Desert Cretaceous Dinosaurs: The Botucatu Paleodesert and the Footprints Across the Dunes

Tetrapod fossil footprints are common in the aeolian sandstonesAeolian sandstones from the Botucatu FormationBotucatu formation in many Brazilian states, all around the edge of the Paraná BasinParaná basin. This unit is represented by well-selected, reddish aeolian sandstonesAeolian sandstones, related to an extensive dune fieldDune fields. Its age is Early Cretaceous (Berriasian-Barremian). The main ichnosite from the Botucatu FormationBotucatu formation occurs in the interior of São Paulo State, in the AraraquaraAraraquara region, at the São Bento quarrySão Bento quarry, where slabs for covering and paving of public sidewalks, were extracted. This quarry presents a section of a large dune, about 20 m high and 100 m long, exhibiting foresets with a dip of 29° in the S-SW direction. Alongside the bedding surfaces there are abundant tracks attributed to mammalsMammals, TheropodaTheropoda and Ornithopoda. These are herein grouped in four morphotypes, in addition to other kinds of isolated footprints difficult to classify. All these occurrences belong to bipedal and functionally tridactyl dinosaurs; no SauropodomorphaSauropodomorpha tracks were found. To these theropodTheropods and ornithopodOrnithopods footprints and trackways from the eastern side of the Paraná BasinParaná basin are added those of the western side, in the area of NioaqueNioaque tracksites, Mato Grosso do Sul State. The Botucatu paleodesertBotucatu paleodesert harbored a possibly endemic fauna, of bipedal carnivorous and herbivorous dinosaurs, which makes difficult a faunistic comparison with other localities, in other paleobiogeographic contexts.