Feathers of extinct birds found in 99 million year old amber: a clue to the extinction of the dinosaurs?

In the world of fossils, feathers are rare, much less the feathers of baby birds. However, a recent discovery by scientists may hold clues as to why dinosaurs went extinct while some of their relatives survived. Feathers from a young chick of an extinct species were found in 99 million-year-old amber.

Bird chicks, including the ugly duckling, hatch with different types of feathers. Some come out of the egg with disheveled young feathers, while others go bald. This depends on whether they are altricial or precocial. Altricial chicks hatch naked and helpless, but sit under their parents to retain body heat. On the other hand, precocial birds hatch with young feathers and can go to the water almost immediately after hatching.

Adult birds and chicks molt, but they use different strategies. Adult birds shed all their feathers at once during simultaneous molting, relying on the warmth of their parents. Chicks, on the other hand, molt more gradually and shed feathers over time to maintain a constant supply of feathers.

The recent discovery of young chick feathers in amber is the first conclusive fossil evidence of juvenile molting. Interestingly, however, the life history of this chick does not fit the pattern of any modern bird. All feathers are at the same stage of development, indicating simultaneous or nearly simultaneous feather growth.

Scientists believe that this chick belonged to a group of extinct animals called enantiornithines. These birds were very precocious, but their young feathers tell a different story. Perhaps a mismatch in molting approaches may have led to the extinction of this group of birds.

Enantiornithines were the most diverse group of birds of the Cretaceous period, but they went extinct along with all other non-bird dinosaurs. Scientists hypothesize that when the asteroid hit, global temperatures plummeted and resources became scarce. This created high energy needs for birds to keep warm, but there were not enough resources to meet those needs.

The discovery of feathers in amber by researchers from Chicago’s Field Museum is published in the journal Cretaceous Research. The discovery may help scientists better understand the evolution of birds and the reasons for the extinction of dinosaurs.

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