A recent discovery by a Univ. of Florida geologist may lend
support to the theory that one of the defining moments of evolution may not
have occurred as currently thought.
While studying the ancient microcontinents that make up
the geography of central Kazakhstan
in Asia, geological sciences professor Joe
Meert and
colleagues uncovered evidence that multi-cellular organisms may have evolved
100 million years earlier than previously thought, well before the Cambrian
Era. His findings are published in the journal Gondwana Research.
The Cambrian era is known for an explosion of
multi-cellular life, including the first hard-shelled organisms. Most modern
species can trace their evolution back to this event, which is unique in the
evolutionary record. Prior to the Cambrian era, the fossil record becomes more
cryptic, as the soft-shelled organisms of the era leave relatively few fossils.
The prevailing theory is that multi-cellular life developed just after a series
of glacial episodes 750 to 653 million years ago.
Meert discovered the fossilized remains of two Ediacara
fauna, Nimbia occlusa and Aspidella terranovica, in a rock formation that
predates the earliest glacial period by more than 50 million years.
“I am sure that the fossils will be controversial due to
their enigmatic nature and the fact that they are more than 100 million years
older than similar fossils” Meert said.
While the findings may support the theory than metazoan
life developed much earlier than previously assumed, the exact nature of Nimbia
Occlusa remains a subject of controversy. Scientists are split on whether it is
a multi-cellular animal, a bacterial colony, or a microbial mat. The new
fossils are identical to those that appear in the fossil record up to 150
million years later, meaning it passed through tectonic, climatic, oceanic, and
atmospheric events without significant change.
The research was supported by the National
Science Foundation.
