Preresa site

The urban development of the first years of the XNUMXst century generated a great extraction activity of aggregates, such as gravel, sand and gravel, in the Manzanares and Jarama valleys, which daily removed hundreds of m³ of deposits likely to contain Pleistocene vestiges. In one of the few sandboxes that remained active in the Manzanares valley, called PRERESA, 9 km from the mouth of the river in the Jarama, two archaeologists from the project, Iván González García and Nuria Gallego Lletjós, identified in September 2003 some bones that, due to their size, could only correspond to an elephant or mammoth during an inspection carried out in September 2003 in some levels of silt and clay deposited during the Pleistocene

In order to check whether there was human action on the skeletal remains, a grid measuring two meters on each side was excavated, showing part of the skeleton of a large bovine 2.5 m high, and a carved flint piece. In the second campaign, the excavation was expanded to 80 m2 and the remains of the great bovine continued to appear, especially vertebrae and ribs, as well as bones from the extremities and the skull. 

The discovery of only three flakes of flint made it necessary to excavate a larger surface to understand the role that Neanderthals played in this scenario, so the excavated surface was enlarged by another 175 m2. Eighty-two elephant bones scattered around the site were documented, including bones from the legs, vertebrae, ribs, a scapula, a nearly complete tibia, and several long bone fragments. Several of them show evidence of human intervention, specifically, fractures, cut marks and percussion marks produced by stone tools.

At the PRERESA site there is indisputable evidence that a group of Neanderthals consumed the meat of an elephant. In addition, and for the first time in Europe, it has been shown that they also consumed the marrow of their bones, which is an important source of nutrients and contains easily digestible and good-tasting fatty acids. 

The PRERESA fauna study includes another novelty, the presence of the Mediterranean deer (Haploidoceras mediterraneus), a practically unknown species, represented by part of the skeleton of one individual and remains of at least another. The most striking thing about these deer are their antlers. Currently, the presence of Mediterranean deer has been recorded in three sites: Cova de Rinoceront and PRERESA in Spain and Lunel des Rameaux in France. This species may have evolved in Asia and migrated to Western Europe coinciding with climate or environmental change, having a chronology between 300.000 and 85.000 years.

In addition to these large mammals, a large number of the remains of 21 small vertebrate species have also been found in PRERESA, such as micro-mammals (the vole of Cabrera and the rabbit), amphibians (such as the spadefoot toad, the running toad). and the common frog) and reptiles such as the long-tailed lizard. The accumulation of the remains of these small species is attributed to the activity of predators, as demonstrated by some concentrations of bones recovered in the site, which could correspond to the remains of raptor pellets, that is, balls formed by food remains. undigested that some birds regurgitate.

A total of 754 carved stone pieces have been found that can be ascribed to the Middle Palaeolithic. Except for six pieces of quartz, a material that abounds in the Manzanares valley, the rest are all flint. All phases of the stone tool making process have been recorded, from the first flakes obtained when starting to work a core, to those that were configured as tools, along with hundreds of chips that jump during the carving process. The absence of bifaces and the low proportion of retouched tools stand out. The presence of carving remains shows that a good part of the tools were made on site from the flint edges transferred to the site.

The distribution of the stone tools together with the dispersion and composition of the paleontological remains, the cut marks and percussion in some bone remains, indicate that some of the large mammals found in the site were undoubtedly used by Neanderthals. 

The discovery of the PRERESA site was produced within a research project promoted by the General Directorate of Heritage of the Community of Madrid on the study of remains of the Pleistocene (A time that occupies the first part of the Quaternary era, which extends from 1,8 million years to 10.000 years and is known as the "Age of Ice", when large mammals such as the Mastodon, the saber-toothed tiger and the ground sloth, became extinct worldwide) of the valleys of the Manzanares and Jarama rivers, carried out between the end of 2002 and 2006, by a multidisciplinary team made up of archaeologists, geologists, paleontologists, and paleobotanists.