Cenogramas, análisis bioclimático y muestreo en faunas de mamíferos: implicaciones para la aplicación de métodos de análisis paleoecológico

In this work we analyzed the problems derived from the potential species loss associated to the taphonomic processes occurring in fossil sites. We seek to resolve the possible utility of cenograms and bioclimatic analysis as methodologies applicable in Paleoecology. Supposedly, if species are deleted in a community, significant changes in its structure might appear, which would make these paleoecological techniques dysfunctional. The analysis has been carried out with the data of two modern mammalian communities, Barrow (Alaska) and Jaipur (India), on which we have deleted species randomly. Our results have allowed us to conclude that these methodologies are useful in Paleoecology, since they are functional with a satisfactory level of confidence, as long as the species loss is not excessively elevated (for communities with 20-40% of the original species).En este trabajo hemos analizado la problemática derivada de la posible pérdida de especies asociada a los procesos tafonómicos que se dan en los yacimientos de fósiles, para determinar la posible utilidad de los cenogramas y el análisis bioclimático como metodologías aplicables en Paleoecología. Podría suponerse que si eliminamos especies en una comunidad se podrían producir cambios significativos en su estructura que convertirían en no funcionales a estas metodologías. El análisis se ha llevado a cabo con los datos de dos comunidades de mamíferos actuales, Barrow (Alaska) y Jaipur (India), de las que hemos eliminado progresivamente especies de forma aleatoria. Los resultados obtenidos nos han permitido concluir que tanto los cenogramas como el análisis bioclimático son útiles en Paleoecología, ya que son funcionales con un nivel de confianza adecuado, siempre y cuando la pérdida de especies no sea excesivamente elevada (en comunidades con un 20-40% de las especies originales).La presente investigación ha sido parcialmente financiada por los proyectos PR1/06-14470-B (UCM) y CGL2006-01773/BTE (MEC) y por una ayuda de la Universidad Complutense de Madrid y la Comunidad Autónoma de Madrid al Grupo de Investigación UCM-CAM 910607 sobre Evolución de Mamíferos y Paleoambientes Continentales Cenozoicos, dirigido por Marián Álvarez Sierra. Asimismo, el mencionado grupo de investigación ha financiado la presentación de estos resultados en las XXII Jornadas de la Sociedad Española de Paleontología. M.H.F. disfruta de un contrato UCM del Programa «Ramón y Cajal» del Ministerio de Educación y Ciencia.Peer reviewe

Influencia de los cambios climáticos globales en la estructura de las comunidades de mamíferos del Neógeno-Cuaternario

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Geológicas, Departamento de Paleontología, leída 04-03-2015Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEunpu

Tempo and mode in the influence of global climatic changes on mammalian evolution

Comunicación presentada en: XVIII INQUA Congress, 21st–27th July, 2011, Bern, Switzerland.Due to their extraordinary fossil record during the Cenozoic, mammals are a key factor in order to understand how global climatic changes have shaped biotic evolution, especially in continental environments. During the last decades, climatic influence on the evolution of mammal faunas has been reflected mainly in two sets of studies. First, there are works focused in the use of observed variations in the structure of mammalian palaeocommunities through extensive time sequences in order to detect significant palaeoclimatic changes. These studies are based in the concepts of community convergence and uniformitarism, and make use of modern ecological analogues to infer the climatic conditions in which the extinct faunas lived. On the other hand, when data on faunal change through time are confronted with independent data on palaeoclimatic changes it may be statistically inferred whether there has been simultaneous occurrence of climatic changes, faunal turnover and modifications in the ecological structure of the palaeofaunas. The second set of studies is based on the statistical analysis of ecological data from modern faunas. Extant assemblages reflect in their ecological characteristics the past influence of global climate changes on the evolution of mammalian lineages living today, both in geographical and cladal basis. Finally, there are new works based on the study of the phylogenetic signal that can be found in modern clades, which are able to identify periods of enhanced or reduced cladogenesis. Although all these approaches cannot be used simultaneously because of latent problems derived of circular reasoning, the development of methodological protocols for the combined analysis of their results has the potential to shed new light on the question of how and when climate changes affect evolution of biotic communities.The authors also thank the Unit of Information Resources for Research (URICI-CSIC) for the co-financing of this publication in Open Access.Peer reviewe

The Somosaguas palaeontology project: an envision of Nieves López Martínez for linking science and society

The palaeontological site of Somosaguas is located in Pozuelo de Alarcón, to the west of the city of Madrid (Spain), and contains fossils of Miocene age corresponding to 24 species of micro- and macromammals as well as other vertebrates. The Somosaguas Palaeontology Project is focused on this site and was coordinated by Nieves López Martínez between 1998 and 2010 as an example of management of a palaeontological site by university students and young researchers. This project began with fi eld seasons for students in natural sciences grades and today is a multidisciplinary project open to students from any university degree. The signifi cance of the investigations around this fossil site is refl ected in a large number of papers published in national and international journals. Additionaly, there are numerous outreach activities in geology and palaeontology with special attention to what we call Social Palaeontology. Finally, this project has a strong commitment to educational innovation in both non-formal (during school visits, open days at the site and science fairs) and formal university education, with the establishment of an introduction to investigation group in order to prepare young researchers in different fi elds of geology, palaeontology and education

MICE (Mammalian Intercontinental Communities for Ecology): Organizando datos a escala global para lograr una paleoecología más integradora

This paper introduces a new database, “Mammalian Intercontinental Communities for Ecology” (MICE), which seeks to increase and improve, among others, the available material used in palaeoecological studies. Information on climate and terrestrial mammalian communities will be obtained for 500 localities from all around the world. Based on such information, both palaeoecological and neoecological studies will be produced. Problems identified in previous works are being taken into account while the new database is being compiled. When complete, this database will be uploaded to the World Wide Web in order to make it available to the scientific community. It will be interesting to see how the future development of MICE, with a strong dynamic and interactive character, will stimulate production in various scientific fields

The fossil record of the Neogene Carnivore Mammals from Spain

© 2015, Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg. Carnivore mammals (Carnivora, Mammalia) constitute a significant component of the Spanish Neogene faunas, not so much due to their fossil abundance, which is generally low, but rather because of their high degree of taxonomic diversity. We assessed their evolutionary dynamics from the fossil record of Iberian carnivores using per-taxon rates of origination, extinctions and turnover combined with a recent approach for removing the sampling signal from diversity curves. Our analysis interval covers most of the Neogene and the early Pleistocene (MN 2 to MN 17), spanning from around 21.6 to 1.8 Ma. We identified six carnivore associations by applying factor analysis to our data. The diversification pattern shows four origination episodes: MN4, MN7/8, MN12 and MN14. We also identified four extinction episodes. The first two are coincident with the onset of the MN 4 and MN7/8 faunas. The last two extinction episodes take place during MN9, coinciding with the Mid Vallesian Crisis (MVC), and MN13, co-occurring with the Messinian Salinity Crisis (MSC). Two major turnover pulses are recognised during MN4 and MN14, the turnover rate remaining moderately high between MN6 and MN13. We suggest that the pattern observed might be primarily triggered by the biogeographic and climatic shifts that took place during the Neogene.The authors are also grateful to Project CGL2011-25754, MINECO (Spanish Government) and to Research Group BSCH-UCM 910607. A.V. is a trainee researcher of CSIC program JAE-PRE-CP2011 (CSIC program “Junta para la ampliación de estudios”), co-funded by the European Social Fund. D.H. is a trainee researcher of the FPU 2013 program granted by the Spanish Ministry of Education, Culture and Sports.Peer Reviewe

Correction: Body-size structure of Central Iberian mammal fauna reveals semidesertic conditions during the middle Miocene Global Cooling Event.

[This corrects the article DOI: 10.1371/journal.pone.0186762.]

Body-size structure of Central Iberian mammal fauna reveals semidesertic conditions during the middle Miocene Global Cooling Event

We developed new quantitative palaeoclimatic inference models based on the body-size structure of mammal faunas from the Old World tropics and applied them to the Somosaguas fossil site (middle Miocene, central Iberian Peninsula). Twenty-six mammal species have been described at this site, including proboscideans, ungulates, carnivores, insectivores, lagomorphs and rodents. Our analyses were based on multivariate and bivariate regression models correlating climatic data and body-size structure of 63 modern mammal assemblages from Sub-Saharan Africa and the Indian subcontinent. The results showed an average temperature of the coldest month higher than 26°C for the Somosaguas fossil site, a mean annual thermal amplitude around 10°C, a drought length of 10 months, and an annual total precipitation greater than 200 mm per year, which are climate conditions typical of an ecotonal zone between the savanna and desert biomes. These results are congruent with the aridity peaks described over the middle Aragonian of Spain and particularly in the local biozone E, which includes Somosaguas. The aridity increase detected in this biozone is associated with the Middle Miocene Global Cooling Event. The environment of Somosaguas around 14 Ma was similar to the current environment in the Sahel region of North Africa, the Horn of Africa, the boundary area between the Kalahari and the Namib in Southern Africa, south-central Arabia, or eastern Pakistan and northwestern India. The distribution of modern vegetation in these regions follows a complex mosaic of plant communities, dominated by scattered xerophilous shrublands, semidesert grasslands, and vegetation linked to seasonal watercourses and ponds

Taphonomy of mammalian fossil bones from the debris-flow deposits of Somosaguas-North (Middle Miocene, Madrid Basin, Spain)

Debris-flow hosted assemblages dominated by mammalian remains are very scarce in the fossil record and few examples are reported. Herein we present a detailed taphonomic study of Somosaguas-North (Madrid Basin,Spain), a Middle Miocene mammalian-dominatedsite embedded in debris-flow deposits, in order to increase our knowledge of the mode of formation of fossiliferous assemblages in this depositional context. The assemblage includes 6592 large-mammal remains belonging to at least 10 different species. Fossils are found in matrix-supported, poorly-sorted coarse arkosic sandstones and fine conglomerates, which are interpreted as the result of successive debris-flow deposits. Breakage constitutes a pervasive taphonomic alteration in the bone assemblage; however, together with unidentifiable bone fragments, we also found complete to almost complete skeletal elements Bone remains are isolated, a fact that is indicative of a time of exposure of the carcasses long enough to enable decay and complete disarticulation. There are no associations of elements belonging to the same individual, which suggests that, prior to or during debris-flow transport, bones were profusely dispersed. Based on the taphonomic evidence, we suggest that Somosaguas-North assemblage was formed by successive debris-flow transport and burial of pre-existing thanatocoenoses. Bones from those thanatocoenoses were modified by biostratinomic agents (trampling, weathering) in varying degrees depending on their time of exposure. Debris-flow transport produced further abrasion and breakage in collagen-depleted bones. Our results are congruent with an environmental context of semiarid landscapes presenting long arid periods and highly irregular hydrological seasonality. Finally, we compared the Somosaguas-North assemblage with other debris-flow hosted vertebrate assemblages. Although Somosaguas-North shares taphonomic features with some of these sites, it is not possible to define consistent and singletaphonomic patterns for debris-flow assemblages, given the varied taphonomic histories of the remains prior to and during debris-flow transport