Animals with bones and shells dominate the fossil record. Their hard body parts endure long after traces of softer creatures have vanished. So paleontologists always greet the rare discovery of the fossils of soft- bodied, boneless creatures with excitement, as did Derek Briggs when he got his first look at some fossils that a mineralogist had collected in Herefordshire, England, about three years ago. The fossils had been shelved in the University of Leicester since their discovery, ignored until Briggs, a geologist at the University of Bristol, and his colleagues finally got a chance to study them carefully. The remains turned out to be those of soft- bodied marine animals that lived some 424 to 430 million years ago, during the Silurian Period, and include a host of worms and bizarre arthropods that have never been seen before.
Most known fossils of ancient boneless animals date from the Cambrian Period, ...
