CANADA – Scientists have long known that birds descended from dinosaurs.  What has been less clear is how the birds’ ancestor survived the period after the asteroid impact that killed the dinosaurs and the majority of the small bird-like dinosaurs.

Asteroid crackdown that took place at the end of the Cretaceous period 66 million years ago led to major environmental changes. The researchers believe that the carnivorous raptors mania have been difficult to adapt to environmental changes. However, toothless bird beak-like dinosaurs, with the help of the beak, could peck in the seeds. These mini dinosaurs became some of the closest relatives of modern birds.

Per Ahlberg, a professor of evolutionary organism biology at Uppsala University agrees that the birds’ ancestor survived the period after the asteroid impact.

Diversification of modern birds had begun even before the end of the Cretaceous, so it was not just a small group of bird-like dinosaurs, but at least two-three who survived, according to Ahlberg.

Difficult conditions

The reason for the scant natural resources after the asteroid impact is that particles were hurled into the atmosphere and returning glowing against the earth.

They subjected the earth with infrared radiation that killed off most living organisms. The dark subject matter covered in the end the atmosphere and everything became dark.  Plant photosynthesis ceased impeding their leaves and fruit production.

Therefore, hard seeds have been a winning strategy for survival until there were to be new food sources according to the researchers.

Per Ahlberg think however that it is difficult to say whether all survivors birdlike dinosaurs were fruitless.

In other animal groups, we see very different patterns, for example, the majority of the mammals that survived the extinction of small insectivores.

Analyzed 3000 teeth

One question the researchers wanted to find out where the demise of the carnivorous Maniraptora occurred abruptly or in a slow decline.

The researchers used data from over 3000 fossilized teeth from four different Maniraptora families to study variations in the teeth. The teeth covered up a period of 18 million years until the end of the Cretaceous Period.

If the teeth would show a gradual decrease in the variation would indicate a slow decline in species diversity.

But the teeth showed a stable variation during the 18 million years to the end of the Cretaceous period, which suggests that mania raptors died abruptly after the asteroid impact at the end of the Cretaceous Period.

The study is published in the journal Current Biology.