Aquatic, worm-like animals capable of crawling through mud appeared at least 550 million years ago, according to new fossil evidence. The discovery is helping to resolve a longstanding question as to when segmented, mobile animals first appeared on the planet.
It’s the paleontological equivalent of finally being able to put a face to a name.
In this case, a team of scientists from Virginia Tech and the Chinese Academy of Sciences were able to connect an ancient species to the trail marks it left behind. Prior to this study, the same group of scientists detected animal tracks in rocks dated to between 551 million and 539 million years old. Trouble is, these tracks could not be connected to a specific organism, leaving the features ambiguous in nature; it’s exceptionally rare to find a fossilized creature resting next to its fossilized trail marks.
New research published today in Nature showcases one such example. The fossilized remnants of a newly described creature, dubbed Yilingia spiciformis, were found in rocks pulled from China’s Dengying Formation in the Yangtze Gorges area. These rocks date back to the Ediacaran period, long before the appearance of dinosaurs and the Pangea supercontinent. The track marks found in these rocks are among the oldest known on Earth—and we finally know who made them.
Related slideshow: Ancient bird foot found in amber has bizarrely long toes (Provided by National Geography)
Yilingia spiciformis featured a back, stomach, head, and tail. It looked similar to a millipede, featuring a long, narrow body composed of around 50 body segments. Yilingia spiciformis was around 26 millimeters (1 inch) wide and about 27 centimeters (10.6 inches) long. The creature would’ve dragged its body across the muddy ocean floor, creating trails as long as 58 centimeters (23 inches). In total, the scientists managed to identify 35 fossils of this species, along with 13 trace fossils of the trails. The “smoking gun” fossil, however, shows the creature with its associated trail mar
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