Early Paleocene siluroid catfish from Bolivia and its evolutionary and paleogeographic importance
Eva Caron, Diogo Mayrinck, Ricardo Cespedes, and Olga Otero
The fossil genus Yuskaichthys, previously known only from Eocene deposits of the Maíz Gordo site in Argentina, is here identified based on three isolated parieto-supraoccipital bones collected in the Tiupampa locality, Cochabamba-Potosí Basin, Bolivia. This discovery notably extends both the paleogeographic and temporal distribution of the genus into the early Paleocene. Morphological traits including the bifid posterior margin of the supraoccipital process and the transverse pit lines closely resemble those described for Yuskaichthys. Futhermore, these fish share a longitudinal groove along the entire supraoccpital process, supporting a provisional assignment to Yuskaichthys. The occurrence of Yuskaichthys in both Tiupampa and Maíz Gordo is consistent with regional fluvial systems associated with the Andean foreland basin evolution. This finding supports an early diversification of modern catfish lineages, including extinct genera displaying long time range.
Key words: Teleostei, Siluriformes, Yuskaichthys , catfish, Paleocene, Bolivia.
Eva Caron [eva.caron44@gmail.com, ORCID: https://orcid.org/0009-0009-7551-9679], Programa de Pós-Graduação em Biociências, Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro.Boulevard 28 de setembro 87, PAPC, Maracanã, 20551-030, Rio de Janeiro, Brazil. LICTAE (Laboratório de Ictiologia Aplicada: anatomia e evolução), Departamento de Ensino de Ciências e Biologia, Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro. Rua São Francisco Xavier 524, PHLC sala 504, Maracanã, 20559-900, Rio de Janeiro, Brazil. Diogo Mayrinck [mdiogobio@yahoo.com.br, ORCID: https://orcid.org/0000-0002-6899-1432]. LICTAE (Laboratório de Ictiologia Aplicada: anatomia e evolução), Departamento de Ensino de Ciências e Biologia, Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro. Rua São Francisco Xavier 524, PHLC sala 504, Maracanã, 20559-900, Rio de Janeiro, Brazil. Ricardo Cespedes [ricardojcespedes@gmail.com, ORCID: https://orcid.org/0000-0003-1004-8246], Museo de Historia Natural Alcide d’Orbigny, avenida Potosí n°1458, Cochabamba, Bolivia. Olga Otero [olga.otero@univ-poitiers.fr, ORCID: https://orcid.org/0000-0002-8129-2054], Université de Poitiers, laboratoire PALEVOPRIM (UMR 7262 CNRS-UP), 6 rue Michel Brunet, 86000 Poitiers, France.
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