What if the dinosaurs never went extinct?

James - How might man have fared in a world where t rex’s roamed? In a bid to answer your question, I’ve enlisted the help of Charlotte Kenchington from the Department of Earth Sciences at the University of Cambridge…

Charlotte - That is an excellent question! There are so many factors that play into whether or not a species, or a group of species, will become or remain dominant. Evolution is a complex dance between biological processes like competition, and non-biological ones like climatic change - let alone extraordinary events like major volcanic eruptions or meteorite impacts. When we think of groups like the dinosaurs, we also need to think of them in all their diverse glory - there were little unimpressive beasts, as well as the iconic giants of popular culture. And in fact, there are many dinosaurs alive today - in your garden, on your bird feeders, in your local pond. But of course, usually when we talk about dinosaurs we mean those big scaly beasts, rather than our feathered friends.

James - So, why might the larger species have declined? Here’s Charlotte again…

Charlotte - Non-avian dinosaurs were already on the decline before the mass extinction event that wiped them out. The exact reasons are still a question of ongoing debate, but the Earth’s cooling would have made it more difficult for larger creatures, with their enormous dietary needs, to thrive. In contrast, the smaller, more agile mammals which were appearing on the scene were much better able to withstand this global cooling, which continued over the next few tens of millions of years. There was also a dramatic temperature rise around 20 million years ago - that saw the evolution of huge land mammals like the giant sloth, and enormous Terror birds - true heirs to the T-Rex crown. The earliest hominins - which are ape-like fossils - are from around a similar time - roughly 7 million years ago. Once apes - with their complex brains, capacity for tool use, wide-ranging diet and remarkable stamina appeared - the rise of a dominant hominin species feels almost inevitable.

James - So, the great big what if…would our ancestors have become the dominant species had dinosaurs not become extinct?

Charlotte - Certainly, the dinosaurs could not have withstood the global climate changes that came their way towards the end of their reign. But, without the ecological turbulence at the end of this period, some of them might have survived - and indeed they did. But ultimately , the non-avian dinosaurs were already on their way out - the meteorite and volcanic activity just finished them off. That said, without all the other climatic shifts and evolutionary trajectories that followed, there is no saying that apes - and therefore humans - would have evolved and risen to our present day dominance.

James - It’s hard to look back on the story of life and draw many conclusions about how it could have panned out differently because of the simple fact - it didn’t!