Over 500 million years ago, there was a worm that resembled an ear of wheat. It moved along an area of sediment underwater. It then paused, then left a detailed imprint in the wet earth, moved a little more, and then eventually died.
Its body, seven inches long and segmented, became a fossil. So did its near-final resting place, creating a mortichnia: a body preserved with its final “death march.”
This happened at least 10 million years before the Cambrian Explosion — the era “during which many of the animal groups that exist today appeared” — began.
The creature, Yilingia spiciformis — named after the Yiling district in which it was discovered — was a complicated one by the standards of the Ediacaran Period: mobile, segmented, trilobate (each body segment composed of three lobes) and bilaterally symmetrical.
Yilingia and its death march are the subject of a study published on Wednesday in Nature. The worm is remarkable itself, as is the record of its death. A mortichnia is very rare — the imprint-maker tends to wander off. “It’s like in forensics,” said Shuhai Xiao, a geobiologist at Virginia Tech and one of the authors of the study. “You find a footprint and can probably tell something about the suspect, but you’d rather catch the suspect on camera.”
Head over to The New York Times to know more about this worm.
(Image Credit: Zhe Chen, Nanjing Institute of Geology and Paleontology and Shuhai Xiao, Virginia Tech)