Stygimys is an extinct mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

 genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 from the Upper Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 and Paleocene

Paleocene

The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

 of North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. It was a member of the extinct order Multituberculata

Multituberculata

The Multituberculata were a group of rodent-like mammals that existed for approximately one hundred and twenty million years—the longest fossil history of any mammal lineage—but were eventually outcompeted by rodents, becoming extinct during the early Oligocene. At least 200 species are...

 within the suborder Cimolodonta

Cimolodonta

The Cimolodonta are a taxon of extinct mammals that lived from the Cretaceous to the Eocene. They were some of the more derived members of the extinct order Multituberculata. They probably lived something of a rodent-like existence until their ecological niche was assumed by true rodents...

, family Eucosmodontidae

Eucosmodontidae

Eucosmodontidae is a poorly preserved family of fossil mammals within the extinct order Multituberculata. Representatives are known from strata dating from the Upper Cretaceous through the Lower Eocene of North America, as well as the Paleocene to Eocene of Europe. The family is part of the...

.

The genus Stygimys ("Styx mouse") was named by R.E. Sloan and Leigh Van Valen

Leigh Van Valen

Leigh Maiorana Van Valen was an American evolutionary biologist. He was professor emeritus in the Department of Ecology and Evolution at the University of Chicago....

 in 1965

1965 in paleontology

-Newly named dinosaurs:Data courtesy of George Olshevsky's dinosaur genera list and Dr. Jeremy Montague's dinosaur genus database.-New taxa:-Non-mammalian:...

. The name comes from the Styx

Styx (mythology)

The Styx is a river in Greek mythology that formed the boundary between Earth and the Underworld . It circles the Underworld nine times...

 (river of hell) from Greek mythology

Greek mythology

Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

. The genus has also been known as Catopsalis

Catopsalis

Catopsalis is a genus of extinct mammal from the Paleocene of North America, though some Canadian finds may be upper Cretaceous. This animal was a relatively large member of the extinct order of Multituberculata. Most Multituberculates were much smaller....

(partly); Cimexomys

Cimexomys

Cimexomys is an extinct North American mammal that lived from the Upper Cretaceous to the Paleocene. For a while, it shared the world with dinosaurs, but outlived them. It was a member of the extinct order Multituberculata and lies within the suborder Cimolodonta...

(partly); Eucosmodon

Eucosmodon

Eucosmodon is a genus of extinct mammal from the Paleocene of North America. It is a member of the extinct order of Multituberculata within the suborder of Cimolodonta, and the family Eucosmodontidae. This genus has partly also been known as Neoplagiaulax...

(partly); and Parectypodus

Parectypodus

Parectypodus is a genus of extinct mammal that lived from the Paleocene to the Eocene of North America. Some of the known fossil material may also be from the Upper Cretaceous. It was named by G.L. Jepsen in 1930....

(partly). Some skull material is known, but not much.

Species

The species Stygimys camptorhiza was named by P.A. Johnston and R.C. Fox in 1984.
Place: Puercan

Puercan

The Puercan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 65,000,000 to 63,300,000 years BP lasting . It is usually considered to be within the Paleocene...

 (Paleocene)-age strata

Stratum

In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...

 of Rav W-1 in Saskatchewan

Saskatchewan

Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....

, Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

. The holotype

Holotype

A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 for this species is in the University of Alberta

University of Alberta

The University of Alberta is a public research university located in Edmonton, Alberta, Canada. Founded in 1908 by Alexander Cameron Rutherford, the first premier of Alberta and Henry Marshall Tory, its first president, it is widely recognized as one of the best universities in Canada...

 collection.

The species Stygimys cupressus was named by R.C. Fox in 1989

1989 in paleontology

-Newly named dinosaurs:Data courtesy of George Olshevsky's dinosaur genera list and Dr. Jeremy Montague's dinosaur genus database.-New taxa:-New taxa:-Non-mammalian:-References:...

. Remains are known from the Puercan (Paleocene)-age strata of the Long Fall Horizon of Canada.

The species Stygimys jepseni was named by George Gaylord Simpson

George Gaylord Simpson

George Gaylord Simpson was an American paleontologist. Simpson was perhaps the most influential paleontologist of the twentieth century, and a major participant in the modern evolutionary synthesis, contributing Tempo and mode in evolution , The meaning of evolution and The major features of...

 in 1935

1935 in paleontology

-Dinosaurs:* Charles Gilmore returned to prospect for fossils in the Two Medicine Formation.-New taxa:-Non-mammalian:-References:* Trexler, D., 2001, Two Medicine Formation, Montana: geology and fauna: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University...

 and Sloan and Van Valen in 1965. It is also known as Eucosmodon sparsus (Simpson 1937a); E. jepseni; and Parectypodus jepseni (Simpson 1935d). Remains are known from the Torrejonian (Paleocene)-age strata of Montana

Montana

Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...

 (USA). This species has been cited as a descendant of S. kuszmauli. The animal weighed about 90 g.

The species Stygimys kuszmauli was named by R.E. Sloan and Leigh Van Valen in 1965. It has also been known as Catopsalis foliates (Cope 1882); Cimexomys gratus (Jepsen GL, 1930

1930 in paleontology

-Newly named dinosaurs:-New taxa:-Non-mammalian:...

); Eucosmodon gratus (G.L. Jepson 1930); Eucosmodon kuszmauli ; and Stygimys gratus. Remains were found in Maastrichtian

Maastrichtian

The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...

 (Upper Cretaceous) - Puercan (Paleocene)-age strata of the Polecat Bench Formation of Wyoming

Wyoming

Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...

 and the Hell Creek Formation

Hell Creek Formation

The Hell Creek Formation is an intensely-studied division of Upper Cretaceous to lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana...

 of Montana. Some scraps of jaw are known. This species is the most basal member of the genus, with a weight of 300 g.

The species Stygimys teilhardi was named by W. Granger & George Gaylord Simpson in 1929

1929 in paleontology

-Newly named crustacean taxa:-Newly named insect taxa:-Newly named dinosaurs:Data courtesy of George Olshevsky's dinosaur genera list and Dr. Jeremy Montague's dinosaur genus database.-Non-mammalian:-References:...

 and R.E. Sloan and Leigh Van Valen in 1965. It has also been known as Eucosmodon teilhardi (Granger W. & Simpson G.G. 1929). Remains are known from the Torrejonian

Torrejonian

The Torrejonian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 63,300,000 to 60,200,000 years BP lasting . It is usually considered to overlap the Selandian and Thanetian within the...

 (Paleocene)-age strata of the San Juan Basin

San Juan Basin

The San Juan Basin is a geologic structural basin in the Four Corners region of the Southwestern United States; its main portion covers around , encompassing much of northwestern New Mexico, southwest Colorado, and parts of Arizona and Utah....

 of New Mexico

New Mexico

New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...

. This species has been cited as a possible descendant of S. kuszmauli.