THEROPOD & ICHTHYOSAUR SKIN

[darren.naish@port.ac.uk]

On the integumentary structures in Yixian theropods, 
DinoBoyGraphics (or Scott Hartman to his friends I think) 
wrote of Larry Martin that...

> He still argues that all integumentary structues from the 
> Yixian are muscle/collogen fibers, except, presumably     
> those from critters he considers birds.  As evidence, he is 
> citing an icthyosaur described 2 or 3 issues ago in Lethia 
> (I haven't gotten ahold of the paper yet, if anyone can 
> share, I'd appreciate it).  He claims that it shows "fur-like" 
> structures, and since icthyosaurs weren't (likely) furry, it   
> must be a diagenetic event.  

The papers being referred to are....

Lingham-Soliare, T. 1999. Rare soft-tissue preservation 
showing fibrous structures in an ichthyosaur from the 
Lower Lias (Jurassic) of England. _Proc. R. Soc. Lond._ B 
266, 2367-2373.

- . 2001. The ichthyosaur integument: skin fibers, a means 
for a strong, flexible and smooth skin. _Lethaia_ 34, 287-
302.

The fibres seen in these fossils are not diagenetic artefacts 
but represent helically-wound cross-fibre arrays in the 
dermis and epidermis similar to those seen in assorted 
extant sharks and aquatic mammals (actually, some of the 
features identified by Lingham-Soliare as skin fibres may be 
bone fabric: arguments over their identity are covered in the 
2001 paper). 

Incidentally, Martin is not the first person to try and pretend 
that the structures seen on the theropods are just like those 
seen in some soft-tissue-bearing ichthyosaurs as Mike 
Howgate has also made this claim in some of his talks on 
bird evolution here in the UK. Any examination of the 
specimens concerned (or good images of them, as seen in 
the above-cited papers) will reveal that ichthyosaur skin 
fibres have nothing to do with the bristles and fuzz seen in 
the Yixian theropods. I hate to sound like Paul Davis, but if 
only someone would (a la Schweitzer et al) do the required 
keratin testing on the specimens concerned, most of the silly 
scepticism would be removed.

Incidentally I say all this after spending several hours with 
NGMC-91, _Caudipteryx_, _Sinosauropteryx_, 
_Protarchaeopteryx_, the London _Archaeopteryx_, 
_Liaoxiornis_, _Changchengornis_, _Cathayornis_ and 
_Confuciusornis_ last week. My wife Toni and Luis Rey 
were there too:)

Does anyone know Ilja's current whereabouts? I am 
reviewing Paul Chambers' _Bones of Contention: The 
Archaeopteryx Scandals_ and would like to ask him some 
stuff.

-- 
Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL

email: darren.naish@port.ac.uk
tel: 023 92846045