The School of Geography, Earth and Environmental Sciences organises a regular series of research seminars throughout the academic year to which everyone is welcome to attend. Speakers - both external and internal to the University - will talk on topics related to all aspects of Earth Sciences.
Today's speaker is Dr Susannah Maidment from the University of Brighton.
The latitudinal biodiversity gradient (LBG), the difference in number of species from the equator to the poles, is the most pervasive pattern of biodiversity distribution on today’s Earth, but its causes remain unknown.
One way of testing various hypotheses about the causes of the LBG is to examine it at a time in Earth’s history when conditions were different. During the Mesozoic, the Earth was in a ‘greenhouse’ state: there were no ice caps at the poles, and thus latitudinal temperature gradients were significantly reduced. Susannah examined biodiversity distribution with latitude in dinosaur faunas in the Upper Jurassic Morrison Formation, USA. The Morrison Formation crops out over 1.2 million square kilometres, 12 degrees of latitude, and is home to some of the most iconic and well-known dinosaurs, such as Stegosaurus and Diplodocus. Susannah divided the Morrison Formation into chronostratigraphic packages of around one million years, and examined how diversity varied with latitude and through time in the formation. There is no evidence for an LBG at this time in this geographic location, but there is some evidence for niche partitioning among species. The results suggest that the modern LBG may be the artefact of the unique set of Cenozoic climatic conditions.