How many kinds of dinosaur were there?
According to dinosaur diversity expert Steven Wang at Swarthmore College in Pennsylvania, US, there are approximately 550 widely accepted genera of dinosaurs (representing about 650 to 700 species), and new ones continue to be discovered. This figure is likely to be just a fraction of their true diversity, as many species may be absent from the fossil record. Using statistics Wang and palaeobiologist co-worker Peter Dodson, estimate that as many as 1,900 dinosaur species may have existed in total, meaning just a fraction have so far been discovered in the fossil record. Some names have turned out to be mistakes. For example, Brontosaurus and Apatosaurus, initially thought to be different genera, were later merged. Under the formal naming rules, Apatosaurus – the first legitimate name given – became the official name. Scientists group dinosaurs according to their view of the evolutionary family tree. Three major groups evolved from Ornithischia: the armoured dinosaurs such as ankylosaur
