Ancient, Fossilized Crustacean Hunted its Prey with Spiny Limbs

A carnivorous crustacean that roamed Earth's seas about 435 million years ago once grasped its prey with spiny limbs before devouring it. Now, scientists have taken a closer look at this newly discovered species in order to learn a bit more about its lifestyle.

The fossil of the new species was discovered near Waukesha, Wisconsin. Called Thylacares brandonesis, the fossil represents the oldest example of the Thylacocephala group, which are shrimp-like creatures mostly from the Jurassic period. These creatures are known for their bulbous eyes and multiple limbs.

In this case, the new fossil reveals that the creature used long, claw-like appendages to catch is prey in a similar way to modern remipedes, which are blind crustaceans that can still be found in water-filled caves.

"This new research extends the range of this enigmatic group of fossil arthropods back in the Silurian, some 435 million years ago, and provides evidence that they belong among the crustaceans, the modern group that includes lobsters, shrimps and crabs," said Derek Briggs, one of the researchers, in a news release.

The new research actually represents part of a wider investigation into this particular group of fossils, including several new Jurassic specimens. Modern imaging techniques allow the scientists to visualize new features, such as the tiny details of the species' muscle structure. This reveals a bit more about how this creature lived millions of years ago.

"T. brandonensis was probably an actively hunting predator, which caught the prey with its front claws and crushed it into smaller pieces with the protrusions nearer its mouthparts. This early Silurian example of Thylacocephala is in many ways much less extreme than the more recent Jurassic species," said Carolin Haug, one of the researchers. "It still has normal-sized eyes in contrast to the very enlarged ones that came later, and shorter front claws in T. brandonensis compared to the extremely elongated ones in the more recent Jurassic representatives."

The findings are published in the journal BMC Evolutionary Biology.