465 Million Years of History

Arouca Trilobites


The animals that inhabited the Earth millions of years ago are now extinct, having left behind a record of their existence in fossils. Many of these vestiges are found in rocky formations that serve as witnesses of the planet’s geological past. These fossilized elements hold an enormous historical value that is essential to the paleontological study of the evolution of the species and life on Earth.

In Canelas, a village in the Arouca Municipality located in the northern region of Portugal where schist is extracted, several fossils of Trilobites, a marine animal that disappeared 250 million years ago, have been found. The name of these animals alludes to their back, which is transversely divided by three lobes. The fossils show us an imprint of their exoskeleton, a type of shell, also divided into 3 parts: Cephalon (one-piece head section including the eyes, mouth and part of the digestive tract); Thorax, a jointed mid-section made up of identical segments; Pygidium, a singular posterior part of the carapace that in some species could include spikes and various forms of ornamentation.



© Luís Lopes

Trilobites disappeared from the planet because they were not able to survive the volcanic and seismic phenomenon provoked by the conjoining of the continental masses that created Pangaea, the supercontinent of the Palaeozoic era.


The fossils of the Canelas Trilobites are from a far-off period dating back 465 million years and are recognized throughout the world for their pristine state of preservation and large dimensions. Trilobites are known to have been on average between 3 cm and 10 cm long, but some specimens reached lengths up to 80 cm. Their sight was excellent, similar to that of insects, and they could be detritivorous, carnivorous or filter feeders.  

Part of this extensive sampling can be seen at the local Museum of the Canelas-Arouca Geological Research and Interpretation Centre. The Geological Museum in Lisbon also holds in its collection a one of a kind plate of Canelas schist that presents perfect fossils of two adult specimens of the Hungioides bohemicus Arthropods.


© Luís Lopes


© Luís Lopes


© Luís Lopes