Fossil Reveals Ancient Animal's Evolution from Apex Predator to Gentle Feeder

A class of ancient marine animals known as Tamisiocaris evolved from apex predators to gentile suspension-feeders that used giant, specialized appendages on their face to filter plankton in a way similar to modern whales, according to a new study.

Tamisiocaris, an early type of arthropod, came into existence during the "Cambrian Explosion," a surge of life and evolution that occurred about 520 million years ago.

Paleontological records indicate that Tamisiocaris swam using large flaps on either side of their body and had large appendages in the front of their mouths that were likely used to capture larger prey such as trilobites.

But new fossil evidence indicates that Tamisiocaris evolved from predators to suspension feeders, their trilobite-eating appendages transforming into a filtering apparatus that could be swept through the water like a net.

"These primitive arthropods were, ecologically speaking, the sharks and whales of the Cambrian era. In both sharks and whales, some species evolved into suspension feeders and became gigantic, slow-moving animals that in turn fed on the smallest animals in the water," said Jakob Vinther, a lecturer in macroevolution at the University of Bristol.

In a study published in the journal Nature, Vinther and his colleagues report their work 3D modeling the Tamisiocaris to get a better understanding of its feeding motions and range of movement.

"Tamisiocaris would have been a sweep net feeder, collecting particles in the fine mesh formed when it curled its appendage up against its mouth," said Martin Stein of the University of Copenhagen, who created the computer animation. "This is a rare instance when you can actually say something concrete about the feeding ecology of these types of ancient creatures with some confidence."

The new analysis offers revelations on the state of the ancient ecosystem.

"The fact that large, free-swimming suspension feeders roamed the oceans tells us a lot about the ecosystem," Vinther said. "Feeding on the smallest particles by filtering them out of the water while actively swimming around requires a lot of energy - and therefore lots of food."