As a child, Dixon was inspired by H. G. Wells' "The Time Machine", particularly the far future creatures featured in the book, to create his own imaginary future animals descended from creatures of the modern day. These animals often served as background characters in Dixon's own retellings of Wells' work. In the 1960s, Dixon was influenced by the contemporary conservationist movements, especially a campaign to save the tigers. Dixon began to ponder that should the tiger and other endangered animals go extinct, something would inevitably take their place. After seeing a "Save the Whale" badge on a friend in the late 1970s, the idea materialized again. Thinking of what might evolve to take their place if whales did go extinct eventually led to the idea of the giant aquatic penguins in the final book.