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Re: Skin hadrosaur



>Copyright infringement or no, the article says, "The skin was dotted with
>evenly spaced bumps, called tubercles, each a tenth of an inch high. Some of
>the tubercles had mysterious striations starting at the base and converging
>at the top."
>
>Does that soud like a primative feather, or from which that structure could
>have evolved? Or, was this a mechanism to release heat, either by sweating or
>some other way? Is this really old news, or has enough study been done on the
>few skin fossils previous to this find to make any such assumption? DOH!,
>STUPID ASSUMPTION AGAIN!)
>

What you describe sounds more like some skin structures derived from dermal
armour (bones embedded in the skin). Probably the form that dinophiles will
be most familiar with would be the plates and spikes of stegosaurs or the
"shell" of ankylosaurs. Homologous structures are found in some sauropods
as well as crocodiles, aetosaurs, even some extant lizards. Dermal armour
is not only the sensational plates and spikes variety. In 1991, I found a
small piece of Minmi and at first I thought it was something supporting Von
Danikien; 110 million year-old dinosaur killed by alien shotgun blast. What
looked like large (3-5mm diametre) shotgun pellets were actually dermal
armour. From memory, these pellets also has a radiating pattern similar to
the one you describe.

As for the homology between dermal armour and feathers, I think that they
are both derived from the "skin layer" (ectoderm), but that dermal armour
originates deep within the ectodermal layer where as feathers are more
superficial in origin. Can anyone else help out here?

Cheers, Paul

pwillis@ozemail.com.au

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