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Prehistoric worm poop tells tale of ancient ocean

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One never knows which, if any, action they take will leave its mark on our world for millennia to come.

For instance, a simple ocean-floor-dwelling worm engaging in its morning constitution 500 million years ago could have never imagined that action would provide a glimpse back in time to humankind today. But such is the case.

photo courtesy of Julien Kimmig/University of Kansas
The area of the Mackenzie Mountains, at the Rockslide Formation, where several Cambrian-era fossils have been found.

“This (scene) gives us a deeper insight into what was going on at the time,” says Julien Kimmig, who co-authored an article with Brian Pratt for scientific journal Palaios on April 3 describing the scene found at the Rockslide Formation in the Mackenzie Mountains.

The fossilized remains of hyoliths – similar to trilobytes – feeding on the poop left behind by a worm that is similar, and likely related, to today’s Bobbitt Worms. That they, and the poop – referred to as coprolite – itself were preserved, given how quickly feces can deteriorate, adds to the luck of the find.

The hyolith would have all died at once. At this time, the oceans were nowhere near as oxygenated as they are today, and the layer of unoxygenated water may have shifted and killed these hyolith, says Kimmig.

Alternately, there could have been a release of methane or brine nearby. Whatever happened seemed to have happened more than once, given the amount of finds researchers have made in the area.

What is today the Mackenzie Mountain range formed part of the floor of a sea basin then, in the Cambrian period, and the continent was closer to the equator and somewhat tropical.

Several hyolith, in a semi-circle, feed on the feces left behind by a relative of today’s Bobbitt Worm, in a scene from 500 million years ago found in the Mackenzie Mountains.

“We were actually located much closer to the equator at the time than we are nowadays,” says Kimmig. “So it was warmer, subtropical likely in temperature at the time.”

The scene they found would have played out on a slope in the basin, likely 50 to 100 metres beneath the water’s surface.

Researchers have found evidence of other small arthropods nearby but none of the big, nasty ones yet – like the anomalocaris, a nightmarish metre-long shrimp with tarantula-esque mandibles that would have lived at the same time as the hyoliths.

Pratt discovered the Mackenzie Mountain specimens in 1983, and has returned to the area several times to continue the careful excavation of the ancient fossils.

“They were weathering out of the outcrop and Brian (Pratt) was just going through the scree slope at the time and found some specimens, in his first field season.”

Kimmig says there is the potential for more significant finds in the Mackenzie Mountains that could help paint humans a fuller picture of Earth’s heritage.

While the mountains haven’t been well-explored for these finds, he says there are many Cambrian deposits that have the potential to host outcrops with scenes like this one.

“If people keep their eyes open when they go through (the area) and look at the rocks, maybe we will find fauna that’s as extraordinary as what we found in the Burgess Shale,” he says.

The Burgess Shale, in the mountains of British Columbia, is host to a treasure trove of fossils from this period that has advanced knowledge of the period significantly. Researchers first found fossils there 100 years ago and continue to find them today.