Graptolites are found only in Palaeozoic rocks such as those in Scotland, Wales and north-western England. The oldest dendroids occur in middle Cambrian rocks, but they can be found in rocks as young as the Carboniferous. Planktonic graptolites are particularly common in Ordovician and Silurian shales and mudstones.

Are graptolites alive today?

Graptolites—fossil and alive. ... Now we understand graptolites as a nearly extinct group of the Hemichordata, the sister group of the more widely distributed Enteropneusta, found in all marine environments.

What fossils are Graptolite?

Graptolites were floating animals that have been most frequently preserved as carbonaceous impressions on black shales, but their fossils have been found in a relatively uncompressed state in limestones. They possessed a chitinous (fingernail-like) outer covering and lacked mineralized hard parts.