Between 18 million and 12 million years ago, the Great Plains supported an unprecedented variety of hooved mammal species that browsed on leafy vegetation—up to three times more than in any modern ecosystem, including the densest rainforests. That diversity, ecologists figured, could only have emerged in a landscape similarly blanketed with woody, foliage-rich vegetation that employed a form of photosynthesis, C3, favored by roughly 85% of plant species.
Click here for original story, Mammal enamel: Toothy analysis identifies vegetation of ancient Nebraska
Source: Phys.org