The invasion of grass may have been the reason many beasts of the Ice Age underwent mass extinction. Woolly rhinoceros and mammoths died out thanks to this change in source of nutrition.
Many plausible hypotheses have been offered by science as to why the woolly beasts of the Ice Age died. But a recent twist in the knowledge points towards radical changes in their food supply as being a major reason. 10,000 years ago the usual flora that these fauna feasted upon withered away.
They included forbs which vanished and in whose place grasses came along. This invasion of grassland caused the deaths from malnutrition of many of the mammoths and woolly rhinoceros. The habitats of these huge fur-covered animals were Siberia, Canada and Alaska. They thrived on flowering species as is evident from their scatological remains.
But with the rampant arrival of the grasses and similar forms of vegetation, the animals got confused from a gastrointestinal point of view. They couldn’t digest the new and strange food source. Every form of fauna from woolly rhinoceros to mammoths, reindeer, elk and horses began to go extinct. The forbs which included tansies, sagebrush, mums and yarrow were their mainstay.
With a major part of the standard diet of these huge lumbering creatures gone out the window, it was a virtual death sentence for them. The end of the wide variety of flowers and the incoming grasslands was something for which they had not been prepared. They couldn’t accommodate and probably were unable to assimilate the grass.