February 26, 2011
Sorry for the very short post. We have some longer stuff planned, but we’ve been too busy to kick it out this week, and I wanted to leave you with something cool to ponder over the weekend. Here’s the ilium of Giraffatitan overlaid on that of Brontomerus, scaled to the same acetabulum diameter (Giraffatitan is HMN J1, left ilium, modified from Janensch 1961: pl. E, fig. 2; Brontomerus is of course OMNH 66430 from Taylor et al. 2011:fig. 2).
And here’s the same thing comparing Rapetosaurus and Brontomerus (Rapetosaurus is holotype FMNH PR 2209, left ilium, modified from Curry Rogers 2009: fig. 39B). This one was tricky to scale because the ilial margin of the acetabulum is so different in the two taxa.
Here is the same trick performed with the ilium of the canonical pretty basal neosauropod Camarasaurus — specifically, Camarasaurus supremus AMNH 5761 Il. 1, left ilium, modified from Osborn and Mook (1921: fig. 87). In this case, the proportions are so very different that it’s hard to make a meaningful superimposition: we tried to scale to equal acetabulum size, but probably that of the Camarasaurus was proportionally larger than in the other taxa illustrated in this post. Still, here it is:
Finally, in response to Paul Barrett’s comment on a subsequent article, here is a superimposition of the ilium of Alamosaurus on that of Brontomerus:
(Sorry about the poor quality of this one, but the only figure I could find of a complete Alamosaurus ilium was the line-drawing in Lehman and Coulson (2002:fig. 8) — none of the standard descriptive works seem to illustrate a complete or near-complete ilium.)
We had a figure like these in an early draft of the paper, but we ditched it because we felt that doing a broader comparative figure would be more valuable. But I like the kick in the brainpan that these overlays provide.
- Curry Rogers, Kristina. 2009. The postcranial osteology of Rapetosaurus krausei (Sauropoda: Titanosauria) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 29:1046-1086.
- Janensch, Werner. 1961. Die Gliedmaszen und Gliedmaszengurtel der Sauropoden der Tendaguru-Schichten. Palaeontographica, suppl. 7 (1), teil 3, lief. 4: 177-235.
- Lehman, Thomas M. and Alan B. Coulson. 2002. A juvenile specimen of the sauropod dinosaur Alamosaurus sanjuanensis from the Upper Cretaceous of Big Bend National Park, Texas. Journal of Paleontology 76(1):156-172.
- 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.
- Taylor, Michael P., Mathew J. Wedel and Richard L. Cifelli. 2011. A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA. Acta Palaeontologica Polonica 56(1):75-98. doi: 10.4202/app.2010.0073
February 10, 2011
As we all know, the International Code of Zoological Nomenclature is a large and intimidating document. As a result, zoologists naming new animals often do not read it in its entirety (I know I haven’t). It’s probably because of this that many of the more avoidable nomenclatural mistakes occur.
Whatever might or might not eventually be possible in terms of simplifying the Code, everyone recognises that that would be a huge job, and something that would take years to do. So let’s ignore that possibility for now.
In the short term, what would be much more useful would be if someone could work up a very short document — no more than a single page of A4 and hopefully much shorter — that states in simple bullet-points what MUST be done to ensure that a new name is valid. Then there would be no excuse for zoologists venturing into nomenclature for the first time not to read such a document — let’s call it the ICZN Cheat Sheet.
Because it’s easier to steer a moving ship, I wrote to the ICZN email list this morning proposing an initial set of bullet points. I did not for a moment expect that they were complete, consistent or even necessarily correct; but I hoped that they could at least serve as a starting point for a very quick process of putting such a list together.
I am pleased to say that response on the list was fairly positive, and at the suggestion of one of the list members I have now posted the in-progress checklist as a page on this site, having revised it in accordance with several suggestions.
If you’re interested in contributing to this effort — helping us to derive a clear, concise and correct one-page guide to naming new zoological genera and species — please head over to the page and comment there. (Comments on this post are closed, to avoid splitting discussion across two places.)
December 14, 2010
Over at his truly unique blog Paleo Errata, Jeff Martz is claiming that Stereopairs Are Cool. This assertion he supports with the following figure that he put together, showing a set of five stereopairs of a Longosuchus braincase:
Unfortunately, I am one of those who can’t “see” stereopairs, so these images are uninformative to me — or, at least, no more informative than your average inch-wide braincase photo.
So how else can we envisage the stereo information in these pairs of photos that Jeff took? My favourite way is using red-cyan anaglyphs — those goofy 3d images that you look at through 3d glasses. To compare, I did this to Jeff’s image. The process is simple: take two copies of the stereopair image, cut out all the right-eye views from one set and all the left-eye views from the other, then edit the colour levels of both layers. In one, take the red right down to zero, so you only have blue+green=cyan; in the other take the green and blue down so you only have red. Then stack one layer on top of the other and change its mode to “Lighten only”. Export the result as a JPEG and you get this result:
Armed with my red-cyan glasses (which, remember, I got as a freebie with a Lego catalogue), I can now make out the 3d structure really easily. Positives for the anaglyph approach:
- The 3D image is much easier to see
- The result takes up less space on the page
- Most importantly, the size limitation is removed: I have some beautiful whole-screen anaglyphs (e.g. Archbishop cervical, wallaby skull), whereas stereograms are restricted to a couple of inches’ separation.
The downside is, of course, that you need special equipment to see them –albeit equipment so laughably minimal that Amazon.com will sell you THREE PAIRS for $1.39, you cheap gits. But for those of who who are too poor to find $1.39, and who don’t have two friends with whom you can form an ad-hoc 3D-glasses buying consortium at a cost of $0.47 each, there is one further approach: a low-rent technique that I call a “wigglegram” for want of a better term. Here it is:
I discovered this approach by accident, when flipping through a bunch of photographs that I’d taken of, I think, the Archbishop. As a matter of policy, I take most of my photos twice, so that if I shake slightly or the auto exposure gets it wrong, I have a good copy that I can retain. I was trying to decide which of two nearly identical pictures to keep. But as it happened, I’d moved the camera slightly to the side between taking the first and the second, so as I skipped back and forth between them, I was seeing two slightly different perspectives.
So there you have it: three different ways to visualise 3d structure, each built from the same basic set of photos. They each have their merits, and I hope we’ll increasingly see more of all three of them, as we move into the Shiny Digital Future, and arbitrary limits on manuscript length and numbers of figures get lifted.
I leave y0u with an actual application of all this. Matt and I have, for some time, been working on a manuscript about caudal pneumaticity in sauropods, and we wanted to include a brief survey of which genera it’s been reported in. Among the candidates was Saltasaurus, which has a candidate pneumatic caudal vertebra that was illustrated thus by Powell (2003: plate 53, part 3):
Matt can “see” stereograms, and insisted that the dark patch on the side of the centrum is a pneumatic fossa. I wasn’t so sure, and in fact we got into quite an argument over whether or not to include this specimen in our list. The argument was neatly concluded when I had the obvious idea of converting Powell’s stereogram into an anaglyph:
As soon as I saw this, I recognised what the structure is: the crescent moon-shaped dark patch is indeed a deep, invasive fossa, and the broad, roughly circular object above it and to the right is a lumpen lateral process sticking right out into the camera (and partially hiding the fossa). So Matt was right, the vertebra is pneumatic, and a beautiful friendship was saved by the power of red-cyan anaglyphys. Yay!
- Powell, Jaime E. 2003. Revision of South American Titanosaurid dinosaurs: palaeobiological, palaeobiogeographical and phylogenetic aspects. Records of the Queen Victoria Museum 111: 1-94.
A comment by Charles Epting on the recent article about self-publication led me to check the relevant section of the draft Phylocode, which I’ve read once or twice before but not recently enough for this to have hit me with the force it ought:
From Chapter II. Publication, and specifically Article 4. Publication Requirements:
4.2. Publication, under this code, is defined as distribution of text (but not sound), with or without images. To qualify as published, works must be peer-reviewed, consist of numerous (at least 50 copies), simultaneously obtainable, identical, durable, and unalterable copies, some of which are distributed to major institutional libraries (in at least five countries on three continents) so that the work is generally accessible as a permanent public record to the scientific community, be it through sale or exchange or gift, and subject to the restrictions and qualifications in the present article.
4.3. The following do not qualify as publication: (a) dissemination of text or images solely through electronic communication networks (such as the Internet) or through storage media (such as CDs, diskettes, film, microfilm and microfiche) that require a special device to read.
I am … flabbergasted, if that’s the word I want. (I always want to spell that with an “h” after the “g”.) This language is obviously derived from what’s in the ICZN — for example, “must have been produced in an edition containing simultaneously obtainable copies by a method that assures numerous identical and durable copies” becomes “must consist of numerous (at least 50 copies), simultaneously obtainable, identical, durable, and unalterable copies”.
And the result is that, just like the ICZN, the draft Phylocode does not recognise electronic publication.
Just think about that. It means that if you define a clade in most of the PLoS journals, it won’t count (unless the journal does one of its inkjet-and-staples special print runs for you). It also means that any clades you define in Proceedings of the Royal Society of London will not count when the initial online article is published, but only when the later printed edition comes out. In other words, it means that both the science journals that are growing most quickly in influence and prestige and the oldest science journal in the world will both be useless for phylogenetic nomenclature.
I am sure that’s not what the Phylocode authors want.
That’s particularly true in light of the code’s further requirement that in order to be valid, clade definitions need to be registered. Really, once a name is officially registered in the Phylocode database and its definition is in a paper published by a reputable publisher and existing in thousands of bit-for-bit-identicial copies in every country in the world, what else is needed for stability? Fifty stapled inkjet copies?
It seems particularly startling in light of the fact that even the notoriously slow-moving ICZN seems now to be recognising that electronic publishing is inevitable; it would be pretty horrible if by the time the Phylocode is finally implemented, the ICZN has accepted its electronic publishing amendment and the Phylocode is seen to be trailing behind the ICZN in recognising the reality of the world we live in. (For anyone who is not yet convinced of that reality, I recommend *cough* Taylor 2009, which is a pleasantly easy read.)
Is it too late? Can the Phylocode be fixed before it’s implemented? Can it just be done, or will it need lengthy discussion first? If this doesn’t get fixed, will anyone take the Phylocode seriously? Is there even a serious argument for keeping the Article 4.2 language as it is now?
I don’t know the answers to any of these questions. Does anyone else out there?
In other news …
I am astounded at the lack of response to University of California vs. Nature, which seems to me just about the most significant thing that’s happened in the world of academic literature since, well, forever. Can it really be that everyone else’s response is, and I quote, “meh”?
- Curry Rogers, K. 2009. The postcranial osteology of Rapetosaurus krausei (Sauropoda: Titanosauria) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 29(4):1046-1086.
- Taylor, Michael P. 2009. Electronic publication of nomenclatural acts is inevitable, and will be accepted by the taxonomic community with or without the endorsement of the Code. Bulletin of Zoological Nomenclature 66(3):205-214.
June 11, 2010
By now you’ve probably heard that the entire UC system is threatening to boycott the Nature Publishing Group over unsustainable business practices.*
First, a few links to get you up to speed.
- The original letter, which was an in-house UC document that leaked (possibly deliberately, certainly understandably) and then propagated through academia like the proverbial brushfire.
- Nature Publishing Group’s initial response, which accused the UC of distorting several issues.
- The UC’s rebuttal, which showed that, in fact, they had not, and that NPG was guilty of far worse distortions.
- A Chronicle of Higher Education piece that has some very interesting quotes on the UC side.
- Of all the blogging that has been done on this, the now-infamous Fight Club post seems to be getting the most link-love and discussion, and deservedly so.
- This post and those that follow at The Book of Trogool have some good analysis and more scrumptious links. Also at ScienceBlogs, Janet Stemwedel considers this from the standpoint of junior researchers who need high-profile pubs to survive, and with her usual thoughtfulness and humanity.
* It doesn’t matter whose side you’re on, it’s pretty clear that a 7% markup every year is not sustainable for academic libraries whose budgets are flat, if they’re lucky, or more likely declining. If it really costs NPG 7% more each year to maintain their web access, then they’re doing something wrong. So who does this serve, other than NPG shareholders?
Some of the more interesting points that have come up in the ensuing discussions:
As noted by Janet Stemwedel, it would be very nice if the UC would issue a statement that good scholarship on the part of faculty will be recognized and rewarded no matter where it’s published. I am wholeheartedly in agreement with that, and am only sad that it took something like this to force the issue out into the open. Good work is good work, and the people who need it will generally find it. A lot of the battle over OA is getting hidebound administrators to stop thinking with their pseudoheads and find non-retarded ways to assess the output of their faculty. It shouldn’t be part of the battle over OA, because impact factors are orthogonal to publication model (and to the quality and lasting value of the work). But we all know that publications in Cell, Nature, and Science are the ticket to grants, promotions, and tenure. PLoS is successfully driving a wedge into this, but the battle is far from over.
More than one commenter has noted that there is probably some schadenfreude going on here, as faculty who feel like they are under the gun to publish in high-rejection-rate journals get to fight back a little, and as faculty who are being forced to take pay cuts, furloughs, etc., get to shift their anger from university-internal targets to a visible and little-loved external enemy. I think both hypotheses are accurate, and I suppose that it is not 100% fair for NPG to get pasted with more hate than they have coming, but I don’t really care, because the level of hate they have legitimately earned is already extremely high. In some of the online discussions about the future of newspapers–or rather, the lack of a future for newspapers–someone, somewhere, made the point that when you gouge people for decades, you shouldn’t be surprised when they stand aside and refuse to rescue you as you crash and burn. To my massive irritation, I can’t find that quote right now, but it’s exactly appropriate here. A lot of faculty wouldn’t pee in Nature‘s mouth if its teeth were on fire–and now they may get the chance to withhold that pee.
I’ve seen a few comments to the effect that the proposed boycott would never come to pass because the UC could not get junior faculty, who need those CNS pubs, to play ball. I wouldn’t bet that way. In my experience, junior faculty are far more likely to be attuned to the injustices of the high-stakes, for-profit journal world, and thus the ones most likely to understand what is actually at stake, and to have little sympathy for an outfit that they see as an unsympathetic career gatekeeper. If there is faculty resistance, I expect it to come from tenured folks who’ve benefited from having an inside track at Nature. (I know, I know, everyone from Nature on down claims that the “inside track” is a myth, but does anyone actually believe that?)
Many have noted Keith Yamamoto’s SDFy comments at the end of the Chronicle article: “In many ways it doesn’t matter where the work’s published, because scientists will be able to find it”. All I have to add here is “Hell yeah!” and “Bang on!”
For my part, I’d like to point out something that I have not seen widely discussed, but which seems like it ought to be. A not-for-profit organization–like, say, PLoS–has to maintain its infrastructure, pay its employees, and deliver a service. A corporation has all of those demands, plus the mandate to make a profit. So people can whine all they want that open access publishers still have to charge to do the same work as commercial publishers and that the work will cost about the same, but at the end of the day the commercial publisher is in business to make a profit, and PLoS is in business to make science. Absolutely, we should stop letting commercial publishers sell our own fat asses back to us. We should definitely stop paying any for-profit publisher to line its shareholders’ pockets at our expense. Screw them and the horse they rode in on; that is our freakin’ horse.
The big noise on the Dinosaur Mailing List at the moment is this thread about Rob Gay’s newly self-published book Notes on Early Mesozoic Theropods, which you can buy from print-on-demand house lulu.com. (You can also pay to download a PDF if you prefer.)
The interesting thing about about this book is that it contains nomenclatural acts — specifically it names the new theropod Kayentavenator elysiae. But is this act valid according to the ICZN? Opinions differ. The fact that the work was self-published is irrelevant — the Code simply doesn’t care about that. Beyond this, in the book itself, Gay contends that:
Those that are concerned about the naming of a new genus in this format should not be. The availability and distribution requirements are more than met—the relevant institutions have received a copy for their records. In addition “Notes on Early Mesozoic Theropods” will remain available to all who wish to purchase it online, as well as those stores that chose to carry it, for the foreseeable future—far surpassing the availability of many other high profile publications to those anywhere on the globe.
He feels that this satisfies the relevant articles of the code:
8.1. Criteria to be met. A work must satisfy the following criteria:
- 8.1.1. it must be issued for the purpose of providing a public and permanent scientific record,
- 8.1.2. it must be obtainable, when first issued, free of charge or by purchase, and
- 8.1.3. it must have been produced in an edition containing simultaneously obtainable copies by a method that assures numerous identical and durable copies.
The first thing to say is that Gay would have done himself a favour if his preface had discussed these articles specifically and explained how he felt they were fulfilled: by making only the more general statement above, he’s left matters more open to discussion; or at least forfeited the opportunity to get in a good, strong, opening statement in the inevitable debate.
My own feeling, based on a couple of years on the ICZN mailing list and having witnessed many such discussions between the Commissioners and other specialist nomenclaturists, is that a print-on-demand publication like this does not meet requirement 8.1.3 (“simultaneously obtainable copies by a method that assures numerous identical and durable copies”) — it’s because of this requirement that PLoS ONE has had to adopt its frankly rather silly policy of printing 50 hardcopies of each article it publishes that contains nomenclatural acts, rather than just printing copies on demand for anyone who wants them.
[There has also been some talk on the list about whether this book counts as published under Article 8.6, "Works produced after 1999 by a method that does not employ printing on paper", but there's no room for debate about that. That Article states that such a work "must contain a statement that copies (in the form in which it is published) have been deposited in at least 5 major publicly accessible libraries which are identified by name in the work itself", which is not the case for this book.]
But the real question is: so what? The Commission will never produce a ruling on this — it just doesn’t do that, unless presented with a formal petition to conserve a subsequently published name for the same taxon. So in practice, whatever the code says, the reality is that the validity of the name Kayentavenator elysiae will — like the validity of all other names — be determined by whether and how it actually gets used in subsequent work.
In short, it comes down to this: when the next paper comes out on that animal, will it use Gay’s name, or will the worker in question erect his own name for the same animal and claim that it has priority as the first validly published name?
And that in turn comes down to — let’s be frank — the personality of that next worker. We all know of scientists whose goal seems to be to get their name on as many publications and taxa as possible; we all know others who are more concerned with giving credit where it’s due. It seems strange that something like the effective validity of a zoological name should be determined by a personality, but that’s how it looks.
As a side-issue, the way I read this is that Gay has done himself a huge disfavour by charging a fee to download the PDF version of his book. If he wants his work to be accepted, then the best way is to make sure anyone who is remotely interested can get get hold of it with minimal inconvenience and at zero cost. It may seem odd, but the truth is that Kayentavenator elysiae‘s chances of survival are dependent far more on marketing than on any other factor; so the PDFs should be made freely and easily available.
The sky is falling! The sky is falling!
Tim Williams was one of several commenters on the DML to make this point:
This is a HUGE concern. Especially because advances in technology mean that self-publication is now much cheaper than it used to be. All you need is a computer and a printer, and off you go.
This has been true for some time. If anything, it’s surprising that we don’t see a lot more rogue taxonomy than we do, especially in a field as charismatic as dinosaur palaeontology. For some reason, extant animals seem (so far) to have suffered much more from this than we have — see for example Raymond Hoser, whose self-published taxonomic works have been widely referred to as “taxonomic vandalism” and whose name has been used in the term “Hoser taxonomy”.
I think we’re deluding ourselves if we think this isn’t coming to dinosaur palaeo.
The widely expressed fear is that “anyone, regardless of knowledge and abilities, will be able to create valid taxa without any restraints” (Dan Chure to the DML). Because “when it comes to what constitutes a published work, Article 8 of the ICZN Code is so vague and permissive that it is laughably easy to meet the criteria” (Tim Williams again).
Unfortunately, it’s not a simple matter of tightening the language up. Even if the ICZN didn’t move so agonisingly slowly, it’s not really possible to give a rigorous definition of “valid publication”. You could come up with whatever form of words you wanted, and I (if I were sufficiently unethical) could find a way to make an end-run around it.
In particular, requiring peer-review (while a step in the right direction) would not solve the problem: then you have to define what “peer-review” means, and as we’ve seen in certain articles published in in-house journals in recent years, that concept is also slippery.
Here’s where I think this is going. Ultimately, the validity or otherwise of names is always decided by the working taxonomic (and more broadly biological) community. Until recently, the broader community has been able to delegate the process to journals in most cases, because it was easy to see what a “journal” was: it had a publisher, it was printed on glossy paper, and it came out on a regular schedule. It was easy to see whether a given work was in a journal or not.
That is changing very fast. By most of the criteria above, PLoS ONE is not a “journal” (no publisher but itself, no printing on paper, and no regular schedule) yet I don’t think anyone is going to claim it’s not a journal. Although I think PLoS ONE is a wonderful thing (I’ll be sending my own work there), one of its deleterious side-effects is that it, along with Palaeontologia Electronica and others, has shifted people’s ideas of what is “published”. One can easily imagine, say, a museum setting up its own PLoS-like journal — maybe a reputable one, maybe a less reputable one. From there it’s a short slide to a department, a small group or even an individual setting up his own journal. We have to face the facts that (A) it’s going to be hard to say what is and isn’t a “journal” and (B) we have no way of checking, in general, that “peer-review” is meaningful and adequate.
So I see only two possible paths.
One is that names will get published here, there and everywhere — ultimately even on blogs (although we don’t plan to go down that path here on SV-POW!) — and it will be up to the community to determine what is and isn’t counted as valid.
The other possibility is that a formal name-registration database like ZooBank comes swinging in to save the day, and only registered names are considered valid (or only registered names and those published before, say, 2012).
Unfortunately, ZooBank seems to be the only candidate registration system in town, and it’s in trouble: grotesquely underfunded, the work of basically one person, consequently well behind schedule and by no means ready technically or organisationally to do what it’s intended to do. (I mean no criticism of any individual in saying this, but those are the facts.)
The way forward?
It seems that nomenclatural anarchy is inevitable unless something like ZooBank takes off rapidly. So if I were rich and influential, one of the main things I’d be doing would be to pour that money and influence into ZooBank, getting it up to speed as soon as possible and making sure the infrastructure is in place to handle a lot of regsitrations really quickly. Because the current de facto approach of delegating the assessment of legitimacy to journals is on the way out: I give it less than ten years.
But given that science is chronically underfunded, and zoology funded less than most sciences, and zoological nomenclature less than most of the rest of the zoology, I am not optimistic than this can be made to fly. the bottom line for ZooBank is that it’s not anyone’s full-time or primary job; and until it is, there’s always going to be something else more urgent that pushes out this work that is merely important. (Actually it’s urgent, too, but because the deadlines are soft rather than hard, the urgency isn’t apparent — we’ll just all wake up one day and find that they’ve passed.)
I’m not happy about it, but my prediction is: nomenclatural anarchy. For sure, names published in JVP will start out with a better chance than names published in print-on-demand books at lulu.com, but that’s going to become a sliding scale rather than the clear black-and-white distinction we’ve been used to.
How bad is it?
I don’t know. The truth is that lots of nomenclatural decisions are made by the community already, and somehow we all seem to survive. I recently demonstrated, I thought conclusively, that the species formerly known as “Brachiosaurus” brancai cannot be considered congeneric with the Brachiosaurus type species B. altithorax, and must be considered to belong to its own genus Giraffatitan (Taylor 2009); but whether that reassignment is adopted is for the community to decide over the next few years. I was disappointed to see that Chure et al. (2010), for poorly explained reasons, rejected this name; and I was pleased to see that Sander et al. (2010) accepted it. But only time will tell whether it sticks. And yet, somehow, we survive despite all this uncertainty.
Will it be so terrible if, in the same way, the published works of the community determine which nomenclatural acts are considered validly published? Maybe not.
- 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 preprint). doi:10.1007/s00114-010-0650-6
- Curry Rogers, K. 2009. The postcranial osteology of Rapetosaurus krausei (Sauropoda: Titanosauria) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 29(4):1046-1086.
- Sander, P. Martin, Andreas Christian, Marcus Clauss, Regina Fechner, Carole T. Gee, Eva-Maria Griebeler, Hanns-Christian Gunga, Jürgen Hummel, Heinrich Mallison, Steven F. Perry, Holger Preuschoft, Oliver W. M. Rauhut, Kristian Remes, Thomas Tütken, Oliver Wings and Ulrich Witzel. 2010. Biology of the sauropod dinosaurs: the evolution of gigantism. Biological Reviews. 43 pages. doi: 10.1111/j.1469-185X.2010.00137.x
- 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.
May 26, 2010
Just a quick note to let you know I (Mike) was interviewed for the Enlightenment podcast at The Twenty-First Floor, along with Dave “Archosaur Musings” Hone. Dave’s segment is on common misconceptions about dinosaurs; long-time readers will be less than wholly astonished to learn that mine is on: sauropods.
It probably won’t contain much that SV-POW! regulars don’t know already, but anyone who fancies a refresher on the significance of osteological correlates, for example, might find it interesting.
Meanwhile, here is another cervical vertebra of Rapetosaurus, last featured in our previous article the best part of a month ago:
We’ve not yet given this paper the proper SV-POW! treatment, which I feel bad about: it was long awaited, and is now probably the best description of any titanosaur anywhere. It’s going to get cited like crazy in descriptive work. And it’s packed with beautiful pictures — both photos and drawings — of sauropod vertebrae.
We’ll get to it some time.
- Curry Rogers, Kristina. 2009. The postcranial osteology of Rapetosaurus krausei (Sauropoda: Titanosauria) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 29(4):1046-1086.
April 28, 2010
This one’s mostly a housekeeping post, to keep you abreast of some notable developments with SV-POW!sketeers and friends.
- Added April 29 – I’m such a tool, forgot to mention that another awesomely niche-y blog has been unleashed on the paleo-blogosphere: March of the Fossil Penguins, by our friend and sometime sauropod-describer Dan Ksepka. Go waggle your hydrodynamic forelimbs at him, I’m sure he’ll be happy to regurgitate some tasty posts for you.
- I’m tired of paying for sauroposeidon.net so I’m letting it lapse at the end of this week. I’ve already migrated my CV and papers to a new site, where they will hopefully remain forever. As previously noted, The Marsh Repository also has a new home.
- Ask A Biologist is back! Go make yourselves useful/satisfy your curiosity. Don’t forget to thank your friendly local Dave Hone.
- Mike’s new blog, The Reinvigorated Programmer, is all of two months old and has already passed SV-POW! in total hits. So don’t give him any more link traffic. Instead, tell your friends how wonderful SV-POW! is!
- After two and a half years of weekly posts, we’ve decided to stop being so slavish about our titular obligation and will henceforth blog as frequently or infrequently as we please. We’re keeping the title, though. If you’re offended by that, you can backronym SV-POW! as Sauropod Vertebra Picture of the Whenever.
- Similarly, we’re going to start posting about sauropod skulls and appendicular bits from time to time. Not that we haven’t been doing that anyway–heck, even wallaby toes are not safe from our roving curiosity–but we’re going to stop marking such posts off-topic and putting in obligatory sauropod vert photos.
Don’t worry, though, we’ll still be mostly sauropod vertebrae, most of the time. And speaking of, here’s something lovely: a cervical of Rapetosaurus, from Curry Rogers (2009:fig. 5). Cool fossae, eh? Also, check out how dinky the centrum is compared to the neural arch.
Curry Rogers, K. 2009. The postcranial osteology of Rapetosaurus krausei (Sauropoda: Titanosauria) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 29(4):1046-1086.
April 15, 2010
As often happens here, a comment thread got to be more interesting than the original post and ended up deserving a post of its own. In this case, I’m talking about the thread following the recent Mamenchisaurus tail club post, which got into some interesting territory regarding mass estimates for the largest sauropods. This post was inspired by a couple of comments in particular.
Zach Armstrong wrote:
I don’t trust Mazzetta et al.’s (2004) estimate, because it is based off of logarithmic-based regression analyses of certain bone lengths, which a recent paper by Packard et al. (2009) have shown to overestimate the mass by as much as 100 percent! This would mean the estimate of 73 tonnes given my Mazzetta would be reduced to 36 tonnes.
To which Mike replied:
Zach, Mazzetta et al. used a variety of different techniques in arriving at their Argentinosaurus mass estimate, cross-checked them against each other and tested their lines for quality of fit. I am not saying their work is perfect (whose is?) but I would certainly not write it off as readily as you seem to have.
Weeeeell…Mazzetta et al. did use a variety of measurements to make their mass estimates, but they did it in a way that hardly puts them above criticism. First, their estimates are based on limb-bone allometry, which is known to have fairly low accuracy and precision (like, often off by a factor of 2, as Zach noted in his comment). Second, the “raw data” for their allometric equation consists of volumetric mass estimates. So their primary estimation method was calibrated against…more estimates. Maybe I’m just lazy, but I would have skipped the second step and just used volumetric methods throughout. Still, I can see the logic in it for critters like Argentinosaurus where we have limb bones but no real idea of the overall form or proportions of the entire animal.
Anyway, the accuracy of their allometric estimates is intertwingled with their volumetric results, so if their volumetric estimates are off…. The volumetric estimates used a specific gravity of 0.95, which to me is unrealistically high. Taking into account the skeletal pneumaticity alone would lower that to 0.85 or 0.8, and if the critter had air sacs comparable to those of birds, 0.75 or even 0.7 is not beyond the bounds of possibility (as discussed here and also covered by Zach in his comment).
Now, Mazzetta et al. (2004) were not ignorant of the potential effects of pneumaticity. Here’s what they wrote about density (p. 5):
The values from Christiansen (1997) were recalculated using a slightly higher overall density (950 kg/m^3), as the 900 kg/m^3 used in that paper may be slightly too low. Most neosauropods have extensively pneumatised vertebrae, particularly the cervicals, which would tend to lower overall density. However, these animals are also very large, implying a proportionally greater amount of skeletal tissue (Christiansen, 2002), particularly appendicular skeletal tissue, and consequently, they should have had a higher overall density.
This is pretty interesting: they are arguing that the positive allometry of skeletal mass as a fraction of body mass–which is well documented in extant critters–would offset the mass reduction from pneumaticity in animals as big as sauropods. I haven’t given that enough thought, and I definitely need to. My guess–and it is a guess–is that the effects of skeletal allometry were not enough to undo the lightening imposed by both PSP (~10%) and pulmonary air sacs (another ~10%, separate from the lungs), but I haven’t done any math on this yet. Fodder for another post, I reckon.
Getting back to Mazzetta et al., some of the volumes themselves strike me as too high, like ~41,500 liters for HM SII. That’s a LOT more voluminous than Greg Paul, Don Henderson, or Mike found for the same critter. The 16 metric ton Diplodocus and 20.6 metric ton Apatosaurus used by Mazzetta et al. are also outside the bounds of other recent and careful estimates. Not necessarily wrong, but definitely at the upper end of the current spectrum.
Mazzetta et al. got a mass estimate of 73,000 kg for Argentinosaurus, but (1) they used a density that I think is probably too high even if skeletal allometry is considered, (2) at least some of the volumetric mass estimates that form the “data” for the limb-bone regressions are probably too high, and (3) even if those problems were dealt with, there is still the general untrustworthiness of limb-bone regression as a mass estimation technique. 1 and 2, if fixed to my satisfaction, would tend to push the estimated mass of Argentinosaurus down, perhaps significantly (the effect of 3 is, if not unknowable, at least unknown to me). Given that, Zach’s ~52 metric ton estimate for Argentinosaurus is very defensible. (Probably worth remembering that I am a sparse-wing fanatic, though.)
None of this means that Mazzetta et al. (2004) were sloppy or that their estimate is wrong. Indeed, one of the reasons that we can have such a deep discussion of these points is that every link in their chain is so well documented. And there is room for honest disagreement in areas where the fossils don’t constrain things as much as we’d like. You cannot simply take a skeleton, even a complete one, and get a single whole-body volume. The body masses of wild animals often fluctuate by a third over the course of a single year, which pretty well buries any hope of getting precise estimates based on skeletons alone. And no one knows how dense–or sparse–sauropods were. I haven’t actually done any math to gauge the competing effects of skeletal allometry on one hand and PSP and air sacs on the other–and, AFAIK, no one else has either (Mazzetta et al. were guessing about pneumaticity as much as I’m guessing about skeletal allometry). Finally, Argentinosaurus is known from a handful of vertebrae and a handful of limb bones and that’s all, at least for now. If we can’t get a single body volume even when we have a complete skeleton, we have to get real about how precise we can be in cases where we have far less material.
The upshot is not that Argentinosaurus massed 73 metric tons or 52 or any other specific number. As usual, the two-part take home message is that (1) mass estimates of sauropods are inherently imprecise, so all we can do is make our assumptions as clear as possible, and (2) even the biggest sauropods might have been smaller than you think. ;-)
Mazzetta, G.V., Christiansen, P., and Farina, R.A. 2004. Giants and bizarres: body size of some southern South American Cretaceous dinosaurs. Historical Biology 2004:1-13.
March 2, 2010
This is so unspeakably cool. Today in PLoS Biology (yay, free reprints for everybody!), Wilson et al. (2010) describe a new snake, Sanajeh indicus, based on multiple specimens from multiple sauropod nests where they were apparently eating baby sauropods! This is sweet for loads of reasons. There aren’t that many well-documented cases of predation in the fossil record in the first place. Predation on dinosaurs by non-dinosaurs is especially cool–you may remember the announcement of Repenomamus by Hu et al. (2005), a giant (for its time and clade) badger-sized mammal from China that was found with a gut full of baby Psittacosaurus. And as Wilson et al. note, this is only the second secure association of sauropod bones with eggs; the other is the Auca Mahuevo site in Patagonia that produced the first definitive sauropod eggs and embryos. If we learn half as much about sauropod biology from these Indian nests as we have from the Patagonian ones, it’s going to be an exciting decade.
The best bit, though, is the window this gives us into Mesozoic ecosystems. Dinosaurs made lots of offspring, and sauropods seem to have been particularly R-selected. With loads of multiton animals producing zillions of defenseless babies for most of the Mesozoic, it would be weird if other critters, dinosaurian and otherwise, didn’t take advantage of that seasonally abundant food source. It’s great to get some direct evidence.
This is like a swamp full of radioactive awesome. Go roll around in it and let it mutate you.
- Yaoming Hu, Jin Meng, Yuanqing Wang, Chuankui Li. 2005. Large Mesozoic mammals fed on young dinosaurs. Nature 433: 149–152.
- Wilson JA, Mohabey DM, Peters SE, Head JJ. 2010. Predation upon hatchling dinosaurs by a new snake from the Late Cretaceous of India. PLoS Biol 8(3): e1000322. doi:10.1371/journal.pbio.1000322
Addendum (from Mike)
Let’s not miss the opportunity to reproduce this classic, uh, life restoration, executed pre-emptively by William Stout decades before this fossil was even found! It’s from his 1981 book The Dinosaurs: a fantastic new view of a lost era.