Blanca Martínez-García

Combining Small-Vertebrate, Marine and Stable-Isotope Data to Reconstruct Past Environments

Three very different records are combined here to reconstruct the evolution of environments in the Cantabrian Region during the Upper Pleistocene, covering ~35.000 years. Two of these records come from Antoliñako Koba (Bizkaia, Spain), an exceptional prehistoric deposit comprising 9 chrono-cultural units (Aurignacian to Epipaleolithic). The palaeoecological signal of small-vertebrate communities and red deer stable-isotope data (δ13C and δ15N) from this mainland site are contrasted to marine microfaunal evidence (planktonic and benthic foraminifers, ostracods and δ18O data) gathered at the southern Bay of Biscay. Many radiocarbon dates for the Antoliña’s sequence, made it possible to compare the different proxies among them and with other well-known North-Atlantic records. Cooling and warming events regionally recorded, mostly coincide with the climatic evolution of the Upper Pleistocene in the north hemisphere.

EARLY MIOCENE SHOREBIRD-LIKE FOOTPRINTS FROM THE EBRO BASIN, LA RIOJA, SPAIN: PALEOECOLOGICAL AND PALEOENVIRONMENTAL SIGNIFICANCE

Abstract Small shorebird-like footprints have been discovered in Cenicero (La Rioja, Spain). They are preserved in a sandstone block of the transition unit between the Nájera and Haro Formations from the Ebro Basin. This level is positioned in the Y2 local zone (MN2), of Agenian age (early Miocene). The footprints are small, tridactyl or tetradactyl, with slender and proximally unconnected digit impressions. They have phalangeal pads and claw marks, and there is no evidence of a web or metatarsal pad. The footprints are compared with other shorebird-like ichnotaxa and assigned to the Cretaceous ichnotaxon Koreanaornis isp., which is herein identified for the first time in the Cenozoic. Other shorebird-like footprints from the late Eocene to early Miocene in the Ebro Basin and the early Miocene ichnotaxa Aviadactyla media and Aviadactyla vialovi are also related to this ichnotaxon. In addition to the shorebird-like footprints, the Cenicero tracksite has invertebrate traces and sedimentary and organic structures typical of the Scoyenia ichnofacies, suggesting a mud-dominated floodplain in a central-distal alluvial fringe as the paleoenvironment. The morphology, habitat, and behavior inferred from the shorebird-like footprints in the Cenicero tracksite are similar to other fossil footprints found in the Mesozoic and Cenozoic as well as to modern shorebird tracks. This is likely due to morphological, ecological, and behavioral convergences among different avian clades from the Early Cretaceous to the present.

First bird footprints from the lower Miocene Lerín Formation, Ebro Basin, Spain

Fil: Diaz Martinez, Ignacio. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Patagonia Norte. Instituto de Investigacion en Paleobiologia y Geologia; Argentina

Living Ostracod Species From Permanent and Semi-Permanent Ponds of Bardenas Reales De Navarra (Northern Spain) With Remarks on Their Ecological Requirements

Abstract. Ostracod species living in 13 ponds (25 sample points) in Bardenas Reales de Navarra Natural Park and World Biosphere Reserve are studied for the first time. Nineteen species were identified, nine of them being the most abundant. According to statistical analyses (cluster and Correspondence Analysis), the distribution of ostracod species in this semi-arid area is mainly controlled by water conductivity and pH. The hydroperiod, sediment type, dissolved oxygen, altitude and vegetation cover play a secondary role. Thus, in semi-permanent waters with conductivity between 4.5 and 5.4 mS/cm and pH from 7.95 to 8.73 the most abundant species is Sarscypridopsis aculeata (Costa). In ponds with water conductivity from 0.3 to 2 mS/cm, pH between 7.1 and 7.78 and dissolved oxygen from 0.1 to 7.95 mg/l, Cypridopsis vidua (Müller) s the most abundant species. When the vegetation cover increases in this type of ponds, Limnocythere inopinata (Baird) and Potamocypris villosa (Jurine) appear as more abundant. Finally, in ponds with conductivity between 0.34 and 2.8 mS/cm and sporadic input of running waters llyocypris bradyi Sars, is the most important species. When the internal water current increases in these ponds, Pseudocandona albicans (Brady) appears as most abundant. However, the accumulation of dead organic matter within the bottom sediment of these ponds favours the decrease of dissolved oxygen and the development of Eucypris virens (Jurine). With this work, we contribute to the knowledge of the ostracod biodiversity of this semi-arid environment and the ecological preferences of this group.

BENTHIC FORAMINIFERA AND OSTRACODA FROM MIDDLE–UPPER MIOCENE SEQUENCES OF SOUTHERN ECUADOR

Abstract. The debate regarding a possible marine influence during the middle—late Miocene in the Loja, Malacatos-Vilcabamba and Catamayo-Gonzanamá Basins (southern Ecuador) continues. To shed light on this controversy, we present a detailed stratigraphic and micropaleontological (benthic foraminifers and ostracods) study of selected sections from these basins. The facies associations, together with the presence of several benthic foraminifer species from marginal marine and open-water environments and ostracod genera resistant to high salinity changes, verify a marine water influence and sporadic marginal marine conditions in this area during certain periods of the middle—late Miocene. Additionally, six new ostracod species are hereby described: Heterocypris ballentae, Cyprideis lojaensis, Cyprideis petersonae, Cyprideis pachamama, Cyprideis tumi and Cyprideis amaru.

ASOCIACIONES DE OSTRÁCODOS DEL MIOCENO TEMPRANO-MEDIO DE LOMA NEGRA (BARDENAS REALES DE NAVARRA, CUENCA DEL EBRO): EVOLUCIÓN PALEOAMBIENTAL DE UN MEDIO LACUSTRE

Abstract. LOWER—MIDDLE MIOCENE OSTRACOD ASSEMBLAGES OF LOMA NEGRA (BARDENAS REALES DE NAVARRA, EBRO BASIN): PALAEOENVIRONMENTAL EVOLUTION OF A LACUSTRINE SYSTEM. The palaeoenvironmental evolution of the Loma Negra section (Bardenas Reales de Navarra, Ebro Basin) during the lower—middle Miocene, is studied for the first time. The paleoenvironmental interpretation is based on the recovered ostracod assemblages and the sedimentology. The lower part of this section is composed by red, yellow and grey mudstones, and with Paralimnocythere sp. as the most abundant ostracod taxon. The lithological features and the faunistic assemblage allows the interpretation of a paleoenvironment with the development of shallow water bodies with stagnant, warm and fresh to oligohaline waters in distal alluvial flood plains for this section. The presence of some sandstone levels where the most abundant ostracod species is Cyclocypris laevis (Müller) marks punctual higher energy events inside this alluvial system and the presence of more saline waters. The upper part of the section is formed by grey limestones with interbedded fine grey mudstones. In this interval, Pseudocandona parallela Müller is the most abundant ostracod species, indicating the development of a stable lacustrine system with water currents, and temperate to cold and oligohaline to mesohaline waters. The transition between the alluvial and the lacustrine systems shows a gradual evolution.