Global warming throughout ancient history shrunk some animals — even yielding cat-size horses. With warming increasing, scientists are examining the possibility that it could happen again.  

For an article by the Mercury News, University of New Hampshire researcher Abigail D’Ambrosia says that mammals could shrink again in our future with man-made global warming.

According to the report, warm-blooded animals reduced in size significantly at least twice in Earth’s history as carbon dioxide and natural temperatures raised due to natural warming.

The animals shrunk in order to shed more heat. Smaller animals have more skin in comparison to their overall size than large animals, which allows them to release more heat.

The planet suddenly heated up 54 million years ago, resulting in several shriveling species.

One of the species was an early horse. According to an analysis of fossil teeth, the already compact horse shrunk by 14%, going from around 17 pounds to 14.6.

“They may have gone down to the size of a cat,” says D’Ambrosia.

A previous study revealed a similar effect on another horse ancestor 56 million years ago.

Both studies examined fossils found at Bighorn Basin in Wyoming.

“If we start to see patterns repeat themselves, we can learn from that,” says Jonathon Bloch, curator of vertebrate paleontology at the Florida Museum of Natural History.

“And what we learn from these lessons will certainly be important as we think about the possible response of plants and animals to future climate change.”