Could Dinosaurs Live in Today’s Environment?

Popular culture might try have us believe that dinosaurs could live in today’s environment, but the reality is far more complicated.

“Life, uh, finds a way” is perhaps the most memorable quote from the 1993 hit Jurassic Park, uttered by Dr. Ian Malcolm when trying to explain how a park full of genetically engineered female dinosaurs managed to start breeding. In the context of the film which is, of course, far more fantasy than science, it presented an easy cop-out. Nonetheless, in the context of the science of evolution, the doctor wasn’t entirely wrong. Life has, after all, managed to survive through some of the most extraordinarily apocalyptic events of the likes no human eyes have ever witnessed.

The last of the dinosaurs, if we don’t include modern birds that is, died 66 million years ago following one of the most catastrophic events in the history of our planet. The Cretaceous-Palaeogene extinction event forever reshaped the Earth, profoundly transforming its biosphere and climate. With a few exceptions, it left behind no animal larger than a goat, ending the 165-million-year legacy of the dinosaurs in one fell swoop. 66 million years later, our world remains a very different place, one where humans and other mammals thrive and dinosaurs are a thing of the distant past.

Could Dinosaurs Be Brought Back in the First Place?

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Unfortunately, a plastic triceratops toy is likely the closest we’ll ever get to bringing the dinosaurs back.

Despite there being some 66 million years between the last of the non-avian dinosaurs and modern humans, the thought of people mingling with the giant sauropods and ferocious theropods of old has long been a popular theme in fiction. While Jurassic Park introduced the concept of de-extinction to the masses 24 years ago, the process it depicted is, almost certainly, impossible.

Cloning dinosaurs requires two main ingredients – usable DNA and a host organism. No dinosaur DNA has ever been found and, with a half-life of only 521 years, any dinosaur DNA would be too badly fragmented after 66 million years to be of any use. And, good luck trying to use a modern dinosaur, such as a chicken, for carrying a tyrannosaurus embryo.

If you’re wondering why we might be able to clone mammoths in the near future, but not dinosaurs, then there’s a simple explanation. The last mammoth died a mere 4,000 years ago, and modern elephants share almost all their DNA with their Pleistocene relatives. As such, extracting mammoth DNA is much simpler, a modern elephant could act as a host, and after a few decades of selective breeding, we could, theoretically, have an almost pure-bred woolly mammoth.

Even if there is a way to bring back the dinosaurs, the ethical implications would also be enormous, and then there’s the fact that many, if not all of them, would be unable to adapt to today’s environment and thrive as they once did long ago. As Malcolm also quoted, “Dinosaurs had their shot. Nature selected them for extinction”.

The Day the Dinosaurs Died

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The impact of a 6-mile-wide asteroid hurtling into the Earth sealed the fate of the dinosaurs.

If birds, being modern dinosaurs, can live in today’s environment, then why couldn’t the dinosaurs of old? Birds, after all, have been around for some 125 million years, having split off from their dinosauric lineage during the Early Cretaceous. For at least 59 million years, they lived alongside their dinosaur cousins, surviving the apocalyptic event that wiped them out. The reason they survived, while the non-avian dinosaurs vanished, remains the subject of much debate, although studies have suggested that a few species managed to survive the mass extinction due to their larger brains and greater capacity to adapt to the changing conditions.

Some animals are more resilient than others. While a water bear might be able to survive the vacuum of space for days, the Iberian lynx almost went extinct by the 21st century because of the decline in rabbits upon which it preyed.

To understand why dinosaurs probably wouldn’t fair too well in today’s environment, we must consider why they went extinct in the first place. Although the impact event would have wiped out countless wildlife populations in a matter of days, it was the catastrophic environmental change that followed that heralded the end of the dinosaur lineage. In fact, it may have taken as much as 32,000 years for the Cretaceous mass extinction to fully run its course. Larger species, being less capable of adapting to the decimated biosphere and following impact winter, may have died out within a few years or even months, however.

The profound loss of habitats and ecosystems that the dinosaurs had been accustomed to had sealed their fate, and it would be millions of years before biodiversity rebounded, albeit this time in the form of mammals and other previously minor lineages.

A Very Different Climate

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Iconic predators like the T rex lived in a warmer world where plant and animal life, both on the land and in the sea, were based on entirely different ecosystems than those of today.

The impact event that killed the dinosaurs largely left evolution with a clean slate upon which to start again. The world eventually recovered, but global climates had changed dramatically and continued to evolve in a very different direction. If you were to go back in time to the Cretaceous Period, which were arguably the golden days of the dinosaur, you’d find yourself in a very different world. So different, in fact, that you might have trouble surviving the environment (ferocious theropods like tyrannosaurus rex not withstanding).

Many of the most iconic dinosaurs of all time lived during the Cretaceous Period – tyrannosaurus rex, triceratops and ankylosaurus were all victims of the apocalypse. They lived in a world which was constantly warming, a world where average global temperatures were 4°C higher than they are today. CO2 levels were over four times higher than they are now, and this figure even takes mankind’s recent industrial impact on the environment into account.

The global climate was also far more consistent during the Cretaceous than it is today. Temperatures didn’t vary nearly as much between lower and higher latitudes, and there was little or no ice even at the polls during most of the Mesozoic Era. Global trade winds were also milder, meaning oceans were more stagnant and surfaces were much hotter. In fact, ocean temperatures may have reached 42°C in low latitudes, which is some 14°C higher than they are today. Unsurprisingly, such great differences had an enormous impact on the course of evolution.

Oxygen levels have also fluctuated enormously throughout Earth’s history. In the Phanerozoic Aeon, which spans from 541 million years ago to the present, levels have fluctuated between a minimum of 5% and a maximum of 35%. For a long time, general scientific consensus suggested that oxygen levels rose steadily throughout the reign of the dinosaurs, perhaps peaking at around 30% during the Cretaceous. However, this theory has recently been challenged, with suggestions that the dinosaurs may have evolved and lived in a low-oxygen world. Nonetheless, oxygen levels were likely still rising steadily throughout the Mesozoic Era following the Permian-Triassic mass extinction.

Other theories claim that higher oxygen levels might explain how many dinosaur species, such as the mighty sauropods, managed to grow so large. Regardless of the prevailing truth, however, many dinosaur species might have problems just breathing in the modern atmosphere, given its undoubtedly different composition.

Lack of Suitable Habitats

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With their grassy expanses, today’s plains habitats are very different to those the herbivorous dinosaur herds were used to.

The ever-changing climate and atmosphere of our planet is, of course, the driving force behind the environment and, consequently, evolution. Although the dinosaurs were an extremely diverse bunch spanning 165 million years of changing environments, many species lived in habitats that simply don’t exist today.

On the other side, many animals that live today would quickly die out if they were suddenly transported back in time to the Triassic, Jurassic or Cretaceous. Many of today’s herbivorous megafauna, such as deer, horses and bovines, wouldn’t fair too well for a start – most of today’s grazing animals rely on grass, which didn’t exist in any form until the later years of the dinosaurs. Similarly, flowering plants and, consequently, fruits, did not exist until the Early Cretaceous about 120 million years ago. As such, Late Triassic and Jurassic herbivores were used to feeding on quite a different range of foliage than today’s animals.

Dinosaurs lived in a variety of habitats, most of which have analogues in the modern world, such as humid wetlands, swamp forests and deserts. Plains habitats, however, were very different than those of today, covered by ferns and other primitive shrubs rather than grasses. These windswept expanses dominated much of North America, giving rise to some of the world’s best-known dinosaurs, such as the triceratops and his arch enemy the tyrannosaurus.

Some dinosaurs, particularly the sauropods, such as the truly herculean 70-tonne argentinosaurus, also needed enormous tracts of land and vegetation for feeding. Many sauropods also needed vast, wide-open floodplains for nesting. Given mankind’s encroachment into almost every region of the world, we’re already having no small amount of problems looking after our current, relatively tiny, megafauna.

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De-extinction isn’t all fantasy, and technology is already close to reviving some recently extinct animals, such as the woolly mammoth or the thylacine. It’s undoubtedly a controversial topic, and I believe we should instead be focused on conserving currently endangered species. Nonetheless, it’s an interesting thought experiment if nothing else. Which prehistoric beasts would you like to see make a comeback? Let me know in the comments below!

Further Reading