In addition to the set of 12 footprints, belonging to five dinosaurs from three different species, which roamed the area around 120 million years ago, Praia dos Arrifes hides other treasures, invisible to the eyes of tourists who go swimming in the small cove, whose sand almost disappears at high tide.

The scientific advisor for the Algarvensis Geopark project, Octávio Mateus, said that these rocks are recorded as being "a few million years old", with marks from crustaceans, shells, whelks and single-celled beings, although the most impressive are the marks left by dinosaurs in the lower Cretaceous period.

Only accessible at low tide and to those willing to climb over rocks, the site with 12 footprints, some of which are in sequence and three-dimensional, reveals the presence of large sauropods, including the brontosaurus, the long-necked dinosaurs popularized in cinema.

However, this enormous dinosaur, whose footprints reach half a meter in length, is joined on this trail by small sauropods, also herbivores, and three carnivores, all in a crack between two layers in the cliff, made when those rocks were still horizontal.

120 million years ago, the footprints were imprinted in the mud, which was covered with limestone and sand, and after the sediment below had eroded, the natural shape of the footprint was left. The cliffs 'rotated' to their current position due to tectonic movement, explained the paleontologist, a professor at the Universidade Nova de Lisboa.

"There are tectonic forces related to salt deposits, or by the plates, crustal movements, causing it to bend and roll, and what was horizontal became vertical", he explained, stressing that this is a "major discovery", which makes this beach in the Faro district a "geosite of global importance".

At the beginning of the trail, a rock shows the seabed from a few million years ago, bearing witness to the trail of crustaceans, similar to crabs and lobsters, which made galleries and excavated the sand that, over time, was filled with more sand.

Further ahead, heading east, on the face of another cliff also threatened by the action of the sea, four footprints are revealed forming a trail, all over 20 centimetres, of an ornithopod dinosaur that would have been four metres long.

The first deposit had been documented since 2016, but had not been studied, a task that is now being carried out as part of the application for the territory of Loulé, Albufeira and Silves to become a global geopark of the United Nations Educational, Scientific and Cultural Organization (UNESCO).

"[The current scientific coordinator of the Algarvensis Geopark] Paulo Fernandes said that it had been discovered in one of his field classes by a student, but I don't know the date. It must have been between 2014 and 2016. The deposit of sauropod footprints in the crevice was mentioned for the first time in a summary of a conference in 2016, but it does not mention who discovered them", said Octávio Mateus.

However, as far as he knows, the ornithopod footprints are "absolutely new" and were discovered by him on June 12 of this year.

During a working visit to the Algarve to check the progress of the application, the president of the UNESCO Global Geoparks Council, Guy Martini, said he believed in the potential of the Algarve application, stressing that there was still much to be done.

For Guy Martini, the future geopark, which is a project "for the next 20 years", can help "create a new flow of movement, including tourists, from the coast, where they are currently concentrated, to the interior.

"I think this will create a more egalitarian economy in the territory", said the Frenchman, one of the main creators of the geopark concept, noting that the objective "should be a population that can defend its values and its nature".

Artur Sá, coordinator of the UNESCO Chair of Geoparks - Sustainable Regional Development and Healthy Lifestyles, at the University of Trás-os-Montes and Alto Douro (UTAD), also highlighted the importance of the project for the interior of the region.

"This is a holistic approach to the territory, everything that is identifying and differentiating in the territory [...]. Furthermore, it brings new opportunities for development to those who live here", he stressed.