Micromammals in carnivore scats: an actualistic taphonomic study of the rodents digested by the Achala culpeo fox (Lycalopex culpaeus smithersi) in Córdoba, Argentina

DAIANA COLL; CLAUDIA MONTALVO; FERNANDO J. FERNÁNDEZ; MÓNICA PIA; MARIANA MONDINI

Terragona

Encuentro; 3rd Meeting of the ICAZ Microvertebrate Working Group; 2020

Microvertebrate Working Group (ICAZ)

The taphonomy of mammalian carnivores is relevant to the interpretation of the fossil record, asthese agents may accumulate, transport, modify and destroy faunal assemblages, including thoseassociated to anthropic remains. Carnivore activity can not only delete information by biasingfaunal accumulations, but also provide relevant palaeoecological information. The study ofcarnivore taphonomy has been developing in southern South America, particularly in Argentina,since the 1980s. One of the most conspicuous carnivores are foxes. Yet, information on thetaphonomic activity of these canids is still scarce, particularly in some areas, and especially asregards ingested bones. Here we present the first actualistic study of micromammals consumed bythe Achala fox (Lycalopex culpaeus smithersi), a subspecies of the culpeo fox that is endemic tothe Pampa de Achala (31º36?S, 64º51?W), in Córdoba province, central Argentina, andgeographically isolated from other populations of L. culpaeus. The area is in the high Córdoba Mountain range (max. 2884 m.a.s.l.), and is characterized by granite outcrops intermingled with grasslands, shrublands and xeric forests. The aim of this study is to report the taphonomic patterns on the rodents consumed by this canid, based on 83 scat samples collected in 2004, 2007 and 2008. Evaluation included diet composition, relative abundance of skeletal elements (MNE) as a function of the minimal number of individuals (MNI), anatomical indices (postcranial/cranial elements and distal/proximal limb elements), corrosion modifications produced by digestive acids (on teeth, femur and humerus), and breakage of skeletal elements. A total of 931 elements (MNE) and 32 individuals (MNI) were identified in the whole rodent sample. The Caviomorpha Ctenomys spp. and Galea leucoblephara and the Sigmodontinae Reithrodon auritus were identified in samples from all the years. Yet some temporal variation in Sigmodontinae richness was found, with Calomys musculinus, Phyllotis xanthopygus, Akodon dolores and Akodon azarae being represented in only one or two years. Skeletal representation suggests good anatomical relative abundance, with cranial and proximal limb elements being bestrepresented. Only a few mandibles were complete, and skulls were mainly fragmented. Postcranial elements were highly fragmented Most of the elements bear digestion modification, with all categories represented, and a high proportion of heavy and extreme digestion. This data supports the conclusion that the Achala culpeo fox fits best with other mammalian carnivores in the extreme category of modification as defined by Andrews and others, and shows types and proportions of taphonomic attributes similar to other South American mammalian predators.It should be noted that in spite of the high degree of destruction, several small prey remains are complete enough as to be identifiable, both anatomically and taxonomically. This is the first actualistic taphonomic study in the Pampa de Achala highlands of central Argentina. It is also one of the few taphonomic studies available on the digestion effects by South American foxes, and the first on the Achala fox. The results can help characterize digestive modifications by Lycalopex foxes generally in the Neotropics. The implications of these results are relevant to Quaternary archaeological and palaeontological records.