By: Melissa Zhao
Recently, scientists at Durham University led a study that uncovered a small but extremely rare worm fossil, called Youti Yuanshi. This discovery might finally answer a question scientists have been struggling with for many years now: how exactly did the small worms survive when they were so tiny? The tiny worm was kept in surprisingly good shape, giving scientists just enough information to put new theories together.
The fossil is part of the large group of organisms known as Arthropods that includes modern insects, crabs, spiders, and centipedes. Arthropods are extremely unique because of one trait: they are tiny. The fossil was a larva, which is a baby insect, and the insides of the larva were very clearly seen.
The larva was about as big as a poppy seed and was excellently preserved, making it easy to study. It was unearthed from a section of rock that dates to approximately 520 million years ago, and was about 1 mm long.
The larva will help scientists determine how centipedes and worms, including the others in their group, like crabs and spiders, evolved to survive in their time. Youti Yuanshi was such an important discovery because of how clearly the insides were preserved. One of the new facts the fossil revealed was that the head had an ancestral brain region.
The extremely complex head of such a tiny creature allowed for the other Arthropods to thrive and duplicate with new features, dominating places that were once difficult for them to survive in. The ancestral brain region would later form the segmented, complex head of recent arthropods.
Dr. Martin Smith of Durham University, the lead researcher of the project that worked on discovering the fossil, said, “When I used to daydream about the one fossil I’d most like to discover, I’d always be thinking of an arthropod larva, because developmental data are just so central to understanding their evolution.” He continued to describe his hopes of discovering an arthropod larva fossil, stating, “But larvae are so tiny and fragile, the chances of finding one fossilized are practically zero—or so I thought!” After he saw
Youti Yuanshi, he said, “I already knew that this simple worm-like fossil was something special, but when I saw the amazing structures preserved under its skin, my jaw just dropped.”
The intricate puzzle of life includes all the animals that were alive back then: dinosaurs, centipedes, and more. With every fossil and new discovery, every piece weaves and falls into place until, with a click and a final sigh, another tiny detail has been found.