My hobby:

October 17, 2013

oh crap im part furry

Fear and Loathing dinosaur tail 2

Relic cover

polar dinosaur babies

convincing genetic engineers that everyone would look better if they had sauropod tails.

If you have no idea what I’m on about, go check out XKCD.

Advertisements

Anyone else see these images and really, REALLY want to go dissect one of these bad boys?

Pacific Rim kaiju skeleton

From the moment I saw this in the trailer, I was thinking: “WANT!”

Pacific Rim kaiju skeleton 2

Click to embiggen, and check out the heavy equipment being used to cart off the soft tissue.

Welcome, one and all, to Taylor, Wedel and Naish (2009), Head and neck posture in sauropod dinosaurs inferred from extant animals.  It’s the first published paper by the SV-POW! team working as a team, published in Acta Palaeontologica Polonica, and freely available for download here.

Far, far back in the uncharted depths of history, silly people like Osborn and Mook (1921:pl. 84), Janensch (1950b: pl. 8) and Paul (1988:fig. 1), who didn’t know any better, used to depict sauropods with their necks held strongly elevated.

The classic reconstruction of Brachiosaurus brancai, from Janensch (1950b: plate VIII)

The classic reconstruction of Brachiosaurus brancai, from Janensch (1950b: plate VIII. (For some reason, WordPress doesn't allow italics in these captions, hence the roman-font taxonomic names.)

All that began to change with Martin’s (1987) short paper in the Mesozoic Terrestrial Ecosystems volume, and was then turned upside-down by Stevens and Parrish’s (1999) seminal paper in Science: two and a half pages that transformed the way the world looked at sauropods.

xxx

The subhorizontally mounted neck of the Rutland Cetiosaurus skeleton at the Leicester City Museum, in right posterolateral view.

Median part of the subhorizontally mounted neck of the Rutland Cetiosaurus skeleton at the Leicester City Museum, left lateral view.  Mike Taylor for scale.

The median part of the subhorizontally mounted neck of the Rutland Cetiosaurus skeleton at the Leicester City Museum, in left lateral view. Mike Taylor for scale.

John Martin looked at the cervical vertebrae of the Rutland specimen of Cetiosaurus oxoniensis, and concluded that the joints between them couldn’t be as flexible as people thought.  He reconstructed that animal’s neck in a low, near-horizontal pose, and with a very narrow range of movement that didn’t allow it to raise its head far above shoulder level.  Stevens and Parrish brought more rigour to this approach by modelling the cervical articulations of two sauropods (Diplodocus carnegii and Apatosaurus lousiae) using a computer program of their own devising, DinoMorph.  And as most SV-POW! regulars will probably know, they got results similar to Martin’s, showing neutral positions for both animals that were well below horizontal, and finding restricted ranges of motion.  (“neutral pose” here means that the vertebra are aligned such that the zygapophyses overlap as much as possible.)

Diplodocus carnegii, DinoMorph computer model , showing neutral neck posture, and limits of flexibility.  From Stevens (2002:fig. 6a).  [Note that Stevens's more recent models show a slightly higher neck due to its leaving the torso at a less steep angle.]

Diplodocus carnegii, DinoMorph computer model , showing neutral neck posture, and limits of dorsal and ventral flexibility. From Stevens (2002:fig. 6a). (Note that Stevens's more recent models show a slightly higher neck due to its leaving the torso at a less steep angle.)

The DinoMorph posture was quickly adopted as orthodox, and got a lot of exposure in the BBC’s classic CGIumentary, Walking With Dinosaurs: episode 2, Time of the Titans, was primarily about Diplodocus, and under Stevens’s consultancy showed them as having obligate low posture throughout the show.

A still from the BBC Walking With Dinosaurs, episode 2, Time of the Titans, showing Diplodocus in a DinoMorph-compliant posture with a low, horizontal neck.  Image copyright the BBC.

A still from Walking With Dinosaurs, episode 2, Time of the Titans, showing Diplodocus in a DinoMorph-compliant posture with a low, horizontal neck. Image copyright the BBC.

The new horizontal-neck orthodoxy was also reinforced by an exhibition at the American Museum of Natural History featuring a physical metal sculpture of a DinoMorph model:

Physical DinoMorph model at the AMNH, with horizontal-neck advocate Kent Stevens.  Photograph by Rick Edwards, AMNH

Physical DinoMorph model at the AMNH, with horizontal-neck advocate Kent Stevens. Photograph by Rick Edwards, AMNH

This brings us pretty much up to date: there’s been very little in the way of published dissent between 1999 and now, and a couple more Stevens and Parrish papers have reinforced their contention.  Upchurch (2000) published a half-page response to the DinoMorph paper, and Andreas Christian has put out a sequence of papers arguing for an erect neck posture in Brachiosaurus brancai on the basis that this best equalises stress along the intervertebral joints (e.g. Christian and Dzemski 2007), but otherwise all dissent from the DinoMorph posture has been limited to unpublished venues: for example, Greg Paul has posted several messages on the Dinosaur Mailing List disputing the low-necked posture, but has yet to put any of his arguments in print.

But enough of this dinosaury stuff.  Let’s look at a nice, cuddly bunny:

wild-rabbit-41946-480px

Now here’s the thing: you wouldn’t guess by looking at it, but that rabbit has a vertical neck.  In fact, it’s more than vertical: it’s so upright that it bends back on itself.  Don’t believe me?  Then take a look at this X-ray of an unrestrained awake rabbit:

Unrestrained awake rabbit, left lateral view, in X-ray, showing vertical neck. From Vidal et al. (1986:fig. 4B)

Unrestrained awake rabbit, left lateral view, in X-ray, showing vertical neck. From Vidal et al. (1986:fig. 4B)

Amazing.

Can it be that rabbits have unusual cervical vertebrae, such that when you articulate them in neutral pose they curve strongly upwards?  No: and to prove it, here is (ahem) Taylor, Wedel and Naish (2009: fig. 1):

Taylor et al. (2009: fig. 1), reverse for easy comparison with the previous two images: skull and cervical skeleton of the Cape hare (Lepus capensis) in neutral pose and in maximal extension

Taylor et al. (2009: fig. 1), reversed for easy comparison with the previous two images: skull and cervical skeleton of the Cape hare (Lepus capensis) in neutral pose and in maximal extension

(Yes, this is a hare rather than a rabbit, but it’s close enough for government work.)  What we found was that it was only possible to get the cervical skeleton anywhere near the habitual life posture by cranking all the proximal cervical joints up as far as they could physically go.  In fact, it seems that some of the joints in the live animal flex more than the dry bones can — presumably due to intervertebral cartilage moving the centra further apart.

And this is fully in accord with the findings of Vidal et al. (1986), who X-rayed a selection of live animals (human, monkey, cat, rabbit, rat, guinea pig, chicken, monitor lizard, frog) and found that the neck is inclined in all but the frog.  Furthermore, in all the mammals and reptiles, they found that:

  • the cervical column is elevated nearly to the vertical during normal functioning;
  • the middle part of the neck is habitually held relatively rigid;
  • the neck is maximally extended at the cervico-dorsal junction and maximally flexed at the cranio-cervical junction; and
  • it is the cranio-cervical and cervico-dorsal junctions that are primarily involved in raising and lowering the head and neck.

(In life, these facts are obscured from view by soft tissue.)

We also looked at unpublished live-alligator X-rays (thanks to Leon Claessens for access to these) and found that even in these ectothermic sprawlers, the neck is habitually elevated above neutral pose.  Published X-rays of turtles and even (slightly) salamanders also showed the same tendency.

So what does this mean for sauropods?  Simply, unless they were different from all extant terrestrial amniotes, they did not habitually hold their necks in neutral position, but raised well above horizontal.  And if they resembled their closest relatives, the birds — and the only other homeothermic and erect-legged group, the mammals — then their necks were strongly inclined.  As in, all the proximal cervicals were habitually cranked into the most erect positions they could attain.  Kind of like this:

Diplodocus carnegii head, neck and anterior torso, right lateral view, articulated in habitual posture as hypothesised by Taylor et al. (2009).  Skull and vertebrae from Hatcher (1901).

Diplodocus carnegii head, neck and anterior torso, right lateral view, articulated in habitual posture as hypothesised by Taylor et al. (2009). Skull and vertebrae from Hatcher (1901).

Which is a looong way form the DinoMorph posture that we were all getting used to but couldn’t learn to love.  What do you know?  Turns out that Osborn and Mook, and Janensch, were right after all.

So that, in a nutshell, is the contention of the first SV-POW! paper: that sauropods held their heads up high.  That’s not to say that they couldn’t bring them lower when they wanted to — of course they could, otherwise they’d have been unable to drink — but we believe the evidence from extant animals says that they spent the bulk of their time with their heads held high.

I leave you with this rather beautiful piece that noted pterosaurophile Mark Witton drew to illustrate our favoured posture.  Enjoy!

Diplodocus herd -- mostly with necks in habitual raised posture, with one individual drinking.  By Mark Witton.

Diplodocus herd -- mostly with necks in habitual raised posture, with one individual drinking. By Mark Witton.

Stay tuned for more on neck posture …

Update

For more cool stuff about the paper, including blog and media coverage and the chance to hear Mike on BBC Radio(!), see our page about the paper on the sidebar.

References

  • Christian, A. and Dzemski, G. 2007. Reconstruction of the cervical skeleton posture of Brachiosaurus brancai Janensch, 1914 by an analysis of the intervertebral stress along the neck and a comparison with the results of different approaches. Fossil Record 10: 38-­49.
  • Janensch, W. 1950b. Die Skelettrekonstruktion von Brachiosaurus brancai. Palaeontographica (Supplement 7): 97-­103.
  • Martin, J. 1987. Mobility and feeding of Cetiosaurus (Saurischia, Sauropoda) ­ why the long neck? In: P.J. Currie and E.H. Koster (eds.), Fourth Sympo- sium on Mesozoic Terrestrial Ecosystems, Short Papers, 154­-159. Box- tree Books, Drumheller, Alberta.
  • Osborn, H.F. and Mook, C.C. 1921. Camarasaurus, Amphicoelias, and other sauropods of Cope. Memoirs of the American Museum of Natural History, new series 3: 246­-387.
  • Paul, G.S. 1988. The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, Giraffatitan, and a comparison of the world’s largest dinosaurs. Hunteria 2 (3): 1­-14.
  • Stevens, K.A. and Parrish, J.M. 1999. Neck posture and feeding habits of two Jurassic sauropod dinosaurs. Science 284: 798­-800. [Free subscription required]
  • Taylor, M.P., Wedel, M.J. and Naish, D. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54(2): 213-220.
  • Upchurch, P. 2000. Neck posture of sauropod dinosaurs. Science 287: 547b.
  • Vidal, P.P., Graf, W., and Berthoz, A. 1986. The orientation of the cervical vertebral column in unrestrained awake animals. Experimental Brain Research 61: 549­-559.

It’s been a while since we looked at everybody’s favourite partial dorsal vertebra, and there may be those who feel we’ve said all that can be said about it, but there is one feature of Xenoposeidon that we’ve never really highlighted here and which is well worth a look.

For anyone who’s not up to speed, a super-brief resumé: Xeno is an indeterminate neosauropod which Darren and I named in 2007 on the basis of a single element, a superbly preserved partial dorsal vertebra loaded with distinctive features that make it very clearly distinct from any other named taxon.  For anyone who wants more background, the original paper is freely available, as is a page summarising the story for the media, some unnofficial supplementary information, and a whole week’s worth of SV-POW! posts.

Here is the canoncial Xenoposeidon photo: the specimen in left lateral view.  (Don’t worry, this old chestnut is not your Picture of the Week — it’s just setting the scene.)

Xenoposeidon holotype BMNH R1095, left lateral view

Xenoposeidon holotype BMNH R1095, left lateral view. Copyright the NHM.

Up near the top of the preserved part of the vertebra, where the neural arch is broken off, there is a distinctive “V”-shaped pair of laminae, which we identified as accessory infraparapophyseal and infrapostzygapophyseal laminae. The more posterior of the two (on the right as we look at at it here) has a very distinctive wrinkled texture, and that’s what I want to show you today:

Xenoposeidon holotype BMNH R2095, left lateral view. Detail of accessory infrapostzygapophyseal lamina showing wrinkled bone texture

Xenoposeidon holotype BMNH R2095, left lateral view. Detail of accessory infrapostzygapophyseal lamina showing wrinkled bone texture. Copyright the NHM.

Now I’ve heard different things said of those wrinkles: I’ve never seen them on any other specimen of anything before, but then I’ve not seen a whole lot of material. Other people have told me that this kind of thing is pretty common, though I don’t recall anyone ever having told me a specific other specimen that has it.  What is completely clear is that no-one seems to know what it is or what it means.  It’s very hard to see how this could be the result of any kind of post-mortem distortion, so this must be what the bone was like when the animal was alive.  What are the possibilities?

  • I wondered whether it could be some kind of pneumatic feature, perhaps the trace left by a diverticulum or set of diverticula; but IIRC Matt doesn’t think that’s likely.
  • Could it be the result of some sort of infection?  Maybe neontologists, or for that matter doctors, see this kind of thing all the time but we poor palaeontologists are ignorant.
  • Er … what else?  Seriously, I am out of ideas here.

So, comments are open.  Enlighten me.  What is the cause of this distinctive texture?

Oh, and finally — for some reason, I don’t think I’ve ever mentioned that I uploaded most of the Xenoposeidon news spots onto Youtube a while back.  So if anyone wants to hear me talking about my favourite subject, and arguing with the Channel 4 News guy, or indeed just wants to see how mainstream media can get a science story completely right when we trouble to give them good information, get over to http://www.youtube.com/user/Mirk101

ronto

I ended the last post with this teaser:

There is another sauropod (sort of) in Episode IV (sort of), but I’ll wait a week before I blab about that one. I wonder if anyone will guess what it is in the meantime?

The mystery lasted all of a single comment. Several of you got it right, but the title of First (w00t w00t LOL!!1!!11!!) goes to Paul and his terse economical, “Would it be a ronto?”

rontos

It is apparently no secret that the Rontos briefly glimpsed in A New Hope: Special Edition and The Phantom Menace are morphed versions of the Brachiosaurus from Jurassic Park.

jp-brach

Here’s the official line, from the Star Wars Databank entry:

The rontos added into the Mos Eisley scenes for the Special Edition release of A New Hope are entirely computer-generated. It was a cousin of sorts to the digital models crafted for Jurassic Park; the ronto used a brachiosaur as a starting point with enough modification to make it distinctly Star Wars. Throughout the making of the sequence, the ILM animators referred to the otherwise nameless creature as a “bronto.” When asked to name the animal, George Lucas dropped the ‘b’ from the name, and thus the ronto was christened.

So now you know.

Rontos are apparently allergic to photography (possibly related to Nessie?), as I found just about zip for decent images in my exhaustive 10-minute web search.

I did learn that there is a competitive rib-eater named Ronto, who got a beat-down from Joey Chestnut, who ate 8.4 lbs of ribs in 12 minutes. Someday I will do a post about all the wacky search terms that bring people to SV-POW! “Basement” is always in the top 20, which must be a surprise for those folks who just want to remodel their cellar.

ANYWAY, the link to Brachiosaurus, no matter how tenuous, gives me an excuse to post this:

 

matt-with-brachiosaurus

Next week we’ll get back to science. Almost certainly.

The sauropods of Star Wars

January 1, 2009

I’m sure Mike will deride this as sordid linkbait, but what the heck. I’ve been meaning to blog about the sauropods of Star Wars for a while now, and I was finally spurred into action by this comment over at TetZoo.

kraytbones-480

The first (and best) sauropod of Star Wars will be no surprise to anyone with reasonably sharp eyes and rudimentary knowledge of sauropod osteology: the Krayt dragon skeleton that C-3PO walks past on Tatooine is composed mainly of cast sauropod vertebrae.

krayt-cervicals

You can see that the monster’s cervicals have big cervical rib loops. The deeply bifurcated neural spines mean that they are either from a diplodocid or Camarasaurus. Some of them are also fairly long and low-spined, especially those close to the head, which rules out Camarasaurus. I find the purely fictional skull pretty unconvincing next to the real (cast) sauropod vertebrae.

krayt-dorsals

Moving on down the series, we see that all of the dorsals have high neural spines, some of which are deeply bifurcated, which again is consistent with diplodocids but not with Camarasaurus, whose bifurcated spines are all short (and fairly ugly).  The vertebrae also have broad transverse processes that give them a ‘t’ shape. You can see that whoever laid out the dorsals scrambled their order (perhaps deliberately) so that the deeply cleft vertebra in the middle is bordered ahead and behind by verts with little or no bifurcation of the neural spine. In articulated diplodocids, the neural spine cleft first appears in the anterior cervicals, grows larger and deeper through the rest of the neck, and then disappears around the middle of the dorsal series.

nhm-diplodocus-480

So which diplodocid is it? My vote is Diplodocus, probably a cast of the mounted Carnegie skeleton like the one shown here in London’s Natural History Museum (this particular mount turns up here at SV-POW! quite frequently). The cervical rib loops of the anterior cervicals attach near the bottoms of the centra instead of hanging far below them as in Apatosaurus. Also, you can see below that the cervical ribs loops of the posterior cervicals are narrow, as in Diplodocus, but not Apatosaurus (images of Diplodocus cervicals are from Hatcher’s 1901 monograph).

krayt-and-diplodocus-compared

The final piece of evidence for the Diplodocus ID is a closeup of part of one of the vertebrae. According to Wookieepedia (from which I stole the Ep IV screencap I’ve used throughout this post) Lucas and crew left the prop skeleton out in the desert when they were done shooting back in the 70s, and rediscovered it when they returned to Tunisia to film the Tatooine sequences for Attack of the Clones. I don’t know if the skeleton was scavenged by prop hunters before, during, or after the ATOC filming, but pieces of the skeleton turn up on movie prop sites, including the one shown here:

krayt-cervical-rib

This is a cervical rib of a sauropod, and it looks to me more like the slender ribs of Diplodocus than the massive ribs of Apatosaurus. I could be wrong about the genus, but if the bones in the movie don’t belong to Diplodocus they have to be Apatosaurus, and the balance of the evidence points to Diplodocus.

Oddly enough, Wikipedia states that, “The artificial skeleton used for the movie was left there after filming and still lies in the Tunisian desert. During filming of Attack of the Clones, the site was visited by the crew and the skeleton was still found there. The skull used resembles that of a Diplodocus, a herbivorous dinosaur related to the Apatosaur” (emphasis added). Good call, Wiki-trolls.

The “Krayt dragon” locality has been visited, and blogged about, by paleontologist and paleo-blogger Michael Ryan.

One more thing: Diplodocus and Apatosaurus both have 25 presacral vertebrae. The photo above is not crisp enough to determine precisely how many vertebrae are in the cervical+dorsal regions, but it’s more than 25. Also, none of the dinky anterior cervicals of Diplodocus are visible. So I think they must have gotten two sets of presacrals (possibly two whole columns) and used only the bigger vertebrae. I wonder what happened to the verts they didn’t use…I’d give a non-essential organ for a cast Diplodocus cervical.

That’s it for this one. There is another sauropod (sort of) in Episode IV (sort of), but I’ll wait a week before I blab about that one. I wonder if anyone will guess what it is in the meantime? Update: the reveal! (Which, okay, was not much of a reveal, since the answer was guessed by the first commenter!)