REPORTAJE A LOS PALEONTÓLOGOS JOSÉ IGNACIO CANUDO Y LEONARDO SALGADO

Durante el segundo semestre de 2006, Desde la Patagonia se entrevistó con dos paleontólogos, español uno y argentino el otro, que charlaron extensamente sobre sus actividades y la actualidad de la paleontologÌa en los dos países

FIGURE 4. Cypridopsis silvestrii comb. nov. A. A1 in Taxonomic revision of Cypridopsis silvestrii comb. nov. (Ostracoda, Crustacea) from Patagonia, Argentina with morphometric analysis of their intraspecific shape variability and sexual dimorphism

FIGURE 4. Cypridopsis silvestrii comb. nov. A. A1 (UNC-PMIC 153 ES female). B. A2 (UNC-PMIC 155 ES female). C. A2 (UNC-PMIC 160 ET male). D. Md (UNC-PMIC 153 ES female). E. Md Palp (UNC-PMIC 153 ES female). Scale bar: 100 µm

Morphological diversity and discrimination tools of the non-marine ostracod Cypridopsis silvestrii across temporal and spatial scales from Patagonia

Geometric morphometric methods are powerful tools to discriminate between closely related ostracods taxa as well as to study the relationship between their morphological variations, taxonomy and paleoecology. In this study, valve outline analysis allows the discrimination between the non-marine ostracod C. silvestrii and R. whatleyi juveniles, pointing out differences in the posterior valve area and surface ornamentation. Modern female specimens of C. silvestrii from 23 sites located in a spatial transect (41 to 51 °S) exhibited extensive morphological variability, on the basis of which three morphotypes (acuminated, transitional, subtruncated) were determined. Multivariate analyses showed that acuminated and transitional shapes are not arranged in groups but the subtruncated morphotype, previously described as E. cecryphalium, seems to be associated with low water conductivity (372 μS cm-1), dominant cold (5 ºC) and windy (8.6 m s-1) climatic conditions. The fossil cluster which included nine cores spanning the last 15.6 kyr, only covered acuminated and transitional shapes, which may indicate that these lineages might be older than the subtruncated morphotype. In addition, morphological differences between reproduction modes suggested that parthenogenetic females exhibit de posterior margin more acuminate than sexual females. These results set the ground for more precise ecological and paleoenvironmental studies in Patagonia

Late quaternary environmental changes in Patagonia as inferred from lacustrine fossil and extant ostracods

In the present study, we compare modern and Quaternary ostracods from two lacustrine basins: Laguna Cari-Laufquen (41 degrees S) and Lago Cardiel (49 degrees S) in Patagonia. Taxonomic and quantitative analyses along with isotopic and chemical studies of the extant ostracod fauna indicate that distinct ostracod associations can be identified as a function of conductivity. Three ostracod associations can be distinguished: (1) springs, ponds and small creeks, characterized by low conductivity (e. g. 1015 ms cm(-1)); (2) lakes and permanent ponds, characterized by medium conductivity (e. g. 1625 ms cm(-1)) and (3) ephemeral lacustrine environments, generally characterized by higher conductivity (e. g. 16 480 ms cm(-1)) These modern ostracod associations were also identified in older sequences from sediments outcropping in the Laguna Cari-Laufquen current shoreline, as well as in sediment cores from Lago Cardiel. The predominance of Limnocythere rionegroensis Cusminsky & Whatley in the Cari-Laufquen sections suggests the development of a saline and turbid lake during the Late Pleistocene and Early Holocene, and thus higher precipitation at these latitudes. Changes in ostracod abundance and associations have been observed in Lago Cardiel during the last approximately 16 000 calibrated years BP. Conductivity is known to change as a function of the ratio of precipitation to evaporation and a decrease in conductivity from the Late Pleistocene to the Middle Holocene suggests substantial hydrological variations (i. e. increase of the precipitation/ evaporation ratio suggests minor conductivity). These two examples show that ostracods provide an excellent proxy for interpreting palaeoclimatic and palaeoenvironmental changes in Patagonia. (C) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103, 397-408