How did ancestors of today’s birds survive the asteroid strike?
Where many creatures living in forests, unsurprisingly, did not survive the asteroid strike 66 million years ago, unsurprising because this impact destroyed the world’s forests, it is a strange fact that the ancestors of modern birds may have survived that destructive strike.
It has been seen in the plant fossil record that this asteroid impact, a most bleak moment in the history of the Earth, caused global deforestation and extinction of most flowering plants, destroying the habitats of tree-dwelling animals.
66 Million Years Ago
Studies into this interesting phenomenon are continuing today, and scientists’ knowledge is only increasing thanks to the analysis of fossilised plants and ornithological data. Through deeper delving into this area, experts are beginning to get a clearer picture of how it could have been the case that bird ancestors managed to survive.
It is not an easy task though, to make an understatement! In Dr Field’s words: "Teasing these stories from the rock record is a challenge when the action took place over 66 million years ago, over a relatively short period of time."
What we already know is that the early ancestors of modern birds were probably capable of flight, and relatively small in size. In piecing together their ecology better though, scientists are now seeking to understand how these ancestors of today’s birds (which were much like partridges) managed not to be wiped out where other animals were not so lucky.
Ancestor Bird Survivors
A very important point though is that these bird ancestors were ground-dwelling, which means that they could have better survived in a landscape in which the trees had been destroyed. Once vegetation began to grow back again, it was then that scientists suggest the bird ancestors took to the trees.
Dr Daniel Field of the Milner Centre for Evolution at the University of Bath explains how much of an advantaged position the ancestors of birds found themselves in: "It seems clear that being a relatively small-bodied bird capable of surviving in a tree-less world would have conferred a major survival advantage in the aftermath of the asteroid strike."
Due to the fact those bird ancestors didn't move back into the trees again until the forests recovered thousands of years later, it is not such a surprise that they survived the mass deforestation, and with this understanding comes the further suggestion that it was this moment in history that saw the developments take place which transitioned these floor dwelling proto-birds into what are more like the tree dwelling birds of today.
A Period of Transition
Dr Antoine Bercovici of the Smithsonian Institution explains: "The recovery of canopy-forming trees such as palms and pines happened much later, which coincides with the evolution and explosion of diversity of tree-dwelling birds."
The researchers who are studying this fascinating area of development found that once the forests had recovered, birds began to adapt to living in trees. This in turn occasioned the acquiring of shorter legs, an evolutionary shift which made it easier for them to perch on trees.
"Perhaps the best modern analogue for one of the surviving birds lineages are modern tinamous - this is a modern group of flying relatives of ostriches: they are relatively small bodied, and live on the ground," said Dr Field, who goes on to say that today’s "amazing living bird diversity can be traced to these ancient survivors".