Avian and mammal footprints from a Neogene peri-marine wetland (Pozo Salado, Río Negro Province, Argentina)

CITTON, PAOLO; CARATELLI, MARTINA; MONTES, ROMINA; DE VALAIS, SILVINA; CÓNSOLE GONELLA, CARLOS; ARCHUBY, FERNANDO M; DÍAZ MARTÍNEZ, IGNACIO

Congreso; 3rd Palaeontological Virtual Congress; 2021

Thevertebrate ichnofauna from the Neogene Río Negro Formation is represented bymammal and avian footprints reported from different localities of the coast ofnorthern Patagonia and Pampean region. Anew track-bearing locality in the unitwas recently found close to Pozo Salado, on the tide-dominated Atlanticshoreline of the Punta Mejillón area (Río Negro province, Argentina). Thetrackmakers were crossing an emergent, fine- to medium-grained, sandy flat of aperi-marine wetland. Some tracks present folds in the surface related withmicrobially induced sedimentary structures, playing a significant role in trackpreservation. As suggested by extramorphological track features, the surfaceand subsurface remained compliant to producers of different size-classes, probablyduring a relatively long time of exposure and trampling. The tracksite presentsabundant footprints but relatively low ichnodiversity. Avian tracks are themost common, although caviomorph and megatherian tracks have also beenidentified. Few footprints display clear morphology and were classified as Gruipeda cf. maxima and cf. Porcellusignum isp., two ichnotaxaclassically related to gruiform/ ciconiiform birds and hydrochoerid rodents,respectively. Shorebird and waterbird tracks are a component of the shorebirdichnosubfacies within the Scoyeniaichnofacies, classicallyaccompanying a prominent suite of invertebrate traces like Taenidium, Skolithos and Helmintoidichnites, apparently lacking in thestudied ichnoassociation. The new finding enriches the vertebrate track recordfrom the Atlantic coast of the Río Negro province and invites to furtherdiscuss the reliability and significance of this type of tracks in refine palaeoenvironmental,palaeoecological and ichnofacial reconstructions.