Genus: Nidimys HUNTER, HEINRICH & WEISHAMPEL, 2010
Etymology: Latin, nidus, "nest" and Latin, mus, "mouse."

Species: occultus HUNTER, HEINRICH & WEISHAMPEL, 2010
Etymology: Latin, occulus, "hidden."

Holotype: MOR 2501

Locality: Shell Hell, Mor Locality 703, SW 1/4 section 19, Township 31 North, Range 9 W, Glacier County, Montana.

Horizon: St. Mary River Formation.

Biostratigraphy:

Age: Edmontonian age, Upper Campanian Stage- Lower Maastrichtian Stage, Senonian subepoch, Upper Gulf Epoch, Late Cretaceous.

Material: Left and right dentary fragments, believed to belogn to the same individual, each with a lower incisor root, p3, p4 and m1.

Referred material:

MOR 2514: Rp4.

MOR 2515: Incomplete Lp4.

MOR 2526-2528: Incomplete right dentaries with partially erupted incisors.

MOR 2629: Fragment of right incisor.

MOR 2520-2525: Anterior upper premolars.

MOR 2502: Fragment of left maxilla with P4-M2.

MOR 2516: PR4.

MOR 2517, 2518: RM1s.

MOR 2507: RM2.