Trilobites of the species Ampx priscus were caught in an avalanche of sediment 480 million years ago as they marched in a single-file line on the seafloor of what is now Morocco. The trilobites go marching one by one, hurrah, hurrah … well, at least they did, some 480 million years ago. New fossils from Morocco show lines of trilobites in orderly queues, likely buried by a storm as they trekked from one place to another under the Ordovician seas in an ancient game of "follow the leader." "I think people think that collective behavior is something new in the course of evolution, but actually sophisticated behavior started very, very early," said study leader Jean Vannier, a paleontologist at the University of Lyon in France. Vannier and colleagues from Marrakech, Morocco, discovered the trilobites in the southern part of Morocco in an area known for well-preserved fossils of animals from the early Ordovician, a geologic period that began about 485 million years ago and is one of six periods that make up the Paleozoic era.