A footprint on the ground is much more than a mark. It can reveal information about what or who left it, what it was doing at that time, what the environment was like, where it was wandering, its weight, its size and its habits. For researchers studying prehistoric times, in the absence of biological remains, footprints are the only way to fill in the blank spaces left by time. A new study led by geologists Carlos Neto de Carvalho, Fernando Muñiz Guinea and Luis Cáceres Puro, from the universities of Lisbon, Seville and Huelva, respectively, and published in Scientific Reports, has revealed the discovery of traces of aurochs (Bos primigenius). These animals, with a height of up to two meters (6 ft 5 in) and weighing 1,500 kilograms (3,300 pounds), left tracks a little over 100,000 years ago on the southwestern coast of Spain. The finding extends the reach in space and time of the megafauna that took refuge in the south of the Iberian Peninsula from the ice that conquered much of the continent. It confirms the relationships between the last survivors of the late interglacial period, including Neanderthals, and reveals the first steps towards the domestication of animals, one of humanity’s most important advancements.
At the end of the Pleistocene, a stage that goes from 2.59 million years ago to 11,700 years ago, the aurochs were the only bovines that lived along the great river valleys of Spain’s southern peninsula. The animals’ tracks, found in Trafalgar (in Cádiz province) and Matalascañas (Huelva), date back to about 106,000 years ago. According to Carlos Neto de Carvalho, a geologist, paleontologist and scientist at the Dom Luiz Institute (University of Lisbon) and the UNESCO World Geopark Naturtejo (Portugal), “the fossil record of the behavior of these large mammals is rare throughout the world. It had never before appeared in rocks and sediments as old as those that our team first identified at Cape Trafalgar.”
Ichnology is the study of traces or signs of activity left in sediments or rocks by living beings. Named after the Greek word for footprint, ikhnos, the discipline analyzes footprints within distinct ichnogenera and ichnospecies. For Fernando Muñiz, also a paleontologist, co-author of the study and professor of crystallography and mineralogy at the University of Seville, “the discovery of a new ichnogenus and species (Bovinichnus uropeda) in Trafalgar is one of the study’s achievements. So is the correlation with the traces in the mid-late Pleistocene coastal deposits of the Asperillo cliff section in Matalascañas and the known bone remains in Gibraltar. This correlation points to a recurrent use of coastal habitat by these large artiodactyls in southwestern Iberia.”
The entire Gulf of Cádiz was already known to have been a refuge for the megafauna that were contemporaries of Neanderthals. In Huelva, the same team has discovered traces of Palaeoloxodon antiquus, straight-tusked elephants similar to the current-day ones, but up to four meters (13ft) tall, wild boars (Sus scrofa scrofa) that tripled the size of those that exist today and weighed up to 300 kilos (660lb), giant red deer, wolves and other animals.
The Cape Trafalgar footprints also show giant aurochs, with tracks made by hooves up to 27 cm (11 inches) long. As Neto De Carvalho explains, “the rounded footprints of a current adult bull rarely exceed 10 centimeters.” He adds, “We had the experience in Matalascañas of measuring the footprints of Cariñoso, a bull weighing 1,128 kg (2,487 lb), and they did not exceed 18 cm (7 in). The Cape Trafalgar aurochs would have measured more than two meters in height from the head (6 ft 5 in), not counting the horns, which are known to reach 80 cm (31 in), and weighed around 1,500 kg (3,300 lb). The females were smaller and showed a strong sexual dimorphism [variation in appearance between the two sexes], which also seems to be present when we compare the auroch footprints in the new paleontological site of Cape Trafalgar with those of Matalascañas.”
But the study of tracks goes beyond the identification of the physiological characteristics of animals. The beach and dune footprints, according to the work, “show a preferential orientation of movement towards the coast.” This environment might seem unexpected for herbivores, but it coincides with the behavior of present-day herds in coastal areas. “The great Trafalgar trails,” adds the study, “show mostly the same direction of movement and are interpreted as a herd of bulls walking slowly towards the coast in search of some peace, as is currently the case with wild cattle that visit the coasts in different parts of the world.” The aurochs (Bos primigenius), according to Neto de Carvalho, are the ancestors of cattle (Bos taurus) and have been extinct since 1627.
Muñiz explains that “these tracks are important to understand the ecology and the interactions between possible predators and prey, and to determine the beginning of the possible domestication of livestock.”
A foot that left a 31-cm track
The Portuguese researcher mentions another especially relevant finding in the same area. “An impression of a jointed foot 31 cm (12 in) long was found at Cape Trafalgar. This does not necessarily mean that the foot—and, consequently, the hominid that produced it [a Neanderthal]— had such large proportions, since the flexibility of the human foot during locomotion on a sandy dune substrate normally translates into a footprint larger than the foot, especially on sloped surfaces. However, it is a rare find that requires attention. The Neanderthals are part of our genetic ancestors, and they disappeared during the last glacial period, except in the Iberian Peninsula, which was their last refuge. Traces of them are still very rare and give precise indications about their behavior, the population’s structure and their ecology.”
Their presence is highly significant, as explained by the paleontologist and scientist at the Dom Luiz Institute in Lisbon: “We have found Neanderthal human footprints in fossil sediments in Gibraltar, in Matalascañas and now, potentially, in Cape Trafalgar, prior to the anatomically modern humans’ arrival in the Iberian Peninsula. More than 100,000 years ago, Neanderthals and megafauna roamed the southwestern coast. This can’t be a coincidence. Their traces point to a closeness and complicity of behaviors that are established in certain habitats between predator or scavenger and prey or corpse. Neanderthals, like us, would not be averse to eating shellfish and fish, but the large mammals, such as aurochs, elephants and goats, hunted or found dead, would be the main source of protein for their families. This close monitoring of aurochs herds would have been the first step towards domestication.”
The Portuguese researcher also provides an explanation for the animals’ massive size: “The period of megafauna included aurochs, wild boars and giant deer, as well as one of the largest elephants, the Palaeoloxon antiquus, of which there are records of tracks from Portugal to Cádiz. The period came after thousands of years of abundance of food resources in an Iberian Peninsula with a warmer, more humid climate than the current one. Food for herbivorous animals was widely available in the forests of the time, especially along rivers such as the Guadalquivir, whose estuaries, marshes and lagoons would have been the aurochs’ preferred habitat. They were the main source of food for supercarnivores such as the lion, leopard, hyena and wolf, as well as for our ancestors, the Neanderthals. The pressure from predators may have had evolutionary consequences, in the sense that natural selection gave priority to larger animals who could defend themselves against these large predators.”
The study has been carried out by an international team of researchers from Spain (Universities of Seville and Huelva, Doñana National Park), Portugal (Universities of Lisbon, Évora and Coimbra, Naturtejo Geopark, Polytechnical Institute of Tomar), China (Academy of Natural Resources of Henan) and Gibraltar National Museum.