As traditionally defined the genus was very species-rich, ranging through Europe, Asia and North America, but this arrangement was found to be
paraphyletic to the certainly distinct prairie dogs (
Cynomys), marmots (
Marmota), and antelope squirrels (
Ammospermophilus). As a consequence, all the former
Spermophilus species of North America have been moved to other genera, leaving the European and Asian species as true
Spermophilus (the only exceptions being the two Asian
Urocitellus species). The exact relations between these clades are slightly unclear. According to Simonov et al. (2024),
Spermophilus consists of 18 species. Also according to this study, the genus can be divided into four major clades that diverged during the
Late Miocene. }}
Extinct species Discovery and examination of one of the best preserved Eurasian ground squirrel fossils yet recovered allowed the study of many previously unknown aspects of ground squirrel cranial anatomy, and prompted a critical reassessment of their phylogenetic position. As a result, three
Pleistocene species previously considered members of the
Urocitellus genus were moved to
Spermophilus: :*
†Spermophilus nogaici :*
†Spermophilus polonicus :*
†Spermophilus primigenius In addition to the recent species, three now-extinct species are known from the Pleistocene of Europe:
Spermophilus citelloides is known from the Middle Pleistocene to early Holocene of central Europe. It appears to be most closely related to the living
S. suslicus.
Spermophilus severskensis is known from the late Pleistocene (
Weichselian) of the
Desna area, Ukraine. It appears to have been a highly specialised grazer and close relative of the living
S. pygmaeus.
Spermophilus superciliosus is known from the Middle Pleistocene to reportedly the early 20th century, with a vast range across much of Europe, from southern England to the
Volga and the
Ural Mountains. It was similar in size to the recent
S. major, and a probable ancestor of
S. fulvus. ==Relationship with humans==