The Lost World: Where are Jersey’s dinosaurs?

The Lost World: Where are Jersey’s dinosaurs?

It goes without saying that we at the aspiring Jersey Island Geopark love dinosaurs and everything about with them and yet, frustratingly, their fossils are nowhere to be found on Jersey. When it comes Stegosaurus, Diplodocus and Tyrannosaurus, our island is more of a Brassic Park than a Jurassic one. Not that this matters from a Geopark point of view – our rocks, landscapes and seascapes are dramatic and internationally renowned – but periodically we are asked about Jersey’s dinosaurs and their conspicuous absence.

So, where are our dinosaurs? Our rocks are very old (more than 500 million years old) and so we know that there would have been an archaic version of Jersey around when dinosaurs roamed the earth. We also know that for much of the Mesozoic Era (when dinosaurs evolved and proliferated) Jersey would have been hot, dry and vegetated, an ideal environment for large reptilians. Although dinosaur fossils are not preserved, odds are that they did once roam across parts of Jersey that are now fields, gardens and valleys. To understand why, requires a light dip into Jersey’s geological history and the Island’s remarkable ability to wander across the globe.

Jersey’s geostory began over 600 million years ago and some 9,000 miles away from here, near to the South Pole. Our oldest rocks (found on Les Écréhous and Les Minquiers) formed deep within a mountain chain on the continent of Gondwana. Powerful tectonic forces squashed, bent and stretched Gondwana, creating deep ocean trenches, magma chambers, volcanic islands and upland deserts. From these came the sediments, granites and lavas which today outcrop around our island.

These rocks are beautiful, dramatic and scientifically important but the youngest of them (the pebbly conglomerate used to build St Catherine’s Breakwater) is around 500 million years old. That leaves a near half billion year gap, which includes the entire Mesozoic Era, where we have no rocks (and therefore no fossils) at all.

Rocks from Normandy and Brittany, to which Jersey is geologically linked, can help to close this knowledge gap. These suggest that by the middle of the dinosaur era, around 130 million years ago, Jersey had undertaken a tectonically propelled journey from the Antarctic Circle to what is now the North Atlantic region. The climate would have been hot with seasonal rains that fell onto an upland landscape that was situated near the edge of a fledgling European continent.

Upland areas are not great at preserving fossils and so to glimpse what sort of dinosaurs might have been walking around prehistoric St Helier, Grouville, etc., we need to look northwards to rocks found in the Isle of Wight. These contain a remarkable diversity of fossil life, some of which would have walked, swum or flown its way across the flood plain which then separated the Channel Islands from southern England.

Ubiquitous large plant eaters, such as Iguanodon, may once have populated Jersey, as could several species of heavy weight Diplodocus-like sauropods. These would have been too large to be hunted by fleet-footed 10 metre long predators, such as Neovenator, but there would have been plenty of smaller dinosaurs and even primitive mammals for them to eat. In the skies were pterosaurs soaring over rivers and lakes populated with fish and crocodilians.

We shall never know exactly which species roamed our primeval parishes (for that you do need fossils) but we can be pretty certain that Jersey would have had its own Lost World, all trace of which has been turned into dust and swept away. In the eons that followed, the global sea level repeatedly rose and fell but Jersey remained resolutely above the waves, slowly being eroded into the kidney-shaped island that we know today.

It is not until the Ice Age that sediment starts to be preserved, often in the form of jumbled silts, sands and boulders. Within this are the remains of giant beasts like the woolly mammoth and rhino along with tools from the Neanderthal people that hunted them. But theirs is a separate story to that of the dinosaurs. Jersey might not have dinosaur fossils but by carefully blending scientific evidence with imagination we can still turn places like Howard Davis Park into our very own Jurassic Park.

Produced for The Jersey Evening Post by Paul Chambers, Head of Geopark, to celebrate International Geodiversity Day 2025.