''Parahippus'' ("near to

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million y ...

"), is an extinct

equid Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. All extant species are in the genus '' Equus'', w ...

, a relative of modern horses, asses and

zebra Zebras (, ) (subgenus ''Hippotigris'') are African equines with distinctive black-and-white striped coats. There are three living species: the Grévy's zebra (''Equus grevyi''), plains zebra (''E. quagga''), and the mountain zebra (''E. zeb ...

s. It lived from 24 to 17 million years ago, during the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

epoch. It was very similar to ''

Miohippus ''Miohippus'' (meaning "small horse") was a genus of prehistoric horse existing longer than most Equidae. ''Miohippus'' lived in what is now North America from 32 to 25 million years ago, during the late Eocene to late Oligocene. ''Miohippus'' ...

'', but slightly larger, at around tall, at the

withers The withers is the ridge between the shoulder blades of an animal, typically a quadruped. In many species, it is the tallest point of the body. In horses and dogs, it is the standard place to measure the animal's height. In contrast, cattle ar ...

. Their fossils have been found in North America, primarily in the Great Plains region and

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

Description

''Parahippus'' was larger than ''Miohippus'', with longer legs and face. The bones in the legs were fused and this, along with muscle development, allowed ''Parahippus'' to move with forward-and-back strides. Flexible leg rotation was eliminated, so that the animal was better adapted to fast forward running on open ground without moving from side to side. Most importantly, ''Parahippus'' was able to stand on its middle toe, instead of walking on pads, which gave it the ability to run faster; its weight was supported by ligaments under the

fetlock Fetlock is the common name in horses, large animals, and sometimes dogs for the metacarpophalangeal and metatarsophalangeal joints (MCPJ and MTPJ). Although it somewhat resembles the human ankle in appearance, the joint is homologous to the ba ...

to the big central toe. Since leafy food had become scarce, these animals were forced to subsist on the newly evolved

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...

es that were by now taking over the plains, and their teeth adapted accordingly. The extra molar crest that was variable in ''Miohippus'' became permanent in ''Parahippus''. The molars developed high crowns and a hard covering for grinding the grass, which was typically covered with high-silica dust and sand.

References

Horse Evolution

Miocene horses Miocene odd-toed ungulates Transitional fossils White River Fauna Prehistoric placental genera Miocene genus extinctions Miocene mammals of North America Fossil taxa described in 1858 Taxa named by Joseph Leidy {{horse-stub

Description

See also

References