The fossil record is our primary window to study life in the past and to infer episodes of faunal and floral change associated with past environmental changes. Nevertheless, before obtaining evolutionary or environmental information from the fossil record, it is necessary to evaluate the taphonomic processes that have transformed information from living faunal and floral communities to death assemblages and, eventually, to buried fossil assemblages. Taphonomy is the sub-field of palaeontology that 'studies the transition of the organic remains from the biosphere into the lithosphere' as defined by the Russian palaeontologist I. A. Efremov in 1940.
A synthesis of the processes that result in fossilization can only be achieved if taphonomic analyses are also conducted in modern faunal and floral death assemblages (i.e. actualistic studies). Death-assemblage surveys in modern ecosystems have documented comprehensive information on the multiple processes affecting organic remains and controlling their eventual recycling or preservation.
In the field of mammal taphonomy, the work by Johannes Weigelt (1927) was one of the first studies on the processes governing the death, decomposition and potential preservation of modern vertebrate carcasses. Nevertheless, long-term mammal bone surveys did not started until the 1970s with the work carried out by A.K. Behrensmeyer and others in Amboseli National Park (Kenya). These authors monitorized carcasses of large mammals to (1) compare the faunal representation (fidelity) of the bone assemblage to the living community and (2) document processes that modify modern bone assemblages and result in either their preservation or destruction. Since these initial efforts, a few more mammalian bone surveys have been conducted but are still scarce and have occurred in regions with tropical and temperate climatic regimes. With this project, we seeked to expand the monitoring of modern vertebrate remains to Mediterranean ecosystems. The goal of this research programme is to better understand early postmortem processes that affect the information enclosed in modern death assemblages, and eventually in the fossil record, and that affect our ability to reconstruct past environments and biotas.
The study site is Doñana National Park (DNP), a UNESCO World Heritage Site and Biosphere Reserve, in a Mediterranean biome in Andalusia, Spain. DNP is an excellent natural laboratory for actualistic taphonomic research because: (1) it has been protected since 1969 and is a restricted area devoted to conservation and research (tourism takes place in the periphery of the Park and limited guided tours are permitted inside the Park); (2) this natural area has been intensively studied with several decades of records about the history of the physical environment and censuses of selected vertebrate species; and (3) it includes several habitats that vary according to the local geomorphology.
In addition to offering important insights about the biases and filters that affect recent death assemblages before they become fossil assemblages, this type of studies have been shown to also be a useful, non-invasive way to track different aspects of the living populations (e.g. changes in their abundance, habitat and resource utilization, or mortality through time) in areas lacking historical records, and thereby can be used to inform decisions about conservation biology and wildlife management.
In the course of this action, we have carried out two field campaigns and we have sampled and analyzed from a taphonomical viewpoint 33 transects belonging to 10 different habitats. We have recorded information for a total of 3796 bones belonging to 344 individuals. Relationships have been established between the taphonomic preservation of bones and aspects such as the predatory pressure, the scavengers' action and the depositional environment where bones were found. Also, ecological information regarding the geographic distribution and pr
