The Old World rats and mice, part of the subfamily Murinae in the family Muridae, comprise at least 519 species. Members of this subfamily are called murines. In terms of species richness, this subfamily is larger than all mammal families except the Cricetidae and Muridae, and is larger than all mammal orders except the bats and the remainder of the rodents.
Description
The Murinae are native to Africa, Europe, Asia, and Australia. They are terrestrial placental mammals. They have also been introduced to all continents except Antarctica, and are serious pest animals. This is particularly true in island communities where they have contributed to the endangerment and extinction of many native animals.
Two prominent murine species have become vital laboratory animals: the brown rat and house mouse are both used as medical subjects.
The murines have a distinctive molar pattern that involves three rows of cusps instead of two, the primitive pattern seen most frequently in muroid rodents.
Fossils
The first known appearance of the Murinae in the fossil record is about 14 million years ago with the fossil genus Antemus. Antemus is thought to derive directly from Potwarmus, which has a more primitive tooth pattern. Likewise, two genera, Progonomys and Karnimata, are thought to derive directly from Antemus. Progonomys is thought to be the ancestor of Mus and relatives, while Karnimata was previously thought to lead to Rattus and relatives, although it is now thought to be a member of the extant tribe Praomyini. All of these fossils are found in the well-preserved and easily dated Siwalik fossil beds of Pakistan. The transition from Potwarmus to Antemus to Progonomys and Karnimata is considered an excellent example of anagenic evolution.
Taxonomy
Most of the Murinae have been poorly studied. Some genera have been grouped, such as the hydromyine water rats, conilurine or pseudomyine Australian mice, or the phloeomyine Southeast Asian forms. It appears as if genera...
