WASHINGTON - 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...
