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The Bizarre Sex Lives of the Ancient Rangeomorphs

ByFedor KossakovskiNOVA NextNOVA Next

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Some of the earliest multicellular organisms had more reproductive options than most of today’s complex species.

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Fractofusus , a genus of sessile marine creatures that are part of a now-extinct taxon known as the rangeomorphs, lived 565 million years ago on the ocean floor of what is now Canada’s Eastern coastline. Not much is known about these organisms besides how they looked—sort of like a cowry shell crossed with feathery coral. Scientists first found Fractofusus fossils were first found in the 1960s, scientists have had difficulty drawing comparisons between rangeomorphs and modern life.

fractofusus

Their final resting place has confounded our study of them. These Fractofusus fossils are located in two ecological reserves, Mistaken Point and Bonavista Peninsula on the southwest of Newfoundland, which means they cannot be extracted from the rock and studied in the lab.

Instead, Emily G. Mitchell of the University of Cambridge and her colleagues used GPS to plot the distribution of over 4,000 individual specimens on site. In some areas where this was not possible, the scientists traced the fossils onto large sheets of acetate paper. Back in the lab, they analyzed the clustering patterns of the colonies with various statistical models and compared them to growth patterns of modern plants. The best-fitting model revealed a refined reproductive strategy with two distinct modes. Rebecca Morelle, reporting for BBC News, shares the findings:

In one method, the organism sprouted young from its body in much the same way that a spider plant or strawberry plant multiplies.

In another, it produced seeds or tiny buds into the water column.

This allowed the ancient life-form to produce clones that could colonise a new patch of seabed.

Although the reproductive style of Fractofusus seems similar to that of certain modern plants, it is still too early to tell if rangeomorphs are, in fact, our direct ancestors—it is also possible that evolution stumbled upon similar reproductive strategies more than once.

Photo credit: CG Kenchington