History Files


Sinian World

Fossils from a Forgotten Time

BBC News, 13 May 1998



Rare fossil creatures from a mysterious time known as the Ediacaran are amongst the most exquisite examples of the earliest complex life, experts say.

The 560-575-million-year-old specimens from Canada, of marine organisms called rangeomorphs, are preserved in three dimensions, Science magazine reports.

The organisms appear to be somewhat plant-like, with "frondlets" - leafy structures that branch from stems.

These were probably free-floating, elevated above the sea floor by a stalk.

Guy Narbonne, of Queen's University in Ontario, Canada, found the new assemblage of fossils in an area called Spaniard's Bay in eastern Newfoundland.

The rocks at nearby Mistaken Point on the island have also yielded Ediacaran fossils, but these are squashed flat.

Lighting the fuse

Dr Narbonne believes rangeomorphs are a single biological group, which can neither be classified as animals nor as plants.

The Ediacaran Period occurs just before the "Cambrian explosion", an evolutionary blossoming in which many important animal groups appeared for the first time.

Professor Jim Ogg, secretary-general of the International Commission on Stratigraphy (ICS), has speculated that the mysterious Ediacaran organisms were probably "torn to shreds" by the predatory animals that became more common in the Cambrian.

The soft-bodied rangeomorphs were probably buried in a mud-flow, which was itself then covered over by ash from a nearby volcano.

This year, geologists accepted the Ediacaran into their official calendar of Earth history - the first new period to be added in 120 years.

The organisms may have had an asexual, or vegetative, method of reproduction.

The Ediacaran begins at the end of the last ice age of the "Snowball Earth", or Cryogenian Period, a term given to a series of glaciations that covered most of our planet between 850-630 or 600 million years ago.

One theory proposes that these climate shocks triggered the evolution of complex, multi-celled life.



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