Comparison of the left anterior portion of the rostrum, viewed from left side, in four species of Thomasomys: A T. otavalo sp. nov. (MECN 6912, holotype); B T. ucucha (MECN 7937); C T. igor sp. nov. (MECN 702, holotype); D T. silvestris (MECN 4928). Thomas’ angles according to incisive and molar planes are indicated as well as the extension of the molar series. Arrow in (A) point to the anterior border of the nasal bone extending beyond the anterior face of the incisors relative to (B); abbreviations: n, nasal; nc, nasolacrimal capsule; p, premaxillary; sf, supraorbital foramen; zp, zygomatic plate. Scale bar: 5 mm