Cetiosaurus nomenclature, redux — comments from Paul Barrett and Pete Galton

For those of you who care about such things, the new issue 66(2) of the Bulletin of Zoological Nomenclature contains two comments on our petition to the ICZN to fix Cetiosaurus oxoniensis as the type species of the historically important genus Cetiosaurus (Upchurch et al. 2009) — both of them supporting the proposal  (Barrett 2009 and Galton 2009).

Cetiosaurus oxoniensis dorsal vertebra in anterior, right lateral and posterior views. From Upchurch and Martin (2002:fig 5)

Paul Barrett wrote (in part):

Cetiosaurus was the first sauropod dinosaur to be scientifically described (Owen, 1841) and one of the earliest dinosaurs to be recognised: the taxon is clearly of historical importance and stabilising its taxonomy would represent an important contribution to dinosaur studies.
[...]
Cetiosaurus is not only a historically important taxon, but also one that has been used to specify other groups within Dinosauria, including Cetiosauridae. In addition, Ornithischia, one of the major dinosaur sub-groups, has been defined as all dinosaurs that are more closely related to Iguanodon than they are to Cetiosaurus (Norman et al., 2004).

(I’d completely missed that use of Cetiosaurus as an external specifier for Ornithischia, which I suppose just goes to show that I should pay more attention to the ornithischian literature.)

Pete Galton wrote (in part):

It should be noted that the “Monograph of the genus Cetiosaurus” by Owen (1875) is based almost entirely on the Bletchington Station material of C. oxoniensis (Owen even used Phillips’ figures!). Also, as noted by Galton & Knoll (2006), the family CETIOSAURIDAE Lydekker, 1888 is based on C. oxoniensis Phillips, 1871 because Lydekker (1888, p. 137) indicated it as being the type species of Cetiosaurus Owen.

More good arguments there for the conservation of prevalent usage by formally recognising C. oxoniensis.

Anyone else who has strong feelings on this subject, either way, should get them in writing to the Executive Secretary, ICZN., c/o Natural History Museum, Cromwell Road, London SW7 5BD, U.K. (e-mail: iczn@nhm.ac.uk).

References

• Barrett, Paul B.  2009.  Comment on the proposed conservation of usage of Cetiosaurus Owen, designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species [comment 1 of 2].  Bulletin of Zoological Nomenclature 66(2): 187-188.
• Galton, Peter M.  2009.  Comment on the proposed conservation of usage of Cetiosaurus Owen, designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species [comment 2 of 2].  Bulletin of Zoological Nomenclature 66(2): 187-188.
• Galton, Peter M., and Fabien Knoll.  2006.  A saurischian dinosaur braincase from the Middle Jurassic (Bathonian) near Oxford, England: from the theropod Megalosaurus or the sauropod Cetiosaurus?  Geological Magazine 143: 905­921.
• Lydekker, Richard.  1888.  Catalogue of the fossil Reptilia and Amphibia in the British Museum (Natural History), Cromwell Road, S.W. Part 1. Containing the orders Ornithosauria, Crocodylia, Dinosauria, Squamata, Rhynchocephalia, and Proterosauria. British Museum (Natural History), London.
• Norman, David B., Lawrence M. Witmer, and David B. Weishampel.  2004.  Basal Ornithischia.  pp. 325­334 in David B. Weishampel, Peter Dodson and Halszka Osmólska (eds.), The Dinosauria, Second edition.  University of California Press, Berkeley and Los Angeles.  861 pp.
• Owen, Richard.  1841.  A description of a portion of the skeleton of Cetiosaurus, a gigantic extinct saurian occurring in the Oolitic Formation of different parts of England.  Proceedings of the Geological Society of London 3: 457-462.
• Owen, Richard.  1875. Monograph of the Mesozoic Reptilia, part 2: Monograph on the genus Cetiosaurus. Palaeontolographical Society Monograph 29: 27­43 and plate X.
• Phillips, John.  1871.  Geology of Oxford and the Valley of the Thames. Clarendon Press, Oxford.
• Upchurch, Paul and John Martin.  2002.  The Rutland Cetiosaurus: the anatomy and relationships of a Middle Jurassic British sauropod dinosaur.  Palaeontology, 45(6): 1049-1074.
• Upchurch, Paul, John Martin, and Michael P. Taylor. 2009.  Case 3472: Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species.  Bulletin of Zoological Nomenclature 66(1): 51-55.

Range of motion in intervertebral joints: why we don’t trust DinoMorph

Wait, what?  So let’s assume for a moment that you accept our contention (Taylor et al. 2009) that, since extant terrestrial tetrapods habitually hold their necks in maximal extension, sauropods did the same.  That still leaves the question of why we have the neck of our Diplodocus reconstruction at a steep 45-degree angle rather than the very gentle elevation that Stevens and Parrish’s (1999) DinoMorph project permits.

As a reminder, here is fig. 6A of Stevens (2002), a paper on the computer science behind DinoMorph which used exactly the same models as the 1999 study but which conveniently illustrates them in lateral view:

Stevens (2002: fig. 6A), illustrating the fully extended, neutral and fully flexed poses attainable by Diplodocus according to the original DinoMorph model

As you’ll see, not only does the neutral pose show the characteristic subhorizontal neck with the drooping end, but even the maximally extended pose barely gets the head above the level of the back.  In the most recent version of his Diplodocus model, Kent has slightly changed the angle at which the neck leaves the torso, due to a reconfiguration of the pectoral girdle, but this still leaves the neck very low.

So why did we do 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).

Doesn’t the DinoMorph model show that the posterior cervicals just can’t do this?

Well, maybe not.

Remember that the precursor to the DinoMorph project was John Martin’s (1987) paper on the mounting of the Rutland cetiosaur at the Leicester City Museum, in which he calculated neutral pose and the extreme extended and flexed poses by manipulating actual bones without the benefit of a computer.  Martin ended up with a similar result to that Stevens and Parrish were later to get:

Martin (1987:fig. 2) showing claimed limits of extension of and flexion in the neck of the Rutland cetiosaur

But when Matt and I looked at the actual mounted skeleton a few years back, what we saw didn’t fit with this at all:

Rutland cetiosaur, anterior part of neck in right lateral view, showing extreme disarticulation between the cotyle of C4 and condyle of C5

Check out that huge gap between the centra of the fourth and fifth cervicals!  There’s no way to avoid this without putting a comically extreme downward kink in the neck at this point.  And there are similar gaps at other points along the neck, including some near the neck-base that would require a strong upward kink in order to articulate both the centra and the zygapophyses simultaneously.

Are we saying that in life, this specimen did have strong kinks in the neck?  No, we’re not (despite the pleasant coincidence that this would force the neck into an extreme version of the elevated pose we’re advocating).  What we’re saying is that sauropod cervicals are rarely — I’d go so far as to say never — preserved undistorted, and so you just can’t rely on how they seem to articulate, at least not for quantitative analyses.  This post-mortem distortion should not be too surprising: unlike femora and other such solid bones, remember that the cervicals were highly pneumatic and composed primarily of laminae, which would be subject to all sorts of taphonomic and diagenetic distortion.  In the extreme case of Sauroposeidon, the cervicals, which were up to 140 cm in length, “are of extremely light construction, with the outer layer of bone ranging in thickness from less than 1 mm (literally paper-thin) to approximately 3 mm” (Wedel et al. 2000:110-111) — it’s astonishing that they are not much more smushed up than they are.

So Martin’s cetiosaur seems too distorted to give meaningful articulation results, but what about the specimens that Stevens and Parrish used for the DinoMorph paper?  Well, the Apatosaurus model is certainly based on questionable material.  As pointed out by Upchurch (2000):

A second difficulty with Stevens and Parrish’s analysis is that their data for Apatosaurus was derived from a single specimen in the Carnegie Museum (CM 3018). This generally well preserved specimen has suffered severe damage at the base of the neck, and the three most posterior cervicals are thus represented by plaster models that cannot provide reliable anatomical data (Gilmore 1936, pers. obs.). Although Stevens and Parrish acknowledge that the morphology of the posterior cervicals is particularly influential in determining the nature of the feeding envelope, they do not mention this problem, and it is not clear how this gap in the data was addressed in their analyses. This deficit could have had a profound impact on Stevens and Parrish’s conclusions.

And Gilmore’s observations are really rather damning: as well as the account of the damaged neck-base, he also noted (p. 195) that “the type of A. louisae [i.e. CM 3018] lacks most of the spine tops, only those of cervicals eight, ten and twelve being complete”.  (You would NEVER guess this from Gilmore’s Plate XXIV, which shows all of the cervicals but C5 essentially complete.)  So all in all, the DinoMorph study’s Apatosaurus is not one I’d want to build an argument on.

What about the Diplodocus carnegii holotype CM 84, which is the Diplodocus used in the DinoMorph papers?  That’s just about the best preserved sauropod skeleton in the world, right?  Well, yes.  But even that is distorted enough that the neck can’t be articulated without some sleight of hand.  I don’t have good photos of the mounted neck, unfortunately (and probably won’t have until someone at the NHM gives me a stepladder and access to the holy of holies that surrounds the mount), but I did have the experience of photoshopping the cervcial vertebra illustrations from Hatcher (1901: plate III)  in an attempt to get them into a good pose, and I found that even these don’t really fit properly:

Diplodocus carnegii holotype CM 84, partial neck (cervicals 6-9) in right lateral view, composed from elements in Hatcher (1901: plate III)

You’ll see that, while the condyles are sat nicely in the cotyles, the zygapophyses are not at all well articulated: in particular, the C7-C8 and C8-C9 junctions have the prezygs shoved much too far forward, so that a double downward kink would be necessary to accomodate these articulations without pulling the condyles out of the cotyles.

Finally, while Matt and I were in Berlin last November, as part of the excursion associated with the awesome all-sauropod-gigantism-all-the-time workshop, we got to play with the superbly preserved set of anterior brachiosaur cervicals HMN SI, and we tried to articulate the real bones.  We had to stop for fear of breaking them, because they simply would not fit nicely together.

In conclusion, the distortion of all sauropod cervicals renders them poor subjects for quantitative analysis such as that of the DinoMorph project.  While the approach of Stevens and Parrish is a real and valuable contribution to rigour in the analysis of posture, the output of DinoMorph is a hypothesis to be tested by other lines of evidence rather than a firmly established fact.  (That last bit was quoted verbatim from our paper.)

I’ve gone on much longer than I intended to in what was supposed to be a quick-and-easy post, so I’ll leave it here.  In order to keep the recent paper short and snappy, we didn’t go into this in much detail, summarising down to a mere 88 words (Taylor et al 2009: 216-217), so maybe this will bear repeating (in more rigorous form) in a future publication.

References

• Gilmore, C.W.  1936.  Osteology of Apatosaurus with special reference to specimens in the Carnegie Museum. Memoirs of the Carnegie Museum 11: 175-300.
• Hatcher, J.B. 1901. Diplodocus (Marsh): its osteology, taxonomy and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1: 1-63 and plates I-XIII.
• Martin, J. 1987. Mobility and feeding of Cetiosaurus (Saurischia, Sauropoda) ­ why the long neck? In: P.J. Currie and E.H. Koster (eds.), Fourth Symposium on Mesozoic Terrestrial Ecosystems, Short Papers, 154­-159. Box-tree Books, Drumheller, Alberta.
• Stevens, K.A. 2002. DinoMorph: Parametric modeling of skeletal structures.  Senckenbergiana lethaea 82(1): 23-34.
• 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.
• Wedel, M.J., Cifelli, R.L. and Sanders, R.K. 2000. Sauroposeidon proteles, a new sauropod from the Early Cretaceous of Oklahoma. Journal of Vertebrate Paleontology 20, 109-114.

end

Sauropods held their necks erect … just like rabbits

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. (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.

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

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 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 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

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:

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)

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), 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 selected of life 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).

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.

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.

Sorting out Cetiosaurus nomenclature

Today saw the publication of the most startlingly dull paper I’ve ever been involved in (Upchurch et al. 2009) — and remember, I write this as co-author of a paper on the phylogenetic taxonomy of Diplodocoidea.  Not only that, but one time when I was practising a conference talk with my wife Fiona as audience, she fell asleep actually while I was speaking.  Actually asleep.  And yet the new paper beats them all hands-down for boredom.  If you don’t believe me, feast your eyes, gloat your soul, on the accursed ugliness of the very title of the new paper: “Case 3472: Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species.”  What is it all about?

Well, take a look at the type material of Cetiosaurus:

Type material of Cetiosaurus medius, from Upchurch and Martin (2003: fig. 2). Scale bars 50 mm.

Yes indeed — the most historically important of all sauropods is based on a set of non-diagnostic uninformative eroded partial mid-to-distal caudal centra.  That is because this is the type material of the species which, for complex technical reasons, is the type species of the genus Cetiosaurus.  We tend to ignore this fact because the material is clearly rubbish: the taxon C. medius is not valid.  Sadly, however, the name C. medius is valid — nomenclaturally valid, even though it’s not taxonomically valid.  But the International Code of Zoological Nomenclature (ICZN), which governs all zoological nomenclature, is purely a code of nomenclature, and does not take taxonomic considerations such as diagnosability into account.  (It can’t, after all: how could the code contain rigorous rules that let you determine whether material is diagnostic, or whether a description is adequate?)

Anyway, the material of C. brevis, C. brachyurus, C. medius and C. longus, all published together (Owen 1842) is all pretty useless; but Phillips (1871) described in detail the much better material of a new species C. oxoniensis, and this is what everyone has meant by the name Cetiosaurus ever since.  Upchurch and Martin (2003:215) even explicitly stated that they were provisionally using C. oxoniensis as the de facto type speces, pending a petition to the ICZN to overrule strict priority.  And no wonder: the C. oxoniensis material really is way better.  For example, check out this dorsal vertebra (which is by no means the best one — just one that I have a convenient photo of):

Cetiosaurus oxoniensis partial dorsal vertebra OUMNH J13648 (part of the lectotype series), right lateral view

Today’s new paper is that long-promised petition: in it, we recount the nomenclatural history of the name Cetiosaurus and its species, explain with a big list of references that C. oxoniensis has been overwhemingly used historically and is overwhelmingly used today, and ask the Commission to legitimise this universal behaviour.

Will they do it?  We actually don’t know, although I can’t think of any reason why they shouldn’t.  The process now is that interested workers can send their comments, either in favour of or against our proposal, to the Executive Secretary of the ICZN (address at the end of the PDF), and these comments are weighed before a decision is returned.  From my informal sampling of previous petitions, the process seems to take between one and two years.  So we’re probably stuck in type-species limbo until 2011.  Oh well — at least the main step has been taken.

So.  I’m not exactly as excited about this paper as I was of Xenoposeidon — don’t worry, we won’t be launching a nine-post Cetiosaurus Type Species Redesignation Week — nor as pleased with it as I am with a certain in-press paper that all three of us SV-POW!sketeers are very much looking forward to because REDACTED.  But it’s a dirty job that someone had to do.

References

• Owen, Richard.  1841.  A description of a portion of the skeleton of the Cetiosaurus, a gigantic extinct saurian reptile occurring in the oolitic formations of different portions of England.  Proceedings of the Geological Society of London 3: 457-462.
• Owen, Richard.  1842b.  Report on British fossil reptiles, Part II. Reports of the British Association for the Advancement of Science 11: 60-204.
• Phillips, John.  1871.  Geology of Oxford and the valley of the Thames.  Clarendon Press, Oxford.
• Upchurch, Paul, and John Martin.  2003.  The anatomy and taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England.  Journal of Vertebrate Paleontology 23: 208-231.
• Upchurch, Paul, John Martin, and Michael P. Taylor.  2009.  Case 3472: Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species. Bulletin of Zoological Nomenclature 66 (1): 51-55.

Update (3 April 2009)

Here’s that photograph of a leopard seal pulling the head right off a penguin you ordered:

Leopard seal PULLING THE HEAD RIGHT OFF a penguin

Acknowledgement: I got this photo from http://img238.imageshack.us/img238/873/1627.jpg but I have no idea how it got there or who owns the copyright.

Cetiosaurus, Pelorosaurus, Streptospondylus or maybe Iguanodon(?!) in bizarre Fused Chevrons scandal!

We have sometimes neglected tails on SV-POW!, in favour of the more obviously charismatic charms of presacral vertebrae, but every now and then you come across a caudal vertebra so bizarre that it just cries out to be blogged.

One such is this specimen, which may or may not be BMNH R 2144:

Sauropod caudal with co-ossified chevrons, right lateral view

Sauropod caudal with co-ossified chevrons, right posterolateral view

The reason I’m not sure whether this is BMNH R2144 is that I noticed this at the very last minute while visiting the NHM collections to see a different specimen, and just had time to take a couple of quick photos before kicking-out time.  The label on the side of the vertebra has the unexplained number 2144 written on it, so I am guessing this is the specimen number, but I wouldn’t stake my life on it.

(By the way, both these photographs are copyright the NHM.)

The interesting thing about this vertebra is of course that that the chevrons are co-ossified with the centrum — an extremely rare condition in sauropods, in fact unique as far as I know.  As we’ve shown here and here, among other places, the chevrons are usually separate bones from the vertebrae.

This vertebra caught my eye not only because it’s, well, weird, but also because I’d seen it a couple of times in published figures.  It’s in Mantell’s (1850) description of Pelorosaurus, where it appears as figure 11 in plate XXIII, and is considered to belong to Pelorosaurus; and also in Owen (1859: plate V: figs. 3-4).  Owen seems pretty confused about the identity of this element, and in this paper alone assigns it to Streptospondylus (p. 22), Iguanodon(!) (p. 25) and implicitly Cetiosaurus (p. 34).  So what is it?  Well, its provenance is vague in the extreme, so given that it’s not associated with any more diagnostic material, about the best we can say with any honesty is that it’s Sauropoda incertae sedis.

Let’s take a look at those old figures:

Mantell (1850: plate XXIII, fig. 11)

Owen (1850: plate V, figs 3-4)

If you’re like me, your first thought was that Owen’s figures are simply mirror images of Mantell’s.  I checked this out by Photoshopping the two sets of figures, flipping them horizontally, scaling and rotating as necessary, and found to my mild surprise that Owen’s figures are in fact redrawn, despite the startling resemblance they bear to Mantell’s.  As it happens, the same is true with the Owen 1859 plate that is the humerus of Pelorosaurus figured by Mantell 1850, and in that case Owen’s figure is rather better than Mantell’s, so let’s give a bit of credit to Owen here.  Most embarrassing for Mantell (not that he cares, having been dead for 157 years) is that Owen’s flipped images seem to be correct (at least, as best I can judge from the photographs I took) — looks like Mantell or his illustrator badgered this up.

So what is going on with these co-ossified chevrons?  As is so often the case, we just don’t know.  Some possibilities: this might be a pathology of an individual, caused either by injury or infection; it might be a natural ontogenetic character in very old individuals; or it might by a taxonomically significant character of a taxon we’ve not yet found — or one that we have found, but don’t yet recognise as being the same thing.  It’s perfectly possible that this is a chevron of Xenoposeidon, for example, but until someone finds a nice complete specimen we’ll never know.

Not much is known about skeleton fusion in sauropods, and most of what’s in the literature is anecdote.  That is set to change, I am pleased to say, as Matt is putting together a paper with his colleague Elizabeth Rega that will survey and interpret the various fusions known in sauropod vertebrae.  I’m looking forward to seeing what they have to say about this vertebra.

References

• Brusatte, Stephen L., Roger B. J. Benson, and Stephen Hutt.  2008.  The osteology of Neovenator salerii (Dinosauria: Theropoda) from the Wealden Group (Barremian) of the Isle of Wight.  Monograph of the Palaeontographical Society 162 (631): 1-166.
• Calvo, Jorge O., Juan D. Porfiri, Claudio Veralli, Fernando Novas and Federico Poblete.  2004.  Phylogenetic status of Megaraptor namunhuaiquii Novas based on a new specimen from Neuquen, Patagonia, Argentina.  Ameghiniana 41 (4): 565-575.
• Mantell, Gideon Algernon.  1850.  On the Pelorosaurus: an undescribed gigantic terrestrial reptile, whose remains are associated with those of the Iguanodon and other saurians in the strata of Tilgate Forest, in Sussex.  Philosophical Transactions of the Royal Society of London 140: 379-390.
• Owen, R.  1859a.  Monograph on the fossil Reptilia of the Wealden and Purbeck formations.  Supplement no. II (pages 20-44 and plates V-XII): Crocodilia (Streptospondylus, &c.) [Wealden].  Palaeontographical Society, London.

Update

Thanks to Mickey Mortimer for pointing out that this kind of centrum-chevron fusion is known in the theropod Megaraptor.  Here is the relevant figure from Calvo et al.’s (2004) revision of that genus:

Calvo et al. (2004: fig. 5). Caudal vertebrae of Megaraptor with co-ossified chevron

The strange thing is this comment in the text (p. 569): “Two articulated caudal vertebrae are preserved (figure 5), slightly laterally compressed.  Their centra and the neural arches are firmly co-ossified, as well as their respective haemal arches [i.e. chevrons].  This fusion, not infrequent among dinosaurs, may be pathological.”  Not infrequent?  Is this going on all over the place and I’ve just never noticed it?  Anyone have any more examples?

Update 2

Here is that pair of fused Neovenator caudals with a co-ossified chevron, which Darren mentions in the comments below.

Brusatte et al. (2008: fig. 16d), fused Neovenator caudals with co-ossified chevron

…just passing through…

Here’s Mike checking out the cervicals of the mounted Cetiosaurus at the Leicester City Museum back in 2004. I like this photo because I was a ways back from Mike, and Cetiosaurus was not a particularly large or long-necked sauropod (actually in scientific terms I would describe it as being on the puny side of average), but the cervical series still goes right across the frame. Nothing but neck, as the youngsters say.

Mammals are so pathetic. To wit:

Just try to grasp Mike’s deep unhappiness as he ponders the world’s–snort!–tallest mammal, at Oxford that same spring.

SV-POW! on tour: Oxford University Museum of Natural History

It’s very rare that all three of us SV-POW!ers get together: in fact, until Tuesday this week, it had only ever happened once, at SVPCA 2005. But as Matt was spending nearly a fortnight with me (Mike) in England, far from his native land — an unholy blend of Oklahoma and California — it would have been stupid not to have all got together. So we did, on the 19th, at the Oxford University Museum of Natural History (OUMNH).

The public gallery of the OUMNH is my favourite in the whole world, despite its inexplicable failure to exhibit so much as a single sauropod presacral. That’s because it is just so darned full of stuff. For example, here is Darren, with me, trying to figure out how ventral compressing-bracing of the neck is supposed to work in crocodiles:

Above our heads is a sequence of whale skeletons; to the right is a cabinet full of stuffed crocodilians; in the background, poking its head over the cabinet is a cast of the T. rex “Stan”. Further cabinets in the isle we’re in contain turtles, bizarre fish skulls, giant frog skeletons, and much, much more. Turn a corner and you’re confronted by a vampire squid; face the other direction and there’s a giant Japanese spider crab, or an absurdly oversized pliosaur mandible, or a cast of a Bernissart Iguanodon, or the skeleton of an echidna, giraffe or juvenile gorilla — or any one of a hundred thousand other fascinating exhibits. What you won’t find is “interactives” (i.e. the low-rent video games that infest nearly all museums and which are embarrasingly lame compared with what the kids can play at home on their X-boxes.)

Does this mean that the museum has made itself interesting for clever, sophisticated adults at the cost of being too “difficult” for children? Not a bit of it: Fiona and I took our three sons to the OUMNH a couple of months ago, and I have literally never seen them so excited about anything. Ever. All three of them were running from exhibit to exhibit for two solid hours, constantly calling each other and us to Wow! Come and see THIS! Guess what? Turns out that, when people go to Natural History museums, they like to look at Natural History. So OUMNH is a salutory lesson to every museum whose public galleries have been ruined by people who have, somehow, failed to understand this very, very, very simple principle.

Anyway, sorry for the tangent. What I wanted to show you was The Three SV-POW!sketeers, together at last! So here we are, in front of a bunch of awesome artiodactyl skeletons. From left to right, Mike, Matt and Darren.

(In case you’re wondering, those four grey blobs on my T-shirt are dorsals 8 and 9 from Migeod’s Tendaguru brachiosaurid, BMNH R5937, in posterior, right lateral and anterior views. One of these days, I’ll show you those properly.)

Anyway: packed though the museum is with wonderful things, there is one particular exhibit that stands head and shoulders above every other — a specimen so literally awe-inspiring that, wherever you are in the museum, whatever you’re looking at, you can hardly help but be aware of it, lurking in your peripheral vision and ready to command your full attention. We’re talking about a dinosaur so iconic that it needs no introduction: so, here we are, studying an anterior caudal vertebra of Cetiosaurus oxoniensis:

And finally, here we are having torn ourselves away from the Caudal Of Awesomeness, facing the camera for your pleasure:

That’s all for today — hope you can forgive the “lite” nature of this week’s post: we’ll get back to your usual hardcore action real soon now (though possibly not before a few more OUMNH pictures).

And, yes, we did also visit the collections at OUMNH; and, yes, we did find something absolutely fascinating. But we won’t be saying much about that on here, because we want to Wait For The Paper.

A new view of sauropod vertebrae

Ventral, to be precise. Here are the first few cervicals of Cetiosaurus oxoniensis, from the mounted skeleton in the Leicester City Museum. A more typical lateral view is shown below. Forget about the skull, it’s plastersaurus.

We tend to think of vertebrae as cylinders with weird bits hanging off, and in most mammals that’s true. (Incidentally, the next time you eat a t-bone steak, have a look at the bone. It’s one half of a lumbar [non-rib-bearing trunk] vertebra. Proof at the bottom of the post.) But sauropod vertebrae are wacky, and nowhere more so than in the neck. The condyle and cotyle are round and point to the ancestral cylindrical state, but the centrum in between is often nothing like a cylinder. First, it is frequently waisted–narrower in the middle than at the ends, like an hourglass–as you can see in the ventral view at top. Second, the ‘walls’ of the cylinder are usually so eaten away by pneumatic openings that what is left looks like more like an I-beam or stick person in cross-section. So sauropod cervicals are often only round where they have to be–where they fit together.

Hey, look, something red for Valentine’s Day! Awwww!