Merychippus was named by Joseph Leidy (1856). Numerous authors assigned the type species – Merychippus insignis – to Protohippus, but this is ignored. It was assigned to the Equidae by Leidy (1856) and Carroll (1988), and to the Equinae by MacFadden (1998) and Bravo-Cuevas and Ferrusquía-Villafranca (2006).[3][4][5] Its name means "ruminant horse", but current evidence does not support Merychippus ruminating.
Descriptionedit
M. sejunctus front and back feet (right) and M. sphenodus lower jaw fragment
Merychippus lived in groups. It was about 100 cm (39 in) tall[6] and at the time it was the tallest equine to have existed. Its muzzle was longer, deeper jaw, and eyes wider apart than any other horse-like animal to date. The brain was also much larger, making it smarter and more agile. Merychippus was the first equine to have the distinctive head shape of today's horses.
The Miocene was a time of drastic change in environment, with woodlands transforming into grass plains.[7] This led to evolutionary changes in the hooves and teeth of equids. A change in surface from soft, uneven mud to hard grasslands meant there was less need for increased surface area.[7] The foot was fully supported by ligaments, and the middle toe developed into a hoof that did not have a pad on the bottom. In some Merychippus species, the side toes were larger, whereas in others, they had become smaller and only touched the ground when running. The transformation into plains also meant Merychippus began consuming more phytolith rich plants. This led to the presence of hypsodont teeth. Such teeth range from medium to intense crown height, are curved, covered in large amounts of cement, and are characteristic of grazing animals[8]
Equid size also increased, with Merychippus ranging, on average, between 71 and 100.6 kg.[9]
Classificationedit
By the end of the Miocene era, Merychippus was one of the first quick grazers. It gave rise to at least 19 different species of grazers, which can be categorized into three major groups. This burst of diversification, termed an adaptive radiation, is often known as the "Merychippine radiation".[citation needed]
The first was a series of three-toed grazers known as hipparions. These were very successful and split into four genera and at least 16 species, including small and large grazers and browsers with large and elaborate facial fossae. The second was a group of smaller horses, known as protohippines, which included Protohippus and Calippus. The last was a line of "true equines" in which the side toes were smaller than those of other proto-horses. In later genera, these were lost altogether as a result of the development of side ligaments that helped stabilize the middle toe during running.
Referencesedit
Illustration
^"Fossilworks: Merychippus insignis". from the original on 10 August 2022. Retrieved 17 December 2021.
^"Fossilworks: Merychippus". from the original on 13 May 2022. Retrieved 17 December 2021.
^R. L. Carroll. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company, New York 1–698
^B. J. MacFadden. 1998. Equidae. In C. M. Janis, K. M. Scott, and L. L. Jacobs (eds.), Evolution of Tertiary Mammals of North America 1:537–559
^V. M. Bravo-Cuevas and I. Ferrusquía-Villafranca. 2006. Merychippus (Mammalia, Perissodactyla, Equidae) from the Middle Miocene of state of Oaxaca, southeastern Mexico. Géobios 39:771–784
^Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. pp. 256–257. ISBN1-84028-152-9.
^ abMacFadden, B. J.. 1992. Fossil Horses: Systematics, Paleobiology, and Evolution of the Family Equidae. Cambridge University Press, Cambridge.
^Matthew, W. D.. 1926. The Evolution of the Horse: A Record and Its Interpretation. The Quarterly Review of Biology, 1:139–185.
^MacFadden, B. J. 1986. Fossil horses from “Eohippus” (Hyracotherium) to Equus: scaling, Cope's Law, and the evolution of body size. Paleobiology, 12:355–369.
Wikispecies has information related to Merychippus.
Wikimedia Commons has media related to Merychippus.
Photo of a Merychippus tooth.
Teeth of Merychippus californicus
A classification scheme from The Paleobiology Database 10 February 2012 at the Wayback Machine
Florida Museum of Natural History
January 01, 1970
merychippus, extinct, proto, horse, family, equidae, that, endemic, north, america, during, miocene, million, years, three, toes, each, foot, first, horse, known, have, grazed, temporal, range, miocene, preꞒ, skeletal, reconstruction, display, american, museum. 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 2 It had three toes on each foot and is the first horse known to have grazed MerychippusTemporal range Miocene 15 9 10 3 Ma PreꞒ Ꞓ O S D C P T J K Pg N Skeletal reconstruction of Merychippus on display at the American Museum of Natural History Scientific classification Domain Eukaryota Kingdom Animalia Phylum Chordata Class Mammalia Order Perissodactyla Family Equidae Subfamily Equinae Genus MerychippusLeidy 1856 Type species Merychippus insignisLeidy 1856 1 Species Species M brevidontus Bode 1935 M calamarius Cope 1875 M californicus Merriam 1915 M coalingensis Clark 1921 M coloradense Osborn 1918 M eohipparion Osborn 1918 M eoplacidus Osborn 1918 M gunteri Simpson 1930 M insignis Cope 1874 M labrosus Cope 1874 M missouriensis Douglass 1908 M patrusus Osborn 1918 M primus Osborn 1918 M proparvulus Osborn 1918 M quartus Stirton 1940 M quintus Kelly and Lander 1988 M relictus Cope 1889 M republicanus Osborn 1918 M secundus Abel 1928 M sejunctus Cope 1874 M seversus Cope 1878 M stevensi Dougherty 1940 Contents 1 Discovery and naming 2 Description 3 Classification 4 References 5 External linksDiscovery and naming edit nbsp Restoration of Merychippus insignis Merychippus was named by Joseph Leidy 1856 Numerous authors assigned the type species Merychippus insignis to Protohippus but this is ignored It was assigned to the Equidae by Leidy 1856 and Carroll 1988 and to the Equinae by MacFadden 1998 and Bravo Cuevas and Ferrusquia Villafranca 2006 3 4 5 Its name means ruminant horse but current evidence does not support Merychippus ruminating Description edit nbsp M sejunctus front and back feet right and M sphenodus lower jaw fragment Merychippus lived in groups It was about 100 cm 39 in tall 6 and at the time it was the tallest equine to have existed Its muzzle was longer deeper jaw and eyes wider apart than any other horse like animal to date The brain was also much larger making it smarter and more agile Merychippus was the first equine to have the distinctive head shape of today s horses The Miocene was a time of drastic change in environment with woodlands transforming into grass plains 7 This led to evolutionary changes in the hooves and teeth of equids A change in surface from soft uneven mud to hard grasslands meant there was less need for increased surface area 7 The foot was fully supported by ligaments and the middle toe developed into a hoof that did not have a pad on the bottom In some Merychippus species the side toes were larger whereas in others they had become smaller and only touched the ground when running The transformation into plains also meant Merychippus began consuming more phytolith rich plants This led to the presence of hypsodont teeth Such teeth range from medium to intense crown height are curved covered in large amounts of cement and are characteristic of grazing animals 8 Equid size also increased with Merychippus ranging on average between 71 and 100 6 kg 9 Classification editBy the end of the Miocene era Merychippus was one of the first quick grazers It gave rise to at least 19 different species of grazers which can be categorized into three major groups This burst of diversification termed an adaptive radiation is often known as the Merychippine radiation citation needed The first was a series of three toed grazers known as hipparions These were very successful and split into four genera and at least 16 species including small and large grazers and browsers with large and elaborate facial fossae The second was a group of smaller horses known as protohippines which included Protohippus and Calippus The last was a line of true equines in which the side toes were smaller than those of other proto horses In later genera these were lost altogether as a result of the development of side ligaments that helped stabilize the middle toe during running References edit nbsp Illustration Fossilworks Merychippus insignis Archived from the original on 10 August 2022 Retrieved 17 December 2021 Fossilworks Merychippus Archived from the original on 13 May 2022 Retrieved 17 December 2021 R L Carroll 1988 Vertebrate Paleontology and Evolution W H Freeman and Company New York 1 698 B J MacFadden 1998 Equidae In C M Janis K M Scott and L L Jacobs eds Evolution of Tertiary Mammals of North America 1 537 559 V M Bravo Cuevas and I Ferrusquia Villafranca 2006 Merychippus Mammalia Perissodactyla Equidae from the Middle Miocene of state of Oaxaca southeastern Mexico Geobios 39 771 784 Palmer D ed 1999 The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals London Marshall Editions pp 256 257 ISBN 1 84028 152 9 a b MacFadden B J 1992 Fossil Horses Systematics Paleobiology and Evolution of the Family Equidae Cambridge University Press Cambridge Matthew W D 1926 The Evolution of the Horse A Record and Its Interpretation The Quarterly Review of Biology 1 139 185 MacFadden B J 1986 Fossil horses from Eohippus Hyracotherium to Equus scaling Cope s Law and the evolution of body size Paleobiology 12 355 369 External links edit nbsp Paleontology portal nbsp Wikispecies has information related to Merychippus nbsp Wikimedia Commons has media related to Merychippus Photo of a Merychippus tooth Teeth of Merychippus californicus A classification scheme from The Paleobiology Database Archived 10 February 2012 at the Wayback Machine Florida Museum of Natural History The Evolution of the Horse Biodiversity org Retrieved from https en wikipedia org w index php title Merychippus amp oldid 1221936940, wikipedia, wiki, book, books, library,
