Between the Paiva’s gorge and the village of Paradinha, in a small stream amongst outcroping quartzite ridges formed about 480 million years ago, can be observed traces of fossils of Cabanas Longas, who witness the passage of now extinct arthropods by the sands of the ocean shallows. Those responsible for these fossilized tracks were probably the trilobites, now extinct group but which persisted on Earth during the Paleozoic period. The trace fossils, also known as Cruziana are feeding and locomotion tracks of trilobites. In Cabanas Longas can be seen different species of Cruziana each associated with a distinct eating behavior. To highlight some Cruziana rugosa tracks over 20 cm wide and 1 meter long, corresponding to the passage of major specimens in this location, in a very remote past.
Not far from the Cabanas Longas trace fossils, the village of Paradinha, awarded the seal Aldeias de Portugal® (villages of Portugal), remains proud next to the Paiva river, with its houses made of shale and slate, harmoniously merged with the surrounding nature. Across the river, the Paivô river mouth keeps an adernal of great beauty, where the green olive tree, the myrtle, the strawberry tree and the tutsan are present. The Paiva river, known for its trouts, is also the habitat of protected species such as the river cruisers dragonfly, the iberian frog and the freshwater pearl mussel. At the high cliffs, the furry anarrhinum finds shelter, and the peregrine falcon echoes their alarm calls.
The trilobites, distant relatives of today’s crustaceans, were the main representatives of arthropods (the group to which belong also, for example, crabs and insects) in Paleozoic seas. These dominated all marine environments, in a manner similar to the dominance of dinosaurs during the Jurassic and Cretaceous, and were so abundant (it is estimated that there were 15,000 species of trilobites), that this geological time period was called “Age of Trilobites”. The trilobites had its origins 540 millions years ago, in the early multicellular lifetime and were extinguished 250 millions years ago, in the largest mass extinction there are memory in the life of the Earth; at the end of the Permian period, 95% of marine species disappeared, including the latest trilobites. The height of this group was at the end of the Cambrian and beginning of the Ordovician period, counting over 60 trilobite families in this period.
