Vendian Lichens

["Elizabeth C.Marr" <cheney@xxxxxxxxxxxxx>]

	I, and the rest of the Paleo people at UCDavis, found 
Rettallack's paper outstanding and provocative.  Its certainly a good 
shaker upper, but this doesn't mean as Ben implies that it is wrong.  
Please Ben, tell us why specifically you don't approve of the methodology.
	No one I know actually knows anything about marine lichens, so I 
can't really evaluate any similarity, but the paper really has two 
points and the first one is very interesting, even if the lichen 
arguments are wrong: based on reverse taphonomy the ediacaran fossils were tougher than 
lycopod wood.
	If this interpretation is correct (and I have every reason to 
believe that since there is three dimensionality to the fossils even 
though they are preserved in welded quartzites, that the original 
organism must have had more structural rigidity than your average jelly 
fish, sea pen, or flat worm) then indeed a general solution is required.
In other words if all the fossils had equally anomalous resistance to 
compaction, then that would definately suggest that they form a natural 
group, not that they be dispersed to a host of taxonomic groups which we 
know were relatively flimsy.
	Furthermore at least the concept of a lichen is very appealing 
because a mutualism may have allowed rapid structural innovation and 
large size.  For comparison consider a paper by McKinney et al 1990 in 
Science:  an encrusting bryozoan and an encrusting coral are stuck 
growing on 
flat surfaces until they get together and intergrow and then they can 
form erect colonies.  Besides the large size, and shallow environments 
certainly suggest plant-like creatures.
				Hal Lescinsky