12 March 2017

St Patrick, Snakes and Dinosaurs

Of course there are no snakes in Ireland – because they were banished by St Patrick. There are (almost) no dinosaur remains known from Ireland either, so perhaps St Patrick banished them too? But Ulster Museum curator, Dr Mike Simms, offers a scientific explanation for the lack of snakes and dinosaurs.

“Ireland is right at the western edge of Europe. Following the glacial maximum ~26 thousand years ago, the animals and plants that had been driven south by the ice sheets migrated northwards again to recolonise the emerging ice-free landscape. But as the ice melted so global sea levels rose and Ireland became an island more than 10 thousand years ago. Any animals or plants that were a bit slow in spreading north (and snakes would have been quite late to set off, because they require a warm climate) would have missed the boat. Consequently Ireland has among the lowest diversity fauna and flora of any country in Europe. Britain also has a lower diversity than mainland Europe, for the same reason that it became an island around 8 thousand years ago.”

“The lack of dinosaurs goes back to Ireland’s geology and the long periods of erosion that have removed huge thicknesses of rock in the distant past. Dinosaurs lived on land from the late Triassic, through the Jurassic and to the end of the Cretaceous periods. Most of Ireland’s geology is pre-Triassic in age, so no dinosaurs there. What rocks we do have that are the right age (almost entirely confined to the north-east of Ireland) mostly were deposited out at sea, and even these have a huge gap in them (most of the Jurassic and at least half of the Cretaceous periods). So we may have some of the right age rocks but they were deposited in the wrong place, and then mostly eroded away long ago. We should be grateful for the two small dinosaur bone fragments we do have!”