Like many other people over the holiday break, I saw James Cameron's blockbuster film Avatar. It was absolutely amazing. Set on a far-off world in the not-too-distant future, the film is a sort of Last Samurai or Dances With Wolves in space, but what really grabbed my attention were the creatures that lived on the planet on which the story unfolds.
In his 1989 book Wonderful Life, the paleontologist Stephen Jay Gould wondered what would happen if we could "rewind the tape" of evolution on earth and start it over from the beginning. Would the same organisms evolve, or would life look very different? Unfortunately we cannot actually run this experiment, but if we find life elsewhere in the universe it can act as a sort of test of Gould's idea.
Granted, the creatures of Avatar are entirely speculative and in some cases are modeled closely on familiar animals, but they are still interesting interpretations of different forms evolution might toss up on another planet. Most of the creatures in the film, for example, are hexapods, meaning that they have six limbs instead of four. The earliest land-dwelling vertebrates on our planet, the ancestors of all amphibians, reptiles, birds, and mammals, had four limbs, but what if by some quirk they had six? What might their descendants look like millions of years later? The creatures of Avatar are imaginative answers to such questions. (Though the Na'vi, the planet's humanoid inhabitants, have only four limbs, suggesting either a different ancestry or the recent loss of that "extra" pair of limbs.)
Most of the creatures in the film are vaguely mammalian, from the panther-like Thanator to the obviously equine Direhorse, but at least two creatures have a slightly more reptilian aspect. Both, the Mountain Banshee and the Great Leonopteryx, are brightly-colored flying creatures that are a mix of different animals all stuck together as if some spare parts were just lying around. In general, though, they look like variations of the flying pterosaurs that thrived alongside the dinosaurs, and some prehistoric animals were even taken for inspiration in their design. According to creature creator Wayne Barlowe:
I was influenced by manta rays and skates - sea life motifs were prevalent in my thoughts at the time - when it came to my initial concepts. Their lines informed everything from wings to head profiles. And, yes, being a huge paleontology buff did make me think of the vast variety of relatively little-known pterosaurs and plesiosaurs with their many, unique aerodynamic and hydrodynamic solutions.
There is much more that could be said about the creatures of Avatar, from their extra breathing holes to the way the Na'vi protagonists can interface with them using a sort of biological "plug and play" capability, but most of all they made me think of evolution. What if certain events in the history of life on our own planet had been different? What if the first terrestrial vertebrates had six legs, or what if the extinction that wiped out the non-avian dinosaurs never happened? We can never know for sure, but science-fiction films like Avatar allow special effects artists to take questions like these to create whole new worlds.