The rocks of the Asturian Jurassic are grouped into five geological sets or formations. Their representation, ordered vertically from oldest to most modern, is known as a stratigraphic column. Each formation receives the name of the locality or geographical accident closest to the place where these rocks show the best conditions for observation; in the case of Asturias these formations receive the names of Gijón, Rodiles, La Ñora/Vega, Tereñes and Lastres.
The continuous geographical changes taking place in our region throughout the 55 million years the Jurassic lasted, lead to the conditions for alternating stages of marine domain, rich in fossils and swimming reptiles, with others in which the withdrawal of the sea gave rise to terrestrial and coastal ecosystems populated by dinosaurs and other vertebrates, such as flying reptiles (pterosaurs), turtles, crocodiles and fish.
The footprints and skeletal parts of these Jurassic vertebrates now forming part of the wealth of the MUJA, constitute the best and most complete fossil register of the Spanish territory for this period (this hall exhibits almost 200 fossils); apart from the fact this collection of tracks is among the best in Europe, not only due to their excellent conservation but also as a result of their abundance and variety.
Standing out in particular are the ichnites of stegosaurus and those of sauropods with marks on their skins, both very scarce in the world, the footprints of flying reptiles or pterosaurs, a 1.25 metre long ulna (equivalent to our cubitus bone) belonging to an enormous sauropod, together with the partial skeletons of a stegosaurus and a marine crocodile. There is a display case dedicated to the vertebrate fossil collections, exhibiting the reproduction of a biped dinosaur trace on which some useful parameters are represented to recognise certain aspects on the characteristics and the behaviour of these fascinating reptiles.
Another of the spaces shows the industrial application of some Jurassic materials such as black amber, one of the most precious jewels in the traditional Asturian culture, or the varieties of rock used for centuries in the region to construct buildings.
The location of ichnite deposits on the coast of dinosaurs can be seen in a panoramic aerial photograph found on a backlit panel.