Cretaceous sauropods from the Sahara and the uneven rate of skeletal evolution among dinosaurs

Lower Cretaceous fossils from central Niger document the succession of saur opod dinosaurs on Africa as it drifted into geographic isolation. A new bro ad-toothed genus of Neocomian age (similar to 135 million years ago) shows few of the specializations of other Cretaceous sauropods. A new smalt-bodie d sauropod of Aptian-Albian age (similar to 110 million years ago), in cont rast, reveals the highly modified cranial form of rebbachisaurid diplodocoi ds. Rates of skeletal change in sauropods and other major groups of dinosau rs are estimated quantitatively and shown to be highly variable.