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Tylopoda (order Artiodactyla, suborder Ruminantia) An infra-order that comprises the Camelidae (camels and llamas). These are specialized remnants of a much larger group of ruminant-like artiodactyls, also included in the infraorder, that are known to have lived between the Eocene and early Pliocene: the Old World families Anoplotheriidae, Cainotheriidae, Xiphodontidae, and Amphimerycidae; and the New World families Agriochoeridae, Merycoidodontidae, and Dromerycidae. The anoplotheres were stoutly built animals, about 90 cm high at the shoulder; the cainotheres were rabbit-like, in size and probably in habits; the xiphodonts were possibly close to the ancestral line leading to the camels; and the amphimerycids to the line leading to the pecorans. The New World forms were rather pig-like, although the agriochoeres had long tails and redeveloped claws, leading to suggestions that they were arboreal or that they dug for roots and tubers.