Late Neogene and Early Quaternary Paleoenvironmental and Paleoclimatic Conditions in Southwestern Europe: Isotopic Analyses on Mammalian Taxa

Abstract

Climatic and environmental shifts have had profound impacts on faunal and floral assemblages globally since the end of the Miocene. We explore the regional expression of these fluctuations in southwestern Europe by constructing long-term records (from ∼11.1 to 0.8 Ma, late Miocene–middle Pleistocene) of carbon and oxygen isotope variations in tooth enamel of different large herbivorous mammals from Spain. Isotopic differences among taxa illuminate differences in ecological niches. The δ13C values (relative to VPDB, mean −10.3±1.1‰; range −13.0 to −7.4‰) are consistent with consumption of C3 vegetation; C4 plants did not contribute significantly to the diets of the selected taxa. When averaged by time interval to examine secular trends, δ13C values increase at ∼9.5 Ma (MN9–MN10), probably related to the Middle Vallesian Crisis when there was a replacement of vegetation adapted to more humid conditions by vegetation adapted to drier and more seasonal conditions, and resulting in the disappearance of forested mammalian fauna. The mean δ13C value drops significantly at ∼4.2−3.7 Ma (MN14–MN15) during the Pliocene Warm Period, which brought more humid conditions to Europe, and returns to higher δ13C values from ∼2.6 Ma onwards (MN16), most likely reflecting more arid conditions as a consequence of the onset of the Northern Hemisphere glaciation. The most notable feature in oxygen isotope records (and mean annual temperature reconstructed from these records) is a gradual drop between MN13 and the middle Pleistocene (∼6.3−0.8 Ma) most likely due to cooling associated with Northern Hemisphere glaciation.

Miocene shift of European atmospheric circulation from trade wind to westerlies

“…Although possibly punctuated by dry conditions in particular periods and/or at some locations, especially for that of the middle Tortonian northeastern Iberian Peninsula2021, both faunal and floral data indicate an overall (sub)humid climate in the Tortonian346121822. Moreover, it can be assumed that the Andalucian coastal area and the northern Black Sea coast experienced drier summers.…”

No sedimentary evidence for hydrothermal refugia in the Plio-Pleistocene deposits of the Baza Basin (SE Spain)

“…To support dryer environmental conditions, García-Aguilar et al (2014) also recall the paleoclimatic data by Domingo et al (2013), showing a drop in precipitation rate from 490 mm/yr in the Gelasian (MN17) to 390 mm/yr in the Middle Pleistocene. Actually, the younger sites studied by Domingo et al (2013). are La Puebla de Valverde (MN17, 2.13 Ma) and Hu escar-1 (MP, 0.8 Ma), so that there are no data from the time interval between 2.13 and 0.8 Ma in which the discussed sites fall.…”

“…However, species not directly related to water also point to a humid climate, with little seasonal changes and a warm winter (Furi o, 2003(Furi o, , 2007(Furi o, , 2010Blain et al, 2011). To support dryer environmental conditions, García-Aguilar et al (2014) also recall the paleoclimatic data by Domingo et al (2013), showing a drop in precipitation rate from 490 mm/yr in the Gelasian (MN17) to 390 mm/yr in the Middle Pleistocene. Actually, the younger sites studied by Domingo et al (2013).…”

Extended-range luminescence chronologies suggest potentially complex bone accumulation histories at the Early-to-Middle Pleistocene palaeontological site of Huéscar-1 (Guadix-Baza basin, Spain)

“…Hu escar-1 has played an important role in defining local-scale biozone successions in the Guadix-Baza basin (e.g., Agustí et al, 2010), and has been used as a biochronological reference site for correlating Early-Middle Pleistocene faunal schemes across the Iberian Peninsula (e.g., Martínez et al, 2010;Pacheco et al, 2011). Studies of the Hu escar-1 faunal assemblage have also provided insights into southern European stenonoid horse morphometrics (Alberdi and Palombo, 2013) and isotopic palaeoclimatic reconstructions (Domingo et al, 2013). In addition, the site has formed part of regional-and continental-scale palaeoecological and palaeoenvironmental reconstructions for elucidating hominin dispersal patterns in Europe (O'Regan, 2008;Kahlke et al, 2011).…”