We’ve seen the humerus of the Wealden-supergroup putative titanosaur “Pelorosaurus” becklesi. We’ve seen the bones of the forearm, the radius and ulna. That’s it for bony remains: no other bones have been found.

But there is one other fossil that’s part of the same specimen: this skin impression:

Skin impression of “Pelorosaurus” becklesii holotype NHMUK R1868. (Note that the other elements of this specimen are all catalogued as R1870.)

As you can see, the body — or at least this part of the body — was covered with roughly hexagonal tessellating (non-overlapping) scales, of about 1-2 cm diameter. But what part of the body is it from? The initial — extremely brief — description of this specimen, by Mantell (1852:143) hardly mentions the skin impression at all. All it says is:

A portion of the scaly cuirass which covered the limbs and is composed of hexagonal plates, was exhibited.

Still, this does at least suggest that the skin impression was from a limb — hardly surprising given then the left forelimb was the only part of the skeleton recovered. Upchurch et al. (2004:295) were more specific:

This skin impression was found in close association with the elbow region of the forelimb of Pelorosaurus becklesii.

But I don’t know whether this assertion is based on something written earlier, or is just a surmise.

Assuming that the skin impression is indeed from the elbow, and putting it all together, here’s what we know of “Pelorosaurus” becklesii:

Schematic of “Pelorosaurus” becklesi holotype NHMUK R1870, showing the preserved humerus, radius, ulna, and skin impression of the elbow. Based on Scott Hartman’s skeletal reconstruction of Alamosaurus. This is not a skeletal reconstruction of “Pelorosaurus” becklesi.

It’s not much, but it’s enough to be diagnostic.

But what actually is this beast? A titanosaur, as often assumed? A more basal macronarian? Something else entirely? Who can tell? Someone really ought to get onto that.

References

• Mantell, Gideon A. 1852. On the structure of the Iguanodon, and on the fauna and flora of the Wealden Formation. Notices of the proceedings at the meetings of the members of the Royal Institution, with abstracts of the discourses delivered at the evening meetings 1:141-146.
• Upchurch, Paul, Paul M. Barrett and Peter Dodson. 2004. Sauropoda. pp. 259-322 in D. B. Weishampel, P. Dodson and H. Osmólska (eds.), The Dinosauria, 2nd edition. University of California Press, Berkeley and Los Angeles. 861 pp.