Found in roughly 160-million-year-old rocks in North China, the Yanliao Biota is a diverse array of beautifully preserved fossils, including dinosaurs, pterosaurs and even early mammals. But it isn’t all fur and feathers. Paleontologists have now unearthed fossils of two surprisingly large ancient lamprey species, swimming menaces that latched onto and bored holes into their unsuspecting neighbors.
Modern parasitic lampreys’ funnel-shaped, toothy mouths tend to be adapted to consume blood or flesh. Based on the arrangement of teeth and other feeding apparatuses in the fossils, the newly discovered species probably weren’t bloodsuckers — they were flesh eaters, the team reports October 31 in Nature Communications.
The fossils are the oldest lamprey specimens to clearly indicate a preference in feeding mode, say paleontologist Feixang Wu of the Chinese Academy of Sciences in Beijing and colleagues. In fact, the tooth arrangement of both ancient species strongly resembles that of a modern species of Southern Hemisphere flesh-eating lamprey.
Yanliaomyzon occisor — “occisor” is Latin for “killer” — was the bigger of the two, about 64 centimeters long, the length of a small dog. The species name for its smaller cousin, Y. ingensdentes, comes from the Latin for “large teeth.” Modern adult lampreys range in length from about 15 to 120 centimeters.
Lampreys, a lineage of jawless vertebrates, have been around for 360 million years. But they rarely fossilize well, leaving large gaps in their evolutionary record and uncertainty about their ecology and when their feeding styles evolved.
The earliest lampreys weren’t such fierce predators: They were only a few centimeters long and lacked the powerful teeth of later species. They also didn’t have modern lampreys’ distinct life cycle, which consists of a larval filter-feeding stage, a juvenile parasitic stage and an adult spawning stage.
The newfound fossils suggest that by this time in the Jurassic Period, lampreys had become fierce predators, acquiring larger body sizes and complex feeding structures.