1911 Encyclopædia Britannica/Ancylopoda

by Richard Lydekker

ANCYLOPODA, or Ancylodactyla, an apparently primitive extinct subordinal group of Ungulata showing certain resemblances to the Perissodactyla, both as regards the cheek-teeth and the skeleton, but broadly distinguished by the feet being of an edentate type, carrying long curved and cleft terminal claws. From this peculiar structure of the feet it would seem that the weight of the body was mainly carried on their outer sides, as in Edentates. The group is typified by Chalicotherium, of which the original species was discovered in the Lower Pliocene strata of Eppelsheim, Hesse-Darmstadt, in 1825, and named on the evidence of the teeth, the limbs being subsequently described as Macrotherium. The skull is short, with a dental formula of i. 3/3, c. 0/1, p. 3/3, m. 3/3, but in fully adult animals most of the front teeth were shed. The molar teeth recall those of Palaeosyops (see Titanotheriidae). Remains referred to Chalicotherium have been also obtained from the Lower Pliocene and Upper Miocene strata of Greece, Hungary, India, China and North America. A skull from Pikermi, near Mt. Pentelikon, Attica, shows the absence in the adult state of upper and lower incisors and upper canines, much the same condition being indicated in an Indian skull. There were three toes to each foot, and the femur lacked a third trochanter.

Macrotherium, which is typically from the Middle Miocene of Sansan, in Gers, France, may indicate a distinct genus. Limb-bones nearly resembling those of Macrotherium, but relatively stouter, have been described from the Pliocene beds of Attica and Samos as Ancylotherium. In America the names Morotherium and Moropus have been applied to similar bones, on the belief that they indicated edentates. Macrotherium magnum must have been an animal of about 9 ft. in length.

The South American genus Homalodontotherium is often placed in the Ancylopoda, but reasons against this view are given in the article Litopterna. Professor H. F. Osborn considers that the Ancylopoda are directly descended from the Condylarthra.

See also H. F. Osborn, “The Ancylopoda Chalicotherium and Artionyx,” Amer. Nat. (1893), p. 118, and “Artionyx, a New Genus of Ancylopoda,” Bull. Amer. Mus. vol. v. p. 1 (1893). [N.B.—Artionyx was subsequently found to be an Artiodactyle.]  (R. L.*)