Ancient 'Clingfilm' Preserves Fossils
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are some fossils preserved so beautifully? Dr Jan Zalasiewicz of the University
of Leicester Department of Geology believes it is because they were wrapped in a
sort of clingfilm, hundreds of millions of years ago.
He, together with Helen Jones, a Leicester undergraduate and Professor
Barrie Rickards of Cambridge University, have been puzzling over why some
graptolites (pictured below) - extinct, ocean-going animals – are so curiously preserved.
particular graptolites are cone-shaped open spirals.
Bury them in sea floor muds and they should fill with mud. Yet many remained empty of mud when they were squashed flat, as if these
fossils had been wrapped in clingfilm before they were buried.
Dr Zalasiewicz and his co-workers believe that this ancient
‘clingfilm’ was a combination of microbial films and jelly-like particles of
‘marine snow’ which fell from the ocean surface to a deep sea floor. The
fossils would have been enveloped in this stuff, which prevented mud and silt
from penetrating into their interiors.
beautifully-preserved graptolites provide a clue that thick (and
probably very smelly) layers of this now-vanished organic matter must
have carpeted large areas of sea floors in ancient times. Ocean floors
these days are mostly much ‘cleaner’, because such organic gunk
quickly decomposes: the nearest comparison in existence today can be
found at the stagnant, virtually lifeless bottom of the Black Sea.
finding will help in the interpretation of other fossils, and may also be of
wider significance: for some of the now-vanished ‘clingfilm’ material was likely
converted, after millions of years, into oil.
NOTE TO EDITORS:
is available from Dr Jan Zalasiewicz, University of Leicester Department of
Geology, telephone 0116 252 3928, fax 0116 252 3918, email firstname.lastname@example.org
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