专四晨读美文：Archaeopteryx

Archaeopteryx
Scientists have determined that Archaeopteryx,
the earliest known bird,
was definitely birdbrained,
meaning no disrespect.
Indeed, they consider the fossil's brain size decisive evidence
that Archaeopteryx had what it took to fly.
The new research suggests, moreover,
that birds probably started flying millions of years earlier
than scientists previously thought.
It is just that fossils of those first flying birds—
predecessors of Archaeopteryx-have never been found.
The researchers, at the Natural History Museum in London,
based their findings on the first X-ray examination
and reconstruction of the braincase and inner ear
of a 147-million-year-old Archaeopteryx specimen.
They found that in size, shape and volume,
its brain was similar to that of the modern eagle or sparrow.
Measurements of the semicircular canals,
the mechanism for balance inside the ear,
showed that Archaeopteryx
had the "neurological and structural adaptations
necessary for flight,"
the scientists concluded.
Their research,
involving an X-ray computed tomography scan, or C.T.,
of the fossil's braincase and inner ear,
is described today in the journal Nature.
Previous studies of the feathered wing and tail of Archaeopteryx
and its birdlike anatomy,
including a pronounced wishbone,
supported the prevailing view of experts
that it was capable of some degree of powered flight.
Archaeopteryx is considered a prime transitional species
in the evolution of some reptiles,
probably dinosaurs, into today's birds.
But the research team, led by Dr. Angela Milner,
a paleontologist at the British museum,
wrote that until their investigation of Archaeopteryx,
"little was understood about the extent
to which its brain and special senses
were adapted for flight."
Dr. Milner said the new study not only established
that Archaeopteryx was capable of
"controlling the complex business of flying,"
but also showed "how much there is still to discover
about when and how bird flight began."
In a statement issued by the museum,
Dr. Milner said,
"If flight was this advanced by the time
Archaeopteryx was around,
then were birds actually flying
millions of years earlier than we'd previously thought?"