| San Gregorio Formation | |
|---|---|
| Stratigraphic range: Zanclean-Chibanian (Chapadmalalan-Lujanian) ~ | |
 | |
| Unit of | Urumaco stratigraphic section |
| Sub-units | Vergel Member Cocuiza Member |
| Overlies | Codore Formation |
| Thickness | ~570 m (1,870 ft) |
| Lithology | |
| Primary | Sandstone, mudstone |
| Other | Limestone |
| Location | |
| Country |  Venezuela |
| Type section | |
| Named for | San Gregorio, Venezuela |
 | |
The San Gregorio Formation is a lithostratigraphic unit dating back to the Pliocene to Pleistocene of Venezuela. The formation is split into three members, the older Vergel Member (Late Pliocene to earliest Pleistocene), the Cocuiza Member (Pleistocene) and the Río Seco Member. During this time the region is thought to have been covered by a mixed environment of open grassland and forested areas surrounding a permanent freshwater system. The diverse fauna of the San Gregorio Formation, including a variety of freshwater fish, crocodilians, turtles and snakes, also includes many mammals interpreted to have been part of the first major wave of the Great American Interchange in addition to native clades such as glyptodonts, ground sloths and caviomorph rodents.[1]
- ^ Carrillo-Briceño, Jorge D.; Sánchez, Rodolfo; Scheyer, Torsten M.; Carrillo, Juan D.; Delfino, Massimo; Georgalis, Georgios L.; Kerber, Leonardo; Ruiz-Ramoni, Damián; Birindelli, José L. O.; Cadena, A, Edwin-Alberto; Rincón, ldo F.; Chavez-Hoffmeister, Martin; Carlini, Alfredo A.; Carvalho, Mónica R.; Trejos-Tamayo, Raúl; Vallejo, Felipe; Jaramillo, Carlos; Jones, Douglas S.; Sánchez-Villagra, Marcelo R. (2021). "A Pliocene–Pleistocene continental biota from Venezuela". Swiss Journal of Palaeontology. 140 (9): 9. Bibcode:2021SwJP..140....9C. doi:10.1186/s13358-020-00216-6. PMC 8550326. PMID 34721281.