Pliocene mammals and climatic reconstruction in the Western Mediterranean area
AGUILAR, J.-P., LEGENDRE, S., MICHAUX, J. and MONTUIRE, S. 1999. Pliocene mammals and climatic reconstruction in the Western Mediterranean area. In J. H. Wrenn, J.-P. Suc and S. A. G. Leroy (eds). The Pliocene: Time of change. American Association of Stratigraphic Palynologists Foundation, Dallas, pp. 109-120.
The specffic diversity of extant mammalian faunas, the body weight distribution of component species (as expressed by... more
The specffic diversity of extant mammalian faunas, the body weight distribution of component species (as expressed by cenograms), and the specific richness of some taxonomic groups change with the climate. Using these parameters, we attempt to estimate the climatic conditions of earlier times and to estimate past temperatures and precipitation.
Cenogram analysis shows that there is a contrast between rather closed and warm environments at the beginning of Pliocene times, and more open and cooler environments during the Pleistocene, and also that the Iberian Peninsula, as compared to southern France, was characterized by more open environments. The specific diversity of Murinae in Western Europe shows that the climate was warm with high precipitation (mean annual temperature = 21°C and mean annual rainfall = ca. 1100 mm) at the end of the Lower Pliocene (-4.0 to -3.5 My). The drop in diversity in Murinae that can be seen in Spain and in France is probably related to a deterioration of the climate towards coolness and dryness between -3.2 My and -2.0 My. About 1 My ago, the climate became dryer, with estimates of about 13°C and 700 mm. The first glacial phases are thus characterized by rather mild temperatures.
Mammalian communities document a latitudinal environmental gradient during the Miocene Climatic Optimum in Western Europe
COSTEUR, L. and LEGENDRE, S. 2008. Mammalian communities document a latitudinal environmental gradient during the miocene climatic optimum in western Europe. PALAIOS, 23, 280-288.
A total of 17 mammalian communities from south-central Spain to northern Germany spanning the middle Miocene Climatic... more A total of 17 mammalian communities from south-central Spain to northern Germany spanning the middle Miocene Climatic Optimum (ca. 17–14 Ma) are analyzed. Mammalian body-weight structures (cenograms) are constructed and discussed in terms of paleoenvironmental affinities. They indicate an arid climate and open environments in south-central Spain and closed and densely forested regions with very humid conditions to the north. The data reveal the presence of a strong latitudinal environmental gradient during this period. Other studies based on the fossil records of plants or ectothermic vertebrates showed that virtually no temperature gradient was present in Europe at that time and that mean annual temperatures were very high, probably around 20° C. Mammalian communities, therefore, show the presence of a southwest–northeast aridity-humidity gradient and confirm recent findings based on air-breathing fish distribution and pollen spectra. Atmospheric circulations could be responsible for this meridional gradient, but other regional causes cannot be ruled out. This study indicates that mammal body weight distributions are excellent proxies to investigate the environmental and climatic evolution and compare well with other paleoenvironmental proxies.
Using cenograms to investigate gaps in mammalian body mass distributions in Australian mammals
TRAVOUILLON, K. J. and LEGENDRE, S. 2009. Using cenograms to investigate gaps in mammalian body mass distributions in Australian mammals. Palaeogeography, Palaeoclimatology, Palaeoecology, 272, 69-84.
Body size distribution and cenogram analyses both use body weight distributions of mammalian species to describe... more Body size distribution and cenogram analyses both use body weight distributions of mammalian species to describe structural patterns within communities. Using these methods it has been possible to correlate modern mammalian community structure and habitat. In turn these correlations have been used to infer palaeohabitat from analysis of the structure of extinct mammal communities. We used the cenogram method to construct the body size distribution of both contemporary and pre-European invasion lists of mammal taxa from 52 Australian national parks spanning all major environments. All modern Australian open environments showed a gap in body mass distribution. Historical open environments showed no distinct gap in body mass distribution but had significantly less medium-sized species than closed environments. Large, introduced mammalian predators have been shown to prefer medium-sized prey over large or small prey and to contribute significantly to the extinction of medium-sized species in open environments. Our results are consistent with previous studies which have found that mid-sized mammals are more extinction prone, and this has been suggested to be due to introduced cats and foxes, following the European colonization of Australia. Two methods complementary to cenograms are introduced in this study, which are useful to infer vegetation covertures of fossil localities.
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Palaeoecological analyses of Riversleigh's Oligo-Miocene sites: Implications for Oligo-Miocene climate change in Australia
TRAVOUILLON, K. J., LEGENDRE, S., ARCHER, M. and HAND, S. J. 2009. Palaeoecological analyses of Riversleigh's Oligo-Miocene sites: Implications for Oligo-Miocene climate change in Australia. Palaeogeography, Palaeoclimatology, Palaeoecology, 276, 24-37.
During the Cenozoic, Australian environments changed from being dominated by warm and humid rainforests to mainly... more During the Cenozoic, Australian environments changed from being dominated by warm and humid rainforests to mainly arid/semiarid habitats comparable to those found today. Northern Australia's Oligo-Miocene palaeoenvironment were analysed using mammalian assemblages from the Riversleigh World Heritage Area, northwestern Queensland. Limitations of fossil assemblages were minimised using Minimum Sample Richness and taxonomic distinctness analyses because these identify under-sampled, unrepresentative and taxonomically-biased fossil assemblages which can then be removed from the overall analysis. Cenogram and body mass distribution methodologies were used to help determine the palaeohabitats of seventeen sites from Riversleigh that span the late Oligocene to early Miocene, middle Miocene and early late Miocene. The results suggest a change of environment through time, with the late Oligocene of Riversleigh represented by an open forest, the early and middle Miocene by rainforest, and the early late Miocene represented by open forest.
Cenogramas, análisis bioclimático y muestreo en faunas de mamíferos: implicaciones para la aplicación de métodos de análisis paleoecológico
Gómez Cano, A.R., García Yelo, B.A. & Hernández Fernández, M. 2006. Cenogramas, análisis bioclimático y muestreo en faunas de mamíferos: implicaciones para la aplicación de métodos de análisis paleoclimático. Estudios Geológicos, 62 (1): 135-144.
In this work we analyzed the problems derived from the potential species loss associated to the taphonomic processes... more
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).
