ammonites
Pajcha Pata (Cretaceous of Bolivia)

Also known as Pajchapata

Where: Cochabamba, Bolivia (17.9° S, 65.5° W: paleocoordinates 20.4° S, 51.5° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: El Molino Formation, Maastrichtian (70.6 - 65.5 Ma)

• The fossils described in this paper occur about 30 m above the base of the El Molino Formation. This is in the base of the upper part of the Lower Member of the El Molino Formation

•

•Based on a detailed study of the magnetostratigraphy of the El Molino Formation at the La Palca stratotype section near Potosı́, and applying sequence stratigraphic methods for correlating with the Pajcha Pata section, the fossil bed is ≈68.4 Ma (Sempere et al., 1997, following the time scale of [Cande and Kent, 1992] and [Cande and Kent, 1995]).

• member-level stratigraphic resolution

Environment/lithology: estuary or bay; fine-grained, medium, red, yellow sandstone

• The bed was deposited during a sharp and short regressive phase of the dominantly marine-influenced Lower El Molino at a time when deposition rates for the El Molino were highest. The channel sands derive from a large northeasterly draining river system
• The fossiliferous unit is about 3-m thick, and consists of red to yellow, fine- to medium-grained sandstone.The bed represents a broad channel that can be followed for about 2 km to the northeast of Pajcha Pata.

Size classes: macrofossils, mesofossils

Collected by Marshall, Gayet and Meunier in 1989, 1994

Collection methods: bulk, surface (float), sieve,

• Museo de Historia Natural de Cochabamba, Cochabamba, Bolivia (MHNC) collection

Primary reference: M. Gayet, L. G. Marshall, T. Sempere, F. J. Meunier, H. Capetta and J. Rage. 2001. Middle Maastrichtian vertebrates (fishes, amphibians, dinosaurs and other reptiles, mammals) from Pajcha Pata (Bolivia). Biostratigraphic, palaeoecologic and palaeobiogeographic implications. Palaeogeography, Palaeoclimatology, Palaeoecology 169(1-2):39-68 [R. Benson/R. Benson] more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 12855: authorized by Emmanuel Fara, entered by Emmanuel Fara on 20.12.2001, edited by Roger Benson