The name of the aspiring Geopark Algarvensis has its origin in the fossil that was discovered in this geosite: the Metoposaurus algarvensis, a species of prehistoric amphibian unique in the world.

This deposit located in Penina, on one of the slopes of Rocha da Pena, contains a large number of skull bones and some post-cranial material from several individuals of this species, traces concentrated in a narrow stratigraphic level of the "Grés de Silves".

Living in lakes and rivers about 227 million years ago, in the Upper Triassic period, the Metoposaurus algarvensis fed mainly on fish and small animals. Sometimes, the waterbodies  where Metoposaurus lived suffered from major drought episodes, gradually evaporating until they disappeared. As the lakes and ponds receded, the Metoposaurus concentrated in the last remnants of water, where they died off in large numbers, giving rise to deposits with high concentration of fossils, or "bonebeds", like the one seen at Penina.

However, the best way to get to know the Metoposaurus algarvensis is to visit the Municipal Museum of Loulé, where an example of a skull of this unique species is on display.