Now that the new Wilson and Allain (2015) paper has redescribed Rebbachisaurus, we can use it to start thinking about some other specimens. Particularly helpful is this beautiful rotating animation of the best dorsal vertebra (here captured at the point of the rotation where we’ve viewing it in right anterolateral):

rebbachisaur-dorsal-rotation

As I briefly discussed on Twitter, seeing this made me think of my baby, Xenoposeidon. Now that specimen, beautiful though it is, preserves only the lower one third of the vertebra. But there are some clear commonalities, and they’re clearer if you look at the animation.

Xenoposeidon-TNF

Most obviously, there are laminae running up and down the anterior and posterior margins of the lateral face of Xeno’s neural arch, and those same laminae seem to exist in Rebbachisaurus. We didn’t name these laminae in the Xeno paper, but if they’re the same thing as in Rebbachisaurus, then they’re ACPLs and PCDL — anterior centroparapophyseal and posterior centodiapophyseal laminae.

If that’s right, then we misinterpreted the site of the parapophysis in Xenoposeidon. We (Taylor and Naish 2007) thought it was at the cross-shaped junction of laminae near the anterodorsalmost preserved part of the vertebra. In Rebbachisaurus, this cross exists, but it’s merely where the CPRL (centroprezygapophyseal lamina) intersects the ACPL.

But there’s more. In Xenoposeidon, the base of the CPRL (if that’s what it is) forms a “V” shape with an accessory lamina that proceeds posterodorsally from the same origin. (This is one of the features that’s apparent on the more damaged right side of Xeno as well as the nicer left side.) That lamina also seems to exist in Rebbachisaurus — but with the whole vertebra to consider, we can see that it’s not an accessory lamina, but a perfectly well-behaved CPOL (centropostzygapophseal lamina).

So if Xeno is indeed a rebbachisaurid, then the two branches of the “V” go to support the pre- and postzygs, and the laminae running up the anterior and posterior margins of the centrum support the parapophyses and diapophyses respectively. There are actually two crosses on each side of the neural arch: one at the intersection of CPRL and ACPL, the other at the intersection of CPOL and PCDL; but in the Xeno specimen, the posterior cross is lost, having been just above where the break occurs at the top of the neural arch.

Here’s what I mean:

reconstructed-as-rebbachisaur

In case it’s not clear, the grey lines are an (extremely crude) reconstruction, the blue lines label the important laminae, and the red circles highlight the two crosses.

Hmm. The more I look at this, the more convincing I find it.

But there’s more! The anterior aspect of the Rebbachisaurus vertebra also bears a notable resemblance to what we see in Xeno, with a pair or arched laminae forming a vaulted roof to the neural canal.

 

rebbachisaur-dorsal-rotation2

Jeff Wilson spotted the same thing in a sequence of comments on my tweets, saying:

That’s not a bad call—the infrazygapophyseal region of that vert is elongate, and there is a nice CPRF and those closely positioned TPRLs could mean that prz’s are close to one another or even conjoined. It’s tantalizing, but not much to go on. Would be nice to prep out CPRF & work out laminae on lat sfc.

Jeff is right that more preparation would help to figure this out.

Not that everything about the Rebbachisaurus dorsal is Xeno-ish. Most notably, the lateral foramen is nothing like that of Xeno, being an uninspiringly dull and simple oval rather than the much more elegant foramen-within-a-fossa arrangement that we see in Xeno. But there are other points of commonality, too, such as the flat stretch of bone above the fossa and the way the posterior margin of the neural arch reaches the posterior margin of the centrum.

All in all — while there is plenty of work yet to do — I am increasingly inclined to think that the evidence we currently have suggests Xenoposeidon is a rebbachisaurid. If that’s right, it would be quite an exciting result. It would be the earliest known rebbachisaur, and the only named one from the UK. (Mannion 2009 described, but did not name, a rebbachisaurid scapula from Wessex formation of the Wealden). Could Mannion’s scapula be Xenoposeidon? Unlikely, as it’s 10 million years more recent. But it could be a close relative.

Exciting times!

References

 

Get your red/cyan anaglyph glasses on, and feast your eyes:

xenoposeidon--nhm-r2095--left-lateral--anaglyph

Click through for stupidly high resolution.

Those of you who are still too cheap to have sprung 99¢ for a pair of glasses, you can make do with this grossly inferior wigglegram:

xenoposeidon--nhm-r2095--left-lateral--wigglegram

Friday evening I was in a pub with Mike, Darren, John Conway, and Emma Lawlor. We were killing time waiting for the Pink Giraffe Chinese restaurant down the street to open. I was chatting with John about “All Todays”, his speculative presentation with Cevdet Kosemen (a.k.a. Nemo Ramjet) on how future sentients might reconstruct Holocene animals if they were known only from fossils. Like his “All Yesterdays” presentation last year, John’s flights of scientific fancy had fired my imagination and gotten me thinking about how paleontology forms sort of a skin or membrane between the bubble of what we know and the surrounding ocean of what we don’t. I decided that we should pass a pad around and each sketch a speculative sauropod.

My own entry is based on the holotype of Mamenchisaurus hochuanensis, which was found almost complete except for the skull (naturally) and forelimbs. I have often joked that diplodocids were basically bipeds whose forelimbs happened to reach the ground. Mamenchisaurs were probably not that back-heavy, but their presacral vertebrae were extremely pneumatic and if our hypothetical future paleontologists had no other sauropod material to work with, I think it’s possible that they would reconstruct the M. hochuanensis holotype as a biped.

I’m not sure there’s much to say about Mike’s brachiosaur, beyond the Ebert-like observation that if a brachiosaur dressed up in a coat and top hat and went cruising for dames, this, I am forced to conclude, is more or less how it would look.

John Conway also drew a mamenchisaur, this time Mamenchisaurus youngi with its bizarrely bent-back sacrum. John’s explanation for the weird sacrum brings to mind ground sloths and–for those who saw “All Yesterdays” at SVPCA 2011–a certain black-feathered therizinosaur. I’d also like to note that he knocked this out in about 5 minutes, thus demonstrating the difference between a professional artist and a mere doodler like myself.

Darren’s hindlimb-less sauropod complements my bipedal Mamenchisaurus. Here the animal, evidently known from only the front half of the skeleton, has been restored as a giant bird. Dig the giant thumb claws and spreading metapodials. Surely, you say, future paleontologists of any species or machine culture would know a pectoral girdle when they saw one. But I’ll bet a sauropod scapulocoracoid could pass for an ilium, if said future paleontologists were still in the early stages of understanding the morphology and diversity of vertebrates. Remember that Seeley described the sauropod Ornithopsis as “a gigantic animal of the pterodactyle kind” based on its pneumatic vertebrae. There is also a long and honorable (?) tradition of mistaking sauropods for hadrosaurs (Sonorasaurus), theropods (Bruhathkayosaurus), and tree trunks (Sauroposeidon), so don’t be too quick to rule this out.

What I want to see next is a skeletal reconstruction of Darren’s sauro-bird, using only elements from the front half of a sauropod skeleton. Anyone want to give it a shot?

Our penultimate entry is Emma’s rendering of an evil bastard snake devouring an innocent baby sauropod. Tragically this one is not speculative–we have very good fossil evidence that the scene shown here really happened, probably a lot. She tried to make it up to us with a smiley face on the next page, but it was too late. We were so depressed after this that we could barely choke down four courses of excellent Chinese food.

One more for the road: a totally new depiction of the enigmatic sauropod Xenoposeidon by yours truly. I expect to see this incorporated into future talks and papers dealing with European sauropod diversity in the Early Cretaceous. Just credit me as you normally would.

That’s all, folks. I hope that speculative sauropod sketches get to be a Thing, and that we see lots more of them from future conferences.

The Magi present gifts to the Christ child

Back when Darren and I did the Xenoposeidon description, we were young and foolish, and only illustrated the holotype vertebra NHM R2095 in four aspects: left and right lateral, anterior and posterior.  No dorsal or ventral views.

Also, because the figure was intended for Palaeontology, which prints only in greyscale, I stupidly prepared the figure in greyscale, rather than preparing it in colour and then flattening it down at the last moment.  (Happily I’d learned that lesson by the time we did our neck-posture paper: although it was destined for Acta Palaeontologia Polonica, which also prints in greyscale, and though the PDF uses greyscale figures, the online full-resolution figures are in colour.)

As if that wasn’t dumb enough, I also composited the four featured views such that the two lateral views were adjacent, and above the anterior and posterior views — so it wasn’t easy to match up features on the sides and front/back between the views.  Since then, I have landed on a better way of presenting multi-view figures, as in my much-admire’d turkey cervical and pig skull images.

So, putting it all together, here is how we should have illustrated illustrated Xenoposeidon back in 2007 (click through for high resolution):

(Top row: dorsal view, with anterior facing left; middle row, from left to right: anterior, left lateral, posterior, right lateral; bottom row, ventral view, with anterior facing left.  As always with images of NHM-owned material, this is copyright the NHM.)

Of course, if we’d published in PLoS ONE, then this high-resolution (4775 x 4095), full colour image could have been the published one rather than an afterthought on a blog somewhere.  But we didn’t: back then, we weren’t so aware of the opportunities available to us now that we live in the Shiny Digital Future.

In other news, the boys and I all registered Xbox Live accounts a few days ago.  I chose the name “Xenoposeidon”, only to find to my amazement that someone else had already registered it.  But “Brontomerus” was free, so I used that instead.

I hesitate to inflict these images on SV-POW! readers, but I have to post them somewhere if only so I can point my family to them; and who knows, maybe some of the rest of you will enjoy the amusing hat.

Last Friday (17th July), I drove down to Portsmouth, with my wife Fiona, to graduate — the consummation of my Ph.D programme.  I’d expected to be issued with a sober black robe and one of those hats with a flat square on top, but I was unprepared for just how silly the kit would turn out to be:

Me with Fiona, trying not a laugh at my nice red uniform

Me with Fiona, trying not to laugh at my nice red uniform

In fact, I looked less like a palaeontologist and more like a member of the Spanish Inquisition.  Which, I’m sure I need not point out, was the last thing I’d expected.

My supervisor Dave Martill was there for the ceremony, also dressed up as a silly person; and Darren came along in civvies to say hello before the show, and to meet up afterwards at the reception at the Department:

Me, Dave Martill and Darren, sharing a joke about astrapotheres or something.

Me, Dave Martill and Darren, sharing a joke about astrapotheres or something.

Also present and graduating was Portsmouth pterosaur maven Mark Witton, but I don’t have a picture of him in regalia, as he turned up too late to have his photo taken — wise man.

As I sat through the very, very long ceremony — if you’ve never listened through a list of 600 names being read out and watched 600 people walk up on stage and shake hands with the pro vice chancellor, you don’t know the meaning of the word “party” — I became bored enough to read the programme cover to cover, and so I discovered that photography during the ceremony is strictly forbidden.  Fiona, however, did not realise this, and so I am able to show you this actual photograph of me caught in the act of graduating:

Me at the moment of graduation.  Or perhaps Bigfoot.

Me at the moment of graduation. Or perhaps Bigfoot.

We doctoral graduands got special treatment: not only did we shake hands with the pro vice chancellor — as though this were not thrill enough — but we also had the titles of our dissertations read out.  As mine sounds rather vague (“Aspects of the history, anatomy, taxonomy and palaeobiology of sauropod dinosaurs”) I was left wishing that I’d stuck with my original title.

After the ceremony it was back to the department for nibbles and also to — finally! — pick up the printed-and-bound copies of my dissertation, which until then I’d not seen in the flesh.  Apart from the two mandatory copies (for the University and Department libraries), I had four printed — one each for me, Dave, Darren and Matt.  Those of you not fortunate enough to have received one of the printed copies can assuage your lust for my dissertation by buying it in mug form:

My dissertation, on a mug, for some reason.

My dissertation, on a mug, for some reason.

I’m not quite sure what made me think this would be a cool thing to do, but anyway I did it, and this is now my first-choice mug as I make my way through the numerous cups of tea that, as an Englishman, I am obliged to drink each day.  (And yes, you really can buy one of your very own.)

Irrelevant addendum

You may wish to know that, at the time of writing, the top five search terms that are bringing people to SV-POW! are: rabbit, flamingo, basement, svpow, and twinkie.

OMG: MPT, PHD!

April 29, 2009

If you woke up this morning and thought, “Global warming is on the rise, amphibians are in a race to see who can go extinct first, the economy is in the toilet, any day now my boss will discover that I don’t actually do anything at work,  and my blog will never have the eclectic cachet of SV-POW!, but at least Mike Taylor doesn’t have a Ph.D.,” then it is my happy duty to ruin your day. Mike defended today, successfully.

doctor-taylor-in-da-house-480

Ladies and gentlemen, I proudly present Michael P. Taylor of Ruardean, Englishman, adventurer, raconteur, Doctor of Philosophy in the paleontological arts. Note that when recumbent he is approximately equal in length to 1.5 Sauroposeidon cervicals, and appears to be cradling an invisible wine glass. Don’t stare too long, or you might not be able to look away.

Congratulations, sir! Let the blogosphere ring with the happy news, and undescribed sauropods cry out for recognition.

Update (from Mike)

Thanks to Matt, and all commenters, for your kind words.  I wondered when the “Latin love god” photo was going to appear, and that day has finally come.  What Matt doesn’t know is that this photo was used for the cover of my forthcoming album:

Available wherever good music is sold

Available wherever good music is sold

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