From The Dinosaur Heresies.
I don’t have time to write about this properly, but a few people have asked me about the new Sellers et al. (2012) paper on measuring the masses of extinct animals — in particular, the Berlin Giraffatitan — by having a CAD program generate minimal complex hulls around various body regions. Rather than write something new about it, I’m going to publish the comments that I sent Ed Yong for his Discover piece on the new technique:
Hi, Ed, good to hear from you. Yes, it’s a good paper: a useful new technique that has some useful properties, most importantly that it requires no irreproducible judgements on the part of the person using it, and that it’s ground-truthed on solid data from extant animals.
It’s a reassuring sanity-check to find that my (2009) mass estimate falls well within their method’s 95% confidence interval, and is in fact within 0.6% of their best estimate.
There are a couple of problems with this study, which I hope will be addressed in followups. The authors are honest enough to touch on all of these problems themselves, though! They are:
1. All the extant animals used to determine the fudge factor are mammals, which means they are not necessarily completely relevant to dinosaurs. In particular I would very much like to have seen regression lines and correlation coefficients for this method for birds and crocodilians, both of which are much more closely related to Giraffatitan.
2. Much depends on the reconstruction of the torso, particular the position of the ribs, which is very difficult to do well and confidently with dinosaurs. In my volumetric analysis (Taylor 2009:803) I found that the torso accounts for 70% of total body volume in Giraffatitan, so rib orientation will make a big difference to overall mass. Sauropod ribs that are well preserved and undistorted along their whole length are extremely rare.
3. Use of a single density value for the whole animal, while appropriate for mammals, really isn’t for brachiosaurs, in which the very long neck likely had a density no more than half that of the legs. I’m not sure what can be done about this, though, since any attempt to correct for density variation involves subjective guesswork. Then again, so do all guesses at overall body density in dinosaurs.
Issue 1 bothers me most, because the convex hulls of limb segments in mammals will be proportionally much larger than in sauropods, due to the complex shapes of mammalian long-bone ends. I worry that using mammals as a baseline will underestimate sauropod leg mass.
Still, even with these caveats, it’s a good exposition of an important new method which I expect to see widely adopted.
Hope that’s helpful.
In short: good work, widely applicable, and probably the best mass-estimation technique we now have available for complete and near-complete skeletons. It would be good to see it applied to (say) the Yale, AMNH and CM apatosaurs.
Sellers, W. I., J. Hepworth-Bell, P. L. Falkingham, K. T. Bates, C. A. Brassey, V. M. Egerton and P. L. Manning. 2012. Minimum convex hull mass estimations of complete mounted skeletons. Biology Letters, online ahead of print. doi:10.1098/rsbl.2012.0263
Taylor, Michael P. 2009a. 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.
October 11, 2010
You may remember that when I wrote about Amphicoelias diplobrontobarowassea the other day, I rather ungraciously complained that “I don’t want to talk about that. There are other things I do want to talk about”. Well, with A. suuwatorneriosaurodocus now firmly dealt with, I can talk about what I wanted to — which is Taylor (2010), a little number that I like to call Sauropod dinosaur research: a historical review. You can download the PDF from my website (more on that subject next time) and get the high-resolution versions of the figures separately if you wish.
It’s a comprehensive history of research into sauropod dinosaurs, starting in 1831 with the genera Cardiodon and Cetiosaurus, and bringing us right up to 2008 (which is when the paper was accepted — see below). I cover this history in five stages:
- Stage 1: early studies, isolated elements (1841-1870)
- Stage 2: the emerging picture (1871-1896)
- Stage 3: interpretation and controversy (1897-1944)
- Stage 4: the dark ages (1945-1967)
- Stage 5: the modern renaissance (1968-present)
You could say the the main part of the story begins with Phillips’s (1871) description of Cetiosaurus oxoniensis, the first reasonably complete sauropod, and really kicks into gear with the Marsh-Cope bone wars, but there are plenty of twists and turns between then and now, including — finally — the publication of the table of brachiosaur mass-estimates that I alluded to back in Xenoposeidon week. [Executive summary: published estimates for the single individual HMN SII have varied by a factor of 5.75. Wow.]
History of the history paper
This paper had its genesis in the one-day conference convened at the Geological Society of London on 6 May 2008. [Announcement on Tetrapod Zoology; Tet Zoo report part 1 and part 2]. The extended abstract of my talk has been on my web-site for a long time, and was included in the rather handsome abstracts volume of the conference — which has now been superseded by the proceedings volume containing the full-length papers of which mine is one.
We’d been told to prepare 30-minute talks — a much heftier slot than the 20 minutes we get at SVPCA (or indeed the 15 allowed at SVP, though I wouldn’t know what that’s like as I have never, ever managed to get a talk accepted there). I tend to move very quickly through my talks anyway, so I prepared a monster presentation of 76 slides (plus another 11 that I had to cut from the talk, but which I left hanging around at the end of the slideshow). By the way, this is the very talk that my wife, Fiona, fell asleep in the middle of while I was rehearsing it at her.
So I’d prepared a thirty-minute talk that used every second of every minute. Then on the day of the conference itself, they handed out the schedules, and … the talks were down to twenty-five minutes. Arrrgh! I had absolutely no fat to trim in my thirty minutes, so all I could do was talk even faster, and keep going when I reached the 25-minute mark.
So there I was, talking about how Russell and Zheng (1993) pioneered the use of cladistics in sauropod systematics, when the session moderator — our very own Darren Naish — started trying to wave me off the podium. By the time I was talking about Sander’s (2000) work on the long-bone histology of Tendaguru-Formation sauropods, Darren was edging on to the stage, trying to bring my talk to an end by making moves for the microphone, while I was talking faster and faster in manner more than a little reminiscent of Monty Python’s microphone-stealing sketch.
Poor Darren. I actually don’t quite recall how things ended up, but as far as I know I got through all my slides before being persuaded to retire, and here for your edification is the Conclusions slide.
Anyway, with the conference over, all of us who’d given talks were invited to contribute papers to a proceedings volume, and that’s what’s just come out. (According to the Geological Society’s own page, the book won’t be available to buy until 19 November, but all the PDFs are available to download to those who have the relevant access rights.)
Is my paper worth reading? For seasoned palaeontologists, much of what I cover is going to be familiar ground, though I hope most people will find one or two nuggets of interesting new information in there. But perhaps it will be most useful as a primer for people new to the field, or first approaching sauropods having previously worked on other groups.
Edited volumes vs. journals
You know how some with papers, you submit them, they go through review and then … nothing? I’ve heard horror stories of papers that have been in press for ten years or more, and I am relieved to say that I’ve never experienced that kind of delay. But the reviewed, revised and resubmitted version of my sauropod-history manuscript was accepted and in press as of January 2009, so this has been the best part of two years coming.
I think this is pretty much standard for edited volumes, because they are basically stalled until all the contributing authors have got their jobs done. To be fair to the Geological Society, who were the publishers in this case, I think they’ve done a nice job on the layout, and they got all my proof corrections done. But still: nearly two years in press is a looong time. And the end result is that the paper is in a book that most people will consider very expensive – $190 at amazon.com, £95 at amazon.co.uk — which means that fewer people will read it than I would like. (I will talk more about the price in a subsequent post.)
So would I do it again? This paper is my first contribution to an edited volume, and although I’m pleased to have done it this time, I think it will take a particularly special opportunity for me to do it again: a book that I wouldn’t want not to be in, such as another of the all-sauropods-all-the-time volumes that glutted our shelves in the glorious year of 2005.
Journals are fundamentally wired to move faster: they handle manuscripts on an individual basis, then push out a volume according to a schedule, and your work goes in as soon as there’s a free slot. That can hardly help but be a more efficient model than the edited-volume approach where, however efficiently I get my work done, it can’t be published until 21 other authors have done theirs.
For a much more distressing example, consider my two remaining in-press manuscripts, those defining the clades Sauropoda and Sauropodomorpha for the PhyloCode companion volume. (These are multiple-author works, as we wanted to represent a consensus view among multiple sauropod/sauropodomorph workers.)
I was first invited to put together the Sauropoda entry on 5 March 2007, and told to send it “at your earliest convenience”. I’d put together an initial draft by 11 March, which I circulated to all the co-authors on that date. Because of the wording of the invitation, I told the co-authors that “timelines are very tight for this work — I really need to get a submission back to the editors within a week or so. So if you’re in a position to contribute, I’d appreciate it if you could do so as soon as possible.” Then on 12 March, we were invited to contribute the Sauropodomorpha entry as well, so we worked on both of these in parallel.
All five authors worked hard and quickly on multiple drafts of both of these entries, and we bashed our way through real — though polite — disagreements about the most appropriate definitions to use. (I’ll say right now that it was a pleasure to work with all the co-authors, and I would be delighted to work with any of them again if the opportunity arose.) Because of the difficulties of co-ordinating the work across three continents, it took a little longer than we’d hoped to get the manuscripts finished and polished, but we submitted them both on 17 April, 43 days after the initial invitation was issued.
And now here we are, three and a half years later, and nothing has happened. For all I know, the authors haven’t even all submitted their manuscripts yet — I know they hadn’t a year ago, we can only hope that another twelve months has been long enough for them to get their fingers out.
Really. It makes you want to weep.
And now, on to a happier thought:
My dissertation is 60% published!
I was very taken with Andy Farke’s recent post Crossing the Finish Line for the Dissertation on his fine blog, The Open Source Paleontologist. In it, he celebrates the fact that all the chapters of his dissertation have now been published as peer-reviewed papers. As I said in a comment, I like the perspective that you’re not really done with your dissertation until you’ve made it redundant. I’ve heard too many tales about people who sit on their dissertations for years, always meaning to publish the chapters but never quite getting around to it, until they were obsolete.
So my goal is to avoid that fate. Instead, in emulation of Andy, I want to get all five of my chapters out there in the world as soon as possible. So here’s the score:
- Chapter 1. Sauropod dinosaur research: a historical review — published in the Geological Society special volume.
- Chapter 2. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914) — published in JVP.
- Chapter 3. An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England — published in Palaeontology
- Chapter 4. A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, U.S.A. — in review at a journal that, once revisions are submitted, tends to get papers out pretty quickly.
- Chapter 5. Vertebral morphology and the evolution of long necks in sauropod dinosaurs — in revision after having been rejected for what I frankly thought were specious reasons, but let’s not get into that.
With a trailing wind, I could conceivably be finished by the end of the calendar year. But realistically that would have to classified as a optimistic schedule.
Ah well. Onward and upward.
- Phillips, J. 1871. Geology of Oxford and the Valley of the Thames. Clarendon Press, Oxford.
- Russell, Dale A., and Zheng, Zhong. 1993. A large mamenchisaurid from the Junggar Basin, Xinjiang, China. Canadian Journal of Earth Science 30(10/11): 2082-2095.
- Sander, P. Martin. 2000. Longbone histology of the Tendaguru sauropods: implications for growth and biology. Paleobiology 26(3): 466-488.
- Taylor, Michael P. 2010. Sauropod dinosaur research: a historical review. pp. 361-386 in: Richard T. J. Moody, Eric Buffetaut, Darren Naish and David M. Martill (eds.), Dinosaurs and Other Extinct Saurians: a Historical Perspective. Geological Society of London, Special Publication 343. doi: 10.1144/SP343.22
Taylor, M. (2010). Sauropod dinosaur research: a historical review Geological Society, London, Special Publications, 343 (1), 361-386 DOI: 10.1144/SP343.22
March 19, 2009
That clanking sound you just heard was pretty much the entire field of paleontology evolutionary biology wired humanity dropping a solid gold brick: Tianyulong, a basal ornithischian from (where else?) China, has been found with dino-fuzz (Zheng et al. 2009). Not exactly protofeathers, but pretty darn similar. And if they’re in theropods and ornithischians, they were probably primitive for Dinosauria (at least; comparisons of these integumentary structures to pterosaur ‘hair’ are probably coming). It’s certainly possible that the common ancestor of Ornithodira (the pterosaurs+dinosaurs clade, which encompasses most non-croc-line archosaurs) was fuzzy.
(So much for the “fact” that we “know” that small dinosaurs couldn’t have been endotherms because of their naked skin–see, e.g., pretty much everything ever written by Feduccia, Ruben, and the rest of the BANDits [Birds Are Not Dinosaurs cultists]).
It’s true that we have skin impressions from many dinosaurs that show scaly skin, so if dino-fuzz was primitive for dinosaurs it must have been lost, or had a restricted distribution on the body (like a midline crest), or been ontogenetically transient (possibly present only in babies) in many taxa. If there were any shaggy sauropod skin impressions out there, we’d really, RE-hee-huh-HEEELLY like to know. So far, zip. Even the skin impressions from the Argentinian sauropod embryos show bare, scaly skin (Chiappe et al. 1998).
Still, those skin patches don’t cover the entire embryo. We can’t rule out some fuzz even in the Argentinian embryos, and except for a scrap of bone shard of excellence here and there (Britt and Naylor 1994), sauropod embryos and their skin are otherwise ridiculously unknown to our planet. So we can dream, for a while longer anyway. Back in 1994, Greg Paul drew a hatchling sauropod with dino-fuzz (Paul 1994:fig. 15.3, above), and we’re bringing it back in honor of Tianyulong.
Here’s your obligatory sauropod vert shot for this post. Tremble as the ancient, bloated hulk looms out of the mists of deathless time, like an ageworn stone idol or some eldritch Lovecraftian horror!
Oh, and behind Mike you can just make out the AMNH Brontosaurus (yeah, we know, we’d like to bring that back, too).
UPDATE: MARCH 19
James O’Donoghue wrote a piece for New Scientist on sauropod gigantism, which you can read for free here. He kindly cited my work on air sacs, and even more kindly threw in a link to an SV-POW! post, which I’ll let you find for yourself. Now that I’m sending you there, the hyperlink circle is complete.
Two great things came in the mail yesterday, but those will be subjects of future posts. Stay tuned, true believers!
- Britt, B.B., and Naylor, B.G. 1994. An embryonic Camarasaurus (Dinosauria, Sauropoda) from the Upper Jurassic Morrison Formation (Dry Mesa Quarry, Colorado); pp. 256-264 in Carpenter, K., Hirsch K.F., and Horner, J.R. (eds), Dinosaur Eggs and Babies. Cambridge University Press, Cambridge.
- Chiappe, L. M., Coria, R. A., Dingus, L., Jackson, F., Chinsamy, A., and Fox, M. 1998. Sauropod dinosaur embryos from the Late Cretaceous of Patagonia. Nature 396: 258–261.
- Paul, G.S. 1994. Dinosaur reproduction in the fast lane: implications for size, success, and extinction; pp. 244-255 in Carpenter, K., Hirsch K.F., and Horner, J.R. (eds), Dinosaur Eggs and Babies. Cambridge University Press, Cambridge.
- Zheng, X.-T., You, H.-L., Xu, X., and Dong, Z.-M. 2009. An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures. Nature 458:333-336.