Long considered a relic of deep evolutionary history, new fossils indicate that modern lamprey larvae are actually a relatively recent innovation. A new study out of the University of Chicago, the Canadian Museum of Nature and the Albany Museum challenges a long-held hypothesis that the blind, filter-feeding larvae of modern lampreys are a holdover from the distant past, resembling the ancestors of all living vertebrates, including ourselves. The new fossil discoveries indicate that ancient lamprey hatchlings more closely resembled modern adult lampreys, and were completely unlike their modern larvae counterparts. The results were published today (March 10, 2021) in Nature. Lampreys — unusual jawless, eel-like, creatures — have long provided insights into vertebrate evolution, said first author Tetsuto Miyashita, PhD, formerly a Chicago Fellow at the University of Chicago and now a paleontologist at the Canadian Museum of Nature. “Lampreys have a preposterous life cycle,” he said. “Once hatched, the larvae bury themselves in the riverbed and filter feed before eventually metamorphosing into blood-sucking adults. They’re so different from adults that scientists originally thought they were a totally different group of fish.