Giant shrimp sheds new light on evolution

Savage predator or gentle vegetarian? For years an ancient shrimp-like creature that lived 500 million years ago had a fearsome reputation as an apex predator. New research from the University of Bristol suggests, however, that the creature was far more placid, avoiding meat and living on plankton.

The free-swimming creature Tamisiocaris borealis lived during the Cambrian period between 485 and 540 million years ago. This was a particularly important time for life on Earth, with an explosion of radically new animal designs evolving.

The dangerous-looking met re-long T borealis swam about eating all before it, according to original assumptions made about it. These were largely based on fossil remains showing grasping-like appendages near its mouth that are common in other animals in its group, the Anomalocarids.

Dr Jakob Vinther and colleagues from Bristol dug up a number of fossils from early Cambrian sediments in northern Greenland and they proposed an alterative view of what the creature had for dinner, in their research report published this evening in the journal Nature .

They suggest the appendages on T borealis were used as combs to collect plankton by sweeping it up off the seabed or filtering it out of the water. The appendages had a series of closely placed spines with longer ones and shorter ones and the scientists argue that at least with T borealis , they were used to collect vegetarian fare in the same way as any filter feeder.

The proposal is of interest to palaeontologists studying the emergence of animals during the Cambrian. If this large animal could survive on plankton, there must have been plenty of it about in the seas at the time, something that tells us more about the local food web, the authors say.

It also tells scientists that filter feeding was present at least as far back as the Cambrian era.