When she found the fossil, Rhiannon LaVine, a research associate with the KU Biodiversity Institute and Natural History Museum, was part of a team camping and carrying out fieldwork in the High Creek area of the Spence Shale, a geologic formation straddling northern Utah and southern Idaho. The area has been famed since the 1900s for its abundance in some 90 species of Cambrian trilobites and soft-bodied fossils.
Their findings recently were published in the peer-reviewed journal Historical Biology.
“One of the last times we were out there, I split open one of these pieces of rock and instantly knew it was something that wasn’t typical,” LaVine said. “The first thing we see are these radial blades that look like stars or flowers. Immediately, I showed it to (lead author) Julian Kimmig. He was perplexed. He’s said, ‘I’ve never seen anything like that.’ We were out with Paul Jamison, a local who’s been working the site for years — and if there’s something in there that somebody’s seen, he’s seen it. But he hadn’t seen it.”
After transporting the fossil specimen back to the KU Biodiversity Institute — where today it’s part of the permeant paleontological collection — LaVine consulted with colleagues about the mysterious fossil.
I was showing it to everybody, asking, ‘What do you think this is?,’” LaVine said. “Nobody had an idea. We thought maybe it’s a wiwaxia, a very peculiar animal from about that time — but we don’t have too many representatives of it from the Spence area. Or maybe it’s a scale worm, but there’s no real scale worms known from that time. Maybe it was a juvenile jellyfish, but it’s so bladed and the lines are so straight on those things, it would be kind of odd. So, I couldn’t get a solid answer.”
Next, LaVine teamed with colleagues at the University of Missouri to conduct scanning electron microscopy and energy-dispersive X-ray spectrometry on the fossil.
We mainly wanted to make sure that this was a biological thing, because it’s possible it could have just been some weird mineral growth with the way it looked,” said the KU researcher. “So that was primarily why we brought it to them. It’s about 7 or 8 centimeters long, maybe a little shorter than the length of a smartphone. It’s sizable for a fossil of that sort. We did the scanning to rule out that it wasn’t just a mineral growth, and we were able to do that.”
Finally, LaVine and her co-authors were able to determine the fossil to be a previously unknown species of annelid, a diverse phylum of some 21,000 “segmented worm” species found in terrestrial, freshwater and marine environments all over the world.
