vertebra’s cotyle when the column is articulated).  For Brachiosaurus, Riggs (1904) did not give this measurement, but did give total heights, and using these for scale I was able to measure the functional lengths from his plate LXXII.  For Giraffatitan, Janensch’s (1950:44) superbly comprehensive table supplied measurements for D4 and D8; for D11 and D12 I was able to determine the length by measuring from Janensch’s (1950:fig. 62) figure, knowing the height from his table; and for D5-D7, D9 and D10, I interpolated linearly between the measurements that I had.  Summing the functional lengths of D6-D12, I got 226 cm for Brachiosaurus and 183 cm for Giraffatitan.  So Brachiosaurus is 226/183 = 1.23 times as long as Giraffatitan — in other words, 23% longer, which is pretty much what Greg Paul said.  So I learned something there.

(Yes, brachiosaurs probably had 12 dorsals.)

So: is a 23% longer torso a big deal?  Back when I was trying to answer that question for myself, I figured it would help to take an image of a familiar animal and stretch it — so here is a horse, stolen from here and stretched:

Horse (top); and evil mutant horse with 23% longer torso (bottom).

To me, that second picture is wrong enough to hurt my eyes a little; your mileage may vary, but I suspect those among you who love horses will feel ill when you look at it.  This image was one of the reasons — one of many — that I concluded that generic separation was unavoidable.

But here’s an odd thing: tonight, for this blog post, I did the same thing to a human body, expecting it to seem even more horrible in light of how familiar we are with our own bodies.  Here it is:

Flayed Homo sapiens in orthograde anatomical position, from Vesalius (1543) "Tertia Musculorum Tabula". Modified from Wilson (2006:fig. 1). Left, as drawn; right, with torso elongated by 23%.

To my surprise, the elongated human doesn’t look appallingly wrong to me.  It doesn’t look right, of course, but it seems within the realms of, for example, what might appear as a representation of a human body in the early issues of Fantastic Four.  I am not sure what to make of that fact.  I don’t believe I have a more finely tuned sense of horse anatomy than human anatomy: it might be that I am more used to badly drawn humans than badly drawn horses; or that there is more variation in human proportions than in horse proportions; or maybe weirdness just looks less weird when it’s upright than when it’s horizontal.  I’ll be interested to hear in the comments whether the Long Horse or the Long Human looks most wrong to readers.

(By the way, I casually talk about the type specimens of both “Brachiosaurus” species: while the situation is simple in the case of Brachiosaurus altithorax, whose holotype is FMNH P25107, things are more complex in the case of Giraffatitan brancai.  Janensch nominated “Skelett S” as the holotype of his new species “Brachiosaurus” brancai, but that turned out to be a chimera, composed of the two skeletons which he subsequently designated SI and SII — but Janensch never designated one of these as the type, and so far as I’ve been able to determine, neither has anyone else done so.  SI is represented by cranial elements and the first seven cervicals, but that’s all; SII is a much larger animal and is represented by most of the skeleton, and has been informally treated as though it were the type specimen most of the while, so I formally proposed HMN SII as the lectotype of the species (Taylor 2009:788) — just a bit of housekeeping.)

Here’s our old friend, the 8th cervical vertebra of HMN II, in a rare posterodorsal aspect, showing just how thin and, well, lamina-like the spinopostzygapophyseal laminae are.  All that space in between them?  Filled with diverticula, mostly.  Amazing.

Giraffatitan brancai lectotype HMN SII, 8th cervical vertebra, in posterodorsal view

Meanwhile some good news:

Remember the good news and bad news about the all-dinosaurs special volume of The Anatomical Record?  Well, since we posted that, the entire issue has been made open access!  Fantastic stuff there: details from D. Schachne of the Wiley-Blackwell Communications Team.  It’s not clear why the articles were all paywalled when originally posted, but all’s well that ends well.

And finally …

There’s been a gratifying amount of discussion in the comments on recent articles.  It can be hard to keep track of, but it helped a lot when I found an RSS feed for comments, which is what I now use.  For anyone else who wants it, it’s at http://svpow.wordpress.com/comments/feed/

References

• Janensch, Werner.  1950.  Die Wirbelsaule von Brachiosaurus brancai.  Palaeontographica (Suppl. 7) 3: 27-93.
  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.
  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.
  Vesalius, A.  1543.  Andreae Vesalii Bruxellensis, Scholae medicorum Patauinae professoris, de Humani corporis fabrica Libri septem [facsimile]. Ex Officina Ioannis Oporini, Basel, 659 pp.
  Wilson, Jeffrey A.  2006.  Anatomical nomenclature of fossil vertebrates: standardized terms or “lingua franca”?  Journal of Vertebrate Paleontology 26(3): 511-518.
• Janensch, Werner.  1950.  Die Wirbelsaule von Brachiosaurus brancai.  Palaeontographica (Suppl. 7) 3: 27-93.
• 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.
• 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.
• Vesalius, A.  1543.  Andreae Vesalii Bruxellensis, Scholae medicorum Patauinae professoris, de Humani corporis fabrica Libri septem [facsimile]. Ex Officina Ioannis Oporini, Basel, 659 pp.
• Wilson, Jeffrey A.  2006.  Anatomical nomenclature of fossil vertebrates: standardized terms or “lingua franca”?  Journal of Vertebrate Paleontology 26(3): 511-518.