Those elements are thought to have evolved between the Cambrian and the Devonian periods.
Hence, changes in either will disrupt the relationship that has evolved between the two.
A number of specialized relationships have evolved between floral organization and animal pollinators such as insects.
But most common is a hybrid solution, like the one that has evolved between Mrs. Dunbar and her son-in-law, Frank Taylor.
Mr. Unger succeeds in the first task, detailing the business interests and personal friendships that evolved between the Bush family's inner circle and the Saudi elite.
But it is still hard to believe that the pattern of institutions that evolved between 1955 and 1970 remains optimal now.
The shelled bodies of turtles, for example, evolved between 250m and 200m years ago, while the body plans of scorpions have been around for more than 400m years.
With heavy restrictions in place on internet usage in parts of the world, a complex game of cat and mouse has evolved between the bureaucratically determined and the technologically astute.
This got me thinking about variation in tail lengths and how this might have evolved between various pterosaurs, and that led me onto thinking about the tails of dinosaurs.
The chairs that evolved between the world wars and thereafter combined grace and beauty: Saarinen's 1956 Tulip Chair is a sleek mix of fiberglass-reinforced polyester and cast aluminum, balanced like a Degas dancer on a single molded stem.
Afghanistan thereby became one of the first states to recognize the Soviet government, and a "special relationship" evolved between the two governments that lasted until December 1979, when the Soviet Union invaded Afghanistan.
