Porcupines are large rodents with coats of sharp spines, or quills, that protect them against predation. The term covers two families of animals: the Old World porcupines of the family Hystricidae, and the New World porcupines of the family Erethizontidae. Both families belong to the infraorder Hystricognathi within the profoundly diverse order Rodentia and display superficially similar coats of rigid or semi-rigid quills, which are modified hairs composed of keratin. Despite this, the two groups are distinct from one another and are not closely related to each other within the Hystricognathi. The largest species of porcupine is the third-largest living rodent in the world, after the capybara and beaver.
The pacarana is a rare and slow-moving hystricognath rodent indigenous to South America. Native Tupi people call it the pacarana because it is superficially similar to the paca, a different rodent which is not in the same family. The pacarana has a chunky body and is large for a rodent, weighing up to 15 kg (33 lb) and measuring up to 79 cm in length, not including the thick, furry tail.
Mammalia is a class of animal within the phylum Chordata. Mammal classification has been through several iterations since Carl Linnaeus initially defined the class. No classification system is universally accepted; McKenna & Bell (1997) and Wilson & Reader (2005) provide useful recent compendiums. Many earlier ideas from Linnaeus et al. have been completely abandoned by modern taxonomists, among these are the idea that bats are related to birds or that humans represent a group outside of other living things. Competing ideas about the relationships of mammal orders do persist and are currently in development. Most significantly in recent years, cladistic thinking has led to an effort to ensure that all taxonomic designations represent monophyletic groups. The field has also seen a recent surge in interest and modification due to the results of molecular phylogenetics.
The Hystricognathi are an infraorder of rodents, distinguished from other rodents by the bone structure of their skulls. The masseter medialis passes partially through a hole below each eye socket and connects to the bone on the opposite side. This, together with their lack of an infraorbital plate and the relative size of the infraorbital foramen, distinguishes hystricognaths from other rodent groups.
The Dinomyidae are a family of South American hystricognath rodents: the dinomyids were once a very speciose group, but now contains only a single living species, the pacarana. Several of the extinct dinomyids were among the largest rodents known to date; these included the bison-sized Josephoartigasia monesi and the smaller Josephoartigasia magna. The dinomyids are thought to have occupied ecological niches associated with large grazing mammals due to their ability to compete with the native ungulates of South America. On the other side, they could feed on aquatic or swampy plants along the ancient rivers. These large forms disappeared after the formation of a connection to North America. The modern pacarana is only modest in size, considerably smaller than the capybara.
Hutias are moderately large cavy-like rodents of the subfamily Capromyinae that inhabit the Caribbean islands. Most species are restricted to Cuba, but species are known from all of the Greater Antilles, as well as The Bahamas and (formerly) Little Swan Island off of Honduras.
The rodent parvorder or infraorder Phiomorpha comprises several living and extinct families found wholly or largely in Africa. Along with Anomaluromorpha and perhaps the extinct Zegdoumyidae, it represents one of the few early colonizations of Africa by rodents.
The term Hystricomorpha has had many definitions throughout its history. In the broadest sense, it refers to any rodent with a hystricomorphous zygomasseteric system. This includes the Hystricognathi, Ctenodactylidae, Anomaluridae, and Pedetidae. Molecular and morphological results suggest the inclusion of the Anomaluridae and Pedetidae in Hystricomorpha may be suspect. Based on Carleton & Musser 2005, these two families are discussed here as representing a distinct suborder Anomaluromorpha.
Geocapromys is a genus of rodent belonging to the hutia subfamily and are currently only found on the Bahamas and Jamaica. However, they formerly ranged throughout the Caribbean, from Cuba to the Cayman Islands to even islands off mainland Central America.
Owl's spiny rat is a rodent species in the family Echimyidae found in Brazil. It is the only species in the genus Carterodon. Owl's spiny rat has evolved characteristics such as a heightened ability to dig in open grasslands during times of environmental change.
The tuft-tailed spiny tree rat is a spiny rat species from Brazil south of the Amazon River, where it has been found in grassland and gallery forest. It is the only species in the genus Lonchothrix. Very little is known about this rodent. It is small with an average adult weight of about 138 grams. It is nocturnal and solitary in habits.
Dactylomys is the genus of South American bamboo rats They are arboreal members of the family Echimyidae.
Diplomys is a genus of rodent in the family Echimyidae. They are found in Costa Rica, Ecuador, Colombia and Panama.
The armored rat is a species of rodent in the family Echimyidae. It is monotypic within the genus Hoplomys. It is found in Latin America, from northern Honduras to northwest Ecuador. It possesses a range of spines on its back and sides of the body.
Mesocapromys is a genus of rodent in the subfamily Capromyinae. The genus is restricted to Cuba and associated islands.
Plagiodontia is a genus of rodent in the subfamily Capromyinae (hutias). All known species are endemic to the Caribbean island of Hispaniola.
Pattonomys is a genus of rodent in the family Echimyidae, named after American mammalogist James L. Patton. It contains the following species:
Clyomys is a South American rodent genus in the family Echimyidae. It contains two species, found in tropical savannas and grasslands from circa 100 m (300 ft) to 1,100 m (3,600 ft) elevation in central Brazil and eastern Paraguay.
Echimyidae is the family of neotropical spiny rats and their fossil relatives. This is the most species-rich family of hystricognath rodents. It is probably also the most ecologically diverse, with members ranging from fully arboreal to terrestrial to fossorial to semiaquatic habits. They presently exist mainly in South America; three members of the family also range into Central America, and the hutias are found in the West Indies in the Caribbean. Species of the extinct subfamily Heteropsomyinae formerly lived on Cuba, Hispaniola, and Puerto Rico in the Antilles.
Echimyini is a tribe of echimyid rodents, proposed in 2016, and containing 13 extant genera: all of the tree rats Echimys, Phyllomys, Makalata, Pattonomys, Toromys, Diplomys, Santamartamys, and Isothrix, the long recognized dactylomines Dactylomys, Olallamys, and Kannabateomys, and the enigmatic and previously classified as eumysopines Lonchothrix and Mesomys. All these spiny rats genera are arboreal. Worth of note, the arboreal genus Callistomys – the painted-tree rat – does not belong to the tribe Echimyini. Because it is phylogenetically closer to Myocastor, Hoplomys, Proechimys, and Thrichomys than to the above-mentioned Echimyini genera, it is classified in the tribe Myocastorini.
