Superregnum: Eukaryota
Cladus: Orthokaryota
Cladus: Neokaryota
Cladus: Scotokaryota
Cladus: Podiata
Cladus: Amorphea
Cladus: Obazoa
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: ParaHoxozoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Cladus: Olfactores
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Cladus: Sarcopterygii
Cladus: Rhipidistia
Cladus: Tetrapodomorpha
Cladus: Eotetrapodiformes
Cladus: Elpistostegalia
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Cladus: Synapsida
Cladus: Eupelycosauria
Cladus: Metopophora
Cladus: Haptodontiformes
Cladus: Sphenacomorpha
Cladus: Sphenacodontia
Cladus: Therapsida
Cladus: Theriodontia
Cladus: Eutheriodontia
Cladus: Cynodontia
Cladus: Epicynodontia
Cladus: Eucynodontia
Cladus: Probainognathia
Cladus: Prozostrodontia
Cladus: Mammaliamorpha
Cladus: Mammaliaformes
Classis: Mammalia
Cladus: Theriimorpha
Cladus: Theriiformes
Cladus: Trechnotheria
Cladus: Cladotheria
Cladus: Prototribosphenida
Cladus: Zatheria
Cladus: Tribosphenida
Cladus: Boreosphenida
Subclassis: Theria
Cladus: Eutheria
Infraclassis: Placentalia
Magnordo: Boreoeutheria
Superordo: Laurasiatheria
Cladus: Scrotifera
Grandordo: Ferungulata
Mirordo: Euungulata
Ordo: Perissodactyla
Subordo: Ceratomorpha
Superfamilia: Rhinocerotoidea
Familia: †Hyracodontidae
Genus: †Hyracodon
Hyracodon ('hyrax tooth') is an extinct genus of perissodactyl mammal.
H. nebraskensis skull, found near Hermosa, South Dakota.
It was a lightly built, pony-like mammal of about 1.5 m (5 ft) long. Hyracodon's skull was large in comparison to the rest of the body. Hyracodon's dentition resembled that of later rhinocerotoids, but it was a much smaller animal and differed very little in appearance from the primitive horses of which it was a contemporary (32–26 million years ago). It had a short, broad snout and its long, slender limbs had three digits.[2]
Like the primitive horses, hyracodonts inhabited open forests and wooded steppes and turned from browsing foliage to grazing grass. They died out without leaving any descendants and they mark the end of the phylogenetic branch of hornless, running rhinocerotoids.
References
McKenna, M. C; Bell, S. K. (1997). Classification of Mammals above the Species Level. Columbia University Press. ISBN 0-231-11012-X.
Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. pp. 283–284. ISBN 1-84028-152-9.
Sources
Benes, Josef (1979). Prehistoric Animals and Plants. Prague, CZ: Artua. p. 220.
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