Spider Webs Developed Once, In The Cretaceous

["Richard W. Travsky" <rtravsky@uwyo.edu>]

http://www.cbsnews.com/stories/2006/06/22/ap/tech/mainD8IDDNSO1.shtml

Will you walk into my parlor, said a Cretaceous spider to an ancient fly. 
The classic spider's web, like Charlotte would have woven, was invented 
just once, way back in the Cretaceous period some 136 million years ago, 
scientists report.

Called an orb web, it's the generally circular style spun by two major 
types of spiders, which had raised the possibility of the two groups 
evolving this form separately.

But a paper in Friday's issue of the journal Science says a comparison of 
the spider genes related to web making shows that the orb web developed 
just once.

Researchers led by Jessica Garb of the University of California, 
Riverside, compared orb-web building spiders in the genuses Deinopoidea 
and Araneoidea.
...
Garb said in a statement that the finding "does not support a double 
origin for the orb web," but indicates that the unique design evolved only 
once.

While the two groups probably developed orb-web spinning from a common 
ancestor, they came up with different ways of making the web catch prey.
...