The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . pment. Under the sub-order Toxodontia may be included not only thetypical Toxodon, but the more aberrant Typothsrium (fig. i) of thePleistocene of Buenos Aires and the smaller Pachyrncns and Hegeto-tkerium of the Patagonian Santa Cruz beds. All the membersof the sub-order have tall-crowned and curved cheek-teeth, someor all of which generally have persistent pulps, while at least one pairof incisors in each jaw is rootless. The bodies of the cervicalvertebrae have flat articular surfaces, the bone
The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . pment. Under the sub-order Toxodontia may be included not only thetypical Toxodon, but the more aberrant Typothsrium (fig. i) of thePleistocene of Buenos Aires and the smaller Pachyrncns and Hegeto-tkerium of the Patagonian Santa Cruz beds. All the membersof the sub-order have tall-crowned and curved cheek-teeth, someor all of which generally have persistent pulps, while at least one pairof incisors in each jaw is rootless. The bodies of the cervicalvertebrae have flat articular surfaces, the bones of the two rowsof the carpus alternate, and in the tarsus the navicular articulateswith the calcaneum. which, as in the Artlodactyla, is articulated to the tibula, while the astragalus, which is slightly grooved above, 114 is formed on the Perissodactyle plan. The number of toes variesbetween three and five, of which the middle one is the largest andthe femur may or may not have a third trochanter The Typo-therudae and Pachyrucidae are remarkable among the Ungulates lor TOY, C. H.—TOYNBEE. (After GcrvafaO Fig. I.—Skull of Typolherimn cristatum^ from the PampasFormation of Buenos Aires. the retention of clavicles, and for their curious approximation indentition and certain characters of the skeleton to the Rodcntia1 he dental formula of Typolhenum is i. i, c. 8, p. f, m. 3; that of thesmaller Patagonian forms differs by the larger number (3) of pre-molars. The toes were unguiculate rather than ungulate in charactern^So ^ °^^ *° ber) of Typalherium. Certainallied Patagonian forms, such as Aigyroltyrax, have been supposedto be related to the Hyraxes. The Tosodontidae differ from the preceding families by the lossof the clavicles and the reduction of the digits to three in each footIhe typical genus Toxodon is represented by animals the size of a
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
