Evolution: Complex Skeletons Evolved Far Earlier Than Previously Thought

Complex skeletons may have evolved far earlier than expected. Scientists have found that about 550 million years ago, tiny marine creatures had complex skeletons, which suggests that the earliest complex animals lived millions of years earlier than previously known.

Until now, the oldest evidence of complex animals came from the Cambrian Period, which began about 541 million years ago. Scientists had long suspected that complex animals had existed before then but until now, they had no proof.

Genetic family tree data suggested that complex animals-known as bilaterians-evolved prior to the Cambrian Period. The finding suggests that bilaterians may have lived as early as 550 million years ago, during the late Ediacaran Period.

The findings suggest that complex animals existed long before a period in the planet's history, known as the Cambrian explosion. During this time period, most of the planet's major animal groups evolved.

In this latest study, the researchers looked at the fossils of an extinct marine animal, called Namacalathus hermanastes, which was widespread during the Ediacaran period. The fossils are remarkably well preserved and reveal that the species had a rigid skeleton made of calcium carbonate, which is a hard material from which the shells of marine animals are made. The complex skeletal structures, in particular, are what interested the scientists.

"This fossil has been known for a long time, and was assumed to have been a primitive animal, such as a sponge or coral," said Rachel Wood, one of the researchers, in a news release. "This study suggests that it was, in fact, more advanced. We have suspected that these complex animals were present in the Ediacaran, but this study provides the first proof."

The findings are published in the journal Proceedings of the Royal Society B: Biological Sciences.

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