The story follows a group of scientists, two geologists (Barton and Davis) and a palaeontologist (Fowler), who are
excavating dinosaur footprints. They come across two physicists (Barnes and Henderson) who are investigating a strange liquid that exhibits
negentropy, which Davis describes as being akin to "Time's Arrow" as "Any clock you care to mention – a pendulum for instance – might just as easily run forward as backward. But entropy is a strictly one-way affair – it's always increasing with the passage of time. Hence the expression, 'Time's Arrow'". == Development ==