New fossils of Meniscoessus major (Cimolomyidae: Multituberculata) are described from the Upper Cretaceous Oldman Formation, Alberta. Associations of P3–4, M1–2, and P4M1 are documented for the first time for this species. M. major, one of the largest known multituberculates in rocks of Judithian age, was probably a direct descendant of M. intermedius, known from the lowermost parts of the Oldman Formation, Alberta. The relationships of M. major to other species of Meniscoessus probably do not include descent from an M. ferox-like ancestor or ancestry of M. robustus-like descendants.

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