Re: fossil lichens? (from R. Hill)

[Benjamin Martin Waggoner <bmw@xxxxxxxxxxxxxxxxxxxx>]

> 
> In the July 8 edition of Science News was an article "The Ediacaran
> Enigma" wherein the author (Richard Monastersky) discusses several
> new interpretations of the 'Edicaran fauna'. One of the researchers
> cited, Gregory J. Retallack of the Univ. of Oregon, puts forth a case
> that these fossils are the fossils of lichens. My question to the
> net is: do we know of any other cases where fossil lichens have been
> unambiguously identified?
> 
I got a little sidetracked from the original question (easy for me to do
when discussing the Retallack paper %)  Anyway, I checked George O.
Poinar's book _Life in Amber_ (Stanford University Press, 1992); 
Poinar mentions in passing two lichens from Baltic amber, but does
not elaborate. His source is a 1961 review by Czechott, which I haven't
seen. Baltic amber is probably late Eocene-early Oligocene, although
it's been reworked all over the place. That's the only other lead I
have on fossil lichens. Has anyone heard of any others?

About the hypothesis that lichens have been excluded from many habitats
by vascular plants: lichens may colonize extreme habitats, but they
do quite well in many not-so-extreme ones, such as northern California
(well, that's increasingly politically extreme, but not biotically
extreme). There are forests here that are quite festooned with the 
"Spanish moss" lichen (not to be confused with the "Spanish moss"
festooning trees in the southeastern US, which is actually an unusual
vascular plant). Crustose lichens also seem to do quite well around here.
I'm no lichenologist, but I wouldn't assume that lichens have been
excluded by vascular plants, because they get along fine with vascular
plants, and are hardly restricted to harsh environments. My problem with
aquatic lichens on soft substrates is a physical one: neither lichens nor
anything else can do well on soft substrate unless they can stay above
fouling sediment, overgrow fouling sediment, or clear it away from 
themselves. I remain unconvinced whether a crustose lichen could do
any of those things.

Just my two leus' worth. 

Ben Waggoner
UCMP
Berkeley, CA 94720