Description:
Coming from the Late Jurassic Morrison Formation, this eminently
aesthetic specimen is some 150 million years old, from a time that
Prokaryotic life forms had long lost exclusive use of earth's shorelines.
Concomitantly, the earth’s coastal habitats had markedly reduced
stromatolite reefs, compared with those of the Proterozoic.
By
this time in geological history, microbial communities consisted
of complex consortia of both prokaryotic and eukaryotic forms with
diverse metabolic needs, and competition for resources and differing
motility among them made for an intriguing microcosm of interacting
life. The organisms responsible for stromatolite formation had retreated
to niches that were hostile to other life forms, particularly those
predators which used the microbial mats as a food source. This one
is a stromatolitic anhydrite (gypsum/selenite) which is the same
as one being formed in the Great Salt Lake of today. It is soft,
and so will not take a high polish, but has a most pleasing appearance
nonetheless. While the Juraasic Morrison Formation is best known
for its diverse dinsaur taxa, particularly the massive sauropods,
this is a fine example of an organism that traces its ancestry back
by OVER TWO BILLION YEARS further into the past.
This remarkable specimen is appropriate for display, teaching or
research, representing primitive prokaryotic life responsible for
forming the atmosphere that we breathe today. Stromatolites have
persisted to the modern day in such places as Shark Bay, Australia
where they continue their billions of years old lifestyle.
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