Hipparion Temporal range: Late Miocene | |
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Skeleton on display at the National Natural History Museum of China | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Perissodactyla |
Family: | Equidae |
Subfamily: | Equinae |
Tribe: | † Hipparionini |
Genus: | † Hipparion De Christol, 1832 |
Species | |
See text | |
Synonyms | |
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Hipparion is an extinct genus of three-toed, medium-sized equine belonging to the extinct tribe Hipparionini, which lived about 10-5 million years ago. [1] [2] While the genus formerly included most hipparionines, the genus is now more narrowly defined as hipparionines from Eurasia spanning the Late Miocene. [2] Hipparion was a mixed-feeder who ate mostly grass, and lived in the savannah biome. [2] [3] Hipparion evolved from Cormohipparion , [2] and went extinct due to environmental changes like cooling climates and decreasing atmospheric carbon dioxide levels. [4]
The genus "Hipparion" was used for over a century as a form classification to describe over a hundred species of Holartic hipparionines from the Pliocene and Miocene eras that had three toes and isolated protocones. Since then, groups such as the genera Cormohipparion and Neohipparion were proposed to further sort these species, typically based on differences in skull morphology. These species are now known as "Hipparion" in sensu lato (s.l.), or a broad sense. [5]
Hipparion in sensu stricto (s.s.), or a strict sense, describes the genus of Old World hipparionines from remains found in Eurasia (France, Greece, Turkey, Iran, and China) from the Late Miocene era (~10-5 Ma, or million years ago). The assignment of remains from elsewhere to the genus, such as North America and Africa, is uncertain. [2]
Hipparion generally resembled a smaller version of the modern horse, but was tridactyl, or three-toed. It had two vestigial outer toes on each limb in addition to its hoof. [2] In some species, these outer toes were functional. [6]
Hipparion was typically medium in size, at about 1.4 m (4.6 ft) tall at the shoulder. [7] [8] The estimated body mass of Hipparion depends on the species, but ranges from about 135 to 200 kg (about 298 to 441 lbs). [2]
Hipparion had hypsodont dentition (high-crowned teeth) for its premolars and molars, with a crown height of about 60 mm (2.36 in). Hipparion had isolated protocones in the upper molars, meaning a cusp of the teeth called a protocone was not connected to a tooth crest called a protoloph. [2] Hipparion is also characterized by its facial fossa, or deep depression in the skull, located high on the head in front of the orbit. [9] [10]
Hipparion lived in the Old World Savannah Biome, or OWSB, consisting of woodlands to grasslands. [2] Hipparion ate a mixed-feed diet, mostly consisting of grass. This diet is indicated by fossil evidence of microscopic wear patterns of scratches and pits on the enamel of Hipparion's teeth, observed using scanning electron microscopy (SEM). [3]
Hipparion achieved skeletal maturity and possibly sexual maturity at about 3 years old. Fossils of Hipparion individuals are up to 10 years old at death. [8]
Hipparion likely evolved from a species of Cormohipparion during the Late Miocene, about 11.4-11.0 Ma. This species, C. occidentale, came to Eurasia and Africa from North America. [2] The last common ancestor of Hipparion and the modern horse was Merychippus. [11]
In the Old World, Hipparion experienced population decline and extinction down a North to South gradient, as did many other Miocene vertebrates. This trend is believed to be due to environmental changes caused by global cooling and decreasing carbon dioxide levels in the atmosphere. [4]
Equidae is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. The family evolved around 50 million years ago from a small, multi-toed ungulate into larger, single-toed animals. All extant species are in the genus Equus, which originated in North America. Equidae belongs to the order Perissodactyla, which includes the extant tapirs and rhinoceros, and several extinct families. It is more specifically grouped within the superfamily Equoidea, the only other family being the extinct Palaeotheriidae.
Merychippus is an extinct proto-horse of the family Equidae that was endemic to North America during the Miocene, 15.97–5.33 million years ago. It had three toes on each foot and is the first horse known to have grazed.
Chasmaporthetes, also known as hunting or running hyena, is an extinct genus of hyenas distributed in Eurasia, North America, and Africa during the Pliocene-Pleistocene epochs, living from 4.9 million to 780,000 years ago, existing for about 4.12 million years. The genus probably arose from Eurasian Miocene hyenas such as Thalassictis or Lycyaena, with C. borissiaki being the oldest known representative. The species C. ossifragus was the only hyena to cross the Bering land bridge into the Americas, and ranged over what is now Arizona and Mexico during Blancan and early Irvingtonian Land Mammal ages, between 5.0 and 1.5 million years ago.
Sinotherium is an extinct genus of single-horned elasmotheriine rhinocerotids that lived from the late Miocene to Early Pliocene. It was ancestral to Elasmotherium, demonstrating a very important evolutionary transition from nasal-horned elasmotheriines to frontal-horned elasmotheriines. Its fossils have been found in the Karabulak Formation of Kazakhstan, lower jaw and teeth have been found in Mongolia, and a partial skull is known from the upper part of the Liushu Formation of western China. Sinotherium diverged from the ancestral genus, Iranotherium, first found in Iran, during the early Pliocene. Some experts prefer to lump Sinotherium, and Iranotherium into Elasmotherium.
Hippidion is an extinct genus of equine that lived in South America from the Late Pliocene to the end of the Late Pleistocene (Lujanian), between 2.5 million and 11,000 years ago. They were one of two lineages of equines native to South America during the Pleistocene epoch, alongside Equus (Amerhippus) neogeus.
The evolution of the horse, a mammal of the family Equidae, occurred over a geologic time scale of 50 million years, transforming the small, dog-sized, forest-dwelling Eohippus into the modern horse. Paleozoologists have been able to piece together a more complete outline of the evolutionary lineage of the modern horse than of any other animal. Much of this evolution took place in North America, where horses originated but became extinct about 10,000 years ago, before being reintroduced in the 15th century.
Equus simplicidens, also known as the Hagerman horse is an extinct species of equine native to North America during the Pliocene and Early Pleistocene. It is one of the oldest and most primitive members of the genus Equus. It is the state fossil of Idaho, where abundant remains of the species were discovered near the town of Hagerman in 1928.
Neohipparion (Greek: "new" (neos), "pony" (hipparion)) is an extinct genus of equid, from the Neogene (Miocene to Pliocene) of North America and Central America. Fossils of this horse have been found in Texas, Florida, Kansas, South Dakota, Montana, Nevada, Alabama, Oregon, and Mexico. This prehistoric species of equid grew up to lengths of 4.5 to 5 ft (1.4 to 1.5 m) long. In Florida, Neohipparion lived in a wooded grassland savanna environment during the dry season but moved to a wet environment when it came time to mate. Speaking of mating, the average age of death for a newborn colt was 3.5 years, with a juvenile mortality rate of 64% during its first 2 years of existence. Its diet consisted of grasses, C3 and C4 plants. δ13C values from ‘’N. eurystyle’’ fossils found in Florida indicate that it fed almost exclusively on C4 grasses.
Pseudhipparion is an extinct genus of three-toed horse endemic to North America during the Miocene. They were herding animals whose diet consisted of C3 plants. Fossils found in Georgia and Florida indicate that it was a lightweight horse, weighing up to 90 pounds. In 2005, fossils were unearthed in Oklahoma. Seven species of Pseudhipparion are known from the fossil record which were very small, following the trend of Bergmann's rule.
Nannippus is an extinct genus of three-toed horse endemic to North America during the Miocene through Pleistocene, about 13.3—1.8 million years ago (Mya), living around 11.5 million years. This ancient species of three-toed horse grew up to 3.5 feet and weighed between 165 pounds to 199 pounds, which was around the same size as a domestic sheep.
Cormohipparion is an extinct genus of horse belonging to the tribe Hipparionini that lived in North America during the late Miocene to Pliocene. They grew up to 3 feet long.
Megahippus is an extinct genus of large Anchitheriine horses found throughout the southern portion of the United States during the middle Miocene. The animal represents one of the latest low-crowned horses, overlapping in time with more derived high-crowned horses.
Hippotherium is an extinct genus of horse that lived in during the Miocene through Pliocene ~13.65—6.7 Mya, existing for 6.95 million years.
Hipparionini is a tribe of three-toed horses in the subfamily Equinae. They had body forms similar to modern equines, with high-crowned teeth. They first appeared in North America during the Early Miocene around 17 million years ago, before migrating into the Old World around 11.4-11.0 million years ago. The youngest species date to the Early Pleistocene, becoming extinct following the arrives of modern equines of the genus Equus to the Old World.
Eurygnathohippus is an extinct genus of hipparionine horse. The majority of known fossils of members of this genus were discovered in Africa, where members of this genus lived during the late Miocene to Pleistocene interval. Fossils of Eurygnathohippus were also reported from the late Pliocene sediments of the Potwar Plateau in Pakistan and the Siwalik Hills in northwest India.
Cremohipparion is an extinct genus of equid that lived in Eurasia and Africa during the Miocene through Pliocene.
Equus stenonis is an extinct species of equine that lived in Western Eurasia including Europe during the Early Pleistocene.
Sivalhippus is an extinct genus of horse that lived in Africa and the Indian subcontinent during the late Miocene.
Bunolistriodon is an extinct genus of pig-like animals from Eurasia and Africa during the Miocene.
Proboscidipparion is an extinct genus of hipparionine equine. It is named after its unusual retracted nasal region of the skull, which may have supported a proboscis. Fossils have been found throughout Eurasia, from England to China. The oldest specimens are known from Asia, dating to the Early Pliocene, around 5.3-5 million years ago. The genus was one of the last surviving hipparionines, with the youngest specimen dating to the end of the Early Pleistocene, around 1 million years ago.