The ichnological Cretaceous sauropod record of South America is analyzed for the first time in relation with skeletal and paleoenvironmental data. The updated database includes 39 tracksites and 71 valid species (53 titanosaurs and 18 non-titanosaurs) from Colombia, Ecuador, Peru, Chile, Brazil and Argentina. The track and bone records analyzed evidence a relationship with continental environments, specifically with fluvial ones. This is observed in all Sauropoda records, indicating an ecological association of the Cretaceous sauropods for these environments. In addition, the paleogeographic reconstruction integrating these records does not evidence any correlation between the distribution of sauropods and the latitudinal range. During the late Campanian–Maastrichtian interval, when the Atlantic transgression event was established, the titanosaur record started to show a singular panorama. The tracksites are preserved not only in continental paleoenvironments but also in marginal-marine ones, being the only last records of titanosaurs associated with that environment in South America. Both the paleoecological aspects based on sauropod Cretaceous record and the paleoenvironmental data collected in this work support the hypothesis that these tracksites were used by titanosaurs as ‘transit areas’ to move among the environments they inhabited.
South America during the Late Cretaceous (Maastrichtian) showing schematically the distribution of the first Atlantic marine transgression (Fig. 5, Tomaselli et al. 2021).
Comments: This study is based on a careful recording of all the findings, which are mentioned in two supplementary tables, one of footprints and the other of bones. A first thing we see is that many of the published records have focused on purely systematic paleontological aspects, leaving aside detailed sedimentological and taphonomic studies. It is therefore necessary to promote this type of study in all dinosaur finds. A second important aspect is that the record shows us a direct correlation between sauropods and fluvial environments and, to a lesser extent, lake environments. There are, to date, no bone deposits in marginal marine facies, which indicates that most likely, South American sauropods (most titanosaurs) did not inhabit marginal marine environments, and their footprints only evidence their transit, when the epicontinental sea of the end of the Cretaceous covered more than half of the continent. This reduction in terrestrial environments produced a reduction in the resources available for sauropods (space and vegetation).
