The Riochican () 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.Paleo Database: Riochican 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.

Formations

Formation Country Basin Notes Río Chico Group Golfo San Jorge Basin Bogotá Formation Altiplano Cundiboyacense Bororó Formation Golfo San Jorge Basin Chota Formation Bagua Basin Koluel Kaike Formation Golfo San Jorge Basin Las Flores Formation Austral Basin Maíz Gordo Formation Salta Basin Mealla Formation Salta Basin Mogollón Formation Talara & Tumbes Basins Muñani Formation Altiplano Basin Peñas Coloradas Formation Golfo San Jorge Basin Río Loro Formation Sierras Pampeanas Salamanca Formation Golfo San Jorge Basin

Fossils Group Fossils Formation Notes Mammals Etayoa bacatensis Bogotá Brandmayria simpsoni, Ernestokokenia chaishoer, E. ?yirunhor, Isotemnus cf. primitivus, Palangania brandmayri, Anisolambda sp., Henricosbornia sp., Josepholeidya sp., Notopithecus sp., Othnielmarshia sp., Polydolops winecage, Ricardolydekkeria sp., Trigonostylops sp., Victorlemoinea sp., ?Eohyrax sp., ?Nemolestes sp., ?Notostylops sp., ?Pleurostylodon sp., ?Polystylops sp., ?Postpithecus sp., Dasypodidae indet. Koluel Kaike Eoastrapostylops riolorense, Notonychops powelli, Satshatemnus bonapartei Río Loro Reptiles &amphibians Testudines indet. Koluel Kaike Pelomedusoides sp. Maíz Gordo Lorosuchus nodosus, Pelomedusoides cf. argentinensis Río Loro Fishes ?Cyprinodon primulus Maíz Gordo Insects Anthicus sepultulus, Austrolibellula noroestenia, Carabites harringtoni, Celinapterix bellissima, Cryptophagus sunchalensis, Curculionites harringtoni, C. jujuyensis, C. magdalinus, C. parastictus, C. stebingeri, C. sunchalicus, C. wielandi, Curviarculia delicata, C. lamasi, Gryllites vocalis, Jujusia maizgorda, Latibasalia elongata, L. quispeae, Lebia harrelli, Ormenis devincta, Otiorhynchites aterrimus, O. crassus, Palaeomacromia multicellulata, Palaeophya argentina, Promegalestes singularis, Tenebrionites inclinans, Thyridates novokschonovi, ?Anthonomus sunchalensis, ?Corizus deflagratus, ?Cossonus devoratus, ?Haruspex defectus, ?Molanna derosa, ?Podabrus santaritensis, ?Trichodes stebingeri Maíz Gordo Flora Banaraphyllum ovatum, Cissites patagonica, Cryptocaryoides mariasantisimensis, Dryophyllum australis, Fagophyllum duseni, Laurophyllum chubutensis, Laurophyllum piatnitzkyi, Myrica premira, Nothofagidites visserensis, Paranymphaea aristolochiaformis, Sterculia acuminataloba, Zizyphus chubutensis Río Chico Palmoxylon patagonicum Bororó Cordioxylon prototrichotoma PeñasColoradas Palmoxylon patagonicum Salamanca

References

Bibliography Bogotá Formation

Bororó Formation

Chota Formation

Las Flores Formation

Koluel Kaike Formation

Maíz Gordo Formation

Mealla Formation

Mogollón Formation

Muñani Formation

Peñas Coloradas Formation

Río Loro Formation

Salamanca Formation