Climatic constraints on the biogeographic history of Mesozoic dinosaurs.

Dinosaurs dominated Mesozoic terrestrial ecosystems globally. However, whereas a pole-to-pole geographic distribution characterized ornithischians and theropods, sauropods were restricted to lower latitudes. Here, we evaluate the role of climate in shaping these biogeographic patterns through the Jurassic–Cretaceous (201–66 mya), combining dinosaur fossil occurrences, past climate data from Earth System models, and habitat suitability modeling. Results show that, uniquely among dinosaurs, sauropods occupied climatic niches characterized by high temperatures and strongly bounded by minimum cold temperatures. This constrained the distribution and dispersal pathways of sauropods to tropical areas, excluding them from latitudinal extremes, especially in the Northern Hemisphere. The greater availability of suitable habitat in the southern continents, particularly in the Late Cretaceous, might be key to explaining the high diversity of sauropods there, relative to northern landmasses. Given that ornithischians and theropods show a flattened or bimodal latitudinal biodiversity gradient, with peaks at higher latitudes, the closer correspondence of sauropods to a subtropical concentration could hint at fundamental thermophysiological differences to the other two clades. [Display omitted] • Sauropod dinosaurs never invaded polar palaeolatitudes • Sauropods were constrained to lower latitudes more than the other dinosaurs • Sauropods were more abundant in the Southern rather than in the Northern Hemisphere • Sauropod ranges were more sensitive to temperature than those of other dinosaurs Chiarenza et al. investigate the different biogeographic patterns exhibited by the main dinosaur groups (Ornithischia, Theropoda, and Sauropoda), finding that the distribution of sauropods differs from the others in being constrained at lower latitudes by low minimum temperatures, hinting to a fundamentally different thermophysiology of this group. [ABSTRACT FROM AUTHOR]