Fossils Redefine Evolutionary Timeline Millions of Years Ago in Biodiversity Explosion

First Posted: Jul 08, 2015 08:58 AM EDT

Some stunning fossils are redefining evolutionary timelines. Researchers have taken a closer look at some of the oldest animals on the planet and have found that they survived millions of years longer than previously thought.

In this case, the researchers looked at the Lower Fenzouata formation, which has a wealth of fossils. It preserves life in the Ordovician, which was around 485 to 444 million years ago.

"The Fezouata is extraordinarily significant," said Derek Briggs, one of the researchers, in a news release. "Animals typical of the Cambrian are still present in rocks 20 million years younger, which means there must be a cryptic record in between which is not preserved."

The researchers documented over 160 genera in the Fezouata. These include animals such as armored lobopodians, which were worm-like creatures with stubby legs and spines on their backs. The findings don't only show a variety of species, though; they also show that many species lasted longer than previously thought.

"Horseshoe crabs, for example, turn out to be at least 20 million years older than we thought," said Peter Van Roy, one of the researchers, in a news release. "The formation demonstrates how important exceptionally preserved fossils are to our understanding of major evolutionary events in deep time."

The new discoveries actually suggest that there was the Great Ordovician Biodiversification Event, which was an explosion of biodiversity throughout the earlier part of the Ordovician period. This actually may have been a continuation of the Cambrian explosion.

"There is much more to learn from the Fezouata," said Briggs. "Why do we not see more assemblages like this in the Ordovician? What ecological changes happened at the Cambro-Ordovician interval? Are the Cambrian Explosion and the Great Ordivician Biodiversification Event separate, or phases of the same event?"

The findings are published in the Journal of the Geological Society.

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TagsFossil, fossils, Cambrian Explosion