Was an asteroid really to blame for dinosaurs’ extinction?

Dinosaurs were doomed long before the asteroid previously believed to have taken them out hit the earth, two experts from the University of Albany are claiming.

A new report details the factors that were derailing dinosaurs’ survival prior to the arrival of the asteroid that supposedly pushed them to extinction 65 million years ago.

The pair assert that toxic plants and dinosaurs’ failing defense mechanisms played major roles in the animals’ road to extinction. 

Dinosaurs were doomed long before the asteroid previously believed to have taken them out hit the earth, two experts from the University of Albany are claiming. Computer generated simulation pictured 

Their work was published in the journal Ideas in Ecology and Evolution.

Professor Gordon Gallup and one of his former students, Michael Frederick, point to dinosaurs’ lack of ‘learned taste aversion’ in their analysis.

The evolutionary defense mechanism has been developed by a number of species and allows animals to associate eating a certain food with poor consequences, such as getting sick.

Professor Gallup referenced rats, specifically, in his report to describe the usefulness of learned taste aversion.

He said: ‘A reason why most attempts to eliminate rats have not been successful is because they, like many other species, have evolved to cope with plant toxicity.

‘When rats encounter a new food, they typically sample only a small amount, and if they get sick, they show a remarkable ability to avoid that food again because they associate the taste and smell of it with the negative reaction.’

Angiosperms, the oldest flowering plants, appeared before the asteroid that wiped out dinosaurs, according to the fossil record.

The plants arrived right before dinosaurs began to disappear, which led the University of Albany team to believe angiosperms were responsible for the species’s downfall.

‘Gallup and Frederick claim that, as plants were evolving and developing toxic defenses, dinosaurs continued eating them despite gastrointestinal distress,’ the report explained.

However, the researchers acknowledged that the exact timing of the arrival of plants’ toxicity has not been nailed down.

Two University of Albany researchers believe that an asteroid was not the sole cause of dinosaur extinction. Rather, they believe dinosaurs were doomed because they did not possess a defense mechanism called 'learned taste aversion' (file photo)

Two University of Albany researchers believe that an asteroid was not the sole cause of dinosaur extinction. Rather, they believe dinosaurs were doomed because they did not possess a defense mechanism called ‘learned taste aversion’ (file photo)

WHEN WERE EARTH’S ‘BIG FIVE’ EXTINCTION EVENTS?

Traditionally, scientists have referred to the ‘Big Five’ mass extinctions, including perhaps the most famous mass extinction triggered by a meteorite impact that brought about the end of the dinosaurs 66 million years ago. 

But the other major mass extinctions were caused by phenomena originating entirely on Earth, and while they are less well known, we may learn something from exploring them that could shed light on our current environmental crises.

  1. The Late Ordovician This ancient crisis around 445m years ago saw two major waves of extinction, both caused by climate change associated with the advance and retreat of ice sheets in the southern hemisphere. This makes it the only major extinction to be linked to global cooling. 
  2. The Late Devonian: This period is now regarded as a number of ‘pulses’ of extinction spread over 20m years, beginning 380m years ago. This extinction has been linked to major climate change, possibly caused by an eruption of the volcanic Viluy Traps area in modern-day Siberia. A major eruption might have caused rapid fluctations in sea levels and reduced oxygen levels in the oceans.
  3. The Middle Permian:  Scientists have recently discovered another event 262m years ago that rivals the ‘Big Five’ in size. This event coincided with the Emeishan eruption in what’s now China, and is known to have caused simultaneous extinctions in the tropics and higher latitudes.
  4. The Late Permian: The Late Permian mass extinction around 252m years ago dwarfs all the other events, with about 96% of species becoming extinct. The extinction was triggered by a vast eruption of the Siberian Traps, a gigantic and prolonged volcanic event that covered much of modern day Siberia, which led to a cascade of environmental effects.
  5. The Late Triassic: The Late Triassic event, 201m years ago, shares a number of similarities with the Late Permian event. It was caused by another large-scale eruption, this time of the Central Atlantic Magmatic Province, which heralded the splitting of the supercontinent Pangaea and the initial opening of what would later become the Atlantic Ocean.

But there is no doubt about the fact that plants’ toxicity and dinosaurs’ gradual disappearance began around the same time.

‘Though the asteroid certainly played a factor, the psychological deficit which rendered dinosaurs incapable of learning to refrain from eating certain plants had already placed severe strain on the species,’ Professor Gallup said.

‘The prevailing view of dinosaur extinction based on the asteroid impact implies that the disappearance of dinosaurs should have been sudden and the effects should have been widespread, but the evidence clearly shows just the opposite: dinosaurs began to disappear long before the asteroid impact and continued to gradually disappear for millions of years afterward.’



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