Palaeoenvironmental andstratigraphic aspects of animal traces and plant remains in Spanish Permian red beds (Peña Sagra, Cantabrian Mountains, Spain)

Abstract

Various vertebrate and invertebrate traces and plants remains have been discovered in the Permian of Pico Paraes (Cantabrian Mountains). They occur in the Sagra Formation, a 400 m thick unit consisting of a vertical alternation of channels with conglomeratic sandstones and fossiliferous red siltstones with a caliche horizon at the top. The most common trace is Hyloidichnus major which is attributed to approximately 50 cm long Captorhinomorphs. Other tracks provisionally assigned to Limnopus could also indicate the presence of Temnospondyls. The bedding planes with traces also show some tracks of Isopodichnus cf. minutus which is ascribed to small triopsid crustaceans. Like the footprints, these are sometimes cut off by insect burrows like cf. Steinichnus, Scoyenia gracilis, Ancorichnus sp. or Skolithos. These fossiliferous levels have also yielded conchostracans, unidentifiable plant stems and a rather well-preserved frond of Supaia sp. The fossil association and sedimentological features suggest that the Sagra Formation is a floodplain deposit; the water depth was limited and fluctuated. Longer drier intervals also occurred. The vegetation was meso-xerophilous. The occurrence of the ichnopopulation Hyloidichnus major and Supaia in the Permian of France (Lodève basin) and North America (Grand Canyon, U.S. A) suggests that the Sagra Formation can be correlated with the Rabejac Formation of the Lodève basin. Based on comparisons with the Supaia-bearing Hertmit Shale, the Sagra Formation might be dated as early Leonardian, or even Artinskian when the Leonardian can indeed correlated with the Artinskian + Kungurian.