Tafonomía y sedimentología de la Paleobiota Estuarina en los Cerros Barbudal (Costa Rica) sepultada por vulcanismo neógeno

Abstract

A marine taphocoenosis constituted by brachiopods and mollusks (bivalves and gastropods) was found interbedded in a Neogene volcaniclastic sequence (ignimbrites and tuffites from Bagaces Formation). It is remarkable the finding of the first fossils of inarticulate brachiopods in Central America: Glottidia sp. These remains are well preserved because their calcium phosphate skeleton, while those from the mollusks, composed by calcium carbonate, are only preserved as internal casts. The fossils are now located just 10 m a.s.l., in spite of their age of several million years. This may be due to a complex equilibrium between the region's subsidence and uplifting history.Keywords: Cerros Barbudal, Neogene volcanism, paleobiota, Glottidia sp., taphonomy, estuarine sedimentology. RESUMEN:Intercalada dentro de una secuencia volcaniclástica del Neógeno (ignimbritas y tobitas de la Formación Bagaces), se encontró una tafocenosis marina constituida por braquiópodos y moluscos (bivalvos y gasterópodos), en la que sobresale el hallazgo de los primeros braquiópodos inarticulados fósiles en América Central: Glottidia sp. Estos restos se encuentran bien preservados por poseer un esqueleto de fosfato de calcio, mientras que los moluscos de carbonato de calcio, se preservan solo como moldes internos. Los fósiles se ubican actualmente a sólo 10 m s.n.m. a pesar de tener varios millones de años, lo cual puede deberse a un complejo equilibrio entre subsidencia y levantamiento de la región.

The post‐Palaeozoic fossil record of drilling predation on lingulide brachiopods

“…4). High drilling frequencies of naticids feeding on mollusc prey have been reported from the geological units that yielded drilled lingulids in our study (Kelley et al 2001;Aguilar & Alvarado 2004;Brezina et al 2016). The much higher frequency of predatory attacks on molluscs suggests that naticids were common in those ecosystems.…”

“…High drilling frequencies of naticids feeding on mollusc prey have been reported from the geological units that yielded drilled lingulids in our study (Kelley et al . ; Aguilar & Alvarado ; Brezina et al . ).…”

“…Kelley et al . ; Aguilar & Alvarado ; Brezina et al . ), which is consistent with our interpretation that drillholes were made by these predators.…”

Evaluating Complex Magma Mixing via Polytopic Vector Analysis (PVA) in the Papagayo Tuff, Northern Costa Rica: Processes that Form Continental Crust

“…Pyroclastic units are interbedded with lava flows, terrigenous sediments and paleosols [25,28]. One sequence is also interbedded with shallow marine units containing ripple marks and invertebrate fossils [29]. Gillot et al [30] estimated a volume of 100 ± 40 km 3 for the Bagaces Formation.…”

Marine Fossils

“…These were low diversity communities, where Nuculana fundationis was the most representative element of the association (Fischer & Aguilar 1995). Other estuarine fauna included the first inarticulate brachiopods reported from Central America found interbedded within the ignimbrites of the Bagaces Formation (Aguilar & Alvarado 2004).…”