The skin impression of “Pelorosaurusbecklesii

June 2, 2015

We’ve seen the humerus of the Wealden-supergroup putative titanosaur “Pelorosaurusbecklesi. 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

Skin impression of “Pelorosaurusbecklesii 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

Schematic of “Pelorosaurusbecklesi 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 “Pelorosaurusbecklesi.

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.
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6 Responses to “The skin impression of “Pelorosaurusbecklesii

  1. Zach Miller Says:

    THANK YOU for the disclaimer on the skeletal. We need that sort of disclaimer on a lot of “representative of…” restorations, both skeletal and otherwise.

    How much of Alamosaurus is known?

  2. Aaron Natera Says:

    Awesome!

  3. Mike Taylor Says:

    Thanks, Zach. Scott has written in some detail about the composition of the Alamosaurus skeletal that the “Pelorosaurusbecklesii schematic is based on. I should have linked to that from the article, and will now remedy that deficiency.

  4. John Scanlon Says:

    The part of the specimen nearest the camera seems clearly to be skin impression as described, but what about the rest of the block? The triangle of darker surface (where the two dots and ‘Beckles Coll.’ label are) looks interesting also, suggesting bone or smooth cornified scutes either abutting or underlying the scales. Has anyone had a close look?

    And speaking of skin impressions, paper just out from Barrett et al. on evidence for feather evolution
    http://rsbl.royalsocietypublishing.org/content/11/6/20150229

  5. Mike Taylor Says:

    I’m not sure about that, John. To my eyes, the best of the block just looks like matrix. But, no, I’m not aware that anyone has taken a close look at it.


  6. […] I was posting images of “Pelorosaurus” becklesi‘s humerus, radius and ulna, and skin impression. There I was saying that this beast is due a proper description, and warrants its own generic […]


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