New ornithopod footprints from the Areia do Mastro Formation (Lower Cretaceous), Espichel Cape (Portugal, Western Iberia) and their context in the Iberian ichnological ornithopod record

Abstract

Two new ornithopod natural casts are reported from the Praia do Areia do Mastro site, at Espichel Cape (near Sesimbra), western central mainland Portugal (western Iberia). In this Tracksite two geological formations occur: Areia do Mastro Formation and Papo-Seco Formation (lower Barremian). This locality (Praia do Areia do Mastro) occurs in a sedimentary succession comprising limestones, marls, sands and conglomerates, interpreted as marine, lagoonal and estuarine deposits. In the Papo-Seco Formation have yielded fossil remains of dinosaurs (teeth and bones) and other vertebrates (Figueiredo et al., 2015, 2016). The ichnological record is composed by two footprints, one of them incomplete, preserved as natural casts in convex hiporelief. They are tridactyl, mesaxonic and wider than long. The digit impressions are short, wide and have a blunt edge. The footprints present a round and wide posterior surface and have one pad impression in each digit and a wide and subrounded metatarsophalangeal pad impression. Based on the commented features, they are assigned herein to Caririchnium isp. This ichnogenus is present in other Lower Cretaceous sites in the Iberian Peninsula and is also present in other Barremian tracksites of Portugal. In Spain, Caririchnium tracks are typical of continental settings, while in Portugal they were mainly found in estuarine paleoenvironments. This contribution enhances the knowledge of the Early Cretaceous ornithopod diversity and distribution in the Iberian Peninsula.