The rodent subfamily Sigmodontinae includes New World rats and mice, with at least 376 species. Many authorities include the Neotominae and Tylomyinae as part of a larger definition of Sigmodontinae. When those genera are included, the species count numbers at least 508. Their distribution includes much of the New World, but the genera are predominantly South American, such as brucies. They invaded South America from Central America as part of the Great American Interchange near the end of the Miocene, about 5 million years ago. Sigmodontines proceeded to diversify explosively in the formerly isolated continent. They inhabit many of the same ecological niches that the Murinae occupy in the Old World.
Pagaibamba Protection Forest is a protected natural area in the region of Cajamarca, Peru. The area was declared a protection forest in order to preserve the water supply of surrounding towns, preserve the water cycle of the area, protect road infrastructure and protection of soils by preventing erosion.
The ash-colored Oldfield mouse is a species of rodent in the genus Thomasomys. It is found in montane forests of the Department of Cajamarca in northern Peru, at elevations of 1,524 to 3,818 metres. Until 2023, it was thought to be more widely distributed, ranging into southern Ecuador, but these populations are now identified as three separate, closely related species, T. lojapiuranus, T. pagaibambensis, and T. shallqukucha.
Daphne's Oldfield mouse is a species of rodent in the family Cricetidae. It is found in Bolivia and Peru.
Rosalinda's Oldfield mouse is a species of rodent in the family Cricetidae. It is found only in Peru.
Oryzomyini is a tribe of rodents in the subfamily Sigmodontinae of the family Cricetidae. It includes about 120 species in about thirty genera, distributed from the eastern United States to the southernmost parts of South America, including many offshore islands. It is part of the clade Oryzomyalia, which includes most of the South American Sigmodontinae.
The Apeco Oldfield mouse is a species of rodent in the family Cricetidae. It is known only from a single locality in north central Peru, which includes Rio Abiseo National Park, where it was found in cloud forest at an elevation of 3300 m. The species name comes from the acronym for the Asociacion Peruana para la Conservacion de la Naturaleza. It is among the largest members of the genus.
The cinnamon-colored Oldfield mouse, also called the "cinnamon-colored Thomasomys", is a species of rodent in the family Cricetidae. It is present in the Cordillera Oriental of the Andes from north central Ecuador to southern Colombia, at elevations from 2,400 to 3,800 m. It has terrestrial habits, and has been found in cloud forest and mossy areas. It was formerly considered a subspecies of T. gracilis.
The large-eared Oldfield mouse is a species of rodent in the family Cricetidae. It is known only from a single locality in the Andes in north central Peru, in montane forest at an elevation of 3300 m. It has terrestrial habits and is sympatric with T. apeco.
The Popayán Oldfield mouse, also called the "Popayán thomasomys", is a species of rodent in the family Cricetidae. It is present in the Andes of southwestern and central western Colombia, at elevations from 1800 to 3200 m. It has been found in páramo, montane forest, and secondary forest. It was formerly considered a subspecies of T. aureus. T. nicefori, presently considered a synonym, will likely be raised to the status of a separate species. The specific name comes from the Colombian city of Popayán.
The Cajamarca Oldfield mouse is a species of rodent in the family Cricetidae. It is present in the Andes of northwestern Peru, where its habitats include shrubby páramo, montane forest, and secondary forest. The rodent is nocturnal and may be partly arboreal. It was formerly considered a subspecies of T. aureus. The common name comes from the Peruvian city and region of Cajamarca.
Thomasomys ucucha, also known as the ucucha thomasomys, is a rodent in the genus Thomasomys of the family Cricetidae. It is known only from high altitude forest and grassland habitats in the Cordillera Oriental of Ecuador. Seven other species of Thomasomys live in the same areas. First collected in 1903, T. ucucha was formally described as a new species in 2003 and most closely resembles T. hylophilus, which occurs further to the north. The species is listed as "vulnerable" in the IUCN Red List as a result of habitat destruction.
In anatomy, posterolateral palatal pits are gaps at the sides of the back of the bony palate, near the last molars. Posterolateral palatal pits are present, in various degrees of development, in several members of the rodent family Cricetidae. Many members of the family lack them or have only simple pits, but Arvicolinae and Oryzomyini have more highly developed posterolateral palatal pits. Posterolateral palatal pits are also present in some other rodents, including Glis, Jaculus, Hystrix, Abrocoma, Ctenomys, Chinchilla, and Lagidium.
Rhagomys is a genus of South American rodents in the tribe Thomasomyini of the family Cricetidae. Two species separated by about 3100 km are known, from southeast Peru and Bolivia east of the Andes, and in the Atlantic Forest of southeast Brazil. An undetermined species of Rhagomys has also been reported from Mato Grosso in central Brazil. The species are as follows:
Bibimys chacoensis is a species of small rodent of the family Cricetidae living in the north-central part of Southern Cone of South America. The common name of this species is Chaco crimson-nosed rat. It is one of the three species currently recognized under the genus Bibimys.
Anderson's Oldfield mouse is a species of rodent in the family Cricetidae.
Antonio Brack's Oldfield mouse is a species of sigmodontine rodent in the family Cricetidae known from Peru. The species is named after Peruvian ecologist Antonio Brack Egg.
Thomasomys lojapiuranus is a species of rodent in the genus Thomasomys known from Peru and Ecuador. It consists of populations that were identified as Thomasomys cinereus until they were identified as a new species in 2023.
Thomasomys shallqukucha is a species of rodent in the genus Thomasomys known from the Andes of northern Peru. It consists of populations that were identified as Thomasomys cinereus until they were identified as a new species in 2023.
Thomasomys pagaibambensis is a species of rodent in the genus Thomasomys known from the Andes of northern Peru. It consists of populations that were identified as Thomasomys cinereus until they were identified as a new species in 2023.
