Earliest Known Lamprey Larvae Fossils May Shed Light on Evolution

Archaeologists have made a surprising discovery. They've unearthed the oldest known lamprey fossil to day. The finding could shed light on the ancient origins of the eel-like, blood-sucking lamprey and, in turn, reveal a bit more about the evolution of other animals.

"Among animals with backbones, everything, including us, evolved from jawless fish," said Desui Miao, one of the researchers, in a news release. "To understand the whole arc of vertebrate evolution, we need to know these animals. The biology of the lamprey holds a molecular clock to date when many evolutionary events occurred."

Lamprey evolution actually reveals a bit more about the development of all animals with a backbone. With a three-phased lifecycle, though, it's difficult to find all three phases in the fossil record. Lamprey larvae, in particular, are small and soft and seldom fossilized.

"They just don't have hard parts," said Miao. "Even fully developed fossil lampreys are rare because they lack skeletons. Most fossil fishes are bony fishes-fish we eat and leave bones on the plate. But lampreys don't have bones or teeth that can be preserved as fossils."

Fortunately, scientists struck a bit of luck in the form of the freshwater lakes that once covered Inner Mongolia. Many fossils of lamprey became preserved in a layer of late-Cretaceous shale, including lamprey larvae. The new discoveries show the scientists a bit more about lampreys.

"Our larvae look modern," said Miao. "The developmental stage is almost identical to today's lamprey. Before this, we didn't know how long lampreys have developed via metamorphosis. Now, we know it goes back 125 million years at least. In other words, lampreys haven't changed much-and that's very interesting."

The findings reveal a little bit more about the evolution of lampreys. More specifically, it shows that these animals haven't changed much over time, which shows that they're evolutionarily effective.