So I finally got to see the Discovery Channel’s new series, Clash of the Dinosaurs. The show follows the common Discovery Channel MO of cutting between CGI critters and talking heads. I’m one of the talking heads, and I get a lot of air time, and I suppose I should be happy about that. But I’m not, for reasons I’ll explain.

I need to preface what follows by saying that I thought the other talking heads did a great job. My experience suggests that the scientific problems with the series didn’t originate with the scientists, infrasound weapons excepted. Tom Holtz–another of the talking heads, and a good one–nailed it on the DML:

For those going to watch the show, a warning:
The documentarians often take anything that any of the talking heads speculated about, and transformed these into declarative statements of fact. In some cases this is particularly egregious, because I strongly disagree with some of these statements and believe the facts are against some of these (say, about tyrannosaurid cranial kinesis…) and they present these as facts rather than suppositions.

Dangerous

In the fall of 2008 the folks  at Dangerous Ltd, a London-based film production company, asked me if I’d be interested in being part of a new documentary project, which had the working title “Dino Body” (this isn’t a trade secret or anything, that title was on the Dangerous webpage for months). The grand idea was to show how much we’ve learned about how dinosaurs actually lived.

Now, this is something I care about a lot. In the past couple of decades we’ve learned about the physiology, diets, nesting habits, growth rates, and social lives of dinosaurs, in unprecedented detail. Things no one predicted and that I would have bet heavily against, like burrowing dinosaurs, four-winged raptors, and comparative studies of dinosaur and pterosaur genomes, are backed by solid evidence. We are in a golden age of dinosaur paleobiology, and new discoveries, even new kinds of discoveries, are stacking up faster than I can really keep up. So it would be a great time to bring all this new evidence to the public.

In the late 2008 and early 2009 I spent a LOT of time with the people at Dangerous Pictures, going over all kinds of questions about dinosaur biology. I sent them papers, links to blog posts, diagrams, you name it. They seemed really keen to get the science right, and I was hopeful that we’d get a dinosaur documentary that wasn’t overly speculative sensationalized BS.

Sadly, that hope was to be mercilessly crushed.

Deja vu

The series has some obvious faults. It is incredibly repetitive, to the point that I found it hard to watch for any length of time without my attention wandering. Not just the CGI clips, but the narration as well. You’ll learn in 30 seconds why females tend to be choosier about mates than males (eggs are more expensive than sperm), and spend the next 15 minutes having that slowly beaten in your brain using as much empty verbiage as possible. Ditto every other fact on the show.

More galling are the places where animation is cleverly cut with talking head bits so that we end up describing things that were never in the script. I explained on camera about the unavoidably high mortality among juvenile sauropods, and how groups of Deinonychus could probably pick off the baby sauropods like popcorn. I had been speaking of hatchlings, but my words are cut together with a scene–which you’ll see about 15,000 times–of three Deinonychus taking down an elephant-sized subadult Sauroposeidon. In the real world, it would have pulped them. In the dramatically-lit world of Clash of the Dinosaurs, the three raptors inflict a handful of very shallow flesh wounds with their laughably tiny claws and the Sauroposeidon expires theatrically for no visible reason.

(If they really wanted to impress the audience with the implacability of Mesozoic death, they would have shown the three raptors mowing down a field of newly-hatched babies like so much wheat…)

I spent a long time explaining the evidence that sauropods buried their eggs, and at their request I mocked up diagrams showing the possible proportions of a hatchling Sauroposeidon. So naturally the program shows a mother abandoning her eggs in an exposed nest, and then a few minutes later, hatchlings that are perfect miniatures of the adults struggling up out of the ground. I guess they cut the scene in which the Sand Fairy buried the eggs, and lacked the budget to perform the simple morph of the digital model that would have made the babies look like babies, instead of ponderous adults emerging from the Sarlacc pit.

Some may complain that I am picking nits. But what the heck is the point of bringing on scientific advisors if you’re then going to ignore the stuff they tell you? Why not just make the crap up out of the whole cloth? In fact, there is far too much of that in the show. There is no evidence that Quetzalcoatlus could see dinosaur pee with its ultraviolet vision, or that a herd of hadrosaurs could knock over a predator with their concentrated infrasound blasts. Sorry, paleontologists, you’ll be fielding questions about these newly invented “facts” for the next decade at least.

It’s like I had this great working relationship with the researchers, and they were really curious and careful, and we went to great lengths to do the best work we could, and then somewhere in between my filming back in February and the airing of the completed show, all of our diligent work was flushed right down the crapper, and a fresh script was written by a hyperactive child whose only prior preparation was reading Giant-Size X-Men and getting hit on the head a few times.

Do I sound too harsh? I’m just getting started. Let me tell you about the sacral expansion in sauropods.

Back in the Back in the Day

In many sauropods and stegosaurs and a few other archosaurs, the neural canal (the bony tube that houses the spinal cord) is massively enlarged in the sacral vertebrae. This is the origin of the goofy idea that big dinosaurs had a “second brain” back there to control their hind end, because the real brain up front was (supposedly) just too darn tiny and remote. The researchers at Dangerous asked me about this sacral enlargement, and this is what I told them (quoted from an e-mail I sent November 25, 2008):

The sacro-lumbar expansion is possibly the most misunderstood thing in sauropod biology. First, there are two separate things that have been referred to as sacro-lumbar expansions. The first is the slight swelling of the spinal cord in that region in almost all vertebrates, including humans, to accomodate the neurons that help run the hind limbs (you also have a swelling in the spinal cord at the base of your neck to help run your arms). Contrary to popular belief, a lot of your stereotyped actions require little direct involvement from the brain and are instead controlled by the spinal cord. When you walk, for example, most of the motor control is handled by the spinal cord, and your brain only steps in when you have to actually worry about where to place your feet–when you step over a puddle, for example. So there would be nothing remarkable about sauropods using their spinal cords to drive many of their limb movements, this is something that pretty much all vertebrates do, it’s just not widely known to the public. [Aside: this is true. Also, I have heard it claimed that sauropods could not have reared because their brains were too small to coordinate such an action. This was claimed by a non-biologist who evidently doesn’t know how the nervous system works.]

The other sacro-lumbar expansion really is an expansion, but it’s not unique to sauropods and it has nothing to do with running the hind limbs. Most birds have a very large expansion of the spinal cord in the sacro-lumbar region called the glycogen body. As the name implies, it stores energy-rich glycogen, but the function of the glycogen body is very poorly understood. It has been hypothesized to be an accessory organ of balance, or a reservoir of compounds to support the growth and maintenance of the nervous system. Since we don’t even know what it does in birds, we’re straight out of luck when it comes to figuring out what it did in sauropods. Here’s a brief overview:
http://www.innerbird.com/other_special_features/hips/other_features_hips.html

Here’s an explanatory diagram I sent with the message:

This business about the glycogen body caused some consternation and dithering in the production process. They wanted to bring up the second brain because it’s so entrenched in the popular consciousness (i.e., bad dinosaur books), but they were unhappy that the real explanation turned out to be so unsatisfying (“We don’t know what it does, but not that!”). In the end, we did discuss it briefly on camera. I said something like, “There was this old idea that the sacral expansion functioned as a second brain to control the hindlimbs and tail. But in fact, it almost certainly contained a glycogen body, like the sacral expansions of birds. Trouble is, nobody knows exactly what the glycogen bodies of birds do.”

Somebody in the editing room neatly sidestepped the mystery of the glycogen body by cutting that bit down, so what I am shown saying in the program is this, “The sacral expansion functioned as a second brain to control the hindlimbs and tail.” I’m paraphrasing because I don’t have a DVR, but that’s basically it. (Update: my memory was pretty good. Here’s the interview transcript.)

Do you see, do you understand, what they did there? I was explaining why an old idea was WRONG and they cut away the frame and left me presenting the discredited idea like it’s hot new science. How freaking unethical is that?

So. I don’t know if the decision to turn my words around 180 degrees was a mistake made by an individual editor, or if it was approved from someplace higher up the line. I aim to find out. Until I do, I’m boycotting Dangerous Ltd, and I encourage you to do likewise.

The Final Insult

Oh, and they spelled my name wrong, throughout. And also mispelled Sauroposeidon in one of the quiz bits at commercial time. “What does Sauroposeiden mean?” It means you don’t know the Greek pantheon, sauropods, or basic spellchecking, dumbasses.

Science journalism FAIL.

UPDATE, January 27, 2010

This is so perfect that it hurts. For “Science Channel” feel free to substitute any of the ignotainment feeds operated by Discovery Communications.

Broadly speaking, pneumatic sauropod vertebrae come in two flavors. In more primitive, camerate vertebrae, modeled here by Haplocanthosaurus, the centrum is a round-ended I-beam and the neural arch is composed of intersecting flat plates of bone called laminae (lam above; fos = fossa, nc = neural canal, ncs = neurocentral suture; Ye Olde Tyme vert pic from Hatcher 1903).

In more derived, camellate vertebrae, the centrum and neural arch are both honeycombed with many small air spaces. This inflated-looking morphology is very similar to that seen in birds, like the turkey we recently discussed. The fossae and foramina on the outside tend to be smaller and more numerous than in camerate vertebrae, as shown here in a titanosauriform axis from India (Figure 3 from Wilson and Mohabey 2006). The green arrows show that the fossae visible on the external surface are excavations or depressions into the honeycombed internal structure of the bone.

External fossae on bones can house many different soft tissues, including muscles, pads of fat or cartilage, and pneumatic diverticula (O’Connor 2006). Pneumatic fossae are often strongly lipped and internally subdivided and may contain pneumatic foramina, which makes them easier to diagnose (but they may also be simple, smooth, and “blind”, which makes them harder to diagnose as pneumatic). But in all of these cases we are usually talking about the same thing: a visible excavation into a corpus of bony tissue, which may have marrow spaces inside if it is apneumatic, or air spaces inside if it is pneumatic (the corpus of bone, not the dent). That’s probably how most of us think about fossae, and it would hardly need to be explained…except that sometimes, something much weirder happens.

Consider this cervical of Brachiosaurus (this is BYU 12866, from Dry Mesa, Colorado). Brachiosaurus and Giraffatitan have an in-between form of vertebral architecture that my colleagues and I have called semicamellate (Wedel et al. 2000); the centrum does have large simple chambers (camerae), but smaller, thin-walled camellae are also variably present, especially along the midline of the vertebra and in the ends of the centrum. As in Haplocanthosaurus, the neural arch is composed of intersecting plates of bone; unlike Haplocanthosaurus, these laminae are not flat or smooth but are instead highly sculpted with lots of small fossae. Janensch (1950) called these “Aussenkaverne”, or accessory outside cavities, because and they are smaller and more variable than the large fossae and foramina that invade the centrum.

And that’s the weird thing. As the red arrows in the above image show, the “Aussenkaverne” are not excavations or depressions into anything, except the space on the other side of the lamina (which in life would have been occupied by another diverticulum). The neural arches of Brachiosaurus and Giraffatitan are not excavated by fossae, they’re embossed, like corporate business cards and fancy napkins.

What’s up with that!? We tend to think of pneumaticity as reducing the mass of the affected elements, but the shortest distance between two vertebral landmarks is a smooth lamina. These embossed laminae actually require slightly more bony material than smooth ones would.

As you can see above, the outer edges of the laminae are thick but the bone everywhere else is very thin. Maybe, like the median septa in pneumatic sauropod vertebrae, the thin bone everywhere except the edges of the laminae was just not loaded very much or very often, and was therefore free to get pushed around by the diverticula on either side, in the sense of being continually and quasi-randomly remodeled into shapes that don’t strike us as being very mechanically efficient. But also like the median septa, the thin parts of the laminae are only rarely perforated (but it does happen), for possible (read: arm-wavy) reasons discussed in the recent FEA post. And maybe the amount of extra bone involved in making embossed laminae versus smooth ones was negligible even by the very light standards of sauropod vertebrae.

Another question: since these thin sheets of bone were sandwiched in between two sets of diverticula, why are the “unfossae” always embossed into them, in the medial or inferior direction? Why don’t any of them pop out laterally or dorsally, looking like domes or bubbles instead of holes, like Mount Fist-of-God from Larry Niven’s Ringworld? Did the developmental program get accustomed to making fossae that went down and into a corpus of bone, and just kept on with business as usual even when there was no corpus of bone to excavate into? I’m only half joking.

I don’t have good answers for any of these questions. I scanned this vert a decade ago and I only noticed how weird the “unfossae” were a few months ago. I’m putting all this here because “Hey, look at this weird thing that I can only wave my arms about” is not a great basis for a peer-reviewed paper, and because I’d like your thoughts on what might be going on.

In Other News

The Discovery Channel’s Clash of the Dinosaurs premiered last night. I would have given you a heads up, except that I didn’t get one myself. I only discovered it was on because of a Facebook posting (thanks, folks!).

COTD is intended to be the replacement, a decade on, for Walking With Dinosaurs. I’m happy to report that one of the featured critters is Sauroposeidon. I grabbed a couple of frames from the clips posted here.

I haven’t seen the series yet, because I don’t have cable. But I’m hoping to catch it at a friend’s place next Sunday night, Dec. 13, when the entire series will be shown again. With any luck, I’ll have more news next week.

Finally, I got to do an interview at Paw-Talk, a forum for all things animal. I’m very happy with how it turned out, so thanks to Ava for making it happen. While you’re over there, have a look around, there’s plenty of good stuff. Brian Switek, whom you hopefully know from this and this, is a contributor; check out his latest here.

References

More out than in

November 24, 2009

I drew a couple of these a while back, and I’m posting them now both to fire discussion and because I’m too lazy to write anything new.

Apato neck v2 480

Here’s the neck of Apatosaurus, my own reconstruction based on Gilmore (1936), showing the possible paths and dimensions of continuous airways (diverticula) outside the vertebrae.

Lovelace et al fig 4 480

Here’s figure 4 from Lovelace et al. (2007), which first got me thinking about pneumatic traces on the ventral surfaces of the centra and what they might imply. You can see pneumatic spaces between the parapophyses in Supersaurus (A) and Apatosaurus (C) but not in Barosaurus (B).

Apatosaurus-soft-tissues v3 480

This is another of my moldy oldies, again based on one of Gilmore’s pretty pictures, showing how I think the soft tissues were probably arranged. The muscles are basically the technicolor version of Wedel and Sanders (2002). Two points:

  1. How bulky you make the neck depends mainly on how much muscle you think was present (which of course depends on how heavy you think the neck was…). Here I was just trying to get the relationships right without worrying about bulk, but it’s worth considering.
  2. The volume of air inside the vertebra was dinky compared to the probable volume of air outside. In Apatosaurus, either of the canals formed by the transverse foramina has almost twice the cross-sectional area of the centrum.

A fair amount of this has been superseded with better data and prettier pictures by Schwarz et al. (2007), so don’t neglect that work in any ensuing discussion (it’s free, fer cryin’ out loud). And have a happy Thanksgiving!

References

Postscript

Mike asked me to add the labeled version of Nima’s brachiosaur parade, so here you go. Click to embiggen.

Bifid Brachiosaurs, Batman!

September 6, 2009

These are the days of miracle and wonder, especially for all you right-minded people out there who are lovers of fine brachiosaurs.  I heard yesterday evening about a new paper in Proceedings of the Royal Society B: You and Li’s (2009, duh) description of a new brachiosaur, the first one known from the Cretaceous of Asia: Qiaowanlong kangxii. Best of all, it’s based primarily on vertebral material:

You and Li (2009:fig. 2)  Cervical vertebrae of Qiaowanlong kangxii holotype FRDC GJ 07-14.

You and Li (2009:fig. 2) Cervical vertebrae of Qiaowanlong kangxii holotype FRDC GJ 07-14. (a) Photograph and (b) interpretative line drawing of C4-C7 in left lateral view; (c) a distal portion of a cervical rib; C9 in (d) cranial, (e) left lateral, (f) caudal, (g) right lateral, (h) dorsal and (i) ventral views. di, diapophysis; f1-f5, fossa 1-fossa 5; pa, parapophysis; poz, postzygapophysis; prz, prezygapophysis; sp, neural spine. Scale bars, 10 cm.

Brachiosaur aficionados will be gazing slack-jawed at parts d, f and h of this figure (the anterior, posterior and dorsal views of C9), which clearly show that the neural spines of the new taxon are bifid (i.e. have two peaks side by side and a trough between them) — just like the cervical neural spines of flagellicaudatans (diplodocids and dicraeosaurs) and camarasaurs.  And mamenchisaurs.  And some titanosaurs.  And Erketu.  Finding this feature yet again — apparently independently evolved in brachiosaurs — makes it about the most plastic character in the matrix.  Very exciting.

That is, it’s exciting if this really is a brachiosaurid.  Now as it happens, Matt was one of the reviewers for this paper (and by the way did an amazingly professional job of not telling me about it until it came out, the git).  He’s told me in email that he’s satisfied that Qiaowanlong really is a brachiosaur, and I hesitate to question that identification given that (A) unlike the authors I’ve never seen the material, and (B) unlike Matt, I’ve spent most of my brachiosaur-presacral quality time with dorsals rather than cervicals.  But, with that caveat, I’m not sure that a compelling case has yet been made for a brachiosaurian identity.

The authors cite three characters in support of a brachiosaurid identity:

  • The most persuasive is the deeply excavated cervical neural spines.
  • Next is a transition in neural spine height: this is quite abrupt in “Brachiosaurusbrancai between cervicals 6 and 7, and also in Sauroposeidon — presumably also between C6 and C7, but that can’t be known for sure, since it’s only the assumption that this is the case that led to the identification of the four preserved Sauroposeidon cervicals as C5-C8 in the first place.  In Qiaowanlong, this transition is “much less pronounced”, with spines increasing in height by only 25% rather then 100% in the other taxa — and occurs between C8 and C9.  All in all, not really very similar to the condition in “B.” brancai.
  • The final character supporting the brachiosaurid identity of Qiaowanlong is the absence of an anterior centrodiapophyseal lamina.  As the authors point out, though, this lamina does exist in “B.” brancai and is absent only in Sauroposeidon; so if this is evidence of anything, it’s a synapomorphy of a clade uniting Qiaowanlong and Sauroposeidon to the absence of other brachiosaurs — something that seems very unlikely given the proportions of the vertebrae.

Putting it all together, there seems to be only one convincing brachiosaur character cited; and that stands against several non-brachiosaur characters, most obviously the bifurcation of the neural spine and the low Elongation Index (centrum length divided by cotyle height) but also by a few other characters that are not discussed in the paper.  For example, Matt has previously noted that in brachiosaur cervicals, the diapophyses are more anteriorly positioned than the parapophyses whereas in diplodocids the opposite is the case: as shown in fig 2(b) above, C6 at least of Qiaowanlong resembles diplodocids in this respect.

To try to get more of a handle on this, I put together a comparative figure of the 8th and 9th cervicals of various sauropods:

8th/9th cervicals vertebrae of various sauropods, scaled to the same centrum length.  "Brachiosaurus" brancai, Sauroposeidon; Qiaowanlong, Diplodocus; Haplocanthosaurus, Camarasaurus

8th/9th cervicals vertebrae of various sauropods, scaled to the same centrum length. From top to bottom and left to right: "Brachiosaurus" brancai, Sauroposeidon; Qiaowanlong, Diplodocus; Haplocanthosaurus, Camarasaurus. Six sauropod vertebrae for the price of one!

Based on overall proportions, I don’t find it intuitively obvious that the Qiaowanlong (middle row, left) more closely resembles the brachiosaurs (top row) than it does the other three.

What does all this mean?  Probably nothing: most likely there are further reasons for the brachiosaurid identification of the new taxon, and lack of space prevented their explanation and illustration.  We can hope that the authors, having placed an initial brief description in Proc. B, will follow it up with a more comprehensive description and analysis in a journal that does not impose such tight length restrictions.  But for now at least, my feeling is that the case for a bifid brachiosaur has yet to be made.

Moving on … Qiaowanlong is also represented by some nice appendicular material: the entire right side of the pelvis (ilium, ischium and pubis).  The ilium certainly looks brachiosaury, so that is another bit of support for the systematic hypothesis, but the proportions of the pelvic bones are very odd:

Right pelvis of "Brachiosaurus" brancai (left), based on composite of Janensch's (1961) figures, and Qiaowanlong (from You and Li 2009: fig. 3a).  Scaled to same ilium length.

Right pelvis of "Brachiosaurus" brancai (left), based on composite of Janensch's (1961) figures, and Qiaowanlong (from You and Li 2009: fig. 3a). Scaled to same ilium length.

You and Li (2009) describe their pelvis as having a “much reduced ischium”, but as is apparent by comparison with the pelvis of “Brachiosaurusbrancai, the ischium is in reasonable proportion to the ilium, and the oddity is more that the pubis is enormous.  So much so that it makes me feel a little ill looking at it, and it makes me wonder how certain it is that all three of these bones are from the same individual — sadly, the paper doesn’t discuss the association of the material.

[Not to flog a dead horse, but this kind of omission shows once more the perils of publishing new taxa in general-interest journals such as Proc. B that impose draconian length limits.  This paper just creeps onto page 7, and I simply don’t believe that it’s possible to do anything like justice to the description of a new taxon in that little space, especially when there is also geography, geology, phylogeny and discussion to be got through.  I don’t want to go all This Is How To Do It, but I can’t help remembering that Darren and I took 18 pages, nearly three times as long, to describe the single partial vertebra that is Xenoposeidon (Taylor and Naish 2007), and it’s not as though that paper wastes a lot of words.  To give You and Li credit, they did squeeze in photos of a representative vertebra from all six cardinal directions, which is great; but only at the cost of the photos being too tiny to be much use.  Please, folks: send your new taxon descriptions to a proper descriptive journal, not to a tabloid!  </hobbyhorse>]

Back on the Dinosaur Mailing List, B tH asked how big Qiaowanlong was.  According to the BBC, the authors say that “the dinosaur would have been a relatively small sauropod about 12m long, 3m high, and weighing perhaps 10 tonnes”.  Can we confirm that?  Well, the excellently comprehensive table of measurements in the paper gives centrum lengths, not counting the condyle, totalling 267 cm for the seven vertebrae C5-C11.  Janensch (1950a:44) gave measurements for the corresponding vertebrae of “Brachiosaurusbrancai HMN SII totalling 577 cm, which is more than twice as long.  If Qiaowanlong was 267/577 = 0.46 times as long as HMN SII, which Janensch (1950b:102) gave as 22.46 m, then it would have been 10.4 m long; it’s not obvious how the authors got the larger figure of 12 m unless they had reason to think the neck was proportionally shorter than in HMN SII.  If Qiaowanlong was isometrically similar to HMN SII, then it was 0.46^3 = 0.99 0.099 times as heavy.  Using my own in-press mass of 23337 kg for HMN SII, this would make Qiaowanlong only 2312 kg in mass — pretty pathetic for a sauropod.

That’s it for now.  I’d be the first to admit that there’s an awful lot of speculation in this post based on relatively little published information.  Hopefully You Hai-Lu will drop by and comment — I’ll be letting him know that I’ve posted this.

References

  • Janensch, Werner.  1950.  Die Wirbelsaule von Brachiosaurus brancai. Palaeontographica (Suppl. 7) 3: 27-93.
    Janensch, Werner.  1950.  Die Skelettrekonstruktion von Brachiosaurus brancai.  Palaeontographica (Suppl. 7) 3: 97-103.
    Janensch, Werner.  1961.  Die Gliedmaszen und Gliedmaszengurtel der Sauropoden der Tendaguru-Schichten.  Palaeontographica, suppl. 7 (1), teil 3, lief. 4: 177-235.
    Taylor, Michael P. and Darren Naish.  2007.  An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England.  Palaeontology 50 (6): 1547-1564.  doi: 10.1111/j.1475-4983.2007.00728.x
    You, Hai-Lu, and Li, Da-Qing.  2009.  The first well-preserved Early Cretaceous brachiosaurid dinosaur in Asia.  Proceedings of the Royal Society B: Biological Sciences.  doi: 10.1098/rspb.2009.1278.
  • Janensch, Werner.  1950.  Die Wirbelsaule von Brachiosaurus brancai. Palaeontographica (Suppl. 7) 3: 27-93.
  • Janensch, Werner.  1950.  Die Skelettrekonstruktion von Brachiosaurus brancai.  Palaeontographica (Suppl. 7) 3: 97-103.
  • Janensch, Werner.  1961.  Die Gliedmaszen und Gliedmaszengurtel der Sauropoden der Tendaguru-Schichten.  Palaeontographica, suppl. 7 (1), teil 3, lief. 4: 177-235.
  • Taylor, Michael P. and Darren Naish.  2007.  An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England.  Palaeontology 50 (6): 1547-1564.  doi: 10.1111/j.1475-4983.2007.00728.x
  • You, Hai-Lu, and Li, Da-Qing.  2009.  The first well-preserved Early Cretaceous brachiosaurid dinosaur in Asia.  Proceedings of the Royal Society B: Biological Sciences.  doi: 10.1098/rspb.2009.1278.

And finally … two announcements!

Traumador the Tyrannosaur has asked us to point out that over on ART Evolved (the palaeo-art blog), the next big art gallery is to be sauropod themed.  Details are on the site, so get over there and submit your sauropod art!

And Matt and I will shortly be teaming up with Andy Farke, the open-source paleontologist, on a new project where we plan to actually do some of this Shiny Digital Future that we keep on talking about.  Andy will be announcing the details on Tuesday 8th September.  Mark the date well!  For now, I shall say no more …

In an email, Vladimir Socha drew my attention to the fact that Tom Holtz’s dinosaur encyclopaedia estimates the maximum height of Sauroposeidon as 20 meters plus, and asked whether that was really possible.  Here’s what Tom actually wrote: “Sauroposeidon was one of the largest of all dinosaurs.  At perhaps 98 to 107 feet (30 to 32.5 meters) long and weighing 70 to 80 tons […] Sauroposeidon would have been the tallest of all dinosaurs. […] If it could crane its neck up, it might have been able to hold its head 66 to 69 feet (20 to 21 meters) high or more” (Holtz and Rey 2007:207).  Vladimir was understandably skeptical.  But can it be true?

Wedel and Cifelli (2005: fig. 15) shows Matt’s best skeletal reconstruction of Sauroposeidon, with Boring Old Brachiosaurus and a human for scale:

Sauroposeidon with Boring Old Brachiosaurus and human for scale and 20 m height indicated. Lightly modified from Wedel and Cifelli (2005: fig. 15)

Sauroposeidon with Boring Old Brachiosaurus and human for scale and 20 m height indicated. Lightly modified from Wedel and Cifelli (2005: fig. 15)

Amazingly, those dummies didn’t include an actual scalebar; but apparently the human figure is 1.8 m tall, so by measuring pixels and cross-scaling, I determined that in this image, Sauroposeidon is a mere 13.43 m tall.  I took the liberty of adding in a marker for the 20 m height proposed by Holtz, and as things stand you’d have to say that it doesn’t look probable.

But let’s see what we can do.  We’ll begin with the classic brachiosaur skeleton of Paul (1988), which shows the well represented species Brachioaurus brancai:

Brachiosaurus brancai skeletal reconstruction in left lateral view. From Paul (1988:fig. 1)

Brachiosaurus brancai skeletal reconstruction in left lateral view. From Paul (1988:fig. 1)

(Some other time, we should take a moment to discuss the differences between this and the Wedel brachiosaur reconstruction; but it will not be this day.)

This reconstruction is in a nice erect-necked posture which, in light of our own recent paper, is probably not too extreme.  Since all the neural arches and processes are missing from the only known posterior cervicals of this species, we don’t know how much flexibility they allowed, and so in light of how the rest of the animal is built (high shoulders and all) it seems reasonable to allow a lot of extension at the base of the neck.  So let’s assume that the pose offered by Paul is correct.  By measuring my scan of that figure, and I see that the 2.13 m humerus is 306 pixels long.  The entire reconstruction, from tip of cranial crest down to forefoot, is 1999 pixels tall, which is 1999/306 = 6.53 times as long as the humerus, which scales to 6.53*2.13 = 13.91 m — a little taller than Sauroposeidon (not Brachiosaurus) in Matt’s reconstruction, which seems about right if we imgine Matt’s Brachiosaurus raising its neck into a Paul-compliant posture.

Now Paul’s reconstruction is based on the Berlin mounted skeleton HMN S II.  Cervical 8 is very well preserved in that animal, and has a centrum length of 98 cm (Janensch 1950a:44).  By contrast, the centrum of C8 of Sauroposeidon OMNH 53062 (the only known specimen) is 125 cm long (Wedel et al. 2000a: 110). So if Sauroposeidon is merely an elongated Brachiosaurus brancai, then it’s 125/98 = 1.28 times as long and tall, which would be 17.74 m.

But wait: it seems that Sauroposeidon is to Brachiosaurus brancai as Barosaurus is to Diplodocus — similar overall but more elongate.  And it turns out that Barosaurus has at least 16, maybe 17 cervicals (McIntosh 2005:45) compared with Diplodocus‘s 15.  So maybe Sauroposeidon also added cervicals from the brachiosaur base-state — in fact, that would hardly be surprising given that Brachiosaurus brancai has so few cervicals for a long-neck: 13, compared with 15 in most diplodocids, 16 or 17 in Barosaurus, and 19 in Mamenchisaurus.  If you reconstruct Sauroposeidon with two more C8-like cervicals in the middle of the neck, that adds 2*125 = 250 cm, which would give us a total height of 17.74+2.5 = 20.24 m.

So I don’t think Tom Holtz’s estimate is completely unrealistic, even for the one Sauroposeidon specimen we have now — and remember that the chances of that individual being the biggest that species got are vanishingly small.

On the other hand, maybe Sauropodseidon‘s neck was the only part of it that was elongated in comparison to Brachiosaurus brancai — maybe its forelimbs were no longer than those of its cousin, so that only the neck elongation contributed to greater height.  And maybe it had no additional cervicals, so its neck was “only” 1.28 times as long as that of Brachiosaurus brancai — 1.28*8.5 = 10.88 m, which is 2.38 m longer; so the total height would be 13.91+2.38 = 16.29 m (assuming the additional neck length was vertical).  And maybe the neck couldn’t get very close to vertical, so that the true height was lower still.

All of this just goes to show the perils of reconstructing an animal based only on a sequence of four cervicals.  (Reconstructing on the basis of a single partial mid-to-posterior dorsal, on the other hand, is a much more exact science.)

Finally: Matt’s reconstruction of Sauroposeidon is really rather conservative, and looks very much like a scaled-up vanilla brachiosaur.  Just to see how it looks, I’ve made a reconstruction of the putative (and very possible) elongated, attenuated version of Sauroposeidon, showing the legs and cervicals 28% longer than in B. brancai, and with two additional cervicals.  I made this by subjecting Greg Paul’s 1988 brachiosaur to all sorts of horrible and half-arsed distortions, so apologies to Greg.  But remember, folks: this is just as likely correct as Matt’s version!

A different view of Sauroposeidon, based on elongation of the cervicals and legs of Brachiosaurus brancai and the insertion of two additional cervicals. Heavily and carelessly modified from Paul (1988: fig. 1)

A different view of Sauroposeidon, based on elongation of the cervicals and legs of Brachiosaurus brancai and the insertion of two additional cervicals. Heavily and carelessly modified from Paul (1988: fig. 1)

References

.

Little, big: the reveal

August 2, 2009

WNV-1

Here’s the answer to last week’s riddle. The big vertebra was obviously cervical 8 of Sauroposeidon, which you’ve seen here more than once. The small vertebra is also a mid-cervical, also from the Early Cretaceous, but from Croatia rather than Oklahoma. The very long centrum, unbifurcated neural spine, and extensive pneumatic sculpturing mark it as a brachiosaurid. It was first described by Dalla Vecchia (1998), and lavishly illustrated with numerous photos by Dalla Vecchia (1999). It was also included by Dalla Vecchia (2005:figs. 18.5 and 18.6) in the Thunder-Lizards volume from Indiana University Press, which is where I figured someone might recognize it from.

WNV-1 in hand 480

Here are two of those figures from Dalla Vecchia (1999)–note the thumb and fingers in the left-hand photo. The vertebra is about a foot long (~30 cm), which means it is TINY for a brachiosaurid mid-cervical. Note also that there is no sign of a neurocentral suture, so the critter was probably at least half grown and might have been full grown.

It is worth bearing mind that this super-tiny, pathetically titchy, adorable widdle bwachiosauw ve’tebwa is only a bit smaller than your average giraffe cervical.

Sauroposeidon vs WNV-1 480Speaking of giraffes, from left to right we have:

  • Sauroposeidon, scaled like HM SII x 1.15;
  • a 20-foot-tall world record giraffe;
  • WNV-1, scaled like 0.22 x Sauroposeidon;
  • a 6’2″ human, such as yours truly.

Note that I  could look over the shoulder of WNV-1, but it could not look over the giraffe’s shoulder, nor could the giraffe look over Sauroposeidon‘s shoulder. The giraffe could not walk under Sauroposeidon‘s stomach, but WNV-1 could walk under the giraffe’s.  If the mass of Sauroposeidon was 40 tons, that of WNV-1 may have been around 450 kg, or a little under half a ton.

I wonder which evolved first in brachiosaurids, stupendous size or stupendous necks?

References

  • Dalla Vecchia, F.M. 1998. Remains of Sauropoda (Reptilia, Saurischia) in the Lower Cretaceous (Upper Hauterivian/Lower Barremian) limestones of SW Istria (Croatia). Geologia Croatica 51(2):105-134.
  • Dalla Vecchia, F.M. 1999. Atlas of the sauropod bones from the Upper Hauterivian – Lower Barremian of Bale/Valle (SW Istria, Croatia). Natura Nacosta 18:6-41.
  • Dalla Vecchia, F.M. 2005. Between Gondwana and Laurasia: Cretaceous sauropods in an intraoceanic carbonate platform; pp. 395-429 in Tidwell, V., and Carpenter, K. (eds.), Thunder-Lizards: The Sauropodomorph Dinosaurs. Indiana University Press, Bloomington.

Here at SV-POW! Towers, we often like to play Spot The T. rex — a simple drinking game that can be played whenever you have supply of palaeontology-related news reports.  Each player in turn takes a report off the stack, and if T. rex is mentioned anywhere in the report, the player drinks.  We lay in a lot of beer when we play this game, because as it turns out, T. rex is nearly always mentioned (and nearly always spelled “T-Rex”, no italics, no full stop, gratuitous hyphen, capitalised trivial name).  For example, suppose someone publishes an innocent paper arguing that a particular Eocene clam was an obligate scavenger: then the story in the press will be “… just as has been argued for the terrifying T-Rex, which had teeth like steak knives”.  Or if someone names a new Miocene rodent, it will be introduced as “… which lived 50 million years after the terrifying T-Rex, which had teeth like steak knives”.   (Drink twice if the steak knives are mentioned.  Three times if they are described as “banana-sized”.)

So we didn’t feel our neck-posture paper was real until it had somehow been tied in with T-Rex.  Happily, the Great North Museum came to the rescue: by coincidence, they unveiled their T. rex cast the weekend before the paper came out, and the Sunday Sun wanted our opinion on the way the neck had been mounted.  Here’s their mount (not quite ready to exhibit):

Tyrannosaurus rex mounted skeleton at the Great North Museum.  From journallive.co.uk

Tyrannosaurus rex mounted skeleton at the Great North Museum. From journallive.co.uk

Of course, everything we said about the necks of sauropods in the paper also applies to every other extinct land vertebrate — we only concentrated on sauropods because (A) they are the group whose neck posture has been claimed to depart from the tetrapod norm, and (B) they are cool.  In particular, non-avian theropods such as T. rex are in the same extant phylogenetic bracket as sauropods are (i.e. birds plus crocs), so we’d expect strong extension at the base of the neck and strong flexion at the head joint in habitual pose.

So I replied that “the Newcastle mount has the neck and torso in more of a straight line [than a Vidal-compliant posture], which would probably not have been the habitual pose.  It looks to me as though this animal is crouching down to take a drink”, and I’m pleased that the resulting news story included a rather gracious response from the GNM curator.

I don’t know whether the notoriously litigious Disney corporation would be so mellow, though, regarding their truly horrible mount of a cast of “Sue”:

Tyrannosaurus rex "Sue" cast, at Animal Kingdom, Walt Disney World, Florida.  From wwarby's Flickr photostream.

Tyrannosaurus rex "Sue" cast, at Animal Kingdom, Walt Disney World, Florida. From wwarby's Flickr photostream.

I’m really not sure what the people who mounted this were getting at: unlike the Great North Museum mount, the legs are erect, so it’s not going into or coming out of a crouch; and it’s not going into a drinking posture, because the head is pointing straight forward.  But for some reason, it’s below shoulder height.

Here’s how it should be done:

Tyrannosaurus rex at the American Museum of Natural History. Photo by Mike Taylor

Tyrannosaurus rex at the American Museum of Natural History. Photo by Mike Taylor

It’s good to see that the biggest natural history musuem in the world is ahead of the curve, and has its T. rex mount in a pose consistent with how other land vertebrates habitually hold their necks.

I leave you with the news the T. rex‘s neck is pathetic.  Here is the skull and neck of that same AMNH mount, composited with a single cervical vertebra (C8) of Sauroposeidon.  Please note that the Sauroposeidon cervical is way longer than the whole T. rex neck.

T. rex's neck is pathetic

T. rex's neck is pathetic

No references today!

[You don’t need to be told the reference for Taylor et al. (2009) again, do you?]

OMG: MPT, PHD!

April 29, 2009

If you woke up this morning and thought, “Global warming is on the rise, amphibians are in a race to see who can go extinct first, the economy is in the toilet, any day now my boss will discover that I don’t actually do anything at work,  and my blog will never have the eclectic cachet of SV-POW!, but at least Mike Taylor doesn’t have a Ph.D.,” then it is my happy duty to ruin your day. Mike defended today, successfully.

doctor-taylor-in-da-house-480

Ladies and gentlemen, I proudly present Michael P. Taylor of Ruardean, Englishman, adventurer, raconteur, Doctor of Philosophy in the paleontological arts. Note that when recumbent he is approximately equal in length to 1.5 Sauroposeidon cervicals, and appears to be cradling an invisible wine glass. Don’t stare too long, or you might not be able to look away.

Congratulations, sir! Let the blogosphere ring with the happy news, and undescribed sauropods cry out for recognition.

Update (from Mike)

Thanks to Matt, and all commenters, for your kind words.  I wondered when the “Latin love god” photo was going to appear, and that day has finally come.  What Matt doesn’t know is that this photo was used for the cover of my forthcoming album:

Available wherever good music is sold

Available wherever good music is sold

I made this, just for the heck of it.

big-brachiosaurids-and-pathetic-mammals-480

The critters are, from left to right:

  • OMNH 53062, the holotype of Sauroposeidon proteles, with a reconstructed skeleton grayed in;
  • HM XV2, a fibula of Brachiosaurus brancai, which represents the largest known individual of Brachiosaurus;
  • HM SII, the nearly complete mounted composite skeleton of Brachiosaurus brancai in Berlin;
  • a 20-foot-tall, world record giraffe;
  • a 6’2″ human being, such as myself.

The vertebrae of Sauroposeidon are about a third longer than their counterparts in HM SII, but only about 15% larger in diameter. I have therefore always scaled up the body of Sauroposeidon by only 15% relative to HM SII. It may have been bigger or smaller, I’m just trying to follow what few numbers I have to go on as slavishly, and conservatively, as possible. Sauroposeidon is shown here with a more vertical neck than Brachiosaurus because that’s how I had the necks posed in the  two separate skeleton reconstructions before I decided to combine them, and I’m lazy, and that’s not the point of the post anyway.

The point of the post, or the first point anyway, is that almost everyone, everywhere, at all times underestimates the size of Brachiosaurus. This is because of the immense influence of the HM SII mounted skeleton. Practically every estimate of length or neck length or browsing height or mass or anything else for Brachiosaurus is based on that one skeleton. But we know that there were bigger individuals of Brachiosaurus roaming around, like HM XV2, which was 12-13% larger. Not only that, but we can be pretty certain that HM SII was not fully mature because the scapula and coracoid are unfused, and we know these elements are fused into a single scapulocoracoid in mature brachiosaurids. So between SII being not all grown up and XV2 being considerably bigger, we ought to think of XV2 and not SII when we think about big Brachiosaurus was.

Now, 12-13% might not seem like much, but it’s considerable. It’s the difference between me (6’2″) and someone seven feet tall. HM SII has a neck 8.5 meters long; that of XV2 would have been 9.5 meters long, which is longer than the neck of the holotype of Mamenchisaurus hochuanensis (9 m), but shorter than the estimated neck length of Mamenchisaurus sinocanadorum (~12m).

Crucially, XV2 would have massed 1.4 times as much as SII (1.125^3, because mass depends on volume, which scales with the cube of length). That holds true no matter how much you think SII weighed. If SII had a mass of 40 tons, then XV2 was 56 tons; if SII was 30 tons, XV2 was still 42 tons.

Maybe the most interesting thing about this is that, so far as we can tell, XV2 was almost exactly the same size as the holotype individual of Sauroposeidon. So anything I or anyone else has written about Sauroposeidon being bigger, absolutely, than Brachiosaurus, is bobbins. Sauroposeidon still had a considerably longer neck, 11.5 meters to XV2’s 9.5, but the cervical skeleton weighed about the same thanks to the higher air space proportion in Sauroposeidon. In fact, if the higher ASP of Sauroposeidon applied to the rest of the vertebral column, then the holotype individual of Sauroposeidon might have weighed less than XV2!

The evolutionary upshot is that, as far as we can tell, big brachiosaurids stayed about the same size from the Kimmeridgian-Tithonian (Late Jurassic) to the Aptian-Albian (Early Cretaceous). Maybe they hit some kind of limit, but I doubt it, because Argentinosaurus was probably a lot heavier and Bruhathkayosaurus and Amphicoelias would have knocked any known brachiosaurid right out of the park. I think it is more likely that the debits imposed by large body size finally caught up with the selective advantages of same, within that lineage (but not at the same point within other lineages). Whatever the reason, the biggest known brachiosaurid didn’t get any bigger than Brachiosaurus. Which puts the evolution of the longer, more pneumatic neck in Sauroposeidon into a new light. It might have been a cheat, an evolutionary hack to overcome a limit on whole-body growth, even if that limit was a ‘soft’ one imposed by balanced selection pressures in both directions. That’s sort of assuming that Sauroposeidon was just Brachiosaurus with a redesigned front end, but the weirdness we see in the vertebrae might have extended to the rest of the animal. We won’t know until someone digs up some more specimens. Sigh.

The second point of the post is that, as indicated by the title, Brachiosaurus might have been smaller than we commonly think. Since the 1980s there have been a couple of ~30 ton estimates out there for HM SII, one by Anderson et al. (1985) based on limb bone allometry and one by Paul [1988] based on volumetrics (I have to put 1988 publication dates in brackets rather than parentheses or mrrfin’ frrfin’ WordPress automatically changes the 8 and the ) to a smiley, dammit). I think that by and large people have gotten pretty comfortable with the idea that SII was a 30 ton  critter.

But it might–might–have been quite a bit lighter. Paul (1997) assigned the neck a density of 0.6 g/cm^3 and the torso a density of 0.9 g/cm^3. Those are probably too dense. Some birds have necks as un-dense (sparse?) as 0.3 g/cm^3, and that does not strike me as unreasonable for sauropod necks given the amount of pneumaticity indicated by the skeleton. The lungs and air sacs of birds can account for up to 20% of the volume of the body. Not of the torso, of the whole body. And based on my calculations for derived theropods and sauropods, up to 10% of the whole-body volume was occupied by air in the pneumatic bones. That’s 10% in addition to the 20% for the lungs and air sacs, or 30% of the whole body  volume. That would give a whole-body density of about 0.7 g/cm^3, which is in fact what has been found for some birds.

I got 0.8 g/cm^3 for the whole-body density of Diplodocus in my 2005 paper, and other authors have since used that number for other sauropodomorphs. That’s gratifying, but it’s probably wrong. I erred conservatively at every possible point in that calculation and just flat left out some known air spaces whose volume I could not reliably estimate (e.g., vertebral diverticula outside the vertebrae). I also used 10% rather than 20% for the part of the whole-body volume occupied by the lungs and air sacs, because values as low as 10% have been reported for some birds and I was being conservative. But I don’t think that bird-like densities around 0.7 g/cm^3 are unrealistic for sauropods; in fact, I’d be surprised if the really pneumatic ones–like big brachiosaurids–weren’t about that sparse.

And speaking of big brachiosaurids, Henderson (2004) used computerized volumetrics and a density of 0.8 and got a mass of 25.8 tons for HM SII. If the density was really 0.7 that would shave off an additional 10% and bring the mass down to 22.7 tons. That’s getting crazy light; it’s about half of what Bakker and Alexander were proposing for Brachiosaurus in the mid-80s. And it’s still a quarter lighter than what Anderson (1985) and Paul [1988] got.

So, for the sake of argument, let’s say that HM SII did mass only 22.7 tons. That would give XV2 a mass of 32 tons, and Sauroposeidon a mass of only 34.5 tons without taking any additional pneumaticity into account.

That seems totally nuts. But every step is defensible*, and it might even be true.

* That means if you want to tear me a new one in the comments because teh Brachiosaurus wuz 50 tons!!!1!!111!, please be sure to specify which links in the chain of inference you disagree with, and why.

References

  • Anderson, J. F., A. Hall-Martin, and D. A. Russell. 1985. Long-bone circumference and weight in mammals, birds and dinosaurs. Journal of Zoology 207:53-61.

  • Henderson, D. M. 2004. Tipsy punters: sauropod dinosaur pneumaticity, buoyancy and aquatic habits. Proceedings: Biological Sciences 271 (Supplement):S180-S183.

  • Paul, G. 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, G. S. 1997. Dinosaur models: the good, the bad, and using them to estimate the mass of dinosaurs; pp. 129-154 in Wolberg, D. L., Stump, E., and Rosenberg, G. (eds.). Dinofest International: Proceedings of a Symposium Sponsored by Arizona State University. Academy of Natural Sciences, Philadelphia, 587 pp.

New hotness out today: Miragaia, a new long-necked stegosaur from the Late Jurassic of Portugal (Mateus et al. 2009). What is “long-necked” for a stegosaur? In this case, well over a meter! That may not sound too impressive for those of you who have gotten complacent about 10-meter-plus sauropod necks, but it’s a big deal. Miragaia is described as a sauropod mimic, and with good reason: its body proportions are not that different than those of a basal sauropod.

The number of ways to increase the proportional length of the neck are limited: you can add cervicals, or recruit dorsals into the neck, or make the individual vertebrae longer, or do some combination of  the above. In sauropods, different clades took different routes. Brachiosaurids kept a fairly primitive cervical count of  13 but made the individual vertebrae crazy long. Diplodocids recruited dorsals into the neck, and some (like Barosaurus and Supersaurus) also made the vertebrae crazy long. Mamenchisaurids and Euhelopus added cervicals (independently), up to a total of 17 or more, and some (like Omeisaurus)–are you ready for it?–also made the vertebrae crazy long.

In general, stegosaurs took an evolutionary walk through Door Number 2: turning dorsals into cervicals. Mateus et al. (2009) show this nicely in a table; the number of presacrals (cervicals plus dorsals) in stegosaurs stays about the same, between 25 and 27, but between the basal Huayangosaurus and the derived Stegosaurus 3 or 4 dorsals go forward to play for the other team. Is dorsal recruitment sufficient to explain the long neck of Miragaia? Hard to say, since the dorsal series has not been found. But Miragaia‘s count of 17 cervicals is significantly more than Stegosaurus‘s 13. If Miragaia didn’t add any cervicals but only recruited dorsals, it would have had only 9 of the latter. That’s not impossible–Barosaurus did that very thing–but it’s weird, and extreme. As Mateus et al. (2009:p. 4) state, “Miragaia possessed more cervical vertebrae than any other non-avian archosaur, except the Chinese sauropods Mamenchisaurus, Omeisaurus and Euhelopus, also with 17″. And yet the individual vertebrae are pretty short, no longer than in your not-exactly-average Stegosaurus.

brachytrachelopan-vs-miragaia-480

I couldn’t resist pitting Miragaia, the longest-necked stegosaur (so far!) against Brachytrachelopan, the shortest-necked sauropod (so far!). Miragaia is stolen from Mateus et al. (2009:fig. 1a), and Brachytrachelopan from Rauhut et al. (2005:fig. 1a). Both critters come with the 1 meter scale bars from their respective figures. I’m in there for scale, too, at 6’2″ or 1.88 meters. Sauroposeidon looms in the background, just to keep things in perspective. The entire neck of Miragaia might have been about as long as one of the middle cervicals of Sauroposeidon or Supersaurus.

Still, you know.

Not bad.

(for a stinkin’ ornithischian)

A couple more pictures here.

References