Tertiary Rodent Faunas of Other Continents

Abstract

As in North America, the earliest rodents from Europe (Sparnacian) belonged to primitive Ischyromyidae (Godinot, 1981) (Table 25.1). These ischyromyids were likely immigrants. By the end of the early Eocene (Cuisian) there were also representatives of the hystricomorphous-sciuromorphous family Theri-domyidae and myomorphous Gliridae (Savage and Russell, 1983). The glirids were derived from a reithroparamyine ancestor (Microparamys) in Europe (Hartenberger, 1971) but the origin of theridomyids is uncertain (Hartenberger, 1969). This proportion of rodents, numerous ischyromyids and rare glirids and theridomyids, was maintained until the later Eocene (Robiacian) when theridomyids began to rapidly diversify, glirids increased in number, and ischyromyids were greatly reduced in diversity.