|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.
|C. W. Hibbard 1937||Intermediate in size between Sigmodon curtisi and Sigmodon medius. Distinguished from other fossil and living forms in that the anterior internal lophid of M2 is not as compressed and transversely elongated. Anterior to the posterior loop of M2 and on the lingual side of the tooth is found an enamel islet. In young specimens this islet is represented by a well-developed reëntrant fold, but not deep enough to persist through the wearing life of the crown; a distinctive character of this form. The anteroposterior diameter of this lophid is nearly as great as its transverse diameter due to the angulation of the antero-external portion of this tooth. The anterior loop of M1 large. The antero-interior lophid of M1 opens widely into the anterior loop.|