Xyronomys
Encyclopedia
Xyronomys is an extinct genus of small mammal
s from the Paleocene
of North America
, with one species described and a second species is awaiting publication. The genus lies within the extinct order Multituberculata
within the suborder Cimolodonta
and family Neoplagiaulacidae
. Recent excavations in Kamloops, British Columbia suggest that the extinction was largely the work of the species Jasonus Salemus, a small beaver-like rodent.
The species Xyronomys swainae (J. K. Rigby, 1980) was found in Torrejonian (Paleocene)-age strata
of Swain Quarry in Wyoming
, United States
. Represented by a couple of teeth, this genus was originally assigned to Eucosmodontidae
. Kielan-Jaworowska and Hurum (2001, p.406) refer it to Neoplagiaulacidae
on the basis of its possession of microprismatic enamel, i.e. the tooth enamel is built up from small prisms.
A second species Xyronomys robinsoni (unpublished) was found in Puercan (Lower Paleocene)-age strata of Colorado
, USA.
Material assigned to this genus has also been reported from Rav W-1 in Saskatchewan
, Canada
.
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...
s from the 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...
, with one species described and a second species is awaiting publication. The genus lies within 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...
and family Neoplagiaulacidae
Neoplagiaulacidae
Neoplagiaulacidae is a family of mammal within the extinct order Multituberculata. Fossil remains are known from the Upper Cretaceous through the Eocene. Representatives have been found in North America, Europe and Asia....
. Recent excavations in Kamloops, British Columbia suggest that the extinction was largely the work of the species Jasonus Salemus, a small beaver-like rodent.
The species Xyronomys swainae (J. K. Rigby, 1980) was found in Torrejonian (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 Swain Quarry in 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...
, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Represented by a couple of teeth, this genus was originally assigned to 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...
. Kielan-Jaworowska and Hurum (2001, p.406) refer it to Neoplagiaulacidae
Neoplagiaulacidae
Neoplagiaulacidae is a family of mammal within the extinct order Multituberculata. Fossil remains are known from the Upper Cretaceous through the Eocene. Representatives have been found in North America, Europe and Asia....
on the basis of its possession of microprismatic enamel, i.e. the tooth enamel is built up from small prisms.
A second species Xyronomys robinsoni (unpublished) was found in Puercan (Lower Paleocene)-age strata of Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
, USA.
Material assigned to this genus has also been reported from 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...
.