Extinct order of rather rodent-like mammals, which appeared first in the late Jurassic in Europe, flourished during the Cretaceous and Palaeocene, but became extinct during the Eocene. Probably they were the first herbivorous mammals, with skull and teeth analogous to those of rodents. Most were small, but some attained the size of modern woodchucks. The limbs sprawled more widely than those of most mammals. The olfactory bulbs were large, which suggests that the animals depended heavily on their sense of smell. The skull was massive, but unlike that of other mammalian groups. The multituberculates appear to have been a side branch from the main line of mammalian evolution, and they are believed not to be related closely to other groups.