HORNY male trilobites may have been fighting it out over the females hundreds of millions of years ago, making them the earliest combatants known to take part in such sexual contests.

Rob Knell, a biologist at Queen Mary University of London and Richard Fortey of London’s Natural History Museum noticed that some of the trilobites in the museum’s collection had horns on their heads similar to those of modern beetles. Male beetles use their horns to battle each other for supremacy, with the winner getting the opportunity to mate. Knell and Fortey wondered if the trilobites used their horns for…