Dinosaurs were already in decline when asteroid hit 66 million years ago, study finds

They are often described as going out with a “bang” after a massive asteroid hit Earth 66 million years ago.

But a new study suggests that dinosaurs came out with more “groans”.

Researchers from the Chinese Academy of Sciences have studied more than 1,000 fossilized dinosaur eggs and eggshells and say the animals were already in decline 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 paved the way for the mass extinction of late Cretaceous non-avian dinosaurs,” wrote the team in their study, published in PNAS.

They are often described as going out with a “bang” after a massive asteroid hit Earth 66 million years ago. But a new study suggests dinosaurs came out with more moans than bangs

Researchers from the Chinese Academy of Sciences have studied more than 1,000 fossilized dinosaur eggs and eggshells and say the animals were already in decline when the asteroid hit

Researchers from the Chinese Academy of Sciences have studied more than 1,000 fossilized dinosaur eggs and eggshells and say the animals were already in decline when the asteroid hit

Dinosaurs ruled and dominated the Earth until about 66 million years ago.

A six-mile-wide asteroid called Chicxulub slammed into what is now Mexico, triggering a mass extinction that killed more than 75% of Earth’s species.

While previous studies have shown that a wide range of dinosaurs were on Earth just before the asteroid hit, until now it was unclear whether they were at their peak or already in decline.

Most of the data on the last days of the dinosaurs comes from North America, but for this study the researchers turned to records in China.

The team studied more than 1,000 fossilized dinosaur eggs and eggshells from the Shanyang Basin in central China.  These fossils came from rock sequences, which the researchers were able to age using computer modeling

The team studied more than 1,000 fossilized dinosaur eggs and eggshells from the Shanyang Basin in central China. These fossils came from rock sequences, which the researchers were able to age using computer modeling

Their findings indicate that there was a decline in dinosaur diversity over the two million year period, with the 1,000 egg fossils belonging to just three species - Macroolithus yaotunensis, Elongatoolithus elongatus and Stromatoolithus pinglingensis.

Their findings indicate that there was a decline in dinosaur diversity over the two million year period, with the 1,000 egg fossils belonging to just three species – Macroolithus yaotunensis, Elongatoolithus elongatus and Stromatoolithus pinglingensis.

The team studied more than 1,000 fossilized dinosaur eggs and eggshells from the Shanyang Basin in central China.

These fossils came from rock sequences, which the researchers were able to age using computer modelling.

This allowed them to create a timeline of almost two million years at the end of the Cretaceous – the period just before the extinction – which could then be compared to data from around the world.

Their findings indicate that there was a decline in dinosaur diversity over the two million year period, with the 1,000 egg fossils belonging to just three species – Macroolithus yaotunensis, Elongatoolithus elongatus and Stromatoolithus pinglingensis.

While the reason for this decline leading to the asteroid remains unclear, researchers have several theories

While the reason for this decline leading to the asteroid remains unclear, researchers have several theories

The team studied more than 1,000 fossilized dinosaur eggs and eggshells from the Shanyang Basin in central China.

The team studied more than 1,000 fossilized dinosaur eggs and eggshells from the Shanyang Basin in central China.

A few other dinosaur bones have been found in the area, showing that tyrannosaurs and sauropods also lived in the area around 66.4 and 68.2 million years ago.

“The small number of dinosaurs in the Shanyang Basin and central China is a far cry from the world depicted in Jurassic Park,” the team said in a statement.

While the reason for this decline leading to the asteroid remains unclear, researchers have several theories.

“This long-term global decline in dinosaur diversity until the end of the Cretaceous and the sustained low number of dinosaur lineages over the past few million years may have resulted from known global climatic fluctuations and massive volcanic eruptions. , i.e. Deccan traps in India,” they suggest.

“These factors may have led to ecosystem-wide instability, thus making non-avian dinosaurs vulnerable to mass extinction coinciding with the asteroid impact.”

HOW THE DINOSAURS WERE EXTINCT ABOUT 66 MILLION YEARS AGO

Dinosaurs ruled and dominated the Earth around 66 million years ago, before suddenly disappearing.

The Cretaceous-Tertiary extinction event is the name given to this mass extinction.

It was believed for many years that climate change was destroying the food chain of huge reptiles.

In the 1980s, paleontologists discovered a layer of iridium.

It is a rare element on Earth but found in large quantities in space.

When this was dated, it coincided precisely 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.

The scientific consensus now says that these two factors are linked and that they were both likely caused by a huge asteroid crashing into Earth.

With the projected impact size and velocity, the collision would have caused a huge shock wave and likely triggered seismic activity.

The fallout would have created ash plumes that likely covered the entire planet and made it impossible for the dinosaurs to survive.

Other animal and plant species had a shorter time interval between generations, which allowed them to survive.

There are several other theories about what caused the famous animals to disappear.

One early theory was that small mammals ate dinosaur eggs and another proposes that poisonous angiosperms (flowering plants) killed them.