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MULTITUBERCULATA

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Originally appearing in Volume V18, Page 966 of the 1911 Encyclopedia Britannica.
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MULTITUBERCULATA , a See also:

group of See also:extinct mammals, mostly of small See also:size, whose remains are met with in strata ranging from the Trias to the See also:Eocene, both in See also:Europe and in See also:North See also:America. They are mostly known by their See also:lower jaws, and take their name from the fact that the grinding See also:teeth (fig. 2, m. 1 and 2; and fig. 3 a. b. c.) See also:bear two or three See also:longitudinal rows 0f tubercles, or are provided with tubercles See also:round the edges. From this feature these otherwise unknown animals are believed to be related to the existing See also:egg-laying mammals (See also:duck-billed See also:platypus and spiny See also:ant-eater), constituting the See also:order See also:Monotremata, and are therefore provisionally placed near that group. The largest representative of the Multituberculata is Polymastodon from the Lower Eocene of New See also:Mexico; the same beds also yield the smaller Ptilodus; while from corresponding strata at Rheims, in See also:France, has been obtained the nearly allied Neoplagiaulax. The latter takes its name from its resemblance to Plagiaulax (See also:figs. 1 and 2) from the Purbeck See also:bras. m strata of See also:Swanage, See also:Dorsetshire, which was one of the first-known members of the group. These have cutting teeth in front and multituberculate molars behind. Allodon and Ctenacodon represent the group in the Cretaceous of North America; and the See also:English Purbeck genus Bolodon, in which all the cheek-teeth are multituberculate, also belongs here.

Stereognathus (fig. 3) is another English Upper Oolitic type. Single teeth from the See also:

Rhaetic of See also:England and See also:Wurttemberg described as Microlestes apparently indicate the earliest member of the group. A See also:skull from the Upper Triassic Karoo beds of See also:South See also:Africa described as Tritylodon longaevus, which has multituberculate molar teeth, was also at first placed in this group, but has been subsequently regarded as a reptile, although Dr R. See also:Broom considers that the Fig. 2.-Lower See also:Jaw of Plagiaulax FIG. 3.-Fragment of Jaw of See also:minor, from Swanage. p. 1-4 Stereognathus oolithicus in premolars ; m. 1 and 2 molars. See also:matrix. a b c, molars. See also:original determination is correct. Possibly a fore-See also:limb from the same formation described as Theriodesmus See also:phylarchus indicates a similar or allied See also:animal. Not improbably Tritylodon indicates a See also:direct See also:link between the multituberculate mammals and the anomodont See also:reptiles of the See also:Permian and Trias.

(R.

End of Article: MULTITUBERCULATA

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