Science: Senior Reptiles

Three U.S. zoos, in New York, Chicago and San Diego, will soon have live reptiles that were already old-fashioned when the dinosaurs were still young. Tuataras (Sphenodon punctatus), which look like 2½-ft. lizards but are far more primitive, were plentiful round the world 200 million years ago. Now, almost unchanged, they are found only in New Zealand, that ultimate storehouse for discontinued zoological models.

When white men came to New Zealand, there were tuataras all over the place, but man’s pets and camp followers (dogs, cats, rats, etc.) almost wiped them out. Only on a few small islands did they survive. Even there the cats harried them until the New Zealand government curbed the cats. Then the tuataras multiplied and they are now just plentiful enough to be shared with a few foreign zoos.

Reptile Curator James Oliver of New York’s Bronx Zoo is impatiently awaiting his tuatara. The scaly, sluggish beasts are so ancient a breed, he says, that their forebears flourished when the sea was full of icthyosaurs. They were stepped on by dinosaurs, and their young were probably snatched by flying, reptilian pterodactyls. Some experts believe that all modern snakes and lizards are descended from the tuatara’s order (Rhynchocephalia).

Tuataras are not only ancient, but odd. They have three eyes, one in the middle of the forehead. In humans, who may be descended, like the lizards and snakes, from something very like a tuatara, this third “pineal” eye has become the pineal gland deep inside the head. The tuatara still wears his outside, complete with a lens and an optic nerve. It may see a few dim glimmers with its third eye.

The tuatara is not outstandingly intelligent; its brain, only about the size of a green pea, is hardly a brain at all. When strolling leisurely, it drags its belly and tail slowly over the ground. When chasing a spider or a grasshopper, it rears up on all four legs, like an optional four-wheel drive, and makes better speed. Most of the time tuataras are silent, but during the mating season they speak to one another with froglike croaks. Their eggs, laid in petrel burrows (tuataras eat young petrels), take a year to hatch.

Curator Oliver would like to breed tuataras in the Bronx Zoo, but they have no external sexual characteristics. The only way to distinguish males from females is to wait for the mating season, when the tuataras, croaking, make their own decisions. New Zealand is not yet ready to release enough tuataras for this auto-selection experiment.