Cimexomys
Encyclopedia
Cimexomys is an extinct North America
n mammal
that lived from the Upper Cretaceous
to the Paleocene
. For a while, it shared the world with dinosaur
s, but outlived them. It was a member of the extinct order Multituberculata
and lies within the suborder Cimolodonta
. It is perhaps a member of the Paracimexomys group
, though it's not certain.
The genus Cimexomys ("bug mouse") was named by Sloan and Van Valen in 1965. Most remains are restricted to teeth. Synonyms include Eucosmodon
sp., Stygimys
sp. ("Styx mouse"), and possibly Mesodma
. "Cimex" means "bug", with reference to the type locality of Cimexomys minor in the Bug Creek Anthills in Montana
, USA.
The inclusion of C. in the Paracimexomys group
is tentative, (Kielan-Jaworowska & Hurum, 2001, p.403). Some species are termed here as "Cimexomys", and they're listed towards the end. New species have previously been christened with great enthusiasm, and much reidentification has also occurred.
in Colorado
(USA)
"C. arapohoensis is known from four dental and mandiblar fossils from the Alexander Locality of the Denver Formation (Colorado
) and is the largest known species of Cimexomyx. I estimated its mass at about 120 g based on its lower first molar." (Eric W. Dewar, 2002) C. minor has also been identified from this location.
Age: Puercan (Paleocene) of the Polecat Bench Formation in Wyoming
(USA). This animal weighed something like 130 g, about five mice or a third of a rat
.
of Montana
(USA). A near complete dentition and skeletal elements were discovered at Egg Mountain, a site associated with a dinosaur nesting colony, though this wasn't the original material. C. judithae is reportedly more derived than other species, and the integrity of the genus is suspect, (as reflected here by the later entries for "Cimexomys"). Montellano reassigned this species to the cimex genus in 1992. The body mass is estimated to have been around 20 g.
Based on the new material from Montana, the authors "argued that Cimexomys is too primitive to be included among either the Taeniolabidoidea
or Ptilodontoidea
. This agrees with our conclusion as we tentatively place Cimexomys in the informal "Paracimexomys group", which we erect for plesiomorphic (basal), poorly-known members of the Cimolodonta", (Kielan-Jaworowska & Hurum, 2001, p.393).
Age: Upper Cretaceous - Lower Paleocene
Place: Hell Creek Formation, Montana and Denver Formation, Colorado (USA) and Ravenscrag Formation, Saskatchewan
(Canada
). Remains are small teeth of an eighth to a tenth of an inch in length. The animal weighed about 25 g, the same as a standard mouse.
, Canada. It weighed about 30 g.
.
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...
n 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...
that lived 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...
to 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...
. For a while, it shared the world with dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s, but outlived them. 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...
and lies 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...
. It is perhaps a member of the Paracimexomys group
Paracimexomys group
The Paracimexomys group is a loose grade of extinct mammals which are known from the Lower Cretaceous and possibly through to the Paleocene of North America.They were members of an also extinct order called Multituberculata....
, though it's not certain.
The genus Cimexomys ("bug mouse") was named by Sloan and Van Valen in 1965. Most remains are restricted to teeth. Synonyms include 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...
sp., Stygimys
Stygimys
Stygimys is an extinct mammal genus from the Upper Cretaceous and Paleocene of North America. It was a member of the extinct order Multituberculata within the suborder Cimolodonta, family Eucosmodontidae....
sp. ("Styx mouse"), and possibly Mesodma
Mesodma
Mesodma is an extinct genus of mammal, a member of the extinct order Multituberculata within the suborder Cimolodonta, family Neoplagiaulacidae. It lived during the upper Cretaceous and Paleocene Periods of what is now North America...
. "Cimex" means "bug", with reference to the type locality of Cimexomys minor in the Bug Creek Anthills in 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.
The inclusion of C. in the Paracimexomys group
Paracimexomys group
The Paracimexomys group is a loose grade of extinct mammals which are known from the Lower Cretaceous and possibly through to the Paleocene of North America.They were members of an also extinct order called Multituberculata....
is tentative, (Kielan-Jaworowska & Hurum, 2001, p.403). Some species are termed here as "Cimexomys", and they're listed towards the end. New species have previously been christened with great enthusiasm, and much reidentification has also occurred.
Cimexomys arapahoensis
Age: Lower Paleocene of the Denver FormationDenver Formation
The Denver Formation is a geological formation in Colorado whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-Ornithischians:-Saurischians:-References:...
in 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)
"C. arapohoensis is known from four dental and mandiblar fossils from the Alexander Locality of the Denver Formation (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...
) and is the largest known species of Cimexomyx. I estimated its mass at about 120 g based on its lower first molar." (Eric W. Dewar, 2002) C. minor has also been identified from this location.
Cimexomys gratus
Also known as Cimexomys hausoi (Archibald 1982); Eucosmodon gratus (Jepsen, 1930); Mesodma? ambigua? (Jepsen, 1940), Stygimys gratus (Jepsen, 1930)Age: Puercan (Paleocene) of the Polecat Bench Formation 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...
(USA). This animal weighed something like 130 g, about five mice or a third of a rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
.
Cimexomys judithae
This species (Sahni A. 1972) is also known as Paracymexomys judithae (Archibald J.D. 1982). Fossils come from the Campanian (Upper Cretaceous) of the Two Medicine FormationTwo Medicine Formation
The Two Medicine Formation is a geologic formation, or rock body, that was deposited between 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma , during Campanian time, and is located in northwestern Montana...
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). A near complete dentition and skeletal elements were discovered at Egg Mountain, a site associated with a dinosaur nesting colony, though this wasn't the original material. C. judithae is reportedly more derived than other species, and the integrity of the genus is suspect, (as reflected here by the later entries for "Cimexomys"). Montellano reassigned this species to the cimex genus in 1992. The body mass is estimated to have been around 20 g.
Based on the new material from Montana, the authors "argued that Cimexomys is too primitive to be included among either the Taeniolabidoidea
Taeniolabidoidea
Taeniolabidoidea is a group of extinct mammals known from North America and Asia. They were the largest members of the also extinct order Multituberculata. Lambdopsalis even provides direct fossil evidence of mammalian fur in a fairly good state of preservation for a 60-million-year-old animal...
or Ptilodontoidea
Ptilodontoidea
Ptilodontoidea is a group of extinct mammals from the Northern Hemisphere.They were generally small, somewhat rodent-like creatures of the extinct order Multituberculata.Some of these genera boast a great many species, though remains are generally sparse....
. This agrees with our conclusion as we tentatively place Cimexomys in the informal "Paracimexomys group", which we erect for plesiomorphic (basal), poorly-known members of the Cimolodonta", (Kielan-Jaworowska & Hurum, 2001, p.393).
Cimexomys minor
(Sloan R.E. and Van Valen L. 1965)Age: Upper Cretaceous - Lower Paleocene
Place: Hell Creek Formation, Montana and Denver Formation, Colorado (USA) and Ravenscrag Formation, 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...
). Remains are small teeth of an eighth to a tenth of an inch in length. The animal weighed about 25 g, the same as a standard mouse.
"Cimexomys" antiquus
(Fox R.C. 1971). Fossils are known from the Santonian (Upper Cretaceous) of Utah. The type fossil is in AlbertaAlberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
, Canada. It weighed about 30 g.
Cimexomys gregoryi
Fossil remains of the species "Cimexomys" gregoryi (Eaton J.G. 1993) have been found in Campanian (Upper Cretaceous)-aged strata in the USA. This species shows similarities to the genus BryceomysBryceomys
Bryceomys is an extinct mammal that lived during the late Cretaceous period and thus shared the world with dinosaurs. It was a member of the also extinct order of Multituberculata...
.