The latitudinal biodiversity gradient, the difference in number of species from the equator to the poles, is the most pervasive pattern of biodiversity distribution on today’s Earth. Despite over 50 years of research on the subject, the causative mechanisms of the pattern remain unknown, and to date, around 30 different hypotheses have been proposed. Susannah examined biodiversity distribution with latitude in dinosaur faunas in the Upper Jurassic Morrison Formation, Western Interior, USA, home to some of the most iconic and well-known dinosaurs, such as Stegosaurus and Diplodocus. The results suggest that the modern latitudinal biodiversity gradient may be the artefact of the unique set of climatic conditions present during the late Cenozoic when Earth entered an ‘icehouse’ state.

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