Dinosaur tracks from the Early Cretaceous of Parede tracksite (Cascais, Portugal): New implications on the sauropod palaeobiology of the Iberian Peninsula

Abstract

A recently discovered Early Cretaceous (early late Albian) dinosaur tracksite at Parede beach (Cascais, Portugal) reveals evidence of dinoturbation and at least two sauropod trackways. One of these trackways can be classified as narrow-gauge, which represents unique evidence in the Albian of the Iberian Peninsula and provides for the improvement of knowledge of this kind of trackway and its probable trackmaker, in an age when the sauropod record is scarce. These dinosaur tracks are preserved on the upper surface of a marly limestone bed that belongs to the Galé Formation (Água Doce Member, middle to lower upper Albian). The study of thin-sections of the beds C22/24 and C26 in the Parede section has revealed a microfacies composed of foraminifers, radiolarians, ostracods, corals, bivalves, gastropods, and echinoids in a mainly wackestone texture with biomicritic matrix. These assemblages match with the lithofacies, marine molluscs, echinids, and ichnofossils sampled from the section and indicate a shallow marine, inner shelf palaeoenvironment with a shallowing-upward trend. The biofacies and the sequence analysis are compatible with the early late Albian age attributed to the tracksite. These tracks and the moderate dinoturbation index indicate sauropod activity in this palaeoenvironment. Titanosaurs can be dismissed as possible trackmakers on the basis of the narrow-gauge trackway, and probably by the kidney-shaped manus morphology and the pes-dominated configuration of the trackway. Narrow-gauge sauropod trackways have been positively associated with coastal palaeoenvironments, and the Parede tracksite supports this interpretation. In addition, this tracksite adds new data about the presence of sauropod pes-dominated trackways in cohesive substrates. As the Portuguese Cretaceous sauropod osteological remains are very scarce, the Parede tracksite yields new and relevant evidence of these dinosaurs. Furthermore, the Parede tracksite is the youngest evidence of sauropods in the Portuguese record and some of the rare evidence of sauropods in Europe during the Albian. This discovery enhances the palaeobiological data for the Early Cretaceous Sauropoda of the Iberian Peninsula, where the osteological remains of these dinosaurs are relatively scarce in this region of southwestern Europe. Therefore, this occurrence is also of overall interest due to its impact on Cretaceous Sauropoda palaeobiogeography.Keywords: Sauropod tracks, intertidal palaeoenvironment, Lower Cretaceous, upper Albian, Lusitanian Basin, Portugal Resumen El reciente descubrimiento de huellas de dinosaurios del Cretácico Inferior (inicio del Albiense tardío) en la playa de Parede (Cascais, Portugal) ha revelado evidencias de dinoturbación y al menos dos rastros de saurópodos. Uno de ellos puede clasificarse como estrecho y representa la única evidencia de este tipo de rastros en el Albiense de la Península Ibérica. Estos nuevos datos permiten mejorar el conocimiento tanto de este tipo de rastros como de su posible productor, en una edad en la...

New Dinosaur Tracks from the Lower Barremian of Portugal (Areia do Mastro Formation, Cape Espichel)

“…The fluctuations of sea level in the tidal carbonate environments, with low hydrodynamics, recorded by the dinoturbated stratigraphic surfaces at the top of the Areia do Mastro Formation, likely facilitated the preservation of the dinosaur tracks and probably provided a preferential habitat for these animals, if merely transitional. In other Portuguese ichnofossil sites with occurrence of dinosaur tracks, sediments were deposited in very shallow marine, estuarine or deltaic environments (Santos et al, 2015;Santos, 2003Santos, , 2008Figueiredo et al, 2017). taceous in the Lusitanian Basin.…”

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Dinosaur Palaeontology and their Environment

“…The scarcity of small dinosaur footprints in the fossil record raises questions related to ecological biases, preservation biases, and weathering-erosional processes. In Portugal, Santos et al (2015) report on two recently discovered sauropod trackways from the Lower Cretaceous of Parede, near Lisboa. One of these trackways is narrow-gauge with probable non-titanosaur affinity and represents one of the scarce occurrences of sauropod tracks in the Albian of the Iberian Peninsula (and the youngest sauropod tracks from the Cretaceous of Portugal).…”