Meet the First Creature Ever to Roll Up in a Ball for Self-Defense

A species of tiny trilobite has taken the ball-rolling champion lead by millions of years

Rolly-polly trilobite
Rolly-polly trilobite Javier Ortega-Hernández, University of Cambridge

Trilobites, extinct marine arthropods whose fossilized remains fill many a museum gift shop, turn out to have been pioneers of “one of the most successful defensive strategies of life on Earth,” the Guardian writes. A recently discovered 510-million-year-old specimen shows that they were the first known animal to roll up into a ball for self defense. The scared little guy in question, a species no larger than a fingernail, had been trapped in an ancient mudslide in what is today Alberta, Canada. Although the creature’s defensive strategy proved an evolutionary hit for millions of years to come, in this case, apparently, it didn’t serve its life-saving purpose.

The Guardian elaborates on the discovery:

Javier Ortega-Hernández, a paleobiologist at Cambridge University, was going through the Canadian fossils when he noticed a tiny trilobite from a group called Olenellida. It appeared to have spines poking out of its head. But closer inspection under a microscope revealed that the spines came not from the head, but from the trilobite’s tail, which was tucked under its body.

The trilobite wasn’t exactly a champion ball-roller. It had rolled into a sort of loosey-goosey ball, “as best it could,” the Guardian writes. It would take vastly more time and evolutionary tinkering for the tightly-balled animals of today, like armadillos and pill bugs, to emerge.

The lack of a locking mechanism in older, more primitive trilobites might explain why none has been found curled up before: unless they are swiftly entombed in the position, they flatten out as their muscles fail them.

Nevertheless, Ortega-Hernández did find a second curled up specimen, supporting his hunch that the rolled up trilobite was not just a fluke and meaning that the tiny trilobites have taken the ball-rolling champion lead by millions of years.

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