Ediacaran Lichens?

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Fellow paleolichenologists*,

Retallack's taphonomic observations about the nature of the
Vendiobiota are timely and cast serious doubt on hypothesized
cnidarian, protist, pneu-, and other Vendobiont affinities. Although
his taphonomic assessments are only based on analysis of 3 taxa of
Vendobionts, he suggests that all Ediacaran fossils are taphonomically
similar (esp. in mode of compact.) to lycopod logs - when deposited in
sandy substrates. If one assumes (for the moment) that these taphonomic
similarities are true for all Vendobionts, then I agree with Hal that 
they would seem to form a natural taxonomic group ...likely different
from groups suggested based on previous soft and squishy Vendobiont
interpretations. To test this, it would be interesting to analyze some
more Ediacaran fossils, particularly the stranger forms which don't
look anything like potential lichens/fungi.

Unfortunately, it seems improbable that all of these Vendobionts can
be easily lumped into one group...in this respect I agree with
Ben...Whittington couldn't even reconcile "lumping" the Burgess fauna
into one group, even though (at the time) it was just as bizarre as
the Vendiobionts now seem to us. So why try to lump them into one
group? Retallack makes many very plausible comparisons between
Vendobionts and lichens and fungi. Together with aptations for rapid
growth and large size, it seems plausible that some of these critters
<were> lichens.  However, maybe some of them were not and were just
part of a lichen-dominated? community. In addition, I wonder about the
occurrences of these lichens or fungi in the deepsea Vendian deposits.
Retallack suggests that maybe these deposits were actually shallow
water.  Although I haven't been to these sites, I have a hard time
believing this.**  Would it be possible for shallow water lichens to
be transported to these depths and then "grow" for a short term b/c of
short-term changes in microenvironment (comparable to short-term
sustenance of shallow-water tracemakers in deepsea environments via
increased oxygen and/or nutrient levels shortly after a turbid event)?
Or... are there deepsea lichens & fungi? Or... are there marine forms
which can exist in dark, low-oxygen, methane- or sulfur- rich
environments (possibly in association with chemosynthetic bacteria)?

All in all, I really enjoyed this paper, but it left a lot of
unanswered questions (not all of which are listed). Based on
shallow-water deposits, the lichen/fungi interpretation seems very
plausible for many (but probably not all) of the Vendobionts, assuming
that Retallack's taphonomic interpretations apply to all Vendobionts.
It seems that the deepsea Vendobionts don't fit into this hypothesis
-- unless, however, one reinterprets existing paleoenvironmental
interpretations of these localities.

Of course, it is possible that my own lack of knowledge about fungi &
lichens is compounding my perceptions of problems with this whole
"Vendobiota as lichens?" business.

Off to class,

Whitey Hagadorn
__________________________
Dept. of Earth Science
U. of Southern California
Los Angeles, CA 90089-0740
hagadorn@usc.edu



*If there actually ARE any folks out there who have any expertise in
lichens, fungi, and the like (especially marine and/or fossil forms)
-- I'd be very interested in any suggestions, comments, input you
could give.  

**Also, several Paleonet users (or should I say "readers"?)
have been to many, if not most of these Vendian sites -- for those of
us who are only lucky enough to read the literature, what do you
think of suggested shallow-water interpretations of the Newfoundland,
nw Canada, and NC "deepsea" sites? Are these dramatic revisons of
earlier paleoenvironmental interpretaions plausible? Or even
necessary (i.e., are there "deepsea" lichens/fungi?)?