|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Mammalia - Multituberculata - Djadochtatheriidae
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|G. W. Rougier et al. 1997||Large size multituberculate, with palate length (measured from the posterior margin of the I2) of 30.4 mm and a M1-M2 length of 9.5 mm. Palatal torus is notably strong, more than in any other presently known multituberculate, with an elaborated, stout, crescent-shaped process that projects ventrally on either palatine (as in the weaker torus of Kryptobaatar). MI cusp formula (4:5:2) and size, differentiate Tombaatar from all Mongolian multituberculates. Skull of Tombaatar is similar in dimensions to those of Djadochtatherium matthewi (Simpson, 1925) and Catopsbaatar catopsaloides (Kielan-Jaworowska, 1974, 1994; Kielan-Jaworowska and Sloan, 1979), but differs from these taxa in having the 13 alveolus formed by both the premaxilla and maxilla; a slender, posteriorly tapering process of the premaxilla on the rostrum; a high skull with a deep orbit (flat rostrum, and palate wider and shorter in Djadochtatherium and Catopsbaatar); and a proportionately short and slender anterior process of the frontal on the skull roof (long and wide in Djadochtatherium, but not preserved in Catopsbaatar). P2 absent and rounded premaxillary-maxillary suture in rostrum of Tombaatar and Catopsbaatar (P2 present and suture not rounded in Djadochtatherium; suture rounded in Nemegtbaatar, Kryptobaatar, and Chulsanbaatar, but not in Sloanbaatar, Kamptobaatar, Ectypodus, or Lambdopsalis). Tombaatar and Djadochtatherium are distinguished from Catopsbaatar in having large P1 and P3 (?plesiomorphic) and MI with only two cusps on the lingual row which form a lobe in the posterior half of the molar of Tombaatar. Four lingual cusps cover the posterior two-thirds of the labial margin of the MI in Catopsbaatar. Some additional characters are present in other multituberculates but are rendered autapomorphies of Tombaatar by their distribution on the most parsimonious trees. These are: base of zygomatic arch dorsal or anterior to P3/P4 embrasure, incisive foramina of medium size and elongated, and posterior margin of palate medial to middle of M2.|