Researchers in China have found a major catch of fish fossils, including the oldest teeth from any species. The scientists describe some of the fossils, which are more than 400 million years old, in a series of studies published Wednesday. Researchers say the fossils can help us understand how ancient creatures evolved their jaws and teeth. When fish got their bite, it was a big moment for evolution and set our ancestors on a new path. But fossils showing this transition are rare. The discoveries in China include new fish species and the oldest teeth ever, which can help fill in the gaps in the fossil record.