It's a longstanding puzzle: Were dinosaurs lumbering cold-blooded animals or swift warm-blooded creatures?

The answer, according to a new paper in Science co-authored by SFI External Professor Brian Enquist, is neither. Instead, dinosaurs took a middle path between warm-blooded mammals, or endotherms, and cold-blooded reptiles, or ectotherms.

"Our study shows that dinosaurs did not fit into this current dichotomy of warm- versus cold-blooded," says Enquist, a professor in the University of Arizona's Department of Ecology and Evolutionary Biology. "Instead, their metabolism was somewhere in between."

The researchers derived their results by estimating growth rates from fossils, then estimating metabolic rates from growth rates.

Read the paper in Science (June 13, 2014, subscription required for full text)

Read an analysis of the paper in Science (June 13, 2014)

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Listen to the story on NPR's All Things Considered (June 12, 2014)

Read the article in the Washington Post (June 16, 2014)

Read the article in Nature (June 12, 2014)

Read the article in The Huffington Post (June 12, 2014)