The graptolites constitute one of the geologically most useful taxonomic groups of fossils for dating rock successions, understanding paleobiogeography and reconstructing plate tectonic configurations in the Lower Palaeozoic. Graptolites were largely planktic, marine organisms, and as one of the first groups that explored the expanses of the world's oceans are vital for understanding Palaeozoic ecology. They are the best and often the only fossil group for dating Lower Palaeozoic rock successions precisely. Thousands of taxa have been described from all over the planet and are used for a...