Pe. Ortiz et al., A new fossil Phyllotine (Rodentia : Muridae) from northwestern Argentina and relationships of the Reithrodon group, J MAMMAL, 81(1), 2000, pp. 37-51
We describe an extinct murid, assigned to the tribe Phyllotini, from the la
te Pleistocene (Tafi del Valle Formation) of La Angostura (26 degrees 55'30
" S, 65 degrees 41'50 " W; 1,900 m elevation) in northwestern Tucuman Prov
ince, Argentina. The new genus is characterized by very hypsodont molars wi
th flat crowns and simplified occlusal structure, upper incisors with a med
iolateral groove, a straight premaxillary-maxillary suture, and high zygoma
tic plate with a small spine on its anterodorsal edge. Phylogenetic analyse
s including fossil and living members of the Reithrodon group show that the
new genus is the sister taxon to the Reithrodon-Neotomys-Euneomys clade. T
he paleoenvironmental and paleogeographic significance of the new genus is
discussed within the context of the climatic changes that occurred during t
he late Pleistocene in southern South America. The new phyllotine would hav
e Lived in high-elevation grasslands, which today occur >1,000 m higher und
er cold and dry climatic conditions than those of the last glacial maximum.