Evolution Diary

A giant head and gill-covered body make this newly reconstructed creature (pictured) “one of most bizarre fossil creatures that there is,” one scientist said.

The 505-million-year-old critter was first identified in 1912 from fossil pieces. Over the years, bits of it showed up in museum collections mislabeled as jellyfish, sea cucumbers, and various other creatures.
But expeditions in the 1990s began to uncover more complete specimens, which suggested the animal, dubbed Hurdia Victoria, was much more unique than previously thought.

Now, a well-preserved specimen found in the collections of the Smithsonian National Museum of Natural History in Washington, D.C., and fossil fragments from the Burgess Shale in British Columbia, Canada, have helped scientists to finally piece together the animal’s appearance.

At about 12 to 16 inches (30 to 40 centimeters) long, Hurdia was one of the largest hunters prowling the seas during the Cambrian period.

As a free swimmer—a trait rare at that time—the invertebrate likely caught “whatever it could get its claws onto,” such as mollusks and sponges, said lead study author Allison Daley, a Ph.D. student at Sweden’s Uppsala University.

The shield protruding from Hurdia’s head—which did not offer protection to its body—has particularly stumped Daley and colleagues, whose research appears tomorrow in the journal Science.

Daley speculates that the shield acted as a feeding aid, funneling prey toward the animal’s appendages.

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