A new narrow-gauge sauropod trackway from the Cenomanian Candeleros Formation, northern Patagonia, Argentina

Abstract

Dinosaurs are extremely abundant in the Upper Cretaceous Neuquén Group of the Neuquén Basin (Argentina). Nevertheless, while osteological remains are rich the ichnological record is more restricted. A new sauropod dinosaur trackway with five manus-pes imprint sets discovered in the Cenomanian Candeleros Formation is described here. The trackway belongs to the narrow-gauge type that is identified for the first time in the Cenomanian and possibly for the Late Cretaceous. It is preserved as concave epirelief in fine-grained sandstones from floodplain deposits. The tracks, which are large in size (average length of 98 cm), include conspicuous rims with very well-preserved symmetrical ripples on top that are documented for the first time in the track record. Due to their preservation and the absence of clear anatomical details, the trackway was not assigned to any particular ichnotaxon. Taking into account the presence of rebbachisaurid diplodocoid remains in the Candeleros Formation, the classical association of narrow-gauge trackways with diplodocoids and the inferred gleno-acetabular distance, it is suggested that the studied trackway might belong to a large-sized rebbachisaurid. The worldwide record of Cenomanian dinosaur tracks includes only a few records of sauropod tracks. Thus, this new

Gregarious behaviour among non-avian theropods inferred from trackways: A case study from the Cretaceous (Cenomanian) Candeleros Formation of Patagonia, Argentina

“…J o u r n a l P r e -p r o o f 6 W) is approximately 350 m in straight line from the sauropod trackway documented by Heredia et al (2019). The logged section (1:100) comprises the basal part of the unit (the first 36 m) and follows Heredia et al (2019).…”

“…The new track-bearing level is found in the uppermost deposits interbedded with sandstones showing cross-stratification and reactivation surfaces interpreted as small-scale channel bodies. As in the case of the sauropod trackway (Heredia et al, 2019), the tracks studied here are exposed on a flat surface of about 150 m 2 (Fig. 3F).…”

“…Schieber, 2004;Noffke, 2009;Davies et al, 2016), the analysed interval records deformed ripple crests associated with desiccation cracks and glossy surfaces that suggest the overgrowth of microbial mats. Shallow-water bodies within the floodplain subjected to flooding and drying periods (Heredia et al, 2019) might have represented ideal scenarios for the occurrence of mats. The preservation potential of footprints increases directly with the consolidation and partial lithification of microbial mat-bearing sediments (Marty et al, 2009).…”

“…1A). In the study area (Aguada de Tuco), the basal part of the unit (the first 25 m) is represented by unconfined flow deposits possibly related to ephemeral fluvial systems and channelized to poorly channelized flows and floodplain deposits (Heredia et al, 2019).…”

A diverse Late Cretaceous vertebrate tracksite from the Winton Formation of Queensland, Australia

“…The wide-gauge nature of the AODF 904.S1 trackway distinguishes it from narrowgauge sauropod trackways like Breviparopus taghbaloutensis (Dutuit & Ouazzou, 1980), Parabrontopodus mcintoshi (Lockley, Farlow & Meyer, 1994a), and a trackway from the Cenomanian of Argentina (Heredia et al, 2019). Trackways assigned to Titanopodus mendozensis (González Riga & Calvo, 2009;González Riga, 2011;González Riga & Tomaselli, 2019), as well as unnamed trackways from the Fumanya site in Spain (Vila et al, 2013), are relatively wider-gauge (with significantly lower MTR and PTR values) than the AODF 904.S1 trackway.…”