Torralba and Ambrona (archaeological site)

the Italian commune

Torralba and Ambrona (Province of Soria, Castile and León, Spain) are two paleontological and archaeological sites that correspond to various fossiliferous levels with Acheulean lithic industry (Lower Paleolithic) associated, at least about 350,000 years old (Ionian, Middle Pleistocene). The sites, traditionally studied together, are about 3 km distant, and belong to the settlements of Ambrona (municipality of Miño de Medinaceli) and Torralba del Moral (municipality of Medinaceli). From these sites have been obtained fossils of large mammals, mainly elephants (Straight tusked elephant), with remains of nearly fifty individuals from each site, in addition to large bovines and horses. The sites can be seen as an elephants' graveyard, although the use of the term for a concentration of bones raises a problem of definition. The sites show evidence of successive occupations by human beings, who had a hunting station or, more likely, scavanged carrion and carried out quartering. Known since the end of the 19th century, they were excavated first by the Marquis of Cerralbo between 1909 and 1914, later, in the early '60s and early '80s, by the American Francis Clark Howell with the collaboration of the paleontologist Emiliano Aguirre and later, in the '90s, new campaigns were carried out by Manuel Santonja and Alfredo Pérez González. The remains from the different excavations are scattered, mainly, between the Museo Nacional de Ciencias Naturales, the Museo Arqueológico Nacional, the Museo Numantino de Soria and the museum in situ of Ambrona. They were declared Bien de Interés Cultural in the category of "archaeological zone" on September 7, 1995. They are also declared as "a place of international geological interest of international relevance" ("Geosite") by the Geological and Mining Institute of Spain, with the designations "VP 07: Loma del Saúco, Torralba" and "VP 07b: Loma de los Huesos, Ambrona", within the category "vertebrate sites of the Pliocene Spanish Pleistocene".

In the late 19th century it was decided that a new railway line should link Torralba and Soria. The contract was awarded to a Belgian company. The first remains appeared in 1888, with the works of canalization of the water that the company was carrying out for the first railway station of Torralba (moved later twice, before 1926 and in 1959).

thumb|Detail of Howell's 1963 excavation conserved in situ, with Straight tusked elephant remains (the most important taxon in the site): a defense, a vertebra, a jaw (upside down) and some ribs, among others. The American anthropologist Francis Clark Howell conducted six excavation campaigns in Torralba and Ambrona, between 1961 and 1963 and in 1980, 1981 and 1983. The results of his studies seemed to have demonstrated the practice of active hunting by the human groups of the time hypothesis discussed later, in favor of occasional scavenging. Also carbonaceous remains to indicate the presence of homes: the intentional and controlled use of fire. In 1959, during the Pan African Congress of Prehistory and Quaternary Studies, in which John Desmond Clark was presenting the concept of "occupation sites", the Spanish archaeologist Lluís Pericot (University of Barcelona) interested the anthropologists F. Clark Howell (University of Chicago) and Pierre Biberson (Museum of the Man of Paris), in the works that the Marquis of Cerralbo had done in Torralba and his concept of "station", very similar to the one they were discussing. etc., but highlighting, due to its social impact, those related to the presumed hunting activities of primitive man.

thumb|Aspect of the Ambrona site in 2012. The trenches of the excavations can be seen in the foreground and behind the Museum buildings. As a result of the results of Howell and collaborators, in the following years, extensive discussions took place on some conclusions related to human behavior, mainly those related to active hunting or the use of bone instruments. In order to establish a precise formation model of the deposits, the archaeologist Manuel Santonja and the geologist Alfredo Pérez González proposed and co directed a new stage of excavations, focused mainly to establish with precision the geology and the detailed stratigraphy of the same. The approach was based on the realization, prior to the systematic excavation, of trial pits and sections for detailed stratigraphic analysis, since simultaneous excavation in large areas could lead to confusion among very similar facies, mixing levels that should be differentiated with this other method. The works began in the years 1990 and 1991, with the elaboration of surface geological studies complemented with some soundings, and the main excavation campaigns were carried out, this time only in Ambrona, the summers from 1993 to 2000, without interruption, taking place some complementary sampling and other trials between 2001 and 2002. however, most paleontological remains were left unexploded, consolidated, covered again and protected to prevent spoilage and looting, in anticipation of a possible future extension of the museum exhibition in situ to a much larger extension of the site.

The Ambrona site is located in the "Ambrona formation", whose sediment thickness, as a whole, would not exceed eight meters. Seven levels or litic facies have been identified, grouped into three members: one lower (AS1 to AS5 levels) – gravels, gray silts and clays, another medium (AS6) – sands and gray limes, and the upper one (AS7) – graves and red sands. The AS3 level (silt and clays) is locally eroded, supporting AS4 directly on AS2 at some points. The base, discordant, corresponds to facies of alluvial fans channel (AS1 and AS2). The AS3 level has been interpreted as lacustrine environment. The rest of the lower and middle members (AS4 to AS6) are interpreted as deposited in low energy shallow fluvial lacustrine environments, with some sediments of channel and overflow. The upper member (AS7), with a granulometry higher than the previous ones, corresponds again to alluvial fan facies, in which neither fossils nor lithic industry have been found. It would be more recent than Ambrona, formed at a later time, not determinable, of the encasement of the fluvial network in the valley,

The studies of paleomagnetism have given in all Ambrona samples a normal polarity value, consistent with the cron Brunhes, the current one, which started 779 000 years ago .

The lists of taxa identified in the deposits have been changing over time, depending on the discovery of better diagnostic elements or the vagaries of the systematic; we try to present the most up to date relation.

Algae: diatoms (Amphora, Hantzschia, Surriella, Cyclotella, Anomoeoensis, Epithemia, Rhopalodia, Cocconeis, Pinnularia, Nitzschia), chrysophytes.

Herbaceous: Poaceae, Asteraceae, Cichoriaceae, Fabaceae, Rumex, Plantago. Aquatic: Cyperaceae, Nymphaeaceae, Polygonum , Ranunculaceae, Typha. Shrubs: juniper (Juniperus), Rosaceae, Cistaceae, Ericaceae. Trees: pine (Pinus), alder (Alnus), willow (Salix), elm (Ulmus), oak (Quercus), birch (Betula), chestnut (Castanea), hazel (Corylus), walnut (Juglans).

Ostracodes (Candona, Cypris, Cypridopsis, Eucypris, Herpetocypris, Heterocypris, Ilyocypris, Leucocythere, Plesiocyrpdopsis, Potamocypris).

thumb|Radius of Panthera leo cf. fossilis of Ambrona. Early Middle Pleistocene European cave hyena (Crocuta crocuta aff. praespelaea)
Early Middle Pleistocene European cave lion (Panthera leo cf. fossilis)
Fox (Vulpes sp.) Mosbach's wolf (Canis lupus cf. mosbachensis)

Heidelberg's man? (? Homo heidelbergensis). Without skeletal remains in the sites, human presence is identified by the lithic industry and the activity marks on elephant bones. The species is inferred only by correlation with the Sima de los Huesos site of Atapuerca, of similar age.

The bone remains of large mammals are, in general, dispersed, eroded and fragmented, evidencing trawling by fluvial transport, although in clay or silty sediments there are usually elements in anatomical connection, with little or no transport (primary accumulation), and without predators or scavengers, even the skeleton of an elephant specimen (in the so called "α" concentration) is practically complete. The abundant accumulations of elephant remains in Ambrona are similar to the modern sites popularly known as "Elephants' graveyards". In these places, close to water sources, corpses tend to accumulate, mainly elephants, but also other mammals, and have been well studied in African parks. In this environment trampling and fragmentation of exposed or semi buried remains by elephants or other mammals occurs, which continue to go to the water sources. In Ambrona, the elephant mortality curve also fits into this model, seems to indicate deaths due to natural causes and does not present the typical bias due to selective hunting. The typology is diverse: hand axes, cleavers, racloirs, denticulates, perforators, back knife or burins, among others. The materials are very varied: flint, quartzite, limestone and quartz, of the pieces, according to the levels, they seem not to be eroded, while the rest show signs of light bearing, secondary accumulation, with few elements very rolled. There is no evidence of in situ manufacture, only of secondary retouching, and mainly on quartzite elements.

The existence or not of bone industry from bones and elephant defenses in these sites is very controversial. On the one hand, Villa and collaborators, based on the taphonomic analysis of the types of breaks and superficial alterations of the bones deny the existence of bone industry, at least for the Ambrona site, leaving Torralba with indetermination. In the deposits, more than fifty tips of young elephant tusks have been collected, after almost a century of excavations, which these authors interpret as a result of the natural break during the activity of the animals in the barking of trees or the digging of the ground looking for water, as is the case with today's elephants. On the other hand, Aguirre, among others, maintains that it is very probable a certain rudimentary industry of trihedral and other bone elements endowed with points and edges. It was devised by Aguirre in 1963, for which Howell reserved an area of the excavations from which the fossils found were not extracted. Aguirre and Echaide designed the project, which was completed in November of the same year. It was the first museum of its kind to be opened in Spain. Ten years later Aguirre obtained, in addition, that a road was made that facilitated a route of cultural tourism between the Nacional II, the museum and Sigüenza. In 1985, laboratories and a public exhibition room were built, showing material that was deposited in other museums. Subsequently, the unrealistic figure of a straight tusked elephant at its natural size was incorporated into the exterior of the museum.