Re: paleonet Fossil terminology

[Frank Holterhoff <frank@xxxxxxxxxxxx>]

In the Texas Cretaceous we find lots & lots of ammonites preserved as 
marl steinkerns.  Almost all of them preserve the external topography of 
bumps, ridges, etc. (technical terms!) to some extent.  Many of these 
specimens also preserve some of the suture pattern on the same surfaces. 
  These would then be composite molds according to your definition, 
right?  (In fact, these may be some of the fossil molluscs that Michel 
was referring to.)

So the presence of external and internal topographies or textures on the 
same specimen is generally or always due to compaction?  Seems like in 
many cases the topographies, especially the suture patterns, would 
become obviously distorted, but I wasn't aware that that was observed 
very often if at all in TX K ammonites.

F

Kristen Myshrall wrote:
> Hi Michel,
> 
> A composite mold combines both internal and external features on the 
> same surface. Essentially a composite mold is formed when both of the 
> internal and external surfaces are compacted together resulting in 
> composite impressions on the same surface. Sort of like a combination of 
> an internal mold and an external one.
> 
> Hope this helps,
> Kristen Myshrall
> 
> University of Connecticut
> Department of Molecular and Cellular Biology
> trilobitegirl@msn.com
> 
> 
>> From: "Michel Chartier" <paleo@cam.org>
>> Reply-To: paleonet@nhm.ac.uk
>> To: <paleonet@nhm.ac.uk>
>> Subject: paleonet Fossil terminology
>> Date: Thu, 29 Apr 2004 09:47:24 -0400
>>
>> Colleagues,
>>
>>     In the technical literature on fossil molluscs, one often sees the
>> term "composite mold" to describe the preservation of certain specimens.
>> What exactly is a composite mold, and how does it differ from an
>> ordinary mold (internal or external) or from a cast?
>> Thank you for enlightening me about this
>>
>> Michel Chartier
> 
> 
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