Could Rising Temperatures Mean Smaller Mammals?

February 24, 2012

Teeth of miniature dog-sized horse that lived in Wyoming 56 million years ago.

Scientists say in the ancient past, higher temperatures meant smaller mammals. They’re studying how a brief, but dramatic climate change event affected body size.

It’s called the Paleocene-Eocene Thermal Maximum or PETM for short. It took place 56 million years ago and lasted about 175,000 years. That’s a long time in human terms, but a blink of an eye in the geological record.

Jonathan Bloch said a lot happened back then.

“We had known it was a really unique event for a while in the sense that it was a very rapid, large scale global warming event. And it marks one of the most important moments in mammalian evolution in the sense that we see the first occurrence of several modern orders of mammals, including the primates that are clearly traceable as the direct ancestors of the group that we’re a part of, as well as the ancestors of horses, the ancestors of cows and hippos and camels,” he said.

Jonathan Bloch of the Florida Museum of Natural History

Bloch is associate curator of vertebrate paleontology at the Florida Museum of Natural History at the University of Florida. He and colleagues from eight institutions were collecting fossils in the state of Wyoming’s Bighorn Basin.

Tiny horses