Phiomorpha
Encyclopedia
The rodent
parvorder or infraorder Phiomorpha comprises several living and extinct families found wholly or largely in Africa
. Along with the Anomaluromorpha
and perhaps the †Zegdoumyidae, they represent one of the few early colonizations of Africa
by rodents.
During the Oligocene
, Africa was not connected to any of the other continents. The predominant theory suggests that rodents first evolved in Laurasia
, and expanded outward from there. Although Europe
, Asia
, and North America
were distinct landmasses during much of the Eocene
and Oligocene, they experienced intermittent migration events across the shallow sea separating Europe and Asia, via an ice-free Greenland
(Europe and North America), or across Beringia (North America and Asia). The southern continents were much more isolated leading to the unique faunas of Australia
, South America
, and to a lesser degree Africa.
Although the hystricognath rodents may have evolved from an early entodacryan ancestor in Asia, they migrated to Africa soon after. The Phiomorpha represents the clade
that evolved as a result. Although once diverse, this infraorder is now restricted to the two species of cane rat
s, the Dassie Rat
, and the blesmol
s.
s (Hystricidae) are sometimes included in the Phiomorpha, but many authorities consider them either basal to all hystricognaths or basal to all hystricognaths except the Laotian Rock Rat
(family Diatomyidae
). Molecular results suggest that the Diatomyidae is a part of the Phiomorpha, but this is in contrast to morphological results which place the animal at a basal position to all hystricognaths.
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
parvorder or infraorder Phiomorpha comprises several living and extinct families found wholly or largely in Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. Along with the Anomaluromorpha
Anomaluromorpha
Anomaluromorpha is the name given to a clade that unites the anomalures with the springhare. It has alternately been designated as either a suborder or infraorder...
and perhaps the †Zegdoumyidae, they represent one of the few early colonizations of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
by rodents.
During the Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
, Africa was not connected to any of the other continents. The predominant theory suggests that rodents first evolved in Laurasia
Laurasia
In paleogeography, Laurasia was the northernmost of two supercontinents that formed part of the Pangaea supercontinent from approximately...
, and expanded outward from there. Although Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, and 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...
were distinct landmasses during much of the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
and Oligocene, they experienced intermittent migration events across the shallow sea separating Europe and Asia, via an ice-free Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
(Europe and North America), or across Beringia (North America and Asia). The southern continents were much more isolated leading to the unique faunas of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, and to a lesser degree Africa.
Although the hystricognath rodents may have evolved from an early entodacryan ancestor in Asia, they migrated to Africa soon after. The Phiomorpha represents the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
that evolved as a result. Although once diverse, this infraorder is now restricted to the two species of cane rat
Cane rat
The genus Thryonomys, also known as cane rats, grass cutters, or cutting grass, is a genus of rodent found throughout Africa south of the Sahara, the only members of the family Thyronomyidae. They are eaten in some African countries and are a pest species on many crops.-Characteristics:Cane rats...
s, the Dassie Rat
Dassie Rat
The dassie rat, Petromus typicus, is an African rodent found among rocky outcroppings. It is the only living member of its genus, Petromus, and family, Petromuridae. The name "dassie" means "hyrax" in Afrikaans, and the two animals are found in similar habitats...
, and the blesmol
Blesmol
The blesmols, also known as mole rats, or African mole-rats, are burrowing rodents of the family Bathyergidae. They represent a distinct evolution of a subterranean life among rodents much like the pocket gophers of North America, the tuco-tucos in South America, or the Spalacidae.- Distribution...
s.
Families
The makeup of this infraorder is controversial. At its core lie the extant families Thryonomyidae, Petromuridae, and Bathyergidae and their extinct relatives. The Old World porcupineOld World porcupine
The Old World porcupines, or Hystricidae, are large terrestrial rodents, distinguished by the spiny covering from which they take their name. They range over the south of Europe, most of Africa, India, and the Maritime Southeast Asia as far east as Borneo...
s (Hystricidae) are sometimes included in the Phiomorpha, but many authorities consider them either basal to all hystricognaths or basal to all hystricognaths except the Laotian Rock Rat
Laotian rock rat
The Laotian rock rat or kha-nyou , sometimes called the "rat-squirrel", is a rodent species of the Khammouan region of Laos. The species was first described in a 2005 article by Paulina Jenkins and coauthors, who considered the animal to be so distinct from all living rodents that they placed it...
(family Diatomyidae
Diatomyidae
Diatomyidae is a family of hystricomorphous, sciurognathous rodents found in Asia. It is currently represented by a single known living species, Laonastes aenigmamus.- "Lazarus effect" :...
). Molecular results suggest that the Diatomyidae is a part of the Phiomorpha, but this is in contrast to morphological results which place the animal at a basal position to all hystricognaths.
- Infraorder Phiomorpha
- Family †MyophiomyidaeMyophiomyidaeThe Myophiomyids are an extinct family of Old World hystricognaths....
- Family †DiamantomyidaeDiamantomyidaeDiamantomyidae is a family of extinct hystricognath rodents from Africa and Asia....
- Family †PhiomyidaePhiomyidaeThe Phiomyidae are a family of prehistoric rodents from Africa and Eurasia. A 2011 study placed Gaudeamus in a new family, gaudeamuridae.Genera include:* Acritophiomys* Andrewsimys* Elwynomys* Gaudeamus* Phiomys...
- Family †KenyamyidaeKenyamyidaeThe Kenyamyidae are an extinct family of rodents from Africa....
- Family Petromuridae - the Dassie Rat
- Family Thryonomyidae - cane ratCane ratThe genus Thryonomys, also known as cane rats, grass cutters, or cutting grass, is a genus of rodent found throughout Africa south of the Sahara, the only members of the family Thyronomyidae. They are eaten in some African countries and are a pest species on many crops.-Characteristics:Cane rats...
s and their extinct relatives - Parvorder Bathyergomorpha
- †Paracryptomys - incertae sedisIncertae sedis, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
- Family Bathyergidae - blesmols
- Family †Bathyergoididae
- †Paracryptomys - incertae sedis
- Family †Myophiomyidae
See also
- CaviomorphaCaviomorphaCaviomorpha is the rodent infraorder or parvorder that unites all South American hystricognaths. It is supported by both fossil and molecular evidence.-Origin:...
- HystricomorphaHystricomorphaThe 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...
- HystricognathiHystricognathiHystricognathi is an infraorder of rodents. Hystricognaths are distinguished from other rodents by the bone structure of their skulls. The masseter medialis passes partially through the infraorbital foramen and connects to the bone on the opposite side...
- Laotian Rock RatLaotian rock ratThe Laotian rock rat or kha-nyou , sometimes called the "rat-squirrel", is a rodent species of the Khammouan region of Laos. The species was first described in a 2005 article by Paulina Jenkins and coauthors, who considered the animal to be so distinct from all living rodents that they placed it...