New insights into Late Devonian vertebrates and associated fauna from the Cuche Formation (Floresta Massif, Colombia)

ABSTRACT

New vertebrate remains are reported from the Late Devonian (?Frasnian) Cuche Formation of northeastern Colombia, including a new taxon of antiarch placoderm (Colombialepis villarroeli, gen. et sp. nov., previously reported as Asterolepis) and a new taxon of arthrodiran placoderm (Colombiaspis rinconensis, gen. et sp. nov.). We also report evidence of a stegotrachelid actinopterygian, a diplacanthid acanthodian (cf. Florestacanthus morenoi), a second antiarch placoderm (Bothriolepis sp.), a putative megalichthyid, and a putative tristichopterid. The absence of typical Euramerican markers, e.g., Asterolepis and Strepsodus, in this assemblage suggests that faunal interchange between Euramerica and Gondwana was less pronounced during the Frasnian–Famennian than previously thought (i.e., the Great Devonian Interchange hypothesis). Three arthropod taxa, including two families of spinicaudatan branchiopods and the eurypterid Pterygotus cf. bolivianus, are found to be associated with the reported vertebrate fauna. Pterygotus cf. bolivianus represents the first eurypterid described from Colombia and the youngest known pterygotid eurypterid, highlighting that pterygotids, which were competitors for large predatory fishes, did not go extinct during the major vertebrate radiation in the Early and Middle Devonian.

ACKNOWLEDGMENTS

We gratefully acknowledge the 2017 expedition team in Colombia. We also acknowledge the Colombian Geological Service for the authorization to perform field work activities and for the loan of the studied specimens. The authors thank R. Vacant (MNHN) and N. Vallée-Gillette (RBINS) for the preparation of some specimens. T. Hubin (RBINS), P. Loubry (MNHN), and L. Cazes (MNHN) provided the photographs, and C. Fossé (IPANEMA CNRS) provided assistance with SEM imaging. We thank the Royal Belgian Institute of Natural Sciences for facilitating access to their micro-CT scanner as part of the DIGIT03 project and U. Lefevre (RBINS) for operating the micro-CT. F. Goussard (MNHN) helped in the 3D modeling process. The authors acknowledge the editor and reviewers for their fruitful comments and the improvement given to the English text. H.B. and C.M.P. were supported by the Spanish Ministry of Economy and Competitiveness (research project 926 CGL2014-52662-P), the Valencian Generality (research project GV/2016/102), and the University of Valencia (INV18). Finally, we gratefully acknowledge the Fonds de la recherche scientifique (FNRS) for the travel and study grant to S.O.