Late Pleistocene sigmodontines (Mammalia : Rodentia)from the Tafi valley (Tucuman, Argentina): Taxonomy, taphonomy and paleoenvironmental reconstruction
Pe. Ortiz et Ufj. Pardinas, Late Pleistocene sigmodontines (Mammalia : Rodentia)from the Tafi valley (Tucuman, Argentina): Taxonomy, taphonomy and paleoenvironmental reconstruction, AMEGHINIANA, 38(1), 2001, pp. 3-26
LATE PLEISTOCENE SIGMODONTINES (MAMMALIA: RODENTIA) FROM THE TAFI VALLEY (T
UCUMAN, ARGENTINA): TAXONOMY, TAPHONOMY AND PALEOENVIRONMENTAL RECONSTRUCTI
ON. An exceptionally rich rodent assemblage of Lujanian age (latest Pleisto
cene) at La Angostura (26 degrees 55' 30" S, 65 degrees 41' 50" W, Tafi val
ley, Tucuman province; 1900 m above sea level) provides the first evidence
of sigmodontine rodents in the fossil record of northwestern Argentina. Ide
ntified taxa are: Abrothrix illuteus Thomas, Akodon sp., Necromys cf. N. la
ctens (Thomas), Oxymycterus cf. O, paramensis Thomas, Oligoryzomys cf. O. f
lavescens (Waterhouse), Oligoryzomys cf. O. "longicaudatus" (Bennett), Andi
nomys edax Thomas, Calomys cf. C. laucha C. musculinus, Neotomys ebriosus T
homas, Phyllotis sp., Reithrodon auritus (Fischer), and dagger Tafimys powe
lli Ortiz et al. These include the first fossils of the genera Neotomys Tho
mas and Andinomys Thomas in Argentina. Taphonomic analysis indicates that t
he assemblage is a fossil owl pellet accumulation. Consequently, it can be
assumed to be a biased representation of the small mammal fauna of a relati
vely small area over a relatively brief time span. This association has no
modern analogue because today these species live at different altitudinal v
egetation belts. The fauna indicates a community from the high-altitude gra
ssland ecotone, with elements of the Yungas, Puna and High Andeans. Tempera
tures may have been lower than today. Although the species composition is s
imilar to the modem sigmodontine community in the area, quantitative variat
ions in proportional representation can be attributed to Holocene climatic
conditions and, probably, to the impact of human populations in historical
times.