Mammalian predator–prey relationships and reoccupation of burrows in the Pliocene of the Pampean Region (Argentina): new ichnological and taphonomic evidence

Abstract

Here we describe an unusual fossil assemblage found inside a crotovine from the late Pliocene Chapadmalal ‘Formation’ (Buenos Aires Province). This assemblage contains the greatest vertebrate diversity recovered inside an ichnofossil of this type, including skeletal remains of dasypodids, didelphids, procyonids, anurans and caviomorph rodents within coprolites and disaggregated scatological waste. We describe four general size types for crotovines and palaeoburrows found in the Pliocene to Holocene of Argentina and Brazil, of which the structure found corresponds to the ‘mid-large’ size type and is linked to the activity of the large dasypodid Ringueletia simpsoni. The scatological remains are assigned to a small-sized carnivorous mammal with a body mass of between 1 and 6 kg. Within the guild of Chapadmalalan omnivorous–carnivorous mammals, this inferred mass range is restricted to large didelphids and mid-sized procyonids (represented in the assemblage by Thylophorops chapadmalensis and Cyonasua lutaria, respectively). The data gathered here confirms that the reoccupation of burrows is a common behaviour in small-sized carnivorous mammals at least since the early Pliocene. In addition, we suggest a predator–prey relationship between the studied carnivores and the most abundant small fossorial mammals of the Pampean Pliocene.

Keywords:

• Ringueletia
• Thylophorops
• Cyonasua
• fossoriality
• predation
• coprolites

Acknowledgements

We thank Claudia Montalvo and Rodrigo Tomassini for their valuable suggestions and commentaries on the draft manuscript; Daniel Boh for his assistance in the study of specimens deposited in the MPH; Lucas Marti, Clelia Mosto, Inés Pereda, and Kieren Mitchell for their assistance with the English versions; and Raúl Gómez by indicate the anuran affinities of the specimen found. Comments by the reviewers improved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.