|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Mammalia - Rodentia - Cricetidae
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|J. W. Gidley 1922||Length of cheek-tooth series 7 millimeters; about the size of S. hispidus arizonae, which it seems to resemble more nearly, but it differs from that as well as the other living species in the more open valleys of the reentrant angles, the more compressed lophs, the less hypsodont condition of the cheek teeth, the relatively deeper posterior inner reentrant valley of p4 and m1, and especially the form and proportions of the cusps of the last lower molar, which is relatively larger, with the hinder cusp relatively broader and fuller than in the living species. A feature that is characteristic of this and the species described below [Sigmodon minor] and is not observed in any of the living species is noted in the last molar, in which the great extension and flattening of the inner or lingual wall of the posterior lobe forms a sharp right angle with the posterior wall of the reentrant angle on that side.|