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[dinosaur] L'Espinau (Spain) dinosaur bonebed geology and taphonomy

Ben Creisler

A new paper:

V. Fondevilla, A. Vicente, F. Battista, A.G. Sellés, J. Dinarès-Turell, C. Martín-Closas, P. Anadón, B. Vila, N.L. Razzolini, À. Galobart & O. Oms (2017)
Geology and taphonomy of the L'Espinau dinosaur bonebed, a singular lagoonal site from the Maastrichtian of South-Central Pyrenees.
Sedimentary Geology (advance online publication)
doi: http://dx.doi.org/10.1016/j.sedgeo.2017.03.014

A new dinosaur bonebed is described in a lagoonal setting of the Pyrennes.
A combined study (sedimentology, taphonomy, palaeoecology and geochemistry) is performed.
A cohesive flow is the mechanism of bone accumulation.
Magneto- and biostratigraphy have placed the site in the upper Maastrichtian.

The L'Espinau site is a rich dinosaur bonebed from the Upper Cretaceous of the South-Central Pyrenees (north-eastern Spain) that have provided hundreds of bone remains attributed to hadrosauroids, together with a rich assemblage of herpetofauna, fish and microflora. Magnetostratigraphy calibrated the site with the early late Maastrichtian, and the combined sedimentology, stable isotope geochemistry and palaeoecology revealed that this fossil site formed in a lagoon, in which a mixed freshwater-brackish palaeoenvironment was developed. This setting displays a south-north charophyte zonation from freshwater (Clavator brachycerus-dominated assemblage) to brackish or eurihaline conditions (Feistiella malladae-dominated assemblage), revealing a palaeoenvironment change towards the coast. Sedimentology and taphonomy (bidirectional arrangement of long bones, abrasion and disarticulation) indicate that the L'Espinau site is the result of a cohesive mass flow event originated very close to the sea. This process entrained and mixed fauna from both the terrestrial and the brackish/marine environment of a lagoon. An increasing of the water runoff (e.g. by intense rainfall) reworking poorly consolidated sediments is considered here as the most probable triggering mechanism. Mass flow-hosted bonbeds are commonly linked to fluvial paleoenvironments, so our study case is a rare example of bones accumultating near the sea. This study documents one of the few evidences that hadrosauroids inhabited litoral environments during the Maastrichtian in the southern Pyrenean area.