''Stygimys'' is an extinct mammal

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

from the Upper

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

and

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...

of North America. It was a member of the extinct order

Multituberculata Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the Middle Jurassic, ...

within the

suborder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

Cimolodonta Cimolodonta is 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 eco ...

, family

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 Paleo ...

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

Leigh Van Valen Leigh Van Valen (August 12, 1935 – October 16, 2010) was a U.S. evolutionary biologist. At the time of his death, he was professor emeritus in the Department of Ecology and Evolution at the University of Chicago. Research and interests Amongs ...

1965 Events January–February * January 14 – The Prime Minister of Northern Ireland and the Taoiseach of the Republic of Ireland meet for the first time in 43 years. * January 20 ** Lyndon B. Johnson is Second inauguration of Lyndo ...

. The name comes from the

Styx In Greek mythology, Styx (; grc, Στύξ ) is a river that forms the boundary between Earth (Gaia) and the Underworld. The rivers Acheron, Cocytus, Lethe, Phlegethon, and Styx all converge at the centre of the underworld on a great marsh, ...

(river of hell) from

Greek mythology A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities of ...

. The genus has also been known as ''

Catopsalis ''Catopsalis'' is a genus of extinct mammal from the Paleocene of North America. This animal was a relatively large member of the extinct order of Multituberculata. Most Multituberculates were much smaller. At one time, the genus was also forma ...

'' (partly); ''

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 t ...

'' (partly); ''

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 know ...

'' (partly); and ''

Parectypodus ''Parectypodus'' (meaning "besides '' Ectypodus''") is an extinct genus of mammals that lived from Late Cretaceous (Maastrichtian) to Eocene time in North America. It is a member of the extinct order of Multituberculata, suborder Cimolodonta, f ...

'' (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 Events January * January 1 – The Bornean Sultanate of Brunei gains full independence from the United Kingdom, having become a British protectorate in 1888. * January 7 – Brunei becomes the sixth member of the Association of Southeast As ...

. Place:

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 (NALMA), spanning the interval from 66,000,000 to 63,300,000 years BP lasting . It is usua ...

(Paleocene)-age

strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as e ...

of Rav W-1 in

Saskatchewan Saskatchewan ( ; ) is a province in western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on the south by the U.S. states of Montana and North ...

, Canada. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

for this species is in the

University of Alberta The University of Alberta, also known as U of A or UAlberta, is a public research university located in Edmonton, Alberta, Canada. It was founded in 1908 by Alexander Cameron Rutherford,"A Gentleman of Strathcona – Alexander Cameron Ruth ...

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

1989 File:1989 Events Collage.png, From left, clockwise: The Cypress structure collapses as a result of the 1989 Loma Prieta earthquake, killing motorists below; The proposal document for the World Wide Web is submitted; The Exxon Valdez oil tanker ru ...

. 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 (June 16, 1902 – October 6, 1984) was an American paleontologist. Simpson was perhaps the most influential paleontologist of the twentieth century, and a major participant in the modern synthesis, contributing '' Tempo ...

1935 Events January * January 7 – Italian premier Benito Mussolini and French Foreign Minister Pierre Laval conclude an agreement, in which each power agrees not to oppose the other's colonial claims. * January 12 – Amelia Earhart bec ...

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 () is a U.S. state, state in the Mountain states, Mountain West List of regions of the United States#Census Bureau-designated regions and divisions, division of the Western United States. It is bordered by Idaho to the west, North ...

(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 Events January * January 15 – The Moon moves into its nearest point to Earth, called perigee, at the same time as its fullest phase of the Lunar Cycle. This is the closest moon distance at in recent history, and the next one will be ...

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

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interv ...

(Upper Cretaceous) - Puercan (Paleocene)-age strata of the

Polecat Bench Formation The Polecat Bench Formation is a geologic formation in Montana. It preserves fossils dating back to the Paleogene period.D. E. Russell. 1967. Le Paleocene continental d'Amerique du nord. Memoires du Museum National d'Histoire Naturelle. Serie C. ...

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 sou ...

and the

Hell Creek Formation The Hell Creek Formation is an intensively studied division of mostly Upper Cretaceous and some lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The formation stretches over portions of ...

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 This year marked the end of a period known in American history as the Roaring Twenties after the Wall Street Crash of 1929 ushered in a worldwide Great Depression. In the Americas, an agreement was brokered to end the Cristero War, a Catholi ...

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 The Torrejonian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages The North American land mammal ages (NALMA) establishes a geologic timescale for North American fa ...

(Paleocene)-age strata of the

San Juan Basin The San Juan Basin is a geologic structural basin located near the Four Corners region of the Southwestern United States. The basin covers 7,500 square miles and resides in northwestern New Mexico, southwestern Colorado, and parts of Utah ...

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

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

References

* (Most of the information in this article has been derived from this page.) * * * * * {{Taxonbar, from=Q7629326 Cimolodonts Cretaceous mammals Paleocene mammals Paleocene genus extinctions Cretaceous mammals of North America Hell Creek fauna Prehistoric mammal genera