The story of the Burgess Shale is beautifully told in
Stephen Jay Gould's book "
Wonderful Life - The Burgess Shale and
the Nature of History". For a book that contains some quite
deep
scientific concepts (quite deep if you're not a
biologist
anyway), it's very easy to read, and to me it's
one of the most treasured possessions on my bookshelf.
To me the truly amazing thing about the fossilized creatures found in
the Burgess Shale is their sheer diversity: as SJG says it's almost as
if nature went on a crazy orgy of experimentation. Of all the things
found there, very few of them fit into any modern classification
categories -- most of them being not just members of previously
undiscovered species or genus, but of whole new orders of animal.
Some of the things that once crawled along our ocean floors would be
laughed at in astonishment if a movie producer attempted to put them
into a modern science fiction film: the best example is the truly
freaky animal named Hallucigenia -- a thing so beyond our
usual definitions of life that nobody knows which is its head and
which its tail, or even which way up the thing would have stood!
Gould rounds off his tale by explaining that of all the weird and
wonderful beings found in the Burgess Shale, it would have been almost
impossible to predict which ones would survive the great extinction event
that occurred at the end of the pre-Cambrian period. The animals that
did survive ultimately evolved into all life as we know it,
including homo sapiens. The final mindfuck comes from the
thought that if some of the other creatures had survived, the world as
we know it could be so different as to be beyond comprehension.