Re: New Cretaceous bird fills fossil gap

[Phil Bigelow <bigelowp@juno.com>]

The press seems to have interpreted the reduced medulary cavities/air
sacs as a "primitive" feature, when it looks (to me at least) like a
specialization for diving and wading (aka, character reversal).

What do the authors say about this?  Yes?  No?


<pb>
--
Stigmata free since 1972.
Oh wait....maybe it was only a Ketchup stain.



On Thu, 15 Jun 2006 12:41:52 -0700 (PDT) Guy Leahy
<xrciseguy@sbcglobal.net> writes:
> Fossils show living birds descended from waterfowl 
> By Maggie Fox, Health and Science Correspondent
> 1 hour, 32 minutes ago
>  
> A set of 110-million-year-old fossils from China is
> the earliest example of a modern-looking bird and
> strongly suggests ancestors of all living birds were
> waterfowl, researchers said on Thursday.
> 
> The pigeon-sized bird probably resembled a tern or a
> loon, the researchers said. Called Gansus yumenensis,
> it would have been an accomplished flyer and diver and
> could well be one of the ancestors of modern birds,
> the researchers report in Friday's issue of the
> journal Science.
> 
> "Every bird living today, from ostriches ... to bald
> eagles, probably evolved from a Gansus-like ancestor,"
> Matthew Lamanna of Carnegie Natural History Museum in
> Pittsburgh told a news conference.
> 
> Peter Dodson, professor of anatomy the University of
> Pennsylvania, who oversaw the research, said, "Gansus
> is very close to a modern bird and helps fill in the
> big gap between clearly non-modern birds and the
> explosion of early birds that marked the Cretaceous
> period, the final era of the Dinosaur Age."
> 
> The five skeletons come from an exceptionally rich
> fossil bed in China's Gansu Province, in a poor
> farming area near Changma, 1,200 miles west of
> Beijing.
> 
> In the Cretaceous period, 100 million years ago, it
> would have been a lake, surrounded by lush plant life,
> filled with crocodiles and fish, and with dinosaurs
> and early mammals prowling on land.
> 
> Now the lake bed survives as layers of rock.
> 
> "You can walk up to a rock and peel off sheet after
> sheet like paper until you get to a fossil," said
> Jerald Harris of Dixie State College of Utah.
> 
> Hai-lu You of the Chinese Academy of Geological
> Sciences was studying at the University of
> Pennsylvania when many earlier fossil birds were
> discovered in China's northeastern Liaoning Province.
> He remembered that the rock beds in Gansu were similar
> and took an expedition there.
> 
> They struck paleontological gold and quickly gathered
> five nearly complete fossils of the early bird.
> 
> A computer program reconstructed the bird evolutionary
> tree and suggests the birds that gave rise to modern
> birds were waterfowl.
> 
> Gansus looks more like a modern bird than some birds
> that lived later in the Cretaceous period.
> 
> Its wings, legs and webbed feet closely resemble those
> of living loons and diving ducks, with a few
> exceptions. The birds had not yet evolved the hollow,
> air-filled bones that make modern birds to light and
> nimble, and it still had tiny claws at the end of its
> wings that probably would have made it slightly clumsy
> in flight, Harris said. 
> 
> 
> 
>