Sequence of events (A to B) in the formation of Batallones-1
Taphonomy of modern and ancient ecosystems Taphonomy is the sub-field of paleontology that studies the transition of the organic remains from the biosphere to the lithosphere, as defined by the Russian palaeontologist I. A. Efremov in 1940. Taphonomic studies comprises the compilation of numerous variables including the spatial distribution of fossils in the sites, the estimation of the number of skeletal elements and individuals represented, the preservation state of fossil bones, the geochemical composition of bones and the sedimentological evidence. All these elements eventually allow us to construct reliable scenarios for the formation mode of fossil sites. I have conducted taphonomic studies of the Miocene mammalian fossil sites of Batallones-1 (ca. 9 Ma) and Somosaguas-North (ca. 14 Ma), both located in the Madrid Basin (Spain). Preservation of remains greatly differs between these two locatities as a consequence of their very different taphonomic histories. Batallones-1 remains are exceptionally well preserved as they were deposited in the protected environment of a cavity where bones underwent little or no transport after accumulation. Somosaguas-North bones display varied preservational states but broken, unidentifiable remains are extremely abundant. Somosaguas-North assemblage is formed by a mixture of elements that underwent different pre-burial histories and were eventually buried together by debris flow deposits. I am currently leading the taphonomic study of Batallones-3 and Batallones-10 fossil sites. Also, in the context of the Marie Skłodowska-Curie fellowship that I currently hold (LiveDeadFossil project), I have started a neotaphonomical study of the skeletal remains from the Doñana National Park (Andalusia, Spain).
Origination, p(i), extinction, q(i), net diversification, d(i), and turnover, t(i), rates for the large mammal faunas of the Miocene of Spain. Asterisks denote significant values.
Macroevolution of Neogene mammals Macroevolutionary studies in paleontology put together the discoveries made at the microevolutionary scale (changes within species) to reveal patterns at large temporal and spatial scales. This way, episodes of faunal change or stability become evident and can be analyzed in the light of environmental changes, geological processes or biotic interactions among taxa. Long, continuous fossil records constitute unique windows for investigating the dynamics of past organisms and for evaluating potential drivers of biotic change. My macroevolutionary studies are mainly centered on the exceptional Spanish fossil record of Neogene mammals. During my postdoctoral appointment at the University of Michigan I also had the chance to study the long and dense Neogene mammalian record from the Siwaliks of Pakistan. To perform this type of studies, it is necessary to compile big databases containing taxonomic, trophic, body mass, or locomotor information. Diversity metrics provide rates for origination, extinction, diversification, turnover and trophic and body mass changes through time in the light of environmental change and geological events. Macroevolutionary analyses of past faunas and floras have the potential to contribute essential information leading to the solution of problems concerning the conservation of modern wildlife as they can provide baselines against which to assess current diversity changes.
Stable carbon isotope values (mean ± 1 SD) for BAT-1 and BAT-3 carnivore and herbivore species.
Paleoecology of mammals through stable isotope analyses Stable isotope analysis of skeletal remains is a robust method to infer the diet and resource use of extinct mammals, as well as the habitat where they lived. In deep time studies, stable isotope analyses are performed preferentially on dental enamel since it is the only tissue that preserves a biologic signal due to its structural and compositional features. When working with fossil dental enamel, carbon (δ13C) and oxygen (δ18O) stable isotopes are analyzed. For mammals, the δ13C of tooth enamel tracks primarily the δ13C values of their diet. δ18O typically documents changes in temperature and precipitation. Just as in modern ecosystems, herbivore remains and individuals are far more abundant in fossil sites than carnivore remains, therefore most paleoecological stable isotope studies have focused on herbivore mammals. Due to their exceptional taphonomic history, Cerro de los Batallones fossil sites (specifically Batallones-1 and Batallones-3) are dominated by carnivores so we are having the chance to investigate from a stable-isotope viewpoint not only the herbivores but also the carnivoran fauna from these sites, obtaining a rich picture about the trophic interactions and resource use of the species that inhabited the Madrid Basin 9 million years ago.
Batallones-10 fossil site (Madrid Basin, Spain)
Open-Door Days at Cerro de los Batallones fossil sites
Excavating at Batallones-10
Somosaguas-North fossil site (Madrid Basin, Spain)
Antelope ribs and vertebrae from Batallones-10
Gomphotherium angustidens molar tooth from Somosaguas-North