Scotland in the time of Giants

There are 66 million years between the extinction of the dinosaurs at the end of the Mesozoic Era and now. Marine reptiles, ammonites and pterosaurs also became extinct at this time.

Other groups of animals, including birds and mammals, suffered from extinctions too. Most of the surviving animals were likely small and could adapt faster, or were more flexible with where they lived or what they ate.  These surviving animals evolved over time — and some became giants.

How were giants able to evolve?

The last 66 million years are known as the Cenozoic Era. During this time, the Atlantic Ocean grew, separating Europe and Africa from North and South America. India moved north and collided with Asia, forming the Himalayas. The climate also changed, with periods of global warming and cooling. Plants and animals had to evolve to adapt to these changes. Certain environments were suitable for some animals to evolve into giants.  

Mammals evolved alongside the dinosaurs. Most mammals in the Mesozoic were small and, even now, the most diverse mammal groups are rodents and bats. It was not until the Cenozoic era that some mammals began to evolve into giants.

Recognisable giants

The world that the giants looked upon would be strange to us now. There would be unfamiliar-looking animals and plants, but also some that we would easily recognise today.

For example, the earliest known bats are over fifty million years old. Giant snakes like Titanoboa (dating to 60-58 million years ago) from Colombia were the length of a bus. Early whales including Basilosaurus (dating to 35 million years ago) could be 20 metres long. Later whales included Livyatan (dating 10-8 million years ago). This was a sperm whale with large bone-crushing teeth. It shared the ocean with Otodus megalodon, the megalodon shark. 

Paraceratherium, a hornless rhino, and Palaeoloxodon, an elephant related to the modern African elephant, are the largest terrestrial mammals ever known. 

A warmer Scotland

Unfortunately, most of the rock in Scotland from the last 66 million years has eroded away. We don’t know if Scotland was inhabited by some of the earlier Cenozoic giants like Paraceritherium, or if the megalodon shark swam here a few millions of years ago.

But there are some clues as to what Scotland was like over the last 66 million years. 

We know that the Highlands of Scotland were much warmer 61-58 million years ago than now. We know this because the impressions of fossil leaves were preserved between lava flows in Ardtun, Mull. The hard volcanic rock protected the underlying fossiliferous softer rocks from erosion. At this time, there were active volcanoes on the west coast of Scotland as the North Atlantic was spitting apart. The fossil leaves of plants, including monkey puzzle, ginkgo and magnolia are not found naturally in Scotland now. These are usually found in warmer temperate or tropical areas.

The time around 55 million years ago is known as the Palaeogene Thermal Maximum (PETM). This was a time when global carbon dioxide levels in the atmosphere rapidly increased, causing the global temperature to rise by 5-8°C. This caused the extinction of several marine plankton species. However, this warming period seems to have allowed certain mammal groups to speciate and become more widespread. 

After this, there is no land-based rock record of what Scotland was like until the Ice Age. 

From the Ice Age, onwards

During the Pleistocene Ice Age (about 2.7 million - 10,000 years ago), large amounts of softer rock covering Scotland eroded away by ice. The Ice Age had cold glacial periods with thick ice sheets and a warmer interglacial period. Parts of Scotland that were not covered by the ice sheet would have looked more like the modern-day Canadian Arctic or Siberia. Many of the animals living then are now only found in the Arctic or are now extinct.  

In the National Museum of Scotland, you can see the skull of a polar bear from Assynt dating to 22,000 years ago. Fossils from woolly mammoths, woolly rhino and the giant deer Megaloceros are also on display. 

Moose, reindeer, wild horses, brown bear, wolf, lynx, and aurochs (a type of wild giant cattle), also lived in Scotland. The wolf only became extinct in Scotland in the 1600s due to human hunting. 

Studying Scotland's environments

The landscape of Scotland was important for Victorian scientists in the discovery of former glacial periods, and the concept that the climate was radically different in the distant past. Glacial sediment (called 'till') and peat contained fossils of species that are today found in the colder Arctic.

The physical landscape of lochs and glens was compared to the landscapes of the Alps and Scandinavia where existing glaciers could be seen and studied. 

Studying the environments of the past is still very important today to understand what the consequences of climate change might be like in the future.