Thanks to everyone who joined in the discussion last time on why sauropods had such long necks.  I’ve discussed this a little with Matt, and we are both amazed that so many different hypotheses have been advanced (even if some of them are tongue-in-cheek).  We’ll probably come back to all these ideas later.

But today, we want to draw your attention to a new contribution to this discussion — a paper in the Journal of Zoology, with the tell-it-like-it-is title “The long necks of sauropods did not evolve primarily through sexual selection”, written by the three of us SV-POW!er rangers together with our buddy Dave “Archosaur Musings” Hone (Taylor et al. 2011).

Taylor et al. (2011), fig. 1: Sauropod necks, showing relationships for a selection of species, and the range of necks lengths and morphologies that they encompass. Phylogeny based on that of Upchurch et al. (2004: fig. 13.18). Mamenchisaurus hochuanensis (neck 9.5 m long) modified from Young & Zhao (1972: fig. 4); Dicraeosaurus hansemanni (2.7 m) modified from Janensch (1936: plate XVI); Diplodocus carnegii (6.5 m) modified from Hatcher (1903: plate VI); Apatosaurus louisae (6 m) modified from Lovelace, Hartman & Wahl (2008: fig. 7); Camarasaurus supremus (5.25 m) modified from Osborn & Mook (1921: plate 84); Giraffatitan brancai (8.75 m) modified from Janensch (1950: plate VIII); giraffe (1.8 m) modified from Lydekker (1894:332). Alternating grey and white vertical bars mark 1 m increments.

This is one of those papers that has been literally years in the making, which is why it’s a rather belated response to the paper that we were responding to — Phil Senter’s (2006) argument that sexual selection was the primary driver of neck elongation in sauropods.

Senter supported his hypothesis by laying out six predictions which he argued should be true for sexually selected necks; then showing that, while the first two could not be assessed, the last four all supported sexual selection.  In our paper, we do three things.  First, we make the point that sexual selection and feeding advantage are not mutually exclusive.  Second, we revisit all six predictions and show that they do not in fact support sexual selection — in fact, most of them provide support for feeding advantage.  Finally, we show that no tetrapod clade comparable with Sauropoda has consistently selected for a single sexual signal.

My email records show that Darren, Matt and I were discussing this as early as 22 September 2006, just six weeks after Senter’s paper was published, and that we started working on a response only a couple of days later.  But as so often happens, it got crowded out by a hundred other things.  Then in November 2007 Dave Hone mentioned that he was independently thinking of writing a response, and we decided to join forces.  And then … we all went back to working on other things again, touching on the necks-for-sex issue every now and then.  It’s mostly due to Dave’s repeated prods that this project wasn’t allowed to wither away, and has now, finally, made it across the finish line.

Like the neck-posture paper (Taylor et al. 2009), this was a true collaboration — one of those where, for many parts of the text, none of us is sure which of us originally wrote it.  It went through the wringer many times before reaching its final form, and most of the text must have been rewritten two or three times along the way.  We hope all the shuffling and polishing has resulted in a paper that reads straightforwardly and even seems obvious.  “When something can be read without effort, great effort has gone into its writing” — Enrique Jardiel Poncela.  That’s the goal, anyway.

The paper itself is available at the link below, so take a look and see whether you find our argument convincing.  As always, comments are open!

Update (the next morning)

Co-author Dave Hone discusses this paper on his own blog.

References

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Why did sauropods have such long necks?

Mamenchisaus hochuanensis skeletal reconstruction (Young and Zhao 1972:fig. 4), based on the holotype

It’s the single most obvious and important question about sauropods, so it’s a bit surprising to think that we’ve never really addressed this question directly.

Maybe sauropod necks are so obvious and familiar that we just take them for granted, and move straight on to questions of how they were able to grow so long and remain workable.

Well, let’s fix that.  Let’s think about why they had such long necks.  What were they for?  What were sauropods doing with their necks that was valuable enough to justify all that investment?

Back in the good old days, everyone assumed that sauropod necks were all about high browsing.  If you have a 9.5m neck, then of course you will use it to browse high up in trees — it’s intuitively obvious.  But of course “intuitively obvious” is not the same thing as “true”.

Then John Martin (1987) proposed that the long necks were used for low browsing — not raised above shoulder level, but swept back and forth to allow food to be gathered across a wide area without all that tedious mucking about with locomotion.  This interpretation was of course endorsed by Stevens and Parrish (1999) in their DinoMorph work.

There has been plenty written about habitual sauropod posture — including by us (Taylor et al. 2009).  But actually the high-browsing and low-browsing explanations of sauropod neck elongation have much in common.  Most crucially, they both relate to enlarging the feeding envelope; more broadly they are both explanations that rely on the neck having a survival benefit.  But Senter (2006) proposed a completely different explanation — that sauropod necks were sexual signals, selected not for survival advantage but for reproductive success.  The idea is that female sauropods, being very shallow, would go for the males with the biggest protuberances.

Are there other candidate explanations that I’ve missed?

Or is it between high browsing, low browsing and sexual selection?

Comments are open!

References

People who’ve been paying especially close attention may have noted than on four separate occasions in the last eighteen months, I’ve casually referred to our old buddy HMN SII as the paralectotype specimen of Giraffatitan brancai.  (Butchering a wallaby, photographing big bones, How fat was Camarasaurus, and baby giraffe neck, in case you were wondering.)

Giraffatitan brancai paralectotype HMN SII in the justly underrated left posteroventrolateral view, slightly obscured by a bit of Boring Old Diplodocus neck

But in my Big Brachiosaur Bonanza (Taylor 2009:788), I nominated HMN SII as the lectotype of this species.  So why all this paralectotype stuff?  Well, what I wrote in the paper was:

The original type specimen, “Skelett S” (Janensch, 1914:86) was subsequently found (e.g., Janensch, 1929:8) to consist of two individuals, which were designated SI (the smaller) and SII (the larger and more complete). Janensch never explicitly designated these two specimens as a syntype series or nominated either specimen as a lectotype; I therefore propose HMN SII as the lectotype specimen of Brachiosaurus brancai.

But in May last year, I got an email from Mark Konings, a dinosaur enthusiast from the Netherlands, pointing out (more politely than I deserved) that I’d got this wrong.  In fact, Janensch did nominate a lectotype — the wrong one, SI, but we’re stuck with it.  He did this in a paper on skulls (Janensch 1935-1936:151), which is why I overlooked it.  (Well, that and the fact that he rather inconsiderately wrote in German.)

Once I’d been shown my mistake, I realised that the only thing to do was formally correct it in JVP, where the original article had been, so I sent them the shortest and most boring manuscript I’ve ever written (and it is up against some pretty stiff competition in the “most boring” category).  And that manuscript was published today (Taylor 2011), fixing my dumb mistake.

Many thanks to Mark for spotting this!

References

It’s been a couple of months since Brontomerus came out, but new coverage continues to trickle in. For anyone who’s still following, I thought I’d draw attention to a few that I particularly like.

A favourite is One Hip Dino in The Scientist.  It’s told largely from Matt’s perspective, and includes quotes by Mike D’Emic, Susie Maidment and Ray Wilhite.  (Although D’Emic’s statement that “The ilium projects forward by 55 percent, while in other species it’s 52 percent” could do with some substantiation — I think we’ve shown pretty convincingly how different the ilium is from anything else out there.)

The most recent of the new articles is The biggest, baddest dinos still rule, in Macleans, which describes itself as “Canada’s only national weekly current affairs magazine”.  I guess that makes it Canada’s Time or Newsweek, and it has 2.4 million readers.  Despite the rather unpromising title, the article is good, and touches on some of the potential downsides of palaeo publicity.

But one of the best things about publicising Brontomerus has been hearing about how it’s been used in education.  (As one example, it was the lever that got me an opportunity to give a talk about palaeontology and evolution at my eldest son’s school a few weeks ago.)  One article describing Brontomerus‘s involvement in engaging kids’ interest is Dinosaur teaching topics – how to name a dinosaur at Everything Dinosaur.  The author tells me “we chose Brontomerus as the focus for our teaching session and I introduced concepts such as ontogeny and used the children’s knowledge of how farmyard animals grow and change, relating this to the fossil evidence of the adult and juvenile of the Brontomerus genus.”

Another benefit of letting the world know about Brontomerus was that it opened the door to my writing an article for the Guardian‘s science blog: How I got to know thunder thighs, the dinosaur with a fearsome kick.  They chose the title, sadly: I’d suggested something more like “How we know what we know”, and that is indeed that main topic of the article.  It was a rare opportunity to talk in a mainstream media outlet about how we actually do palaeontology, and the varying levels of certainty in which we hold different conclusions.

I hesitate to mention it, but the New York Times did a piece on, well, mostly me: Dinosaur-hunting hobbyist makes fresh tracks for paleontology.  I’m mostly really happy with it, except that an unfortunate bit of abridgement gives the impression that I described Jack McIntosh as “a minor paleontologist”.  Let the record show, that is not what I said: it’s actually how I described myself.

Finally, I’d like to draw attention to a very cheerful interview that Australian science blogger Bec Crew did for ABC Radio’s Triple J channel, in a program called The Doctor on 8th March.  Bec is best known for her truly unique blog Save your breath for running ponies, (I can’t help inserting the missing comma in the title), and my only regret regarding Brontomerus is that it’s never been given the SYBFRP treatment.

That’s all for now.

Atacamatitan chilensis gen. et sp. nov., caudal centrum SGO.PV.961c in ventral (A) and ventrolateral views (B); caudal vertebrae SGO-PV-961h in lateral (C) and dorsal (D) views. Scale bars: 50 mm. (Kellner et al. 2011:fig. 2)

Although we like to stay sauropod-o-centric on SV-POW!, I just want to take a moment to acknowledge the most astounding publication I have ever seen, Sterling Nesbitt’s new basal archosaur phylogeny (Nesbitt 2011).  Thanks to the wonder of open access publishing, it is freely available, and I urge everyone to check it out, if only to gaze in open-mouthed astonishment at the scale of the thing.

In 292 packed pages, Nesbitt provides a new phylogenetic analysis of basal archosaurs, using 80 species and 412 characters.  But if that doesn’t sound like the hugest matrix you’ve ever heard of, what sets this contribution apart is the incredibly detailed work in describing and illustrating those characters.  In those terms, I can only compare it with Wilson and Sereno’s (1988) JVP monograph — but that described 109 characters, and even then not in such exhaustive detail as in the new work.  And everything else about this paper is also super-comprehensive: the discussion of earlier work, the description of the mechanics of the analysis, the extensive sections talking through the expected and unexpected results of that analysis.  To give just a tiny flavour, here’s a figure showing a bunch of basal archosaur braincases:

Braincases of basal archosaurs in lateral view (Nesbitt 2011:fig. 23)

Knowing nothing about basal archosaurs myself, I have nothing intelligent to say about the content of the paper — I will leave that to others, and I don’t doubt that Bill and Jeff will have plenty to say on their respective blogs.  I just want to marvel at the sheer scale of the undertaking.  My Ph.D dissertation was 285 pages long — by coincidence, almost exactly the same length of Nesbitt’s epic.  But dissertations are much less dense than papers: they are double-spaced (or 1.5x spaced in my case, since that was an option and I hate wide spacing with a passion), and figures each take up a whole page — or even two if the caption is separate.  All in all, I’d say that two pages of dissertation are worth one page of publication, near enough.  Which means that Nesbitt has poured twice as much work into a single paper as most of us do into our entire Ph.Ds.

Dude, pls.  You’re making the rest of us look bad.

(By the way, since a decent dissertation contains four or five non-trivial papers, it follows that there’s enough work in the new Nesbitt tome to have been equivalent to maybe ten papers.  but because it’s all in one package, he’ll only get 1/10 as many citations as he would have, had he written ten papers instead.  This just shows what a stupid way counting citations is for assessing the importance of someone’s work.)

The final thing that should be said about this is that by all accounts, Nesbitt is an uncommonly nice guy.  (I’ve only met him once myself, briefly, which is why I don’t feel justified in using his first name in this article.)  And I have found, almost without exception, that the most impressive palaeontologists are also the ones who are most helpful and generous.  I could mention Randy Irmis, for example, who seems to churn out half a dozen top-class papers for every publication I manage to get out the door, and who would be terrifying to be around if he wasn’t such a good guy.  Steve Brusatte is another one whose rate and quality of work is astonishing, yet who is always ready to help out other people.  (I am going to stop mentioning people by name now, otherwise those who don’t get a mention might feel slighted.  There are plenty of other examples, and you probably know who some of them are.)  I don’t know why it should be that quality × quantity of work correlates so well with niceness, but that’s how it seems to be, and I like it that way.

Anyway, go and look at — I won’t say read, not all the way though — Nesbitt’s giant analysis.  It sets the bar higher for us all.

References

Image borrowed from here.

This isn’t the most perceptive prognostication of all time, and others probably have or will come up with it independently, but I still wanted to get it out there. The upcoming TV show Terra Nova, about a family sent back to the Cretaceous as pioneers from an ecologically wrecked future Earth, will have dinosauroids. I haven’t heard any leaks to that effect, it just seems inevitable. My reasoning is as follows:

It’s awfully hard not to read Terra Nova as Avatar, with time substituted for space to yield the exotic backdrop. Especially with Stephen Lang returning as Colonel Quaritch or whatever they’re calling him this time (“Out there beyond that fence every living thing that goes from the ground up, the trees down, or WAIRs wants to kill you and eat your eyes for jujubes”). Which is what made me realize that they’re going to have dinosauroids. Pandora without the Navi is just a prettier version of the Amazon.

There are only so many human vs. dumb dinosaur plots one can do, and human vs. human plots make the show a normal drama set in a jungle. I am certain that there will be a Treachery plotline, probably of the form Whoever Controls Mankind’s Bolt-Hole in the Past Controls Mankind. And there will be Difficulties Back Home, and Things That We Didn’t Know About This World That Can Kill Us, apart from the Random Dino Danger. But let’s face it, swap out “dinosaurs” for “lions” or “blizzards” and those plotlines would work just as well if the last humans are escaping to the Serengeti or Antarctica. Going into the past brings up the possibility of Them–the intelligent non-human adversary–and the writers will not be able to resist Their siren song.

And it might not be a siren song. It might be a thundering anthem of pure awesome–think BSG with dinos. I don’t think it’s impossible to do a dinosauroid storyline that is smart, or that the show will necessarily be bad because it involves dinosauroids. I’m just pointing out that the eventual arrival of the dinosauroids is as certain as the presence of the Outwardly Tough But Inwardly Vulnerable Hottie and the Lovable Doofus. If the show was set on a moon base, the humans would end up fighting intelligent machines and/or aliens. We’re dealing with inexorable laws of mass entertainment here.

There is a small chance that They will be aliens (probably time-traveling aliens, if so, but Enterprise already did that), but my money is on dinosauroids. They might not look like scaly humanoids–They might just be normal-looking raptors with australopithecine or better intelligence–but I’ll bet you a big pile of SV-POW!bucks that They will be there, and before the curtain drops on Season 1 (addendum: if They haven’t appeared sooner, someone will find a dinosauroid arrowhead at the very end of the season finale).

Any takers?

———————-

If you’d like to read more about dinosauroids, Darren Naish has left a vast trail of dinosauroid-related posts through the blogosphere. In addition to the post linked above, check out this, this, and and this, for starters. Also note that sauropods have not been ignored in the quest for speculative intelligent dinosaurs, as previously covered here.

[This is a guest post by frequent commenter Heinrich Mallison.  Heinrich is maybe best known to SV-POW! readers for his work on digital modelling of sauropodomorphs, though that may change now that his paper on sauropod rearing mechanics is out.  Read on …]

Maybe this post should have been titled “How sauropods breathed, ate, and farted”. Or maybe not. But breathing, eating and fermenting the food will play an important role.

Last week held a special pleasure for me. I spent it in New York, digitizing sauropods bones in the American Museum of Natural History’s Big Bone Room. Treasure trove that this room is, the museum still held something even better: the opening of a new special exhibit titled The World’s Largest Dinosaurs. While all such exhibits are of general interest to me, this one is special. Mark Norell, famous palaeontologist and curator at the AMNH, had a co-curator for this exhibit, Martin Sander of Bonn University, who is the head and speaker of the German Research Foundation Research Unit FOR 533 “Sauropod Biology”. As a member of FOR 533, and having received funding for both my PhD work and my first post-doc project, I am obviously somewhat biased, so please take this into account when you read this report.

The exhibition does not show a large amount of sauropods material. Not that it wouldn’t make for a nice exhibit, as the AMNH’s Hall of Saurischian Dinosaurs doesn’t really have that many sauropods (one Apatosaurus mount, to be exact, with a mashed up Barosaurus vertebral column half-hidden away and a wonderful but obviously depressed “prosauropod”, my old friend Plateosaurus, thrown in to make up a bit for the many, many stinkin’ theropod specimens). But instead of showcasing some of the usually hidden-away bones of the AMNH collection (and believe me, there is some wonderful stuff there), it rather focuses on those parts of the animal that are usually missing: the soft tissues. “How did sauropods get so big?”, or, reversing the question: “Why did and does no other group of terrestrial vertebrates reach such gigantic body sizes?” These were the questions our research group has been busily investigating for the last six years, and the answers to these question are what the exhibit now tries to communicate to the public. And it does so quite successfully!

The centerpiece of the AMNH exhibit: the belly of Mama Mamenchisaurus.

The centrepiece is a full-sized, fleshed out model of a sauropod (Mamenchisaurus hochuanensis), but on one side the skin and superficial musculature has been cut away. The visitor can see the neck vertebrae, the trachea, the carotid artery, and the ribcage. And the ribcage is also a projection area, on which a video is played that shows the internal organs and how they work.

With a voice-over that explains the actions in simple terms, the principle of the avian-style unidirectional lung and the air sacs is explained (albeit with a small error, as lung physiologist and FOR 533 member Steve Perry was quick to point out – the AMNH has promised to fix things), as well as the basic principles of sauropod reproduction (high number of offspring). Many things are not said or shown here, which is a good thing as it allows for the normal short attention span of the average museum visitor for one piece of exhibit. Instead, interesting stuff like how much fodder a sauropod needed per day (or even per hour), a comparison of a sauropod’s and an elephant’s heart, and of a giraffe’s and a sauropod’s neck vertebra (wow, how light the sauropod one is!) are explored at small science stations spread around the room. I won’t go into a detailed description here, you can find that elsewhere on the web. The AMNH did a blogger’s preview a while ago, and invited the press for a press conference and walk-through of the exhibit with the chance to interview the scientists present on Wednesday, so much info has already been plastered all over the web. Instead, I’ll just show you some pics and talk a bit about the concept of the exhibition, and how various issues were handled that can make or break a show.

One thing is how to catch the attention of visitors and direct it to the content of the exhibit. You don’t want people just going “aw, sh*t! That is one HUGE bone/animal!” and wandering off into the next room. If you want to educate them (and that, may I remind you, is the central purpose of a museum exhibit), you need to get them interested in stuff. Get them to read texts, look at stuff (not just let their eyes wander across it for a few seconds), try to get their brains going. The sauropod exhibit manages this by, first of all, being behind a closed door you can’t see through. Usually, the AMNH halls are accessible either through an open doorway, or in a few cases through glass doors. Secondly, the exhibit, especially the rather confined area you enter first, is dark. Very dark. Again a marked contrast to the AMNH’s usually well-lit halls. Just a few plants greet the visitor, and it takes a second to adjust to the dark – enough time to look around a bit and notice the neck and head of Argentinosaurus (fleshed out model) above.

My esteemed colleague Vivian Allen from Royal Veterinary College London going "Aw, sh*t! That is one HUGE sauropod!"

Next, the visitor is channeled along, with only a very few specimens to catch his attention. Well done, because these few pieces (sauropod leg, Komodo dragon skeleton, human skeleton, etc.) focus on getting the main message across (sauropods = way larger than everything else), aided by the largest animals (or their silhouettes) or various groups painted on the wall. Only once the message has been driven home, as I could detect from the comments I overheard, are the visitors released into the main area that contains the sauropod model and the various detail exhibits around it.

The next thing is giving people time to check things out. If you herd them too much, they will get driven along by the masses. That’s why the larger, opener area around the sauropod model and the smaller bits around it works so well: people can sit down to see the projected videos on the sauropod belly, or they can drift around from one specimen or science station to the next.

The stations are not just glass cabinets with some bones in them. Instead, at many of them you can DO things. One allows you to measure either an adult or baby sauropod femur or your own, and then calculate how heavy a sauropod of that size was. At another you can pump a sauropod’s and an elephant’s lung. One I liked very much simply had an unpainted sauropod model, and two sets each (adult and children height) of oculars. One showed a colorful “show-off” version, the other a “camouflage” one. “Which one is true? We don’t know!” is how I’d paraphrase the text that goes with it. One that innocently hides in the corner is among the most impressive: a 5 ½ ft cube (1.7 m, for the civilized) made from Plexiglas filled with sauropod food. A serving sufficient for one day! On it, also, the various plant groups available in the Mesozoic were rated for various factors, getting an easily understood rating in stars. That’s another big thing: make things easily understandable, visualize them!

Yummy! 100% Recommended Daily Value for your average sauropod.

With all these things well done, there remains only one more thing: make things fun for kids! And the AMNH did just that by adding a kids’ dinosaur dig. OK, it is one of those cheesy things where you use brushes and stuff to brush sand off fossils (cast), but it was done well enough that kids lined up like there was no tomorrow.

Overall, the exhibit gets two big thumbs up from me. If you make it to NY while it is on, or to any of its future stations, go see it! However, as FOR 533 member Steve Perry was quick to point out: if you’re in it only for the size, you’ll be disappointed! Aside from a few isolated bones, not much of the largest dinosaurs (Argentinosaurus and Amphicoelias) is to be seen in bone. It is the biological details that matter!  But don’t get me started about the tail musculature, especially the caudofemoralis, of the big model.

And then, there is the other thing about it that is closely tied to shameless self-promotion: the AMNH did not produce a catalogue or anything similar. Instead, the latest book from the “Life of the Past” series (Editor: James Farlow) of Indiana University Press was presented at the press conference. The lucky reporters all even got a free copy! The title is Biology of the Sauropod Dinosaurs: Understanding the Life of Giants, edited by N. Klein, K. Remes, C. T. Gee and P. M. Sander. And by now, I am sure, you have figured out who the authors are … It is intended to be a summary of the research findings of the first (and part of the second) funding period of FOR 533, and yours truly has two chapters in it. The first doesn’t really give much new information; most is already contained in my two papers here and here. The second, however, presents novel research that didn’t make it into the AMNH exhibit. But hey, why spoil the surprise – go and buy our book!) Overall, it is quite a technical book, so laypeople beware, but we did try to make the research as accessible as possible while retaining a high standard. For the even more technically minded there is the summary of our research group’s work (which cost the DFG ~€6.000.000) to be found in Sander et al. 2010. However, reading that paper is not half as much fun as the book, or the exhibit.

References