(Re)discovery of an echinoderm fossil lagerstätte in the Lower Devonian of the Precordillera of the Andes, Argentina

While prospecting in the foothills of the Andes in 1894, near San José de Jáchal (San Juan Province, Argentina), German palaeontologist Wilhelm [Guillermo] Bodenbender discovered a rich fauna of Early Devonian echinoderms at a place called Quebrada de las Aguaditas, after an earthquake. Despite some preliminary notes (Kayser 1897, Ruedemann 1916), it was not described in detail until a century later (Haude 1995), revealing a particularly diverse and remarkably well-preserved assemblage, including asteroids, crinoids, holothurians, ophiuroids and stylophorans. Despite several field campaigns, Bodenbender's original site has not been found. However, the exploitation of equivalent levels in a neighbouring locality (Loma de los Piojos) has yielded very abundant and comparable faunas, perfectly stratigraphically calibrated (upper part of the Talacasto Formation, Upper Lochkovian to Lower Emsian; Wenger et al. 2025). The exceptional preservation of numerous complete and articulated echinoderm remains indicates rapid burial, probably linked to storm/obrution deposits. This interpretation has recently been confirmed by sedimentological and ichnological analysis of the Loma de los Piojos section (Wenger et al. 2025). The echinoderms of the Talacasto Formation show strong affinities with other high-latitude peri-Gondwanan assemblages (Malvinocaffre Province), particularly with those found in South Africa and Brazil, but also with faunas from more distant regions, such as Australia.