Crypto-bioturbation in the Precambrian

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Dear all,

I am a phD student from the ETH Zurich interested in the earliest signs of
metazoan life.

I have pursued the general subject of bioturbation in the Precambrian in
the newsgroups of the usernet and would like to ask a specific question of
the members of Paleonet:

Does anyone know of research into "meiofaunal" activity or
crypto-bioturbation in the pre-Varanger Precambrian? This is a subject
which interests me greatly. I know of several reports of macro-scale trace
fossils from the Precambrian, many of which stand under the shadow of
doubt. One report recently (last year in Geology) discussed possible
feeding trails from rocks which are more than 1000 million years old and
they did seem particularly convincing. Such reports are exceedingly rare,
perhaps because only surface and shallow waters contained free oxygen and
also because many shallow water sediments have been metamorphosed or
dolomitised thus obliterating such very small signs of life.

At any rate, crypto-bioturbation in well preserved sediments may give the
best indication of when metazoans appeared on the Earth. Any
information/discussion on this theme will be most appreciated.

yours,

Graham

ps. by 'crypto-bioturbation' I mean sensu Bromley's text book on trace
fossils. Trails, mixing of sediment, etc. only seen under the microscope.