Caviomorpha

Wild guinea pigs (Cavia aperea )

The guinea pig relatives ( Caviomorpha ) are a group of more diverse, belonging to the porcupine relatives rodents that occur initially exclusively on the Americas.

Features

The unique large rodents within the diversity of the guinea pig relatives is a result of long isolation of the South American continent and the variety of ecological niches occupied by. The group includes many smaller species but, with the Capybara also the largest living rodent in the world. Some species have a silky, soft fur, others have often evolved into spines bristling hair. Some animals are reminiscent of rabbits, rats, others are similar, yet others possess them an own appearance.

The bit has the typical for rodents toothless gap between rodent teeth and molars. Upper and lower jaws contain per jaw half a life renewable incisor tooth and a front and rear three molars. Canines are absent, as with all rodents. The dental formula is 1 0 1 3 = 20

Way of life

Most guinea pig relatives live on the ground, others in trees, on land or in the water. It is almost exclusively herbivorous, but some also feed on insects and larger prey. The grass -eating species are considered South American counterpart is essential for the African ecosystem ungulates. There are both individually as living in large colonies species.

The gestation period is usually long, there are only a few pups per litter and the level of development at birth is quite high. Especially the young of larger species comes with an existing skin and eyes open to the world; many pups can run after a few hours and a short time later from the mother regardless.

Occurrence

Except for the chemical also found in Canada and the United States Urson the guinea pig relatives are limited in their natural range in South and Central America including the West Indies. The nutria was introduced outside of this area. They are found in a variety of habitats: forests and grasslands, river banks and rocky deserts, coastal plains and high mountains.

Some species are common, extinct, some long time and others were only recently eradicated by humans. This provides many relatives in guinea pigs for their meat, their fur; some species are considered pests or disease carriers. The natural predators of the larger species ( Pacas, agoutis, capybaras Pacarana and Viscacha ) include large and medium sized predators such as jaguar, ocelot, pampas cat, maned wolf, bush dog and South American foxes.

Baumstachlerartige

The Baumstachlerartigen ( superfamily Erethizontidae ) are larger rodents, whose back hair have evolved into spines and resemble the outward porcupines. There are spread over almost the entire Americas, with the exception of the islands animals. They only exist which include the Borstenbaumstachler are counted from the family of porcupines.

Guinea pig -like

The guinea pig -like ( superfamily Cavioidea ) are medium to large-sized rodents with a body length of 22.5 to 130 cm, which are adapted to running. The thorax is more or less keeled, narrow sternum and the clavicle is regressed. With the exception of authentics guinea pig 's limb are slim and tall with keels on the main joints. The lateral front and rear toes tend to regress. Because of their more or less hufartig trained claws, they were once called " Hufpfötler ". The tail is short and stubby and bounds. This group includes the Pacas, the agoutis and Acouchis and guinea pigs. They are widespread throughout South and Central America, but not to the West Indies.

Chinchilla -like

The Chinchilla -like ( superfamily Chinchilloidea ) include the very different Pakaranas and chinchillas. There are larger, more widespread in the western and southern South America rodents.

Mirage -like rats

The mirage -like rats ( superfamily Octodontoidea ) are external rat-like, small to medium sized rodents. These include chinchilla rat, rat deceit, comb rats, barbed rat, coypu and tree rats. They are originally spread throughout South America and the West Indies. Only the nutria was recently launched in North America and Europe by man.

Evolution and systematics

History of development

The guinea pig relatives probably descended from porcupine relatives who were in the Old World, especially in Africa, disseminated and their descendants still as sand diggers, rock rats and cane rats live there today. It is generally assumed that the ancestors of the guinea pig relatives had crossed the then much narrower Atlantic on driftwood floating. The date for the colonization of South America is considered the early Oligocene, the oldest fossils are from Chile and is about 31 million years old.

South America was at the time - like during most of the Cenozoic - isolated from the other continents, so there developed a very unique mammal fauna, comparable to the situation in Australia. There were originally only three Säugetiertaxa: the marsupial, the ( " bag hyenas " ) were among others, the opossums, the paucituberculata and Sparassodonta represented the now-extinct South American ungulates ( Meridiungulata ) and the Xenarthra. (Some million years after the guinea pig relatives way also reached the Primate South America in a similar manner. )

For this reason, the guinea pig relatives could take some ecological niches that are not typical for rodents and can be found in this form only in this group. There were gigantic forms: still one with the Capybara the largest rodent to this group, extinct forms such as Phoberomys even reached the dimensions of hippos. It also developed long-legged forms with hufartigen toes as the agoutis and the Maras, which form the ecological equivalents of cloven hoofed animals in a certain way. Addition, however, we also saw the formation of mice or rats of similar animals, and caused it - like the other rodents also - tree and ground-dwelling species, and digging underground living representative.

Prior to around 2.5 million years ago teamed up with the Isthmus of Panama land bridge between North and South America, and there was a Faunentausch great extent. Numerous Säugetiertaxa wandered now in South America, with partly fatal consequences for the endemic fauna: many groups died out, the guinea pigs were relatives but less affected than other taxa. In return, some previously restricted to South America species could expand their range to Central America to North America, it has, however, with the Urson only one type managed.

With the colonization of America by the people, and especially since the arrival of the Europeans the American fauna has been greatly changed. Some species, especially endemic to the Caribbean islands have become extinct, including the entire family of Riesenhutias and some representatives of the sting and tree rats.

Outer systematics

The guinea pig relatives ( Caviomorpha ) form a lineage within the porcupine relatives ( Hystricognathi ). Most them as the combined Phiomorpha families of sandy graves ( Bathyergidae ), cane rats ( Thryonomyidae ) and rock rats ( Petromuridae ) are compared, then form their common sister group of porcupines. A graphical representation of possible external relationships is as follows:

Sand burial ( Bathyergidae )

Cane rats ( Thryonomyidae )

Rock rats ( Petromuridae )

Guinea pig relatives ( Caviomorpha )

Porcupines ( Hystricidae )

Except for the porcupines, guinea pigs relatives were already summarized in Systema Naturae Linnaeus 1735 in the genus Mus. This genus, which now correspond more to the rank of a family or order, but in addition also contained squirrels and mice relatives. The porcupines, however, were combined with the porcupines in the genus Hystrix.

While a relationship of most guinea pig relatives is assumed for some time that porcupines were still often asked outside this group. Older studies on muscles, arteries, skulls and teeth suggest that they represent an early branch of the Porcupine relatives and therefore do not belong to the guinea pig relatives. Also studies on parasitology contradict a common ancestry; Thus the guinea pig relatives have several independent ancestor within the rodents. Recent molecular genetic studies, however, offer support for the descent from a common ancestor, and the development of the Porcupine relatives.

Innerere systematics

Within the guinea pig relatives the family relationships are still largely unclear. The nomenclature used here with subdivision into four superfamilies based on recent molecular genetic studies. The following families are currently distinguished:

• Superfamily Baumstachlerartige ( Erethizontoidea ) Porcupines ( Erethizontidae ), including the bristle tree Stach Jewellers

• Pacas ( Cuniculidae )
• Agoutis and Acouchis ( Dasyproctidae )
• Guinea pigs ( Caviidae ), including the giant rodents

• Dinomyidae
• Chinchillas ( Chinchillidae )

• Chinchilla rats ( Abrocomidae )
• Mirage rats ( Octodontidae )
• Comb rats ( Ctenomyidae )
• Unnamed taxon Sting rats ( Echimyidae )
• Coypu ( nutria also; Myocastoridae )
• Tree rats ( also Hutias; Capromyidae )
• Riesenhutias ( Heptaxodontidae ); died recently, systematic assignment uncertain

The extinct in the late Miocene Eocardiidae are also classified in the guinea pig relatives.

In the past, individual groups were always reunited differently, so there are different definitions in the literature for each of the above superfamilies. Also, the definitions of some families have changed over time. The relationships between the different superfamilies are still not sure; the following representation follows Poux et al. (2006):

Porcupines ( Erethizontidae )

Guinea pig -like ( Cavioidea )

Chinchilla -like ( Chinchilloidea )

Mirage -like rats ( rats deceit )

The porcupines are often not classified because of their different morphology in the guinea pig -like. Together with the Pakaranas a relationship was assumed to be porcupines and spring hares on the basis of related parasites. Also unclear is the assignment of Borstenbaumstachler. Here they will be provided to Tree Stach learning; in other classifications will be classified as a subfamily in the sting rats.

The guinea pig -like form to the Pakaranas a well-defined group; this is supported by both morphological and molecular genetic studies. The agoutis and Acouchis be classified as a subfamily in addition to the Pacas or run as an independent family. Meanwhile incorporated in the guinea pig, the giant rodents have long been regarded as a sister group of these.

The Pakaranas are sometimes found near the tree Stach learning, with whom they share a merger of the second and third cervical vertebra and other morphological features; both are attacked by worms of the genus Made Wellcomia. Tooth pattern, however, suggest a relationship with the guinea pig -like; especially with Pacas, agoutis and Acouchis a close relationship has been accepted. Kinship with chinchillas is also supported by tooth pattern and molecular genetic studies.

The Chinchilla rats are often placed close to the chinchillas. Molecular genetic studies contradict the clear and demonstrate how dental characteristics rather, a kinship with the mirage -like rats. Their closest relatives within this group are not known. The comb rats are often found as a family to the illusion rats. This is related to many to be derived jointly adopted features such as the kidney-shaped molars.

Sting rats, coypu and tree rats form a well-supported by studies of teeth and muscles, as well as molecular genetic studies of kinship group. The coypu be assigned as a separate family or subfamily either rats or the goad the tree rats. Speak immunological and molecular genetic tests for assignment to the sting rats. The tree rats were occasionally found as a family to the sting rats.

The extinct Riesenhutias are often found near the chinchillas because of similar molars; other features of the teeth, such as dental patterns suggest but in a relationship with the tree rats. Nor can it be ruled out that the Riesenhutias themselves do not form a relationship group.

Designation

Carl Linnaeus placed the guinea pig relatives nor the two genera Mus and Hystrix that contain only distant relatives today. The first still -ranked in this group genus named Peter Simon Pallas in 1766 with Cavia, which refers to the of some species visited as shelter caves ( Latin " cavi "). Caviomorpha that still valid name for the guinea pig relatives was introduced in 1955 by Albert Edward Wood; call other sources Kraglievich Lucas (1930 ) as an author. Dan Bryant and Malcolm C. McKenna led in 1995 the designation Caviida.