It is known that the reign of the dinosaurs came to an end 66 million years ago when a giant asteroid slammed into the earth.
But what’s less scientific consensus on is whether the creatures were already in decline before the Chicxulub space rock wiped out more than 75 percent of the planet’s species.
A recent study suggested that climate change may have been to blame for their struggles — but a new piece of research disputes this, providing the strongest evidence yet that dinosaurs were, in fact, thriving shortly before they were killed off.
An international team of experts from the UK and Spain analyzed 1,600 fossil records from North America to come to their conclusion.
Findings: The dinosaurs were in their prime, not in decline, when an asteroid slammed into Earth 66 million years ago, a new study claims. Triceratops is depicted disturbing the primitive cousins of marsupials in the undergrowth
OR WAS CLIMATE CHANGE MORE TOUCH?
Researchers at the Chinese Academy of Sciences studied more than 1,000 fossilized dinosaur eggs and eggshells and claim the animals were already decaying when the asteroid hit — possibly due to climate change.
“Our results support a long-term decline in global dinosaur biodiversity before 66 million years ago, which likely set the stage for the mass extinction of the non-Asian dinosaurs at the end of the Cretaceous,” the team wrote in their study, published in PNAS in September.
Most data on the last days of the dinosaurs comes from North America, but for this study, the researchers turned to records in China.
They wanted to determine why non-avian dinosaurs, including Tyrannosaurus rex and Triceratops, went extinct — while mammals and other species such as turtles and crocodiles survived.
To do this, the experts modeled the food chains and ecological habitats of terrestrial and freshwater animals during the last few million years of the Cretaceous, as well as the first few million years of the Paleogene period after the asteroid impact.
They found that pre-impact mammals were diversifying their diets, adapting to their environment and becoming a more important part of ecosystems as the Cretaceous Period unfolded.
Dinosaurs, on the other hand, already ruled the world and were in their prime, so they had no reason to adapt in the same way. They had already managed to get where they were.
This discovery suggests that mammals not only benefited from the death of the dinosaurs, but created all their own benefits by diversifying prior to the asteroid impact.
Such an evolution meant that they had more varied diets and were better equipped for small shifts in climate, and thus better prepared than the dinosaurs to cope with the abrupt destruction caused to the Earth.
Study author Professor Steve Brusatte, from the University of Edinburgh, said the researchers found dinosaurs were going strong, with stable ecosystems, until the asteroid suddenly killed them.
“Meanwhile, mammals diversified their diet, ecology and behavior while dinosaurs were alive,” he said.
“So it wasn’t just that mammals benefited from the death of dinosaurs, but they made their own benefits, pre-adapting them ecologically to survive the extinction and move into niches left by the dead dinosaurs.”
Although previous studies have shown that there were a large number of dinosaurs on Earth just before the asteroid impact, it was unclear until now whether they were at their peak or already in decline.
Another previous study, published in 2016, claimed that dinosaurs had been on the decline for as long as 50 million years before Chicxulub.
The University of Reading researchers suggested that the creatures were declining in the long run because they couldn’t cope with the way the Earth was changing.
Their analysis showed that long-necked giant sauropod dinosaurs declined the fastest, while theropods, including T.Rexwere in a more gradual decline.
But the new study disputes this, insisting that the dinosaurs thrived until the asteroid “changed the ecological rules of the time.”
Lead author, Alfio Alessandro Chiarenza, from the University of Vigo, said: ‘It seems that the stable ecology of the last dinosaurs precluded their survival in the aftermath of the asteroid impact, which abruptly changed the ecological rules of the time. was standing.
Researchers wanted to determine why non-avian dinosaurs, including Tyrannosaurus rex and Triceratops, went extinct — while mammals and other species like turtles and crocodiles survived
Researchers at the Chinese Academy of Sciences studied more than 1,000 fossilized dinosaur eggs and eggshells and claimed in a paper published in September that the animals were already decaying when the asteroid hit. This contradicts the latest research
“Conversely, some birds, mammals, crocodilians and turtles were previously better adapted to unstable and rapid shifts in their environment, perhaps better able to survive if things suddenly went bad when the asteroid hit.”
Dinosaurs first appeared 230 million years ago when the warm conditions from the pole to the equator provided the perfect environment for them to evolve and dominate mammals for over 100 million years.
Some scientists think that as the climate cooled and sea levels changed, this was the beginning of the mammals taking over, but the authors of the latest study say the asteroid impact still played the most crucial role because dinosaurs were highly evolved at the time. became.
Co-lead author Jorge García-Girón, from the University of León in Spain, added: ‘Our study provides a compelling picture of the ecological structure, food webs and niches of the last dinosaur-dominated Cretaceous ecosystems and the first mammal-dominated ecosystems after the impact of the asteroid.
“This helps us understand one of the age-old mysteries of paleontology: why all non-avian dinosaurs died, but birds and mammals survived.”
The research will be published in the journal Scientific progress.
HOW THE DINOSAURS EDITED ABOUT 66 MILLION YEARS AGO
Dinosaurs ruled and dominated the Earth about 66 million years ago, before they suddenly became extinct.
The Cretaceous-Tertiary Extinction is the name given to this mass extinction.
For years it was believed that the changing climate was destroying the food chain of the huge reptiles.
In the 1980s, paleontologists discovered a low iridium.
This is an element that is rare on Earth, but found in large quantities in space.
When this was dated, it coincided exactly with when the dinosaurs disappeared from the fossil record.
A decade later, scientists discovered the massive Chicxulub crater at the tip of Mexico’s Yucatán Peninsula, which dates to the period in question.
Scientific consensus now says that these two factors are linked and that they were both likely caused by a massive asteroid crashing into Earth.
At the projected size and impact speed, the impact would have generated a massive shock wave and likely generated seismic activity.
The fallout would have created plumes of ash that likely covered the entire planet and made it impossible for dinosaurs to survive.
Other animal and plant species had a shorter time span between generations that allowed them to survive.
There are several other theories about what caused the famed animals’ demise.
One early theory was that small mammals ate dinosaur eggs and another states that poisonous angiosperms (flowering plants) killed them.