Chalicotherium

Chalicotherium (Ancient Greek χαλιξ/khalix, khalik-: pebble/gravel + θηρίον/thērion, diminutive of θηρ/thēr : beast) is a genus of extinct browsing odd-toed ungulates of the order Perissodactyla and family Chalicotheriidae, found in Europe, Africa, and Asia during the Late Oligocene to Lower Pliocene, living from 28.4—3.6 mya, existing for approximately 24.8 million years.[1]

This animal would look much like other chalicotheriid species: an odd-looking herbivore with long clawed forelimbs and stouter weight bearing hindlimbs.

The type species, Chalicotherium goldfussi, from Miocene and Pliocene Europe, was described by Johann Jakob Kaup in 1833 and since then 7 other species have been confidently assigned to this genus. According to current phylogenetic analyses Chalicotherium has two daughter genera nested within it, Anisodon Lartet, 1851 and Nestoritherium J. J. Kaup, 1859, thus rendering it paraphyletic.

Description
Chalicotherium, like many members of Perissodactyla, was adapted to browsing, though uniquely adapted to do so among its ungulate relatives. Its arms were long and heavily clawed, allowing them to walk on their knuckles only. The arms were used to reach for high branches and bring them close to its short-faced head to strip them clean of leaves. The horse-like head itself shows adaptation to a diet of soft vegetation, since, as the animal reached sexual maturity, the incisors and upper canines were shed, suggesting that its muscular lips and the resulting gum pads were enough to crop fodder which was then processed by squarish, low-crowned molars.

Callosities on the ischium imply that these animals would sit on their haunches for extended periods of time, probably while feeding. Pad-supporting bony growth on the dorsal side of the manual phalanges is interpreted as evidence of knuckle-walking, which would probably be useful to avoid wearing down the claws, preserving them for use either as a forage-collecting rake or as a formidable defensive weapon.

All of these characteristics show some convergence with the distantly related ground sloths, gorillas and giant pandas.

Taxonomic history
The type specimens for Chalicotherium goldfussi were found in the Upper Miocene strata of the Dinotherien-sande beds near Eppelsheim, in the Grand Duchy of Hesse, Germany. Kaup, when describing this new animal in 1833, found the teeth to be pebble-like and named the creature accordingly. Later on, limbs found in strata located at Sansan in the department of Gers, Southwestern France, were first described as Macrotherium by Édouard Lartet in 1837. Further study of these fossil remains and subsequent finds by Filhol warranted a referral of the material described as Macrotherium to Chalicotherium. A more recently synonymized genus is Butleria, preoccupied by a butterfly genus.[2]

Referral history for each species is detailed in the species list below along with morphological and geographical data where available.

Valid
The type species, it was found in Upper Miocene beds located in Germany. It weighed around 1500 kg and was 2.6 m high at the shoulder. First described as Macrotherium giganteum Gervais, later sunk into the type species for lack of distinguishing skeletal morphology, it was found in the Upper Miocene strata located at Sansan, France. First described as Macrotherium brevirostris Colbert 1934, this species hails from the Upper Miocene Tung Gur Formation, Inner Mongolia, China. This species hails from the Lower Miocene strata located in Kenya and Uganda. Formerly known as Schizotherium pilgrimi Forster Cooper, then referred to Macrotherium, this species hails from the Lower Miocene Bugti beds of Pakistan. Formerly named as Schizotherium wetzleri this species hails from Oligocene beds located in France and Germany, leading scientists to believe it was widespread in Western Europe. First described as Macrotherium salinum Forster Cooper, this species was first discovered at the Lower Pliocene Lower Siwaliks beds in India; its chronological and geographic range was later extended to the Middle and Upper Miocene, and to Pakistan and China, respectively. This species hails from Upper Miocene strata located in Gansu, China.
 * Chalicotherium goldfussi J. J. Kaup, 1833.
 * Chalicotherium giganteum Pictet, 1844.
 * Chalicotherium brevirostris
 * Chalicotherium rusingense Butler, 1962.
 * Chalicotherium pilgrimi
 * Chalicotherium wetzleri
 * Chalicotherium salinum
 * Chalicotherium wuduensis

Invalid
Found at the same locality as the type species, it was later found wanting of diagnostic features and sunk into the type species. This name pertains to a specimen found in Slovakia that was later lumped into Chalicotherium pentelicum. For sometime considered a species of Anisodon, it was later sunk into the type species. Junior synonym of Chalicotherium sivalense Junior synonym of Chalicotherium sivalense This species hailing from Lower Pliocene beds found in China is now assigned to the genus Nestoritherium. Erected from specimens found in Upper Miocene beds located in India it is now assigned to the genus Nestoritherium. Hailing from Upper Miocene strata of Slovakia and Greece, Samos being a notable locality of the latter, the species named Colodus pachygnathum was later subsumed with it. Further study referred this species to the genus Ancylotherium. Further study after this species' first description as Macrotherium grande Lartet, 1837, and subsequent referral to Chalicotherium by Blainville and later on of M. rhodanicum, M. magnum and M. sansaniense, warranted all the pertaining specimens to be clustered under the revived genus Anisodon Lartet, 1851, by Geraads et al. in 1995, as Anisodon grande.
 * Chalicotherium antiquum J. J. Kaup, 1833.
 * Chalicotherium baltavarense
 * Chalicotherium minus
 * Chalicotherium posterigenium
 * Chalicotherium sindiense
 * Chalicotherium sinense
 * Chalicotherium sivalense
 * Chalicotherium pentelicum (pentelici in some older publications)
 * Chalicotherium grande Blainville, 1849.

Attributed specimens
Hailing for the Tsaidam Basin, northern Qinghai-Tibetan Plateau, China. A nomen nudum, actually a Schizotherium priscum tooth. Hailing from the Oligocene of Saskatchewan, this very fragmentary specimen was the type on which Russel erected the genus Oreinotherium. Specimens found in two Tajikistan localities, thought to pertain to at least two different species.
 * Chalicotherium cf. C. brevirostris Wang et al., 2001.
 * "Chalicotherium modicum" Stehlin, 1905.
 * "Chalicotherium" bilobatum Cope.
 * Chalicotherium spp.