LEFTOVER PREY REMAINS: A NEW TAPHONOMIC MODE FROM THE LATE MIOCENE (CERRO AZUL FORMATION) IN CENTRAL ARGENTINA

CLAUDIA I. MONTALVO; RODRIGO L. TOMASSINI; RENATA SOSTILLO

Mendoza

Congreso; th INTERNATIONAL PALAEONTOLOGICAL CONGRESS,; 2014

CONICET-IPA

The Cerro Azul Formation (La Pampa Province, Argentina) comprises a rich vertebrate fauna corresponding to the late Miocene (Huayquerian Stage/Age), which includes numerous and diverse mammal remains. Taphonomic analysis of micromammal fossils recovered from Estancia Ré locality evidence that the faunistic assemblage is characterized by: high density of remains in small area; high taxonomical diversity; high MNI; high percentage of juvenile individuals; high frequency of disarticulated remains; high frequency of cranial remains; better preservation of several portions of cranial and postcranial remains; high breakage degree in all skeletal elements; presence of remains with spiral and stepped fractures; presence of remains with tooth marks; absence of remains with evidence of corrosion produced by digestion; and lack of remains with evidence of abrasion. The taxonomic representation shows predominance of one taxon (Paedotherium minor, Notoungulata). These features indicate the activity of a predator which accumulated the micromammal remains. Considering this, comparisons with other assemblages recovered from the Cerro Azul Formation in Telén and Caleufú localities (La Pampa Province), also interpreted as produced by predator activity, were made. According to their taphonomic characteristics, assemblages from Estancia Ré, Telén and Caleufú are defined as microfossil bonebeds that differ from any accumulation of feces and pellets produced by modern predators (nocturnal and diurnal raptors and carnivorous mammals). However, due to their anatomical representation, degrees of breakage of the remains and the presence of tooth marks, they can be interpreted as accumulations of uneaten prey remains. This involves that the predator performed a selective use of certain portions of the body prey and discarded others at the same time. The type of predator involved cannot be determined with certainty, although the presence of tooth marks in some remains and the presence of coprolites in Telén and Caleufú suggest that it could be a carnivorous mammal. Similarities in the accumulation mechanism and patterns of preservation, coupled with similarities among the sedimentary contexts involved, support the recognition of a taphonomic mode that includes the three assemblages denominated ?leftover prey remains?.