DNA analysis of fossilized woolly mammoth stomach contents shows that they mainly subsisted on small, nutritious flowering plants called forbs. Modern-day examples of forbs include clover, sunflowers and dandelions.
Woolly mammoths lived in the Arctic during the ice age. In 2014, those regions are covered by tundra, which consists mostly of grasses and woody plants that are low in nutrition. Paleontologists did not believe that these plants were enough to sustain large animals like the mammoth, so they studied the DNA of preserved stomach contents and droppings. Although many of these ancient plants are extinct, their DNA is close enough to existing plants to identify them as belonging to the same families.
According to paleontologist Grant Zazula, the ancient Arctic was probably arid and cold, similar to many high mountain meadows in 2014. Similar plants probably thrived back then, including the prehistoric versions of sunflowers, watercress, alfalfa and carrots. Although they were small, these plants were nutritious enough to nourish the mammoths, along with other large prehistoric animals like woolly rhinos and bison. When the climate changed to the wetter tundra that covers the region today, the grasses and fibrous plants that took over were not enough to sustain the mammoths and this likely contributed to their extinction. It also allowed animals like elk and caribou to thrive.