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Scientists find earliest example of reproduction in a complex organism

"Reproduction in this way made rangeomorphs highly successful," researcher Emily Mitchell said of the unique ancient organism.

By Brooks Hays
An artistic rendering reveals the ancient rangeomorphs and their unusually complex reproductive strategy. Photo by CG Kenchington/Cambridge University
An artistic rendering reveals the ancient rangeomorphs and their unusually complex reproductive strategy. Photo by CG Kenchington/Cambridge University

CAMBRIDGE, England, Aug. 3 (UPI) -- Statistical analysis has revealed the sexual behavior of creatures from the genus Fractofusus, a type of rangeomorph, was surprisingly complex.

In a new study, published in the journal Nature, researchers at Cambridge University say the analysis serves as earliest evidence of reproduction in a complex organism.

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Rangeomorphs are some earliest complex organisms known to man, and are considered by some to be earth's first animals. They thrived in oceans some 565 million years ago, during the Ediacaran age. But the odd-looking animals appeared and behaved more like plants.

"Rangeomorphs don't look like anything else in the fossil record, which is why they're such a mystery," lead study author Emily Mitchell, a postdoctoral researcher in Cambridge's earth sciences department, said in a press release. "But we've developed a whole new way of looking at them, which has helped us understand them a lot better -- most interestingly, how they reproduced."

While researchers can't necessarily verify whether or not Fractofusus rangeomorphs were the earliest animals, they can now say that they offer the earliest example of complex reproduction.

Until now, scientists didn't know much about Fractofusus. But an analysis of the distribution of Fractofusus fossils has allowed scientists to reconstruct the creature's unique two-pronged reproductive strategy.

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The primary technique -- seen in their "generational" clustering patterns -- was a type of localized asexual reproduction using stolons or runners. The technique resembles the reproductive strategies of modern plants like strawberry and spider plants.

But the organism also used a "grandparent" technique to colonize new regions of the ocean floor. Plants were able eject little pieces of themselves out into the ocean, where these seed- spore-like propagules could be carried to new territory.

"Reproduction in this way made rangeomorphs highly successful, since they could both colonise new areas and rapidly spread once they got there," said Mitchell. "The capacity of these organisms to switch between two distinct modes of reproduction shows just how sophisticated their underlying biology was, which is remarkable at a point in time when most other forms of life were incredibly simple."

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