Prehistoric fish fossil in Canada offers clues to evolution of catfish and carp

A tiny prehistoric fish fossil discovered in Canada is providing new insights into the evolution of a major group of freshwater fish. The 100-million-year-old fossil, named Acronichthys maccognoi, is the oldest North American member of the otophysan supergroup, which includes catfish and carp. This discovery suggests the transition from marine to freshwater environments for this fish group may have occurred at least twice, offering clues to the origins of two-thirds of all freshwater species.