When Martin Ebert aimed an ultraviolet flashlight at ancient fish fossils that had been sitting in museum drawers for over 150 years, he expected nothing unusual. What he found was a hidden world no one had ever seen.
Ebert, a paleontologist at the Bavarian State Collection for Paleontology and Geology in Germany, was studying fossils from a mysterious fish family called Mesturidae that swam through the tropical seas of central Europe roughly 152 million years ago. While these fossils had been drawn and described by generations of scientists, something was waiting in the stone — invisible under ordinary light.
Under ultraviolet radiation, tiny structures suddenly appeared on some of the fossils: rows of scales, spines running along nearly the entire body, delicate patterns that had been invisible for centuries. "What astonished me most was that these fine structures remain clearly visible under UV light," Ebert said.
Among these glowing specimens, Ebert spotted something no scientist had ever identified before: the first known juveniles of a species called Mesturus verrucosus. These baby fish measured just 4 to 9 centimeters long — roughly the length of a large thumb. Their adult counterparts, by contrast, grew up to 50 centimeters long, making the mature fish 6 to 13 times larger. Until Ebert's work, no one had connected these tiny fossils to their massive adult versions.
The discovery matters because Mesturus sits near the base of a huge branch of the fish family tree. Scientists still argue about exactly where this group belongs in evolutionary history, and Ebert believes understanding primitive fish like Mesturus could finally settle those debates.
During his re-examination, Ebert also noticed that earlier researchers had mixed up several species under the same name. Using the differences he spotted under UV light, he sorted them apart. He even gave some of the newly identified species names honoring people who died because of political violence, including Jina Mahsa Amini, an Iranian woman who died in custody in 2022, and human rights lawyer Nasrin Sotoudeh, who remains imprisoned in Iran.
"Why not honor people who have championed human rights by naming fossil fish after them?" Ebert said.
Ebert is far from finished. Between 2006 and 2016, he spent years digging for fossils in Bavaria. Since then, he has collected nearly 24,000 photographs of Jurassic fish, working through them one by one to piece together what ancient seas looked like. "The goal is to find out as much as possible about the fish faunas of the various basins," he said.
The UV technique works on some fossils but not others. While specimens from Eichstätt and Solnhofen glow brilliantly, fossils from a site called Painten sometimes stay dark. Ebert says scientists haven't yet figured out why.