The Onzole Formation is an Early Pliocene (Montehermosan to Chapadmalalan in the SALMA classification) geologic formation in the Borbón Basin of northwestern Ecuador. The formation consists of a shallow marine sandstone member containing many fish fossils, among which megalodon, and a deep water member comprising tuffaceous shales and mudstones containing gastropods, bivalves and scaphopods.Onzole Formation at Fossilworks.orgOnozole (sic) Formation at Fossilworks.org
Subdivision The formation consists of the Esmeraldas Member, which is a unit comprising highly foraminiferal tuffaceous calcareous shale. They were deposited by shallow water gravity flows, which brought the Esmeraldas fauna into the deep water () from shallow water, on the order of .Esmeraldas Beds at Fossilworks.org
The Esmeraldas Member is covered by the Súa Member comprising burrowed, bioturbated, silty sandstones deposited in a coastal environment.
Fossil content The formation has provided bivalve, gastropod, and scaphopod fossils and the following vertebrates:Súa Member, Onzole Formation at Fossilworks.orgPunta La Gorda at Fossilworks.orgPunta la Colorada at Fossilworks.org
Carcharhinus egertoni, C. priscus Carcharocles megalodon Diaphus ecuadorensisSchwarzhans & Aguilera, 2013 Galeocerdo aduncus Hemipristis serra Isistius triangulus Negaprion eurybathrodon Odontaspis acutissima Rhizoprionodon taxandriae Brotula cf. ordwayi Chilara taylori Eucinostomus cf. currani Larimus cf. pacificus Lepophidium borbonensis, L. limulumSchwarzhans & Aguilera, 2016 Lepophidium microlepis Merluccius cf. angustimanus Orthopristis cf. cantharinus Otophidium indefatigabile Paraconger californiensis Porichthys analis, Porichthys margaritatus, Porichthys cf. notatus Stellifer onzoleAguilera et al., 2016 Anchoa sp. Apogon sp. Citharichthys sp. Diaphus sp. Haemulon sp. Lampadena sp. Apogonidae indet. Cynoglossidae indet. Gobiidae indet. Gerreidae indet. Opistognathidae indet. Pleuronectidae indet. ?Serranidae indet.
See also List of fossiliferous stratigraphic units in Ecuador
References
Bibliography
Further reading G. Carnevale, W. Landini, L. Radgaini, C. Celma, G. and Cantalamessa. 2011. Taphonomic and paleoecological analyses (mollusks and fishes) of the Súa Member condensed shelled, upper Onzole Formation (Early Pliocene, Ecuador). Palaios 26(3):160-172 A. E. Longbottom. 1979. Miocene Sharks' teeth from Ecuador. Bulletin of The British Museum (Natural History) Geology 32:57-70 W. D. Pitt and L.J. Pitt. 1997. Nassarius (Mollusca: Neogastropoda) from the Neogene of northwestern Ecuador. Tulane Studies in Geology and Paleontology 29:135-150 E. H. Vokes and H. E. Vokes. 2000. Catalogue of Tulane University fossil localities E. H. Vokes. 1988. Muricidae (Mollusca: Gastropoda) of the Esmeraldas Beds, northwestern Ecuador. Tulane Studies in Geology and Paleontology 21(1):1-50