Discover the world's oldest cannibal

A new study has revealed that trilobites, marine arthropods, were the world's first cannibals.

Trilobites are extinct marine arthropods that were first found in fossils about 541 million years ago. They are creatures with thick exoskeletons, which may be one of the reasons why many trilobite fossils have been preserved over the years; Fossilized exoskeleton much easier than softer tissues.

Trilobites, marine arthropods may be the world's first cannibals.

Russell Bicknell, a paleontologist at the University of New England in Australia, has spent five years examining trilobite fossils from the Emu Bay Shale formation on Kangaroo Island in South Australia. Two species of trilobites from the same genus were found in this formation: Redlichia takooensis, which ate seeds on the ocean floor, and the larger predatory R. rex.

Many of the R. takooensis fossils were found with what appeared to be bite marks, mainly on the back of their heads. Paleontologists say that R. rex served as a meal for R. takooensis. In the Emu Bay Formation, fossilized manure, called coprolite, left by R. rex contains trilobite crust remnants.

This suggests that R. rex is capable of predation on smaller trilobites. Unexpectedly, however, were signs of a similar bite on R. rex. The researchers concluded that these wounds could be the result of cannibalism.

Although not much is known about wounds caused by trilobite, Bicknell is certain that these wounds are not "bites" in the traditional sense. Instead, the underside of a trilobite has two rows of legs and on these legs there are few spines pointing inward.

Most of the injuries seen on the Emu Bay fossil are abdominal, not head injuries. Bicknell believes this is because injured animals are trying to escape the clutches of predators. The injured fossils are from animals that have disappeared. Trilobites that cause head injuries may be congeners.

While this is the earliest recorded example of cannibalism of any animal in the fossil record, it is likely that cannibalism is older and more common. much more than these fossils suggest.

"This is a provable record for cannibalism," Bicknell said.