 |
| A specimen of Rana pueyoi from Libros. |
The locality of the sulfur mines of Libros is a classical locality within the Spanish palaeontological sites due to its remarkable fossil record. The fossil vertebrates extracted during the operation of the mines are known worldwide. The rocks of the site were originated from a former lake during the Vallesian (Upper Miocene).
There are many plant and insect fossils found in Libros, but the most prominent are the specimens of Rana pueyoi. In some cases, the excellent state of preservation of these amphibians has maintained part of the 3D structure, including fragments of marrow.
