3. dinosaur mummies

The conditions required to preserve a fossil in the extraordinary detail exhibited by the feathered dinosaurs of Liaoning are very specific and the chances of them occurring when an animal dies are vanishingly small. But over the course of the 180 million years that dinosaurs roamed the planet, those rare conditions will have and did occur.

In 1908, a fossil hunter by the name of Charles Hazelius Sternberg discovered one of the first mummified dinosaurs, an Edmontosaurus (A hadrosaurid, "duck-billed" dinosaur). The skeleton, still in its anatomical position was encased in skin impressions (an estimated two thirds of the skin still present). To preserve a dinosaur in such detail, mineralisation has to be extremely rapid to prevent the decaying process.

One of the best preserved fossils of its size ever found was that of an Ankylosaur named Borealopelta, discovered by operators at an oil sands mine in Alberta in 2011. It was found in the Clearwater Formation (marine sandstones laid down 110-112 million years ago). At the time this area was occupied by the Western Interior Seaway, therefore the Ankylosaur must have washed out to sea, possibly during a flood. Once its carcass burst it rapidly sank, coming to rest with enough force to disturb the underlying sea floor and bury itself in around 6 inches of sediment. The body cavity also became infilled with sand, creating exceptional conditions which led to the preservation of its armour, their keratin sheaths, overlying skin and its stomach contents.