This doesn't seem too far off from reality since a lot of Arctic people such as the Inuit, Eskimo and Sami people eat the lichens from the contents of caribou stomach and this during the winter times is where they get the majority of their plant material. Bitter root plant material found on teeth of Neanderthals suggests their complex diet may have included the stomach contents of hunted animals. http://www.sci-news.com/othersciences/anthropology/science-neanderthals-stomach-contents-01475.html