130-year-old fossil mistaken for caterpillar turns out to be first land-living lobopodian

Neotype of Palaeocampa anthrax from the Mazon Creek Lagerstätte and rediscovered in the Invertebrate Paleontology collection of the MCZ. (Image: Richard J. Knecht)

At first glance, it looked like a caterpillar. For over a century, that’s how it stayed—quietly tucked away in a drawer at Harvard’s Museum of Comparative Zoology. But a closer look has now revealed its true identity: the earliest-known nonmarine lobopodian and a surprising clue to life’s ancient journey on land.

From Caterpillar to Evolutionary Link

The fossil, Palaeocampa anthrax, was first described in 1865. Since then, it shifted labels—from worm to millipede to marine creature. But it was only recently that a former Harvard student, Richard Knecht, saw something different. He found legs on every segment, ruling out earlier guesses. That clue pointed straight to lobopodians—extinct soft-bodied creatures tied to modern arthropods.

These ancient animals are often found in Cambrian marine rocks. Famous ones like Hallucigenia and Aysheaia were all from the sea. But Palaeocampa told a different story. It lived in freshwater swamps, far from the ocean. It is also younger than other known lobopodians, yet comes from an earlier time.

A Fuzzy Fossil with Toxic Spines

Knecht and his team examined 43 specimens from two sites—Mazon Creek in the United States and Montceau-les-Mines in France. These places are known for their rare soft-tissue fossils. Using special scanning tools, they uncovered tiny details. The fossil was covered in nearly 1,000 spiny bristles. These were not just for show.

Tests by Columbia University physicist Nanfang Yu revealed chemical traces at the tip of each spine. This suggested the creature used them to release toxins—possibly to keep predators away. The fossil also had no eyes, no claws, and ten pairs of legs. It was just four centimetres long and looked like a spiky caterpillar.

A Drawer Full of Answers

Perhaps most surprising is where the fossil sat for decades. It was just steps away from the late Stephen Jay Gould’s old office. Gould, a famous evolutionary biologist, had helped bring Cambrian creatures into public imagination. Yet, Palaeocampa remained hidden in a drawer all that time.

Its discovery changes how scientists view certain fossil sites. The French site, once thought to be marine, is now confirmed to be freshwater. This could help explain how some ancient creatures moved from ocean life to land or swamp habitats.

Knecht now works at the University of Michigan but remains connected to Harvard’s museum. He believes more surprises are still waiting in museum drawers. With so few windows into the Carboniferous period, every soft-bodied fossil found becomes a treasure.

As Knecht put it, “Sometimes the biggest clues are right under our noses.”