Chalicotherium


Chalicotherium, meaning "gravel", and θηρίον is a genus of extinct perissodactyls in the family Chalicotheriidae. The genus is known from Europe and Asia, from the Early Miocene to Late Miocene, 23.0~5.3 million years ago.
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 Late Miocene Europe, was described by Johann Jakob Kaup in 1833. When the French naturalist George Cuvier first received a cleft claw from Eppelheim, Germany, he identified it as the toe bone of a gigantic pangolin.

Description

Chalicotherium, like many members of Perissodactyla, was adapted to browsing, though the chalicotheres were uniquely adapted to do so among ungulates. Its arms were long and heavily clawed, allowing them to walk on their knuckles only. The arms were used to reach for the branches of large trees and bring them close to its long 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 as either as a forage-collecting rake or as formidable defensive weapons, or both.
All of these characteristics show some convergence with such other creatures as ground sloths, great apes, bears, and a group of theropod dinosaurs known as therizinosaurs.

Classification

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

Species

; Valid :
  • Chalicotherium goldfussi
  • Chalicotherium brevirostris
  • Chalicotherium salinum
; Invalid :
  • Chalicotherium antiquum
; Misassigned specimens :
  • Chalicotherium cf.
  • "Chalicotherium modicum"
  • "Chalicotherium bilobatum"
  • Chalicotherium spp.

    Palaeoecology

Studies of the dental microwear and mesowear of C. goldfussi indicate that it was a browsing herbivore that consumed bark and twigs in addition to leaves, a finding consistent with morphological adaptations of chalicotheriines such as large ungual phalanges, protractible forelimbs, reduced hindlimbs, and highly pronounced insertion surfaces on the mandible for muscles involved in mastication that would suggest such a diet.