Der Bau der Canini bei den Paulchoffatiidae (Multituberculata; Ober-Jura)

Canines are preserved among Multituberculata only in the upper jaw of the Paulchoffatiidae, the Pinheirodontidae and the North American genusGliodon Engelmann &; Callison, 1999. They resemble the anterior premolars (p^1–3) in the morphology of their crown, but they differ from them by the presence of only one root. In the present paper, 126 isolated canines of the Paulchoffatiidae from the Guimarota coal-pit in Portugal are treated. They show a wide morphological variation, from bicuspid to pentacuspid expression, and they can be grouped into 18 morphological units (Tab. 1). The bicuspid canines (11 specimens) show one buccal and one lingual cusp, arranged side by side, the latter normally being larger than the former. In the tricuspid canines (32 specimens) the cusps (one buccal and two lingual) are arranged in a triangle, with a great variation in the position of the cusps to each other. Tetracuspid canines (69 specimens) are the dominating group. Two buccal and two lingual cusps are present, which differ markedly in their largeness and their position to each other. The teeth differ also much in the shape of their crown. The pentacuspid canines (14 specimens) show two buccal and three lingual cusps. The variation in the arrangement of the cusps and in the shape of the crown is similar as in the tetracuspid specimens. One or two small cuspules can be present at the anterior border of the crown additionally to the main cusps in the canines. Tricuspid and tetracuspid canines are present also in the skulls of the Paulchoffatiidae, whereas bicuspid and pentacuspid canines are known only as isolated specimens. In the Pinheirodontidae the canines are tricuspid or tetracuspid, inGlirodon they are unicuspid. The Paulchoffatiidae and Pinheirodontidae — Paulchoffatiid line sensuKielan-Jaworowska &; Hurum, 2001 — are characterized by increasing premolarization of the upper canines. With that they differ markedly from all other multituberculates where the canini become reduced.