Cerro de los Batallones Paleontological Site
Miocene Paleontological Site in Torrejón de Velasco
Cerro de los Batallones Paleontological Site
It is a witness hill formed on silicified carbonates, located between the Jarama river valley and the Prados-Guatén Depression. It is located in the municipality of Torrejón de Velasco, south of the capital. It is considered one of the most important deposits of the Miocene worldwide. Its exceptionality is given by the quantity, quality and variety of the fossil remains that have been discovered.
The investigations carried out in this site have allowed the reconstruction of the ecosystem that existed in this region approximately 10 million years ago. During the upper Miocene the landscape presented very notable differences with respect to the current one. The most striking was, without a doubt, the presence of a large freshwater lake that occupied the central part of the Madrid basin, whose banks must have been very favorable for the development of various species of vertebrates.
The fossil vertebrate deposits of Cerro de los Batallones constitute one of the most outstanding discoveries of Spanish paleontology. Numerous singularities stand out in them: abundance of fossil remains, excellent state of preservation, high concentration of bones with little or no displacement, which causes numerous articulated elements with anatomical connection to be recorded, presence of all skeletal parts of individuals, including the skull and, above all, the unusual abundance of carnivores. Specifically, among the fossil remains found at the Batallones-1 site, it should be noted that 98% are carnivores, while ungulates are very rare. This fact is very strange, since in nature the opposite usually happens.
The geological study of the deposits has shown that the origin of this paleontological group can be attributed, in principle, to the existence of a system of cavities that acted as natural traps. Numerous vertebrates that inhabited the area 9-10 million years ago were trapped in them. These cavities would have been formed by a process called "piping", also known as "karst in clays" or "tunnel erosion", a phenomenon by which fissures are produced that are enlarged until forming cavities that act as natural traps for animals that they frequent the area.
A fundamental advance in the research was the comprehensive taphonomic study of the Batallones-1 deposit. The results obtained draw a scenario in which the carnivores would individually enter the cavities, looking for water or food, or both, being later unable to leave. The cavities thus became death traps for them. The shortage of herbivores implies that the cavities were also well visible, so much so as to be avoided by these animals. On the other hand, the fossil bones exhibit an excellent state of conservation, a consequence of their deposit in very special environmental conditions.
There are hardly any fossil deposits in this type of geological context, and therefore the Cerro de los Batallones deposits are exceptional from a paleontological and geological point of view.
The fossil fauna of Cerro de los Batallones
The diversity of species represented in the Cerro de los Batallones deposits is only explainable in a very different climatic and environmental context from the current one. 9 million years ago, one of the times of greatest climatic prosperity of those recorded in the last part of the geological history (last 25 million years) of the Iberian peninsula was ending. With a warmer and more humid climate than the current one, large meadows emerged in the southern part of the Madrid region, capable of supporting the presence of large herbivores, together with the large typical Miocene land turtles.
The paleontological deposits of Cerro de los Batallones have become famous worldwide for their carnivore remains, among which are the so-called "saber teeth" (the Machairodus, the size of a tiger and the Paramachairodus, the size of a leopard). There are also remains of two other species of felids, a primitive civet-like hyena (Protictitherium), an anficionid (usually known as dog-bears, due to their mosaic of intermediate characteristics between these two groups), a bear (Indarctos), a family of the red panda (Simocyon) and several mustelids (Tuesday, Sabadellictis and Proputorius). Among the large herbivores, the rhinos (with two species), the Hipparion equine (which would differ from the current horses and zebras by the presence of lateral toes on their legs, while the current ones only have a single toe on each leg) and the Mastodon Tetralophodon.
Along with them, several ruminants have been found, such as the mosquitoes (musk "deer") Micromeryx and Hispanomeryx, a sivaterine (giraffe with a short neck and large cranial appendages - osicones -) and several indeterminate species of antelopes, as well as a deer .
Numerous remains of small and medium mammals have also been found. Among the rodents, hamsters stand out for their abundance, with two species (Hispanomys and Rotundomys). Mice (Progonomys), ground squirrels, dormouse (Eliomys) and beavers (Chalicomys) have also been found. Lagomorphs are represented by Prolagus, a pika. Within the group of insectivores, hedgehogs (Parasorex and Postpalerinaceus) and shrews (Miosorex) have been found. There are numerous remains of birds, mainly raptors from the group of vultures and a varied herpetofauna. Fish remains have been found in some sites (Battalions - 1 and Battalions - 2).
The Cerro de los Batallones provides information of great importance for the knowledge of the geological evolution of the Madrid basin. It is an exceptional window into the past, a unique setting to learn about a small portion of geological time, life and the environment from millions of years ago. It is a site that will serve as a reference and model both nationally and internationally for other investigations.
Image gallery
Archaeological performance
The discovery of the deposits occurred fortuitously in 1991, as a result of the surveys that the company TOLSA SA carried out in Cerro de los Batallones in search of sepiolite (a rock for industrial use) that brought to light fossil bones associated with clayey sediments.
From 1991 to 1993, the first of the deposits was excavated, called Batallones 1. In 1999, the mining work on the hill was resumed and during paleontological monitoring the second deposit (Battalions-2) was identified. Since 2000, and thanks to paleontological monitoring, new sites have been discovered, a total of 10, which have been the subject of prospecting and / or excavation campaigns to date.
Archaeological intervention 2022
The paleontological investigations carried out in these years have allowed the discovery so far of nine sites with faunal assemblages associated with complex pseukarstic deposits, which constitute the most important and best preserved Miocene fossil record of macrovertebrates from the European Tertiary.
The set of sites of Cerro de Batallones is protected by declaration of Asset of Cultural Interest, with the category of Paleontological Zone (Decree 130/2001 of August 2; BOCM 198, 21/08/2001) and has been included in the Plan Visitable Sites of the Community of Madrid.
The actions developed during the 2022 campaign they focused on continuing to excavate the sites of Batallones-7 and Batallones-10, for the delimitation of the geomorphology of the sites and to continue recovering faunal remains.
The Hill of the Battalions
Torrejon de Velasco, Madrid. 2021
Excavations at Cerro de los Batallones
Torrejon de Velasco, Madrid. 2021