Small vertebrate taphonomy of La Cueva del Llano, a volcanic cave on Fuerteventura (Canary Islands, Spain). Palaeoecological implications

Abstract

Cueva del Llano is a volcanic tube of Pleistocene age on Fuerteventura Island. A strand of it (Ramal Nuevo) contains a complex sedimentary infill which has been divided into three sedimentary units and contains at least eight fossiliferous levels of Holocene age. The taphonomic analysis of small vertebrates found in the sediments revealed a scatological origin for the vertebrate assemblage, and that the barn owl (Tyto alba) is the main agent responsible for this concentration of bone remains. Furthermore, the taphonomic analysis allows to reconstruct the changes in the palaeodiet of barn owls during the Holocene of Fuerteventura (Canary Islands) and infer the alterations produced in the vertebrate comunity during that time. In the upper units of the sedimentary infill, the appearance of the house mouse (Mus musculus) is observed. This immigration is correlated that is associated to a decrease of the lava mouse (Malpaisomys insularis) proportions in the fossil assemblage. Also, the study of small vertebrate accumulation in Ramal Nuevo shows that volcanic tubes can be referred to as very useful concentration trap for taphonomic studies.