Did You Know? Excerpt from Dragon Teeth by Michael Crichton: Philadelphia was the busiest city in America that May, nearly bursting with the vast crowds that flocked to attend the Centennial Exposition of 1876. The excitement that surrounded this celebration of the nation's hundredth anniversary was nearly palpable. Dragon Teeth is a posthumously published work of historical fiction from 1974.
William Johnson is a student from Yale who heads West one summer on a bet. He hooks up with a paleontologist, Charles Marsh, headed out on a fossil hunting trip. Dragon's teeth (German: Drachenzähne) are square-pyramidal fortifications of reinforced concrete first used during the Second World War to impede the movement of tanks and mechanised infantry.The idea was to slow down and channel tanks into killing zones where they could easily be disposed of by anti-tank weapons..