February 26, 2010
The hot news on the block right now is the description of the new sauropod Abydosaurus mcintoshi, which, amazingly, is known from four more or less complete skulls (Chure et al. 2010). This is unheard of — absolutely unprecedented. There are few enough sauropods for which a skull is known at all; but four of them, all in decent nick, is breathtaking.
And here is one of them, the holotype:
It’s a real shame that, presumably due to space limitations, this is the only one of the skulls that’s figured in the paper; but the good news is that some of the referred material is illustrated in the supplementary information, which — like the paper itself — is freely available, thanks to the wonder of open-access publishing.
According to the phylogenetic analysis in the paper, Abydosaurus is a brachiosaurid — it is recovered in all MPTs as the sister taxon to Chure et al.’s “Brachiosaurus” OTU (on which, see below). Since it’s from the mid Cretaceous (Cenomanian-Albian, from the Mussentuchit Member of the Cedar Mountain Formation), it’s likely about 105 million years old, which means it lived the best part of 50 million years after the better known brachiosaurs Brachiosaurus and Giraffatitan. It was evidently attracted by the Giraffatitan component of the compound OTU, since the skull and neck are effectively unknown in Brachiosaurus (see Taylor 2009 for a review of the holotype and referred material). Because it lived in pretty much the same time and place as Sauroposeidon, there is the tantalising possibility that it is actually the skull of that animal; on the other hand, the four recovered skulls are all too small to fit the Sauroposeidon holotype, so unless they were all subadult, that appealing idea is probably wrong.
Unlike Giraffatitan — the only other brachiosaur with decent cranial material, so far as I recall — Abydosaurus has narrow teeth , superficially similar to those of diplodocids and titanosaurs. Chure et al. show that this seems to be part of a general trend of sauropods evolving progressively narrower tooth crowns through time, perhaps because narrow teeth can be replaced more quickly and turnover rate is more important than robustness.
One aspect of this paper particularly pleases me, and that is that the new species is named after John McIntosh. For anyone out there who doesn’t know who McIntosh is, he’s been working on sauropods since forever: he’s produced a stream of important papers on the skulls of diplodocids, among many other things, and wrote the Sauropoda chapter in the original The Dinosauria (McIntosh 1990). All of this in his spare time, mind you, because as his day-job he was a professor of theoretical physics at Yale and Princeton. He’s probably seen more sauropod material than anyone else alive. And on top of all that, he is one of the good guys. I drew the long straw at the Austin SVP in 2007, and got to sit next to him at the informally convened sauropod-workers’ lunch, and it was a revelation to see his face light up as I tried to describe the weird morphology of the as-yet-unpublished vertebra that we now know as Xenoposeidon. At an advanced age — I don’t know exactly how old he is, but you can get some idea from the fact that he flew over Hiroshima and Nagasaki less than a week after the bombs were dropped — his enthusiasm remains undimmed, and he is truly an inspiring example to every avocational palaeontologist.
So it’s sort of scandalous that it took so long before McIntosh got a sauropod of his own. (Jensen did name Ultrasaurus after him, but as has been much discussed, that ended up synoymised with Supersaurus). I know there’s at least one more new sauropod in the works that’s slated to be named after him, and I’m in favour.
A note on brachiosaur taxonomy
I suppose I ought to mention this, only because if I don’t, everyone will just ask me about it. Chure et al. (2010) refer to Giraffatitan by the old name “Brachiosaurus” brancai throughout, and explain why they do so on page 2:
Taylor (2009) recently suggested that the North American species Brachiosaurus altithorax is generically distinct from the African species Brachiosaurus brancai, which is known from abundant material including a complete skull and many craniodental elements. Based on numerous differences between overlapping parts of both holotypes, Taylor (2009) proposed that the African species should be known as Giraffatitan brancai. While we are open to this possibility, we do not believe that it is sufficiently justified at present because the identified differences have not been defended as separating genera, rather than species, populations, or individuals. The sister-taxon relationship between the two species recovered in the phylogenetic analysis performed by Taylor (2009) neither supports nor refutes their generic-level separation. At this point, we consider the decision to recognize the African species as a genus apart to be arbitrary. We choose to retain the original nomenclature in this contribution, distinguishing between the two species where appropriate.
I am sort of nonplused by this. I’m certainly not saying that my 2009 paper is unassailable: as soon anyone comes along with evidence that Brachiosaurus and Giraffatitan should after all be considered congeneric, I’ll be first in line to hear them out. But I do feel that now 26 osteological differences have been described between the species, the null hypothesis has shifted, and the burden of proof is now on those who wish to synonymise the genera. “We choose to retain the original nomenclature” is not an argument, and doesn’t really advance understanding. So I’m afraid I think this was a regrettable misstep.
Anyway — I don’t want to end on that note! The big deal here is that we now have four fantastic new brachiosaur skulls, no doubt to be described in more detail hereafter, and John McIntosh has a beautiful sauropod named after him. Happy days!
- Chure, Daniel, Brooks B. Britt, John A. Whitlock and Jeffrey A. Wilson. 2010. First complete sauropod dinosaur skull from the Cretaceous of the Americas and the evolution of sauropod dentition. Naturwissenschaften (online, unpaginated). doi:10.1007/s00114-010-0650-6
- McIntosh, John S. 1990. Sauropoda. pp. 345-401 in: D. B. Weishampel, P. Dodson and H. Osmólska (eds.), The Dinosauria. University of California Press, Berkeley and Los Angeles.
- 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.
February 19, 2010
Lovers of fine sauropods will be well aware that, along with the inadequately described Indian titanosaur Bruhathkayosarus, the other of the truly super-giant sauropods is Amphicoelias fragillimus. Known only from a single neural arch of a dorsal vertebra, which was figured and briefly described by Cope (1878) and almost immediately either lost or destroyed, it’s the classic “one that got away”, the animal that sauropod aficionados cry into their beer about late at night.
I’m not going to write about A. fragillimus in detail here, because Darren’s so recently covered it in detail over at Tetrapod Zoology — read Part 1 and Part 2 right now if you’ve not already done so. The bottom line is that it was a diplodocoid roughly twice as big as Diplodocus in linear dimension (so about eight times as heavy). That makes it very very roughly 50 m long and 100 tonnes in mass.
But Mike!, you say, Isn’t it terribly naive to go calculating masses and all from a single figure of part of a single bone?
Why, yes! Yes, it is! And that is what this post is about.
As I write, the go-to paper on A. fragillimus is Ken Carpenter’s (2006) re-evaluation, which carefully and tentatively estimated a length of 58 m, and a mass of around 122,400 kg.
As it happens, Matt and a colleague submitted a conference abstract a few days ago, and he ran it past me for comments before finalising. In passing, he’d written “there is no evidence for sauropods larger than 150 metric tons and it is possible that the largest sauropods did not exceed 100 tons”. I replied:
I think that is VERY unlikely. […] the evidence for Amphicoelias fragillimus looks very convincing, Carpenter’s (2006) mass estimate of 122.4 tonnes is conservative, being extrapolated from Greg Paul’s ultra-light 11.5 tonne Diplodocus.
Carpenter’s estimate is based on a reconstruction of the illustrated vertebra, which when complete he calculated would have been 2.7 m tall. That is 2.2 times the height of the corresponding vertebra in Diplodocus, and the whole animal was considered as it might be if it were like Diplo scaled up by that factor. Here is his reconstruction of the vertebra, based on Cope’s figure of the smaller but better represented species Amphicoelias altus:
Matt’s answer to me was:
First, Paul’s ultra-light 11.5 tonne Dippy is not far off from my 12 tonne version that you frequently cite, and mine should be lighter because it doesn’t include large air sacs (density of 0.8 instead of a more likely 0.7). If my Dippy had an SG of 0.7, it would have massed only 10.25 tonnes. Second, Carpenter skewed […] in the direction of large size for Amphicoelias. I don’t necessarily think he’s wrong, but his favoured estimate is at the extreme of what the data will support. Let’s say that Amphicoelias was evenly twice as large as Dippy in linear terms; that could still give it a mass as low as 90 tonnes. And that’s not including the near-certainty that Amphicoelias had a much higher ASP than Diplodocus. If Amphicoelias was to Diplodocus as Sauroposeidon was to Brachiosaurus—pneumatic bones about half as dense—then 1/10 of its volume weighed ½ as much as it would if it were vanilla scaled up Dippy, and we might be able to knock off another 5 tonnes.
There’s lots of good stuff here, and there was more back and forth following, which I won’t trouble you with. But what I came away with was the idea that maybe the scale factor was wrong. And the thing to do, I thought, was to make my own sealed-room reconstruction and see how it compared.
So I extracted the A.f. figure from Osborn and Mook, and deleted their dotted reconstruction lines. Then I went and did something else for a while, so that any memory of where those lines might have been had a chance to fade. I was careful not look at Carpenter’s reconstruction, so I could be confident mine would be indepedent. Then I photoshopped the cleaned A. fragillimus figure into a copy the A. altus figure, scaled it to fit the best as I saw it, and measured the results. Here it is:
As you can see, when I measured my scaled-to-the-size-of-A.f. Amphicoelias vertebra, it was “only” 2293 mm tall, compared with 2700 mm in Ken’s reconstruction. In other words, mine is only 85% as tall, which translates to 0.85^3 = 61% as massive. So if this reconstruction is right, the big boy is “only” 1.87 times as long as Diplodocus in linear dimension — maybe 49 meters long — and would likely come in well below the 100-tonne threshhold. Using Matt’s (2005) 12-tonne estimate for Diplodocus, we’d get a mere 78.5 tonnes for Amphicoelias fragillimus. So maybe Matt called that right.
Folks — please remember, the punchline is not “Amphicoelias fragillimus only weighed 78.5 tonnes rather than 122.4 tonnes”. The punchline is “when you extrapolate the mass of an extinct animal of uncertain affinities from a 132-year-old figure of a partial bone which has not been seen in more than a century, you need to recognise that the error-bars are massive and anything resembling certainty is way misplaced.”
- Carpenter, Kenneth. 2006. Biggest of the big: A critical re-evalustion of the mega-sauropod Amphicoelias fragillimus Cope, 1878. pp. 131-137 in J. Foster and S. G. Lucas (eds.), Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 36.
- Cope, Edward Drinker. 1878. Geology and Palaeontology: a new species of Amphicoelias. The American Naturalist 12 (8): 563-566.
- Osborn, Henry Fairfield, and Charles C. Mook. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3:247-387, and plates LX-LXXXV.
February 17, 2010
Hat tip to Open Dinosaur Project contributor Rob Taylor, who drew my attention to this photo of a huge and sauropodoriffic snow sculpture at [what I thought when I wrote this was] the Fairbanks Ice Festival:
(Copied from this page on phombo.com)
Is it real? I really hope so, but I have my doubts. That is a big, big sculpture, and you’d think that such a thing would be better known — my searches on the Internet have turned up only this photo and none from other angles or taken at other times. So I guess that suggests it could be photoshopped. But if it is, that’s OK: just means it’s art of a different kind.
We’ll be back with some proper science in a day or two — just thought you all ought to see this.
Update (later the same day)
The good news is, it seems this is legit: it’s confirmed by a different photo of the same sculpture from a different angle:
This picture is from The PhotoMann Travel Photography site’s Sapporo page, so it looks like the sculpture is, or was, in Sapporo, Japan, rather then Alaska, USA.
Another update (the next day)
Many thanks to commenters ech and MarkR, who found more photographs of the same sculpture and confirmed that it definitely was from the 2004 Sapporo Snow Festival, and not Fairbanks as originally advertised. I’m posting copies of those other photos here for posterity, since it’s nice to have them all in one place.
February 12, 2010
Since I started taking photographs of sauropod vertebrae back in 2004, I’ve got much, much better at it, and for the last few months I’ve been meaning to write an article about what I’ve learned along the way. A few weeks ago, fellow SV-POW!er Ranger Matt Wedel posted an article on his 10 Minute Astronomy blog on how to photograph the moon through binoculars, and that served as a prod to get back into blogging gear in the post-Christmas season.
Before I launch in, let me be really clear that I am not a proper photographer — not at all. I don’t even know what an F-stop is or what Single Lens Reflex means. Probably I should invest some time into learning some of this, since specimen photographs are so important in the world of sauropod vertebrae. (After all, the specimens are more than a little cumbersome to loan, so photos often have to stand as proxies for the actual specimens.) Nevertheless, what I’ve learned in the last five or six years has got me to the point where I am producing much, much better specimen photographs than when I started, and I hope at least some of you can benefit from what I’ve learned.
First up, get a decent camera. However skilled you are, you can’t take better photos than the hardware allows. Although I am to blame for the composition above and for some of blurriness, the over-exposure, poor definition and artifacts are the fault of the camera. I was using a truly horrible camera back then — some super-cheap list-of-features-on-a-discount-website piece of kit.
The good news is that a “decent” camera doesn’t need to break the bank: for our purposes you don’t need to spend a fortune on professional-photographer standard equipment. I am looking on ebay right now, and it seems you can get my model of camera for £100 in the UK or $150 in the US (second-hand of course) which is a level of investment we really should be prepared to put into one of the most important aspects of descriptive work.
What constitutes a decent camera? Mostly, optics. These days, every camera has more than enough megapixels for most purposes, so you can just forget about that statistic altogether. It’s about the quality of the lens and the size of the CCD — those are the factors that determine how much information the camera can capture, and if it puts out more bits than that, then all it’s doing is wasting disk-space and bandwidth.
Can I justify the claim that all modern cameras have enough megapixels? I think so. Suppose you’re preparing a full-page plate for the Journal of Vertebrate Paleontology. In practice, plates are nearly always composites of several photos, but suppose you want a single shot filling the whole plate. The printable area of a JVP page is 182 x 233 mm, which is 7.2 x 9.2 inches. At 300 dpi, that’s 2161 x 2752 pixels, which is 5947072, or a slice under 6 megapixels. So 6 Mp is enough for a full-page plate. (For what it’s worth, my camera does 2272 x 1704 = 3.8 megapixels, and I have never found myself feeling a need for more resolution.)
For the same reason, you definitely want optical zoom rather than digital zoom, which really amounts to just blowing up the image.
Another big win: get a spare battery, so that one can be recharging while you’re using the other. If you don’t do that, your camera is out of commission half the time.
And get a big enough memory card. What’s “big enough”? For me, that means enough space to hold a whole day’s images so I can do a single dump onto the laptop in the evening, rather than having to keep stopping to transfer. I can take maybe a maximum of 300 photos a day. With 1 Mb images, that means I need a 300 Mb card, which is chickenfeed. You literally can’t buy cards that small any more, so this is not really a factor these days and I might just as well not have mentioned it. (The reason I did mention it is that my camera originally came with a 16 Mb card or something similarly stupid, which meant ten minutes or so of photography before downloading.)
Get the specimen in frame
Shoot from cardinal directions
Don’t put anything in front of the specimen
Use a plain background when possible.
But the good news is that all these problems can be ameliorated if you follow the last and most important rule in this section which is:
Take many shots and keep only the good ones
I remember reading once, long ago, that the single biggest factor in the difference of quality between a professional photographer’s work and an amateur’s is that the pro takes ten times as many shots and throws 90% of them away. In these days of digital cameras with huge memory cards, we can all make like professionals now. When Matt and I were at the Field Museum in Chicago, we took 168 photos of those Brachiosaurus dorsals alone. Of those, maybe a dozen or so are really worth keeping. But at least I have those dozen.
In general, I take every photograph twice. As I’ve got better at taking the photos, I am increasingly finding that both come out well and it’s a toss-up which to keep, but maybe one time in ten or twenty, one of them just doesn’t come out right — something is wrong with the focus, or the camera shakes, or something — and that’s when I’m glad I have the spare.
On the other hand, my camera’s built-in flash is pretty lame. Expensive flash units might do much better.
As with flash, it seems that the only thing to do is try photos with and without external lights, and with the lights in various different positions, and see what comes out best.
So what can you do? Well, there are several levels of compensation.
Simply being aware of remaining still
When I have to hold the camera in my hands and I know it’s going to be a long exposure I find myself going into a sort of zen state — I become aware of my heartbeat and try to time the shutter release so that the camera doesn’t get moved by my pulse. It’s error-prone, but at least being aware of it can help.
Brace against a door-frame or similar
The combination of tripod mounting and shutter delay means that you can get good exposure in almost any light.
… And finally …
From: Carol Brown<email@example.com>
We just posted an article, “100 Best (Free) Science Documentaries Online” (http://www.onlineuniversities.com/blog/2010/01/100-best-free-science-documentaries-online/). I thought I’d drop a quick line and let you know in case you thought it was something you’re audience would be interested in reading. Thanks
February 5, 2010
Here’s one of those text-light photo posts that we always aspire to but almost never achieve. In the spring of 2008 I flew to Utah to do some filming for the History Channel series “Evolve”, in particular the episode on size, which aired later that year. I always intended to post some pix from that trip once the show was done and out, and I’m just now getting around to it…a bit belatedly.
Here’s the view out the back door of the BYU Earth Sciences Museum in Provo, Utah. Not bad–the mountains actually made me drag my eyes away from sauropod vertebrae for a few seconds here and there.
Here’s the view in other direction, with Brooks Britt using a forklift to retrieve the big Supersaurus cervical.
And here is said cervical, with a mid-cervical of a giraffe for scale. You may remember the big cervical from this post (and if you click that link, notice how much nicer the new collections area is than the off-site barn where I first encountered the Cervical of Doom). Sauropods FTW!
While the film crew were shooting Brooks and picking up some establishing shots, I was ransacking the collections for pretty vertebrae. We took our treasures up to the University of Utah med center in Salt Lake for CT scanning. Here Kent Sanders is helping me tape down a Diplodocus cervical.
And here’s Kent in the CT reading room playing with the data. Like old times–I spent most of my Saturdays in 1998 and 1999 scanning verts with Kent when he was at the University of Oklahoma Health Sciences Center.
The next morning we went to the North American Museum of Ancient Life in Lehi. Here’s a view down the main drag, with the mounted Supersaurus on the left, mounted Brachiosaurus in the center, and original Supersaurus sacrum (on loan from BYU) in the case on the right.
The highlight of my day trip year.
I was back at BYU just a few months ago shooting another documentary, but that story will have to wait for the dramatically appropriate moment. Stay tuned!