A 121-million-year-old baby arboreal bird,
fossilised while still curled in its egg, has been found in China.
The fossil is thought to be the most ancient unborn
bird ever discovered.
It has piqued researchers' interest because it had
feathers, whereas many modern flying birds are naked and helpless
when they first hatch. The authors say this supports the view that birds
developed the strategy of hatching featherless later in history.
"This fossil is interesting because its
preservation is so exceptionally fine, that even the soft tissues
like feathers have been preserved," commented Dr Angela Milner of
London's Natural History Museum. "For an embryo that is still inside the egg, it is
surprising how advanced the feathers were."
The researchers know the bird, found in north-east
China, was an embryo because the fossil is tucked up in very
characteristic way for an unhatched chick.
"The tucked-in posture of the fossil is consistent
with a late-stage embryo rather than with a hatchling, in which case
the head would have raised beyond the vicinity of the feet," said
authors Zhonghe Zhou and Fucheng Zhang from the Chinese Academy of
Sciences in Beijing, China.
But apart from the chick's posture, it was not very babyish at all.
"The interesting thing about this bird is that for
something that has not yet hatched, it is almost fully formed," said
Dr Milner. "All its bones are formed and its feathers are very