The asteroid responsible for ending the rule of dinosaurs on Earth 66 million years ago had a larger biological impact than just killing the dinosaurs. The impact caused massive fires that decimated forests. This would've killed tree-dwelling birds and left just ground-dwelling birds.
During this period, this had a large impact on the evolution of birds and the ancestors of the current species of birds.
Consequences Of The Asteroid
Researchers from the University of Bath published a study on the consequences of the asteroid strike in the journal Current Biology. In the study, researchers use the plant fossil record and the ecology of ancient and modern birds to determine that only ground-dwelling birds were able to survive the mass extinction created by the asteroid impact. They were able to determine the cause of why tree-dwelling birds were unable to survive the extinction.
Following the asteroid impact, the intense heat would have caused global wildfires that would've wiped out forests. Acid rain would have been triggered by the vapor, which would be rich in sulfates. Trees weren't able to practice photosynthesis due to the soot that blocked the atmosphere.
The plant fossil record showed that global forests collapsed after the impact of the asteroid. They then tracked the evolutionary relationship of birds and how bird ecology changed over their existence. This analysis showed that the common ancestor of current birds most likely lived on the ground during this period.
Diversification Of Birds
During the period that scientists analyzed, tree pollen went missing for a thousand years following the asteroid impact. After the impact, only a few species of birds were able to survive the mass extinction event. The only problem with the theory is that there is a limited amount of birds in the fossil record.
At the time before the mass extinction event, there were many species of tree-dwelling birds, but those species didn't survive. Birds are the most diverse and globally spread group of animals. Even though a handful of birds survived the mass extinction, there are now almost 11,000 living species of birds. They were able to survive with the few remaining species at the time.
Researchers hope to use the information that was gathered for this study to determine how major events are able to have an impact on the evolution of species over time. They plan to figure out when the forests began to come back following the mass extinction and how birds were able to diverge and evolve from the handful of surviving species that were left after the asteroid impact.