FreeLists / va-richmond-general / [va-richmond-general] The history of avian?

["IE Ries" <FEATHERCHASER@xxxxxxxxxxxx>]

  [Article appeared today in the New York Times]
  Birds Flew Earlier Than Previously Thought, Scientists Say

  August 4, 2004
   By JOHN NOBLE WILFORD 

  Scientists have determined that the ancient avian fossil
  Archaeopteryx was definitely bird-brained, meaning no
  disrespect. Indeed, they consider it decisive evidence that
  this earliest known bird had what it took to fly. 

  The new research suggested, moreover, that birds probably
  started flying millions of years earlier than scientists
  previously thought. It is just that fossils of the first
  flying birds have eluded paleontologists. 

  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 the size, shape and volume of its brain were similar
  to that the modern eagle or sparrow. 

  Measurements of the semicircular canals, the organs of
  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 (CT)
  scan of the fossil's braincase and inner ear, is described
  in today's issue of 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. It 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 museum, wrote of Archaeopteryx that
  until their investigation, "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?" 

  Dr. Lawrence M. Witmer, a paleontologist and associate
  professor of anatomy at Ohio University in Athens, who was
  not involved in the research, said the "most exciting
  outcome of this study" is that "we finally have reliable
  data on the brain and inner ear of the most primitive known
  bird, and so can document the neural transition to birds." 

  Dr. Witmer, in separate article in the journal, predicted
  that other scientists "will now race to the fossils of
  other early birds and birdlike" reptiles to look for
  similar characteristics in their brains and inner ears or
  other evidence of flight capability. 

  The first of seven Archaeopteryx skeletons, all excavated
  in Germany beginning in 1861, was the object of the new
  research. The skeleton, embedded in a slab of limestone, is
  of a carnivorous creature the size of a crow that
  apparently lived and died along the shore of an ancient sea
  in what is now Bavaria. The specimen was acquired by the
  London museum a year after its discovery. 

  For the study, scientists isolated the part of the small
  skull that encased the brain. It is an area smaller than
  the last segment of your little finger. Then Dr. Milner
  personally carried the braincase in a small box to the
  University of Texas at Austin, where it underwent detailed
  CT scans that, in effect, mapped every telling contour of
  the brain that once occupied the case. 

  Back in London, the data were used to create computerized
  3-D reconstructions to investigate the anatomy of the brain
  in detail. Dr. Milner's team included researchers from
  Spain and the United States as well as England. 

  The scientists said an analysis of the reconstruction
  revealed that the Archaeopteryx brain was larger than the
  brain of an average reptile of equivalent size and somewhat
  smaller than any similarly sized modern bird brain. But it
  appeared to exhibit "a stage further towards the modern
  bird pattern," the scientists wrote, indicating that
  Archaeopteryx was perhaps not the earliest of flying birds.


  The researchers also determined that Archaeopteryx "closely
  resembled modern birds in the dominance of the sense of
  vision and in the possession of expanded auditory and
  spatial sensory perception in the ear," characteristics
  necessary for flight. An enlarged forebrain, they reported,
  also suggested that the ancient bird had a well-developed
  sensory capacity "demanded by a lifestyle involving flying
  ability." 


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