Vertebrate tracks from the Paso Córdoba fossiliferous site (Anacleto and Allen formations, Upper Cretaceous), Northern Patagonia, Argentina: Preservational, environmental and palaeobiological implications

Abstract

The Paso C ordoba fossiliferous site (Río Negro, Northern Patagonia) is one of the first Mesozoic fossiliferous localities studied in Argentina. There, turtle, crocodile and dinosaur remains as well as dinosaur and bird tracks have been recorded. Recently, a new locality with vertebrate tracks, the Cañad on del Desvío, has been discovered in Paso C ordoba. Six track-bearing layers were located in outcrops belonging to the Anacleto (lower to middle Campanian, Neuqu en Group) and Allen (middle Campanian-lower Maastrichtian, Malargüe Group) formations. The Cañad on del Desvío locality reveals that vertebrate trace fossils are distributed in two distinct environments, floodplains of a meandering fluvial to shallow lacustrine system and a wet interdune deposit that is associated to an aeolian setting. Also, in the logged section several soft sediment deformation structures were found. In regard of this, a sedimentary facies analysis is provided in order to assess the palaeoenvironmental implications of this new record. The analysed tracks are preserved in cross-sections, on bedding-planes and as natural casts. When it is possible, the tracking surface, true tracks, undertracks and overtracks/natural casts have been identified and the track preservation and the formation history of the tracksite are discussed. Only two tracks preserve enough anatomical details to relate them with their trackmakers, in this case hadrosaurid dinosaurs. The stratigraphical, facial and palaeoenvironmental data of this study support the idea of a transitional passage between the Anacleto and Allen Formation in Paso C ordoba. The presence of hadrosaurid dinosaur tracks suggests that the upper part of the log, where this kind of tracks were found, likely belong to Allen Formation due to this dinosaurs appear in the Southern Hemisphere in this epoch. The sum of osteological and ichnological remains improve the Paso C ordoba palaeofaunistic knowledge. The presence of six different levels in which the trackmakers walked reflects the abundance of vertebrates in the transition between Anacleto and Allen formations.

First occurrence of sauropod and theropod footprints in the pre‐Campanian deposits of the Nubian Sandstone, south Eastern Desert, Egypt

“…Footprints are known as biosedimentary structures, and depict a closely relation with the environment and the nature of the substrate. Biodeformation features and the understanding of their origin can predict the paleoenvironmental interpretation (Avanzini, 1998; Carvalho & Leonardi, 2020; Díaz‐Martínez, Cónsole‐Gonella, de Valais, & Salgado, 2017; Falkingham, Bates, Margetts, & Manning, 2011; Gatesy et al, 1999; Menezes, Araújo‐Júnior, Dal' Bó, & Medeiros, 2019; Platt, Hasiotis, & Hirmas, 2012). As described here, footprints are surrounded by an observed swollen and compressed border, indicating the squeezing of the waterlogged sediment due to the weight of the dinosaur.…”

Ostracods from the Cretaceous–Palaeogene boundary at El Matuasto Section, Neuquén Basin, Argentina: taxonomy, palaeoecological and palaeobiogeographical inferences

“…The presence of continental vertebrates and freshwater molluscs, and its sedimentological characteristics suggest that the depositional environment was predominantly lacustrine, with a fluvial influence at the base (Martinelli & Forasiepi 2004; Parras & Griffin 2013; Díaz‐Martínez et al . 2018). The Allen Formation transitions into the Jagüel Formation, composed of partially laminated olive‐green shales, in which a few Maastrichtian marine bivalves can be found, such as Ambigostrea clarae and ‘ Pecten ’ mahuidaensis .…”

Dinoturbation in Upper Jurassic siliciclastic levels at Cabo Mondego (Lusitanian Basin, Portugal): evidences in a fluvial-dominated deltaic succession

“…Dinosaur footprints are common in fluvial settings (e.g., Sciscio et al, 2016;Díaz-Martínez et al, 2018), shallow lacustrine facies (e.g., Xing et al, 2015), fluvialdominated delta depositional systems (e.g., Niedzwiedzki and Pieńkowski, 2004), shallow marine platforms which underwent episodic subaerial exposure (e.g., Kvale et al, 2001), and in tidal flats (e.g., Carvalho and Pedrão, 1998;Figueiredo et al, 2021).…”