Part of the Extreme Mammals exhibition.


The smallest mammal that ever lived could be sitting right on your shoulder and you would hardly know it. Batodonoides vanhouteni, which lived about 50 million years ago in what is now Wyoming, was so small that it could climb up a pencil--and it weighed as little as a dollar bill.

Paleontologist Jonathan Bloch found a tiny fossil jaw of Batodonoides. "Under a microscope, I realized I was looking at the smallest mammal teeth I had ever seen," Bloch said. Several slightly larger species of these mini-mammals lived between 55 and 42 million years ago, but they are now all extinct.

Fun Facts

  • The closest living relatives to Batodonoides are modern day shrews and moles.
  • The smallest mammal alive today is the bumblebee bat, which is only slightly larger than Batodonoides.
  • While Batodonoides is the smallest mammal ever, the largest animal--mammal or otherwise--is the blue whale, with a heart the size of a small car.