Megapedetes is a genus of fossil rodent

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....

s related to the springhare

Springhare

The springhare , or springhaas, is not actually a hare, but a member of the order Rodentia. It is one of a number of species in the genus Pedetes, and is native to southern Africa. Synonyms are P. caffer or P...

 and other species of the genus Pedetes

Pedetes

Pedetes is a genus of rodent in the Pedetidae family. Members of the genus are distributed across southern Africa and also occur in Kenya, Uganda and Tanzania.-Species:...

, with which it forms the family Pedetidae

Pedetidae

Pedetidae is a family of mammals from the rodent order. The two living species, the springhares, are distributed throughout much of southern Africa and also around Kenya, Tanzania and Uganda. Fossils have been found as far north as Turkey. Together with the anomalures, Pedetidae forms the suborder...

. At least four species are known, which ranged through Africa, southwestern Asia, and southeastern Europe from the Miocene

Miocene

The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 to the Pliocene

Pliocene

The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

. The genus was larger than Pedetes.

Species of Megapedetes were larger, relatively low-crowned (brachydont

Brachydont

Brachydont is a type of dentition characterized by low-crowned teeth, as opposed to high-crowned, hypsodont teeth. Human teeth are brachydont.-External links:*http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/tooth_diversity.html...

) pedetids with short, mostly fused roots under their teeth. There was no gutter surrounding the incisive foramina

Incisive foramen

The fossa incisiva is an opening in the bone of the oral hard palate where blood vessels and nerves may pass. There are four of these openings in the incisive fossa.-Formation:...

 (openings in the front part of the palate

Palate

The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...

). The bones are more robustly built than in Pedetes and in another fossil relative of the springhares, Parapedetes. Unlike in Pedetes, the first metatarsal (a foot bone) is present. It may have fed on less rough vegetation than Pedetes does.

In Namibia, two species are known from the early middle Miocene of Arrisdrift—M. gariepensis and M. pickfordi. An isolated phalanx from a slightly older site, Auchas Mine, cannot be reliably identified to species level, but may be M. gariepensis. Megapedetes and other pedetids are reasonably common in the Miocene of East Africa. M. pentadactylus, the type species

Type species

In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

 of the genus, occurs at Songhor, Rusinga, and Bukwa

Bukwa

Bukwa is a town in Eastern Uganda. It is the main municipal, administrative and commercial center of Bukwa District and the headquarters of the district are located there. The district is named after the town.-Location:...

; a species that may be close to M. gariepensis is known from Kirimun, Fort Ternan

Fort Ternan

Fort Ternan is a small town in Nyando District, Nyanza Province, Kenya located 50 kilometres east of Kisumu and five kilometres east of Koru. Fort Ternan is located adjacent the western border of Rift Valley Province . Fort Ternan forms a ward of Muhoroni Constituency and Muhoroni town council...

, and Maboko; a pedetid from Kipsaraman resembles M. pickfordi, but is more low-crowned; and other pedetids may occur in other East African sites. A species of Megapedetes, perhaps M. pentadactylus, is known from Saudi Arabia in sediments about 16 million years old. In the early Miocene of Israel, a yet undescribed pedetid close to Megapedetes is found. Species of Megapedetes are also known from the Miocene and Pliocene of North Africa. Another species, Megapedetes aegaeus, occurs at Bayraktepe in Turkey and the genus has also been found on the Greek island of Chios

Chios

Chios is the fifth largest of the Greek islands, situated in the Aegean Sea, seven kilometres off the Asia Minor coast. The island is separated from Turkey by the Chios Strait. The island is noted for its strong merchant shipping community, its unique mastic gum and its medieval villages...

.

Among the two Arrisdrift species, M. gariepensis is about 15% smaller than the East African M. pentadactylus and more adapted to jumping and has less robust incisor

Incisor

Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...

s, more high-crowned (hypsodont

Hypsodont

Hypsodont dentition is characterized by high-crowned teeth and enamel which extends past the gum line. This provides extra material for wear and tear. Some examples of animals with hypsodont dentition are cows, horses and deer; all animals that feed on gritty, fibrous material. The opposite...

) cheekteeth. The second species, M. pickfordi, is even smaller and more hypsodont. M. aegaeus and M. pentadactylus differ in details of the crowns of the cheekteeth.

Literature cited

• Mein, P. and Senut, B. 2003. The Pedetidae from the Miocene site of Arrisdrift (Namibia). Geological Survey of Namibia Memoir 19:161–170.
• Sen, S. 1977. Megapedetes aegaeus, n. sp. (Pedetidae) et a propos d'autres "rongeurs Africains" dans le Miocène d'Anatolie. Geobios 10:983–986.
• Walker, A. 1969. Lower Miocene fossils from Mount Elgon, Uganda (subscription required). Nature 223:591–593.
• Winkler, A.J. 1992. Systematics and biogeography of Middle Miocene rodents from the Muruyur Beds, Baringo District, Kenya (subscription required). Journal of Vertebrate Paleontology 12(2):236–249.
• Wood, A.E. and Goldsmith, N.F. 1992. Early Miocene rodents and lagomorphs from Israel (subscription required). Journal of Vertebrate Paleontology 18(Suppl. 3):87A–88A.