Re: New in Paleobiology

[Jura <pristichampsus@yahoo.com>]

--- "Jaime A. Headden" <qilongia@yahoo.com> wrote:

>   Main, R. P., A. de Ricqlés, J. R. Horner, and K.
> Padian. 2005. The evolution and function of
thyreophoran dinosaur scutes. _Paleobiology_
31(2):291-314.
> 
> Abstract:

>"The evolution of scutes in thyreophoran
> dinosaurs, based on *Scutellosaurus*,               
> *Scelidosaurus*, *Stegosaurus*, and several         
> ankylosaurs, began with small rounded or ovoid      
> structures that typically had slight,               
  > anteroposteriorly oriented keels. These scutes
were  > elaborated in two general and overlapping
> ways: they could flare laterally and
> asymmetrically beneath the keels that mark the      
> anteroposterior axis, and they could be
hypertrophied > in their distal growth to produce
plates, spikes, and
> other kinds of ornamentation. *Stegosaurus* plates  
> and spikes are thus primarily hypertrophied keels of
   > primitive thyreophoran scutes, sometimes with
> elaboration of dermal bone around their pustulate   
> bases. Histologically, most thyreophoran scute
> tissues comprise secondary trabecular medullary bone
> that is sandwiched between layers of compact primary
> bone. Some scutes partly or mostly comprise
> anatomically metaplastic bone, that is, ossified
> fibrous tissue that shows incremental growth.

++++++++++++++++++++++++++++++++++++

Interesting read, but it does force me to ask one of
those questions that usually results in these threads
completely going off track of the original subject.

What is a scute?

Last I checked, scutes were sort of a catchall term
for any broad, shield like scale. Yet de Ricqlés et
al, are clearly referring to osteoderms in their
description of thyreophoran "scutes." 

So then, does the descriptive umbrella known as a
scute, now include osteoderms; conversely, has it
always?

Jason

"I am impressed by the fact that we know less about many modern [reptile] types 
than we do of many fossil groups." - Alfred S. Romer

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