Anomalous survivors

A new fossil reveals that the likes of Anomalocaris survived for millions of years longer than previously thought: 

Now a team led by former Yale researcher Peter Van Roy (now at Ghent University in Belgium) and Derek Briggs, director of the Yale Peabody Museum of Natural History, has discovered a giant fossilized anomalocaridid that measures one meter (more than three feet) in length. The anomalocaridid fossils reveal a series of blade like filaments in each segment across the animal's back, which scientists think might have functioned as gills. In addition, the creature dates back to the Ordovician period, a time of intense biodiversification that followed the Cambrian, meaning these animals existed for 30 million years longer than previously realized.

A similar creature, Schinderhannes, existed still later-- during the Devonian era, 100 million years after its cousins. It was much smaller (4 inches rather than 3 feet), and bore a pair of swimming fins: