The Puercan North American Stage on the geologic timescale is the first North American faunal stage of the Paleocene epoch, according to the North American Land Mammal Ages (NALMA) chronology. It spans an interval from around 66 to 65.1 million years ago.
The Puercan is the first of four NALMAs corresponding to the Paleocene, followed by the Torrejonian, Tiffanian, and Clarkforkian. The Puercan directly follows the Lancian NALMA, which corresponds to the Maastrichtian age of the Late Cretaceous. The K-Pg boundary and K-Pg mass extinction at 66 million years ago approximates the boundary between the Lancian and Puercan. The Puercan is followed by the Torrejonian NALMA stage.
Few Puercan mammals are closely related to modern North American mammals, most belong to an early adaptive radiation in the aftermath of the K-Pg mass extinction. Some are holdovers from the Cretaceous, such as a diverse array of rodent-like multituberculates alongside marsupial-like mammals (such as Peradectes and Thylacodon) and cimolestans (such as Cimolestes). Other groups first appearing in North America during the Puercan include:
The Puercan is considered to contain the following substages:
The Puercan is named after the "Puerco marls" or "Puerco Formation", historical terms for the lower part of the Nacimiento Formation in San Juan Basin, New Mexico. Some examples of strata preserving Puercan-age fossils include: