One of the most influential studies of the pace of evolutionary change was pub- lished in 1971 by two young paleontologists at the American Museum of Natural History named Niles Eldredge and Stephen Jay Gould. They pointed out that the fossils of a typical species showed few signs of change during its lifetime. New species branching off from old ones had small but distinctive differences. Eldredge carefully documented this stasis in trilobites, an extinct lineage of armored arthropods. He counted the rows of columns in the eyes of each sub- species. He found that they did not change over six million years. Eldredge and Gould proposed that.
