An archosauromorph dominated ichnoassemblage in fluvial settings from the late Early Triassic of the Catalan Pyrenees (NE Iberian Peninsula)

PLoS One. 2017 Apr 19;12(4):e0174693. doi: 10.1371/journal.pone.0174693. eCollection 2017.

Abstract

The vertebrate recovery after the end-Permian mass extinction can be approached through the ichnological record, which is much more abundant than body fossils. The late Olenekian (Early Triassic) tetrapod ichnoassemblage of the Catalan Pyrenean Basin is the most complete and diverse of this age from Western Tethys. This extensional basin, composed of several depocenters, was formed in the latest phases of the Variscan orogeny (Pangea breakup) and was infilled by braided and meandering fluvial systems of the red-beds Buntsandstein facies. Abundant and diverse tetrapod ichnites are recorded in these facies, including Prorotodactylus mesaxonichnus isp. nov. (tracks possibly produced by euparkeriids), cf. Rotodactylus, at least two large chirotheriid morphotypes (archosauriform trackmakers), Rhynchosauroides cf. schochardti, two other undetermined Rhynchosauroides forms, an undetermined Morphotype A (archosauromorph trackmakers) and two types of Characichnos isp. (swimming traces, here associated to archosauromorph trackmakers). The Pyrenean ichnoassemblage suggests a relatively homogeneous ichnofaunal composition through the late Early Triassic of Central Pangea, characterized by the presence of Prorotodactylus and Rotodactylus. Small archosauromorph tracks dominate and present a wide distribution through the different fluviatile facies of the Triassic Pyrenean Basin, with large archosaurian footprints being present in a lesser degree. Archosauromorphs radiated and diversified through the Triassic vertebrate recovery, which ultimately lead to the archosaur and dinosaur dominance of the Mesozoic.

MeSH terms

  • Animals
  • Biodiversity
  • Biological Evolution*
  • Dinosaurs / anatomy & histology
  • Dinosaurs / classification*
  • Dinosaurs / physiology
  • Extinction, Biological*
  • Fossils
  • Paleontology
  • Phylogeny*
  • Spain

Grants and funding

This work was supported by the Universitat Autònoma de Barcelona (www.uab.cat), PhD grant (PIF Geologia) to EM, the Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P, MNHN), the Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR) (http://agaur.gencat.cat/) through grant 2014 - BP-A 00048 to JF, the Generalitat de Catalunya (http://web.gencat.cat/) through fieldwork projects 2014/100606 and 57 641992013 03 to JF, and by the CERCA programme to JF and AB. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.