Bienvenido Martínez-Navarro

The Early–Middle Pleistocene Transition transformed Eurasian ecosystems through intensified climatic instability, increasing aridity, stronger seasonality and repeated shifts between wooded and open landscapes. These environmental changes drove a broad restructuring of mammalian communities, yet the contribution of large carnivores to this ecological transition remains poorly understood. Here we report the earliest securely dated European occurrence of the steppe lion, from the Vallparadís Section in northeastern Iberia, dated to ca. 1.0–0.86 Ma. This record shows that very large lions had already entered Mediterranean Europe during the late Calabrian, earlier than traditionally assumed. Their arrival coincided with the decline of several Villafranchian carnivores and the emergence of more modern predator guilds. As large apex predators, early lions likely reshaped trophic interactions by altering competitive hierarchies, prey selection, carcass availability and spatial partitioning among carnivores. The Vallparadís lion therefore provides more than the earliest European evidence of the lineage: it marks a key stage in the ecological restructuring of European terrestrial ecosystems during one of the most disruptive climatic intervals of the Quaternary.

The fossil site of Venta Micena (Baza Basin, southeastern Iberian Peninsula), dated to the Early Pleistocene (1.6–1.5 Ma), is renowned for its huge assemblage of skeletal remains of large mammals, most of which were unburied from two roughly coeval excavation quarries, VM3 and VM4. These bone accumulations resulted from the scavenging habits of giant hyaenas ( Pachycrocuta brevirostris ), which transported ungulate carcasses to their maternity dens to consume them. The fossils have enabled detailed reconstructions of Western European faunal communities during the Early Pleistocene, but the remains of small vertebrates, particularly birds, are rare and still poorly understood. Here we describe the first avian remains from Venta Micena and assess their palaeoenvironmental and ecological significance. Three taxa were identified: (i) the Common Shelduck Tadorna tadorna ; (ii) the Pleistocene Giant Crane Grus cf. primigenia ; and (iii) the Pleistocene subspecies of Common Raven, Corvus corax antecorax . The presence of T. tadorna and G. cf. primigenia suggests the existence of a wetland environment characterized by oligohaline waters surrounded by brackish pools in the vicinity of the site. The presence of C. corax antecorax is consistent with the abundance of remains of ungulate carcasses exploited by P. brevirostris , indicating rich scavenging opportunities. Palaeosynecological modeling suggests that meat consumption by ravens approached those of each of the large carnivores, thus significantly reducing the available carrion for other secondary consumers. Moreover, digestive corrosion and tooth marks on bird bones evidence the consumption of avian remains by carnivores, probably juvenile hyaenas. Altogether, these findings reveal a more complex structure of the faunal community that inhabited Venta Micena than previously recognized. First avian remains from Venta Micena are described, including a shelduck, Tadorna tadorna , and the oldest records of the large crane Grus cf. primigenia and raven Corvus corax antecorax . Grus and Tadorna support the presence of a mild, oligohaline to brackish wetland environment in the Baza Basin. The scavenging habits of Corvus add complexity to the trophic interactions in the ecosystem surrounding the Baza palaeolake.

On 2015, after the direct study of the most important Late Villafranchian fossil collections of Europe and Western Asia, including Orce (Spain), Pirro Nord and Upper Valdarno (Italy), Appollonia (Greece), Dmanisi (Georgia) and ‘Ubeidiya (Israel), among others, our team proposed the hypothesis that suids disappeared from Europe during the time span between 1.8 and 1.2 Ma. The implications of our conclusions were significant, the arrival of Early Homo into Western Europe, dated to 1.4 Ma at the site of Barranco León in Orce (Spain), preceded the return of pigs into the continent at 1.2 Ma. This hypothesis has been recently challenged because of the finding of an incomplete metatarsal ascribed to Sus sp., with no clear stratigraphic origin, found in the XIX Century Croizet collection of Peyrolles (France), which is housed in the Natural History Museum, London, together with other weak arguments based on the absence of reliable dating for many Early Pleistocene European sites, and other hypothetical records of pigs, with no real fossil support. We answer all these questions and defend that our 2015 hypothesis is correct.

The Lower Pliocene to upper Middle Pleistocene continental sedimentary infillings of the Baza Basin (Guadix-Baza Depression, SE Spain) are worldwide unique by their high stratigraphic completeness and exceptional preservation of their fossil record of terrestrial vertebrates. These sediments were deposited in fluvio-lacustrine environments and preserve huge assemblages of large mammals, including the oldest evidence of hominin presence in Western Europe at the late Lower Pleistocene sites of Barranco León and Fuente Nueva-3, dated to ∼1.4 Ma. Since latest Miocene times, the basin was subject to intense tectonic activity, showing sedimentary deposits originated from ancient hot springs. These hot springs were developed in a spatio-temporal network related to tectonic fractures, showing a higher concentration in the Orce sub-basin during Late Pliocene to Holocene times. Compositional analyses of cherts and other facies associated with these hot springs show geochemical and mineralogical markers linked to hydrothermal scenarios. The contribution of hot springs in the Baza Basin resulted in rich and productive biotopes, which supported a high diversity and biomass of terrestrial mammals. Similar geological, hydrochemical and ecological environments are found along hotspot lines in East Africa, the Levantine Corridor and the circum-Mediterranean realm. We hypothesize here that the presence of these hot springs corridors favored the dispersal of hominins and other large mammals during the Plio-Pleistocene, which led to the first hominin arrival in Europe.

The Early Pleistocene sites of Orce in southeastern Spain, including Fuente Nueva-3 (FN3), Barranco León (BL) and Venta Micena (VM), provide important insights into the earliest hominin populations and Late Villafranchian large mammal communities. Dated to approximately 1.4 million years ago, FN3 and BL preserve abundant Oldowan tools, cut marks and a human primary tooth, indicating hominin activity. VM, approximately 1.6 million years old, is an outstanding site because it preserves an exceptionally rich assemblage of large mammals and predates the presence of hominins, providing a context for pre-human conditions in the region. Research suggests that both hominins and giant hyenas were essential to the accumulation of skeletal remains at FN3 and BL, with secondary access to meat resources exploited by saber-toothed felids. This aim of this study aims to correlate the relative abundance of large herbivores at these sites with their estimates of Carrying Capacity (CC) and Total Available Biomass (TAB) using the PSEco model, which incorporates survival and mortality profiles to estimate these parameters in paleoecosystems. Our results show: (i) similarities between quarries VM3 and VM4 and (ii) similarities of these quarries with BL-D (level D), suggesting a similar formation process; (iii) that the role of humans would be secondary in BL-D and FN3-LAL (Lower Archaeological Level), although with a greater human influence in FN3-LAL due to the greater presence of horses and small species; and (iv) that FN3-UAL (Upper Archaeological Level) shows similarities with the expected CC values for FN3/BL, consistent with a natural trap of quicksand scenario, where the large mammal species were trapped according to their abundance and body mass, as there is a greater presence of rhinos and mammoths due to the greater weight per unit area exerted by their legs. Given the usefulness of this approach, we propose to apply it first to sites that have been proposed to function as natural traps.

The late Early Pleistocene archaeological site of Fuente Nueva-3 (FN3), which lies in the Guadix-Baza Depression (SE Spain) and is dated to ~ 1.4 Ma, contributes some of the oldest evidence of hominin presence in Western Europe, including a huge tool assemblage of Oldowan tradition, manuports (i.e., unmodified stones used as percussion tools) and abundant fossils of large mammals, some of which preserve anthropogenic marks related to defleshing, butchering and marrow processing. In addition, there are bones with tooth marks produced by scavenging carnivores. The fertile layers of the FN3 section have been grouped in a lower archaeological level (LAL) and an upper archaeological level (UAL). Both levels preserve abundant skeletal remains and lithic tools. However, the LAL shows a high density of manuports, which suggests that hominin activity was more intense at this level, while the UAL preserves many remains of megaherbivores, particularly proboscideans (Mammuthus meridionalis), and almost all coprolites unearthed from the site, which points to a greater involvement of the giant hyenas (Pachycrocuta brevirostris). In this paper, we (i) test for statistical differences in the composition of the faunal assemblages preserved in the UAL and LAL; and (ii) analyze particle size in the fertile layers of both archaeological levels. Our results show that megaherbivores are comparatively overrepresented in the UAL, specially by young elephants, while other medium-to-large and large-sized ungulates, particularly equids, are more abundant in the LAL, showing a predominance of adult individuals. Concerning the sedimentology, layers 2–3 of the LAL show a predominance of silts and clays, with sands representing a minor fraction. In contrast, layer 5 of the UAL is composed of two-thirds of fine and very fine sands, with the remaining third consisting of silts and clays. These data and the paleoenvironmental reconstruction of layer 5 suggest that it may be interpreted as a paleo-quicksand in which megaherbivores were trapped due to the elevated weight per unit area supported by their feet, and their half-sunken carcasses attracted the scavengers, particularly the hyenas, which fed on these carcasses and defecated in their surroundings.