We know for certain that the mass extinction that sealed the fate of non-avian dinosaurs dates back 66 million years.
This episode, called the Cretaceous-Paleogene extinction, affected the animal kingdom as a whole as well as all terrestrial flora.
About 50% of the world's species have disappeared, leaving room for the development of new plants and creatures that still exist.
Without this event, birds, mammals and flowering plants would probably not have been able to develop in this way, and our planet would be totally different.
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The fall of an asteroid
The majority of the scientific community agrees that this mass extinction is due to the fall of an asteroid 11 to 81 km in diameter whose impact crater can still be seen at Chicxulub, on the Yucatán Peninsula. in Mexico.
This collision was probably followed by a huge tidal wave, but it was not he who killed the dinosaurs.
Their disappearance seems to have been slower and more gradual, although it is considered extremely rapid on a geological scale.
The Chicxulub meteorite was probably accompanied or preceded by a period of intense volcanic activity;
these events combined most likely darkened the atmosphere, blocking out sunlight.
Species dependent on photosynthesis, such as phytoplankton and land plants, were of course the first to suffer,
even to extinction, and the problem quickly spread to the rest of the world since these species are at the base of the food chain.
It is assumed that herbivorous animals were the first to become extinct when the plants on which they fed became rare.
Predators like the T. rex were among the last dinosaurs to go extinct, starving to death in the absence of their usual prey.
Omnivorous, insectivorous and scavenger animals were more likely to survive.
rex were among the last dinosaurs to become extinct, starving to death in the absence of their usual prey.
Omnivorous, insectivorous and scavenger animals were more likely to survive.
rex were among the last dinosaurs to become extinct, starving to death in the absence of their usual prey.
Omnivorous, insectivorous and scavenger animals were more likely to survive.
A decline over millions of years?
The fossil record being very incomplete, it is difficult to know exactly how long this “domino effect” may have taken before all the non-avian dinosaurs were extinct.
We know, however, that their disappearance may have taken several tens of thousands of years.
According to a study published in the journal
Science
, the Chicxulub meteorite crashed on Earth 66,038,000 years ago, a maximum of 32,000 years before the extinction of the dinosaurs.
The disappearance process could therefore have lasted as long, although other scientists imagine it to be shorter, or longer.
Finally, more and more evidence seems to confirm that non-avian dinosaurs were already in decline several million years before their final extinction.
Their difficulties in replacing extinct species with new ones would have made them vulnerable to a planet-wide disaster, and unable to adapt quickly to survive it.
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