Information on Pelecanimimus

[nino@uam.es]

Hi, folks. I will try to answer several messages on Pelecanimimus. Here we go:

>How do we know about the pouch and crest?  Are there more details?  
>That's some really exciting information! 
>Larry

Yes, there are more details. You have the original description of the
specimen, published in Nature, and the new paper that will be published in
the July issue of the Journal of the Geological Society of London. There are
impressions below the skull and running along the ventral part of the neck
that were interpreted as a possible pouch (nothing to do with the one in the
pelican, just looks similar). And there is a clear impression in the
posterior part of the skull, interpreted as a occipital crest. You can find
photos in the Nature's paper.

Jeff Poling wrote:

>   Given that there are no remains of scales etc., and given the featherlike
>impressions were musculature, is it possible that the true nature of any
>possible integument simply was not preserved?

No, it is not possible, because we actually have the skin impressions in
several parts of the specimen. If you have a photograph of the specimen, you
can see the impressions of the skin as hair-like impression below the skull,
running along the neck, around the pectoral girdle and in the elbow area.
This impressions were those interpreted as some kind of feathers, hair or
something like that in the original description. Their are very similar to
the structures found all around the Sinosauropteryx specimen (at least, in
the Audoubon photographs). They look the same. But they are the wrinkled
surface of the skin, that looks like some kind of digital prints (if you can
see what I mean). In other areas, you can find some isolated remains of
muscular tissues.

Nick Londgrich wrote:
>  I was under the mistaken impression that the soft-tissue remains were
>just from the head and neck. This sounds like a serious blow to insulated
>theropods. It is possible to salvage if you want to be extreme- there are
>things which have secondarily lost (most) hair such as porpoises and
>hippopotami, but that's stretching it, and an absence of insulation on a
>small theropod so close to birds puts a big question mark on an insulated
>Sinosauropteryx and mammal/avian style endothermy in my mind. 
>I won't pretend that I am completely objective and that this isn't a bit
>of a let-down. Any thoughts on what is going on here, the implications,
>etc? 

The implications are that, at least in the more anciente ornithomimosaur
known, the skin is naked. It is a subadult specimen, so it is possible that
the juveniles were feathered (or something like that). Also, a negative
evidence (although a strong one like this one) is not a proof (i.e., you can
think that all the feathers were lost before fossilization). You have a lot
of other alternatives.

Luis Rey wrote:

>Comparing the two specimens, the soft tissue preserved in Pelecanimimus
>shows indeed naked skin and no feathers or scales, but has nothing to do
>with the 'mane' of Sinosauropteryx that runs down its back and actually
>becomes a double row of parallel pre-feather clusters that continues all
>along the tail to the very tip. There's no way those structures are
>muscular remains.
>
>The detailed close-up photographs of the fossil on the latest Audubon
>magazine are so clear that I find it striking that anyone has doubts about
>the structures being feathery or hairlike, although perhaps not in the
>classic avian way. The preservation is perfect, almost Messel-like.

 You have no idea of how the Pelecanimimus integuments looks like in
close-up photographs. Or do you know it? Maybe you have seen the photographs
of the paper at nature, and they are (sincerely) badly published. I tell you
that they looks very similar, like thousands of hair-like structures one
after another. But these structures, in Pelecanimimus, are the wrinkles of
the naked skin, not feathers. Even the color is the same (that yellow-orange
thing). And the preservation  at Las Hoyas is excellent: we have, for
instance, color patterns in the insect wings (do you know of other fossil
site with these things?), along with feathers, stomach remains and the
keratin cover of the claws of the birds, insect larvas, etc... So I think
the preservation is one of the best of the fossil record. It is that good.

>Olshevsky had a theory that bird feathers developed from a double row of
>ornamental scales on the back of arboreal archosaurs. By the time of
>Sinosauropteryx, those scales were well on its way of becoming feathers
>(Developing as display or insulatory elements from the top midline of the
>animal downwards).

The "archosaurs" of George have nothing to do with the theropods (some of
them are not archosaurs, indeed). So those scales has nothing to do with
feathers.
But I think this is a known history to all the people reading this message.

>If Pelecanimimus didn't have feathers or scales, that could be a good proof
>that Pelecanimimus actually didn't need the feathers and shed them. Just
>the typical featherless skin of a bird. Otherwise, it would be funny that
>it actually shed its reptilian scales without passing through any stage of
>feathery, hairlike or  insulatory material.That might be possible, but
>unlikely.

Yes, it is possible, as I told above.

>I advocate the notion of pre-feathers as an archosaurian trait and a very
>specific characteristic of the Dinosauria, wher it was taken to the extreme
>of specialization in birds and proto-birds.

It is also possible, but there is no evidences on this hypothesis. The same
with the one from George.

I think this is all I want to say. I am waiting the torpedoes. Nino.
Bernardino P. Perez-Moreno                      E-mail: Nino@uam.es
Unidad de Paleontologia                         Fax: 34-1-3978344
Departamento de Biologia
Facultad de Ciencias
Universidad Autonoma de Madrid
28049 - Madrid
SPAIN