Re: the Benevento theropod is named!

[Chris Nedin <cnedin@geology.adelaide.edu.au>]

Jamie Headdon wrote:

>PRESERVATION OF SKIPPY'S GUTS
>
>Chris Nedin wrote:
>
><Exceptional preservation such as this depends on a carefully maintained
>microenvironment in order to precipitate the calcium phosphate and
>calcium carbonate necessary to preserve soft tissue.
>Thus only the internal 'soft' tissues will decay rapidly enough to
>produce enough acid  plus dissolved phosphate levels to allow soft
>tissue mineralisation.  The outer tissues will loose acidity and
>phosphate concentration to the external environment and will not
>preserve soft tissues.>
>
>What is the process for the preservation of integument as Archie's  and
>Protarchaeopteryx feathers and Sinosauropteryx's protofeathers, and even
>all the others with such preservation? They all, apparently, came from
>lagoon deposits except the Yixian specimens.

The Solnhofen specimens were preserved as impressions.  The ventral side of
the feathers were in contact with the sediment and colonised with bacteria
which degraded the feather and lithified the surrounding sediment,
producing a mould of the feathers.  Once the feathers decayed, more
sediment filled the impression creating the counterpart.

See Davis & Briggs 1995 Fossilization of feathers. Geology, 23: 783-786

Chris

cnedin@geology.adelaide.edu.au                  nedin@ediacara.org
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Many say it was a mistake to come down from the trees, some say
the move out of the oceans was a bad idea. Me, I say the stiffening
of the notochord in the Cambrian was where it all went wrong,
it was all downhill from there.