The oldest record of a carnivoran mammal in South America corresponds to the extinct procyonid Cyonasua (late Miocene–early Pleistocene). Up to now, this genus was recorded in Argentina, Uruguay, Bolivia, and Venezuela. In this contribution, we report the first occurrence of Cyonasua in the Pacific coast of Peru, recovered from the late Miocene marine deposits of the Pisco Formation. The fossil material comprises postcranial bones of two individuals (MNHN SAS 1625: left femur; MNHN PPI 262: axis, right talus, and left metatarsal III). The morphology and sizes of these new fossil specimens, allow us to refer them to Cyonasua sp. This record reaffirms that procyonids were the first North American carnivorans that arrived in South America prior to the full emergence of the Isthmus of Panama, as part of the proto-Great American Biotic Interchange. The presence of Cyonasua in marine deposit...

The highly productive waters of the Humboldt Current System (HCS) host a particular temperate ecosystem within the tropics, whose history is still largely unknown. The Pisco Formation, deposited during Mio-Pliocene times in the Peruvian continental margin has yielded an outstanding collection of coastal-marine fossils, providing an opportunity to understand the genesis of the HCS ecosystem. We present a comprehensive review, completed with new results, that integrates geological and paleontological data from the last 10 My, especially focusing on the southern East Pisco Basin (Sacaco area). We discuss the depositional settings of the Pisco Formation and integrate new U/Pb radiometric ages into the chronostratigraphic framework of the Sacaco sub-basin. The last preserved Pisco sediments at Sacaco were deposited ~ 4.5 Ma, while the overlying Caracoles Formation accumulated from ~ 2.7 Ma on...