The Riochican (Spanish: Riochiquense) age is a period of geologic time within the early Eocene epoch of the Paleogene, used more specifically within the South American land mammal ages (SALMA) system. This age is named after the Río Chico Group of Argentina's Golfo San Jorge Basin, and in its broad original definition, the Riochican occupies a wide Paleocene-early Eocene time interval.
The Riochican has subsequently been split up into three narrower faunal zones: the Carodnia zone, Kibenikhoria zone, and Ernestokokenia chaishoer zone. The Carodnia zone is late early Paleocene (Danian) in age, about 62 million years old, and follows the Peligran SALMA age. The Kibenikhoria zone is equivalent to the Itaboraian SALMA age, which is early Eocene (53–50 Ma). Finally, the Ernestokokenia zone (Riochican sensu stricto), at around 49 Ma, precedes the informal "Sapoan" and formal Casamayoran SALMA ages.
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