Mouse-like hamsters are a group of small rodents found in Syria, Azerbaijan, Iran, Turkmenistan, Afghanistan, and Pakistan. They are found in rocky outcrops and semi-mountainous area in desert regions.
The mouse-like hamsters are not true hamsters, but represent an early split from the rest of the mouse-like rodents. They were once thought to be hamsters based on the shape of their molars. They lack the cheek pouches, sebaceous flank glands, and short tail of the true hamsters. The closest relatives of mouse-like hamsters may be the fossil Cricetodontidae. Mouse-like hamsters have been placed in a family of their own, Calomyscidae, and have been referred to as living fossils.
All members of this genus were once considered part of the same species, Calomyscus bailwardi. They are now referred to as separate species due to major differences in chromosome number, skull measurements, and other features. There are almost certainly new species of mouse-like hamster yet to be described from places like Afghanistan and Iran.
Mouse-like hamsters hold the record for maximum life span among rodents. They have been recorded as living 9 years, 3 months and 18 days in captivity. They regularly live over 4 years in captivity.