''Armintomys'' is an extinct genus of

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

from North America related to

jerboa Jerboas (from ar, جربوع ') are hopping desert rodents found throughout North Africa and Asia, and are members of the family Dipodidae. They tend to live in hot deserts. When chased, jerboas can run at up to . Some species are preyed on b ...

s and jumping mice. It is the only genus in the family Armintomyidae. It lived during the early

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

, and is the oldest known example of a hystricomorphous zygomasseteric dentition. In addition, Armintomys is also the oldest known rodent that had an incisor enamel transition from pauciserial to uniserial. Its remains have only been found in the

Wind River Basin The Wind River Basin or Shoshone Basin is a semi-arid intermontane foreland basin in central Wyoming, United States. It is bounded by Laramide uplifts on all sides. On the west is the Wind River Range and on the North are the Absaroka Range and t ...

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the s ...

, and could be found there during the species' existence on

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. It was previously assumed that Armintomys belonged to the

Dipodoidea Dipodoidea is a superfamily of rodents, also known as dipodoids, found across the Northern Hemisphere. This superfamily includes over 50 species among the 16 genera in 3 families. They include the jerboas (family Dipodidae), jumping mice (fa ...

family, but has since been understood to have been part of an early radiation of dipodoid rodents, but was not directly ancestral to any later dipodoids, thus it was recategorized into its own family.

References

Eocene rodents Eocene mammals of North America Fossil taxa described in 1990 {{paleo-rodent-stub