Frigid Polar Oceans, Not Coral Reefs, Are Hot Spots for Formations of Fish Species

During the past several million years, cool-water and polar-ocean fishes formed new species twice as fast as the average species of tropical fish, according to the new study, published in the journal Nature.

Lauren Sallan of Penn collaborated with a team from the University of Michigan that led the work, compiling one of the largest fossil fish datasets to date in order to time-calibrate the fish evolutionary tree.

“By using fossils of the earliest ancestors of modern fish, we can get the date around when they showed up on the face of the earth,” says Sallan, the Martin Meyerson Assistant Professor in Interdisciplinary Studies in Penn’s Department of Earth and Environmental. “The fossils help tell us how fast or slow different groups of fish evolved.”

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