Complex sentence: Along the northern coast there is a rich source of fossilised molluscs, crocodiles, turtles and mammal bones, with the youngest dating back to around 30 million years ago.
Split into simpler sentences: Along the northern coast of the island there is a rich source of fossilised molluscs, crocodiles, turtles and mammal bones. The youngest of these date back to around 30 million years ago.