Betonnia undetermined

Clemens, William A., 2019, Puercolestes and Betonnia (Cimolestidae, Mammalia) from the early Paleocene (Puercan 3 Interval Zone) of northeastern Montana, U. S. A., PaleoBios 36, pp. 1-17 : 6

BETONNIA SP. CF. BE. TSOSIA

FIGS. 5–8

Remarks

The genus and species were established on only 11 isolated teeth, many of them fragmentary, from Horizon A (Pu2) and Horizon B (Pu3) of the Nacimiento Formation, New Mexico. Only three upper molars were included in the hypodigm. Of these, the holotype was identified as an M2 missing the parastylar lobe ( AMNH 59852 ). Its distal width, the only dental dimension of an upper molar reported by Williamson et al. (2011, table 3), is 2.50 mm. The two referred upper molars, an M1 ( NMMNH P-47221) and M2 ( NMMNH P-51583), are incomplete. Eight isolated lower premolars and molars were tentatively referred .

Diagnostic characters of Be. tsosia cited by Williamson et al. (2011) are primarily those of the upper molars. The parastylar lobe of M1 is mesiobuccal to the paracone. Pre- and postcingula are present. The mesiodistal width of the molar conular region is greater than 0.51 of the total crown length. Conular cristae are distinct. These characters hold true for the teeth from Montana referred to Be. sp. cf. Be. tsosia . Comparison of the values given in Williamson et al. (2011, tables 1, 3) indicates that, with few exceptions, the dental dimensions of teeth referred to Be. tsosia are smaller than those referred to Pu. simpsoni .