News.Umich.Edu
The Paleocene-Eocene Thermal Maximum, or PETM, was a short interval of highly elevated global temperatures 56 million years ago that is frequently described as the best ancient analog for present-day

climate warming.

Fish are among the organisms thought to be most sensitive to warming climates,

and tropical sea-surface temperatures during the PETM likely approached temperatures that are lethal to some modern marine fish species, according to some estimates.

But newly discovered fish fossils from an eastern Egyptian desert site show that marine fishes thrived in at least some tropical areas during the PETM. The study, from a team of Egyptian scientists and a University of Michigan colleague, provides a snapshot of an ecosystem during an extreme warming event and may provide insights for the future.

“The impact of the PETM event on life at the time is of wide interest. But a major gap in our understanding is how life in the tropics responded, because this region is not well-sampled for many fossil groups,” said U-M paleontologist Matt Friedman, co-author of a study published online May 17 in the journal Geology.

“On the basis of the scant evidence we have for fishes—remembering that this Egyptian site provides our first peek from the tropics—they seem to have weathered the PETM surprisingly well, and there are even hints that important diversification in the group might have happened around or just after this time,” said Friedman, director of U-M’s Museum of Paleontology and an associate professor in the Department of Earth and Environmental Sciences.

The lead author of the Geology paper is Sanaa El-Sayed of Egypt’s Mansoura University, an Egyptian paleontologist who will be an incoming University of Michigan doctoral student this fall.