Fish and tetrapod trace fossils from the Upper Carboniferous of Puertollano, Spain

Well-preserved fish and tetrapod trace fossils occur in Carboniferous (Step hanian C) beds at Puertollano. They represent the first evidence of vertebr ate ichnites in the Carboniferous of Spain. The fish swimming traces are as signed to Undichna britannica and Undichna unisulca. The dimensions and mor phological features of the traces indicate that Orthacanthus (Xenacanthidae : Elasmobranchii), a shark very common in the basin, might have been the tr ace-producer. A morpho-functional analysis of the traces suggests an axial undulatory ( = anguilliform) mode of locomotion of xenacanth sharks. This c onclusion is consistent with the eel-like body found in all known xenacanth ids. Tetrapod trackways, referred to Puertollanopus microdactylus ichnogen. et ichnosp. nov., and resting traces are described. Both walking and resti ng tracks are assigned to a small terrestrial tetrapod. Dimensions and prop ortions of the tracks, and size and morphology of the impressions of manus and pea suggest a microsaur amphibian or a small reptile as the track-maker . This represents the first evidence of these vertebrates in the basin. The superposition of fish trails and tetrapod trackways strongly suggests tida l processes in a marginal-marine depositional setting. This interpretation agrees with recent sedimentological, geochemical and palynological data fro m the Puertollano basin. (C) 2001 Elsevier Science B.V. All rights reserved .