A Proposal for a New Classification and Nomenclature for the Glires (Lagomorpha and Rodentia)

Abstract

The integrity of the Cohort Glires is supported, not only by the numerous previously noted synapomorphies (e.g. distinctive embryology, caecotrophy, evergrowing gnawing incisors) but by new ones (rectangular cross section of rostrum, distance of jaw articulation from middle ear). Lagomorphs are considered highly modified grazing animals derived from a rodent-like ancestor with fully developed gnawing incisors. Zygomasseteric structure is abandoned as the basis for the classification of the Rodentia. The relation of the nasolacrimal canal to the incisor alveolous is the basis for a dichotomy between the Entodacrya, in which the canal runs medial to the alveolus, and the Sciurognathii, in which the canal is lateral (plesiomorphic condition). Entodacrya divide into Ctenodacylida (from which Cocomys has been removed) and Hystricognathii. The Sciuromorpha divide into the Stegaulata, in which the nasolacrimal canal is buried the skull, and the Phaneraulata, in which the canal lies open on the face for some distance. The Stegaulata are roughly the old Sciuromorpha, minus the geomyoids and plus the anomalurids and the paramyids. The Phaneraulata are approximately the old Myomorpha, minus the anomalurids and plus the geomyoids, the glirids, and the Theridomyids. Pedetes may form the sister group to the Entodacrians.