520-million-year-old shrimp-like creatures filtered food like modern whales

Newly discovered fossils of a huge shrimp-like creature that lived 520 million years ago during the Early Cambrian filtered food just like modern whales.

The 'Cambrian Explosion' was a time when there was a rapid appearance of all the major animal groups and complex ecosystems.

Tamisiocaris belongs to a group of animals called anomalocarids, a type of early arthropod that included the largest and some of the most iconic animals of the Cambrian period. They swam using flaps down either side of the body and had large appendages in front of their mouths that they most likely used to capture larger prey, such as trilobites.

However, the newly discovered fossils show that those predators also evolved into suspension feeders, their grasping appendages morphing into a filtering apparatus that could be swept like a net through the water, trapping small crustaceans and other organisms as small as half a millimetre in size.

The evolutionary trend that led from large, apex predators to gentle, suspension-feeding giants during the highly productive Cambrian period is one that has also taken place several other times throughout Earth's history, according to lead author Dr Jakob Vinther, a lecturer in macroevolution at the University of Bristol.

Dr Vinther said: "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."

In order to fully understand how the Tamisiocaris might have fed, the researchers created a 3D computer animation of the feeding appendage to explore the range of movements it could have made.