When a giant asteroid sent a fireball plummeting into Earth approximately 66 million years ago, it wiped out 75% of the world’s animal species – including dinosaurs. In the recent BBC documentary The Day the Dinosaurs Died, scientists explain that, had the asteroid arrived a mere 30 seconds earlier or later, it would have hit a deep part of the ocean which minimised its force.
This fraction of time could have meant the difference between dinosaurs surviving or not, declares the BBC.
Tom Holtz, a carnivorous dinosaur researcher at the University of Maryland, USA, says that, while some dinosaurs would have been made extinct by other natural disasters such as volcanic eruptions, most would have thrived. “There’s nothing otherwise, once you’re into the Palaeocene and Eocene, that would have affected general dinosaur biology,” he states. “It would be a world that Cretaceous dinosaurs would still be comfortable in.”
The University of Edinburgh’s Stephen Brusatte agrees with Holtz, pointing out that dinosaurs had survived diverse climates for around 160 million years prior to the asteroid. “Dinosaurs were still very adaptable at the end of the Cretaceous,” he says. “That’s not the sign of a group that’s wasting away to extinction, just waiting for some asteroid to knock them off. It’s the sign of a group that still has a lot of evolutionary potential.”
Palaeontologist Mike Benton from the University of Bristol, UK, disagrees with the former researchers. “I take a slightly unorthodox view that dinosaurs were doomed anyway because of cooling climates,” he asserts. “We know that mammals were diversifying… [and] dinosaurs had already been declining for 40 million years.”
If Benton was wrong, however and dinosaurs did survive, the species would have undergone various transformations. Victoria Arbour of the Royal Ontario Museum in Canada says that some dinosaurs may have grown woolly coats to adapt to changing climates, while Paul Barrett of the Natural History Museum in London posits the species may become subterranean.
Other species would also have been affected by the presence of dinosaurs, most significantly birds and mammals. While smaller carnivores like rodents, possums and bats and tree-climbing primates could have survived, Brusatte states that most mammals would have died. “It was only the shock of the asteroid knocking off the incumbent dinosaurs that allowed them to break free,” he points out.
As for humans, researchers and scientists are unsure. “You’d probably still get primates and… [perhaps] a version of humanity,” says vertebrate palaeontologist Darren Naish. “Given that we evolved in a world full of giant mammals, it’s plausible.” Yet whether we would have made it this far or not is doubtful. “Just as our ancestors had to deal with sabretooth cats and big antelope, these guys would have to deal with the dromaeosaurs and abelisaurs,” Holtz states.
And if somehow humans and dinosaurs did manage to co-exist? It’s unlikely dinosaurs would have outlived the 20th century, Holtz affirms. The population growth of the human race, paired with ever-growing hunting technologies and deforestation would have eventually caused the striking species to dwindle, just as other species have as a result of human impact.