Montañita/Olón (Oligocene of Ecuador)

Where: Santa Elena, Ecuador (1.8° S, 80.8° W: paleocoordinates 3.6° S, 75.5° W)

When: Zapotal Member (Dos Bocas Formation), Chattian (28.1 - 23.0 Ma)

• Here, we provisionally identify the source horizon for MO-1 as the Zapotal Member of the Dos Bocas Formation, with names following Whittaker [25]. More study is needed to establish the proper terminology of the coastal strata outside, but closely-related to, the Progreso Basin. We did not find foraminiferans that might be used for dating. The presence of Carcharocles angustidens is consistent with a late Oligocene age suggested by Bristow. Elsewhere, in the East Pisco basin of Peru, C. angustidens is not reported from the vertebrate-bearing Chattian to Burdigalian Chilcatay Formation, in which the richest vertebrate-bearing horizon is Burdiga- lian [29–31]), but occurs in older units (M. Urbina and A. Altamirano (Departamento de Paleontolog ́ıa de Vertebrados, Museo de Historia Natural, Universidad Nacional Mayor de San Marcos), personal communication, fide T.J. DeVries (Burke Museum of Natural History and Culture, University of Washington, Seattle)). Thus, the age of MO-1 is consistent with a probable Chattian age (24 to 26 Ma), as shown by Bristow [23] (his Fig 3, Zapotal Member of Tosagua Formation).

Environment/lithology: coastal; sandstone

• quiet setting; estuarine or mid-shelf
• composed of a moder- ately-sorted, fine to medium sandstone with angular quartzo-feldspathic clasts. Conspicuous rounded green grains are probably glauconite, but berthierine cannot be dismissed. The matrix is micritic and volcanogenic, possibly bentonitic. Bedding is massive to indistinct

Size class: macrofossils

Primary reference: Y. Tanaka, J. Abella, Gl Aguirre-Fernández, M. Gregori, and R. E. Fordyce. 2017. A new tropical Oligocene dolphin from Montañita/Oló, Santa Elena, Ecuador. PLoS One 12(12):e0188380 [M. Uhen/M. Uhen]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 190942: authorized by Mark Uhen, entered by Mark Uhen on 26.12.2017, edited by Patricia Holroyd

Creative Commons license: CC BY (attribution)

Taxonomic list

Chondrichthyes
 Lamniformes - Otodontidae
Carcharocles angustidens Agassiz 1843 mackerel shark
Reptilia
 Testudines -
Mammalia
 Cetacea -
Urkudelphis chawpipacha n. gen. n. sp.
Urkudelphis chawpipacha n. gen. n. sp. Tanaka et al. 2017 toothed whale