"Carbonífero de Puertollano" Natural Monument (Puertollano basin, Spain): a window for the knowledge of Early Vertebrates

Abstract

Coal mining at the Puertollano Carboniferous basin has led to the discovery and study of numerous fossiliferous layers, rich in chondrichthyan, actinopterigyan and tetrapod remains. The end of the mining operations and closure of the mines could also represent complete cease of paleontological prospections and field work at the Puertollano basin. Fortunately, three quarries, called María Isabel, La Extranjera and La Tejera, have been declared a Natural Monument. Consequently, they are protected by law and reserved for geological and palaeontological scientific research. In this paper, we describe the geology of the Natural Monument and its vertebrate fossil record. The outcrops of the three quarries show the most superficial part of the stratigraphic series so that they inform about the latest stages of the sedimentological and palaeogeographical evolution of the Puertollano basin. The actual coal basin appears to represent a remnant of a much larger basin which opened eastward to the Paleo-Tethys. The diverse chondrichthyan assemblage (acanthodians, xenacanths and euselachians) and euryhaline actinopterygians, and the presence of tidal rhythmites, indicate an estuarine-deltaic environment. Future sedimentological and paleontological studies at the Natural Monument will inform about the degree of marine influence in the basin and the changes of the vertebrate communities.