By contrast to the very delicate pelican humerus and ulna in the previous post, here is the left femur of Aepyornis OUMNH 4950 — an “elephant bird” from Antolanbiby, Madagascar. It’s just a couple of meters away from the pelican, in the same Oxford gallery:

This is of course a ludicrously robust bone, as befits a gigantic ground-dwelling bird. But the fun thing is that it, too, is very pneumatic. You can see this in lots of ways: the foramina up at the top, the little patch of stretched texture at mid-length, and most of all in the honeycomb structure of the inside of the bone, which we can see where the cortex has broken off at both proximal and distal ends.

Birds: they’re made of air.

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Here are the humerus and ulna of a pelican, bisected:

What we’re seeing here is the top third of each bone: humerus halves on the left, ulna halves on the right, in a photo taken at the 2012 SVPCA in one of our favourite museums.

The hot news here is of course the extreme pneumaticity: the very thin bone walls, reinforced only at the proximal extremely by thin struts. Here’s the middle third, where as you can see there is essentially no reinforcement: just a hollow tube, that’s all:

And then at the distal ends, we see the struts return:

Here’s the whole thing in a single photo, though unfortunately marred by a reflection (and obviously at much lower resolution):

We’ve mentioned before that pelicans are crazy pneumatic, even by the standards of other birds: as Matt said about a pelican vertebra (skip to 58 seconds in the linked video), “the neural spine is sort of a fiction, almost like a tent of bone propped up”.

Honestly. Pelican skeletons hardly even exist.

We all remember Upchurch and Martin’s (2002) description of the Rutland Cetiosaurus, which remains by some distance the best British sauropod specimen in the literature; and the same authors’ (2003) survey of the genus Cetiosaurus. They concluded that nearly all of its many named species are either nomen dubia or misassigned, and that only C. oxoniensis is a valid, diagnosable species.

(Some of) the Cetiosaurus oxoniensis holotype material, on display in the public gallery of the Oxford University Museum of Natural History (OUMNH)

(Some of) the Cetiosaurus oxoniensis holotype material, on display in the public gallery of the Oxford University Museum of Natural History (OUMNH). From left to right: right femur in posterior view, scapula, right humerus in anterior view, tibia and fibula (designations by eyeballing). Above the long bones, some caudal vertebrae.

Accordingly, Upchurch and Martin informally used C. oxoniensis as the type specimen in their descriptive work, noting that this usage should be formalised by a petition to the International Commission on Zoological Nomenclature (ICZN).

Six years layer, we submitted that petition to the Bulletin of Zoological Nomenclature; a few months after its publication, positive comments from Paul Barrett and Pete Galton followed.

That was in 2009. Five years of silence followed, as the Commission meditated on our five-page petition. (That’s two pages plus front-matter and references). Today, finally, the results are in! The abstract says it all:

The Commission has conserved the usage of the generic name Cetiosaurus Owen, 1841 by designating Cetiosaurus oxoniensis Phillips, 1871 as the type species of Cetiosaurus in place of Cetiosaurus medius Owen, 1842.

So Cetiosaurus finally has a decent type species! Two cheers for the Commission!

I’d always assumed that ratifying the petition would be a no-brainer once the Commission got around to examining it. In fact, their report makes it clear that’s not how it was at all. 16 members voted for the proposal, eight voted against and two abstained. So I guess we were only three switched votes away from having the proposal rejected. Which would frankly have been stupid: every sauropod worker would just have carried right on using C. oxoniensis as though it were the type species anyway.

Why would anyone vote against, you ask? I asked myself the same question. Happily, the decision explains the objections in detail. They nearly all seem to come down to complaints that we didn’t clearly enough explain why C. medius was the previous type species. There’s a reason for that: the truth is that the literature is so vague and contradictory that no-one really knew what the heck the type species was — which is one of the reasons we needed to establish one. (Upchurch and Martin 2002:1053 thought C. brevis was the type; as we investigated this in more detail for the petition, we concluded that the claim of C. medius was stronger. But still very weak.)

But all of that seems like pointless pithering to me. Who cares what the type species was? The point of the petition is to establish what it is, and only one Commission member expressed any reservations about the case we’d made — which is basically that C. oxoniensis is what’s always used in comparisons.

Anyway, dissenting opinions notwithstanding, the genus Cetiosaurus now stands before us having been made an honest woman at long last.

NaishMartill2007-british-dinosaurs-fig3-cetiosaurus

The Rutland cetiosaur, reconstruction by Mark Evans (Naish and Martill 2007: fig 3)

… all of which leaves us with the question of what the Rutland cetiosaur is. It’s been assumed to be Cetiosaurus all along, and that identification has to stand until someone publishes a case to the contrary. But there do seem to be persistent rumours that someone somewhere thinks it’s something different. I wonder if anything will ever come of it?

References

 

We jumped the gun a bit in asking How fat was Camarasaurus? a couple of years ago, or indeed How fat was Brontosaurus? last year. As always, we should have started with extant taxa, to get a sense of how to relate bones to live animals — as we did with neck posture.

So here we go. I give you a herd of Indian elephants, Elephas maximus (from here):

056-Elephant-c-Gehan-de-Silva-Wijeyeratne-Minneriya-2004-07-27-165-Gathering

You will notice, from this conveniently-close-to-anterior view, that their torsos bulge out sideways, much further than the limbs.

Now let’s take a look at the skeleton of the same animal in the Oxford University Museum of Natural History (downloaded from here but for some reason the photo has now gone away):

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The rib-cage is tiny. It doesn’t even extend as far laterally as the position of the limb bones.

(And lest you think this is an oddity, do go and look at any mounted elephant skeleton of your choice, Indian or African. They’re all like this.)

What’s going on here?

Is Oxford’s elephant skeleton mounted incorrectly? More to the point, are all museums mounting their elephants incorrectly? Do elephants’ ribs project much more laterally in life?

Do elephants have a lot of body mass superficial to the rib-cage? If so, what is that mass? It’s hard to imagine they need a huge amount of muscle mass there, and it can’t be guts. Photos like this one, from the RVC’s televised elephant dissection on Inside Nature’s Giants, suggest the ribs are very close to the body surface:

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I’m really not sure how to account for the discrepancy.

Were sauropods similarly much fatter than their mounted skeletons suggest? Either because we’re mounting their skeletons wrongly with the ribs too vertical, or because they had a lot of superficial body mass?

Consider this mounted Camarasaurus skeleton in the Dinosaur Hall at the Arizona Museum of Natural History (photo by N. Neenan Photography, CC-BY-SA):

Camarasaurus_skeleton

Compare the breadth of its ribcage with that of the elephant above, and then think about how much body bulk should be added.

This should encourage palaeoartists involved in the All Yesterdays movement to dramatically bulk up at least some of their sauropod restorations.

It should also make us think twice about our mass estimates.