Some of the largest early animals may have used spiny limbs to filter their food rather than impale it.
Fossils found in northern Greenland suggest that, like other predators 520 million years ago, Tamisiocaris borealis, a distant lobster relative, had two long, spiny limbs that jutted out from its face. But unlike other predators, T. borealis’ limbs also had bristles: The appendages’ long, equally spaced, slender spines were covered in much finer, denser ones.
This mesh is similar to the hairy fringes found in modern filter-feeding whales, Jakob Vinther of England’s University of Bristol and colleagues say. With its bristled limbs, the up to 70-centimeter-long T. borealis could have swept through the water, netting small crustacean-like creatures and other prey. The animal could then have curled the appendages inward one at a time to suck the food into its mouth, the researchers argue in the March 27 Nature.
The fossils may be the earliest evidence for filter feeding in large, free-swimming animals, the scientists say.
IN SWEEP T. borealis probably used its spiny appendages to sweep through the water for prey and then bring the food into its mouth, as these animations show. Credit: Martin Stein