"Reptile’s Pet-Store Looks Belie Its Triassic Appeal" - cutest NYTimes article ever!

TUATARA The tuatara, scientists have learned, is in some ways a so-called living fossil.

As a femur-shaped island paradise that snapped away from the Gondwana supercontinent some 80 million years ago, New Zealand is famously home to eccentric forms of wildlife that look like pets for a Hobbit.

There is the kiwi, of course, with its dense, furlike feathers, its catlike whiskers and its long, slender, curving bill tipped by a pair of ultrasensitive nostrils; and the kakapo, a heavy, flightless, nocturnal parrot with the flat-cheeked face of an owl; and the giant weta, a cricket the size of a human hand that displays by waving its formidably serrated rear legs high in the air as if brandishing a pair of saws.

Yet the animal that may well be New Zealand’s most bizarrely instructive species at first glance looks surprisingly humdrum: the tuatara. A reptile about 16 inches long with bumpy, khaki-colored skin and a lizardly profile, the tuatara could easily be mistaken for an iguana. Appearances in this case are wildly deceptive. The tuatara — whose name comes from the Maori language and means “peaks on the back” — is not an iguana, is not a lizard, is not like any other reptile alive today.

In fact, as a series of recent studies suggest, it is not like any other vertebrate alive today. The tuatara, scientists have learned, is in some ways a so-called living fossil, its basic skeletal layout and skull shape almost identical to that of tuatara fossils dating back hundreds of millions of years, to before the rise of the dinosaurs. Certain tuatara organs and traits also display the hallmarks of being, if not quite primitive, at least closer to evolutionary baseline than comparable structures in other animals.

For example, the tuatara has a third eye at the top of its skull, the legendary if poorly understood pineal eye, which is found in only a sprinkling of reptile species and which vision researchers suspect harks back to nature’s original eye — pretty much a few light-sensitive cells on a stalk. A tuatara’s teeth likewise follow the no-nonsense design seen in dinosaur dentition, erupting directly from the jawbone and without the niceties of tooth sockets and periodontal ligaments that characterize the teeth of all mammals and many reptiles. Some researchers are looking at tuataras for clues to how dental implants, which are inserted directly into the jaw, might be improved.

Yet in a startling counterpoint to the notion of the tuatara as a holdover from Triassic Park, researchers lately have discovered that a few regions of tuatara DNA appear to be evolving at hyperspeed, possibly the fastest mutation rate yet clocked in a vertebrate genome. The quick-changing sequences are limited to so-called neutral regions of the tuatara’s DNA, affecting filler codes, rather than the molecular blueprints for how to build a tuatara. The researchers have yet to determine what the observed hypermutability is all about, but obviously, said David M. Lambert of Griffith University, in Brisbane, Australia, an author of the study, “the processes that govern skeletal morphology are decoupled from the biological processes that govern changes in DNA.”

Moreover, while the modern tuatara resembles its distant ancestors anatomically, life aboard a long-isolated land mass clearly has wrought major changes in the reptile’s physiology and behavior, pushing the tuatara to Guinness-worthy extremes. A famous Gary Larson cartoon may have featured a crocodile on the witness stand angrily telling the prosecutor, “Well, of course I did it in cold blood, you idiot! I’m a reptile!” but in reality crocodiles and a vast majority of other reptiles do very little when the thermometer drops and their blood runs cold — except maybe die. Not so for tuataras.

“Their biology is quite distinctive,” said Charles Daugherty of the Allan Wilson Center for Molecular Ecology and Evolution at Victoria University of Wellington in New Zealand. “They have a unique type of hemoglobin, and their enzymes are set to function at lower temperatures than in most reptiles.” As a result, tuataras remain active at night, and in weather just a few degrees above freezing, said Dr. Daugherty, “at temperatures at which most reptiles couldn’t survive.”

Yes, tuataras are out and about, working the night shift, hunting down other New Zealand fauna similarly adapted for the cold. “They like to eat wetas,” said Stephanie S. Godfrey, a postdoctoral researcher at Flinders University in Adelaide, Australia, who has studied parasite transmission among tuataras. “Walking through the forest at night, you can hear the tuataras eating — crunch, crunch, crunch.”

Tuataras are living fossils in more than one sense of the term. Through long-term capture, tag and recapture studies that were begun right after World War II, researchers have found that tuataras match and possibly exceed in attainable life span that other Methuselah of the animal kingdom, the giant tortoise. “Tuataras routinely live to 100, and I couldn’t tell you they don’t live to 150, 200 years or even more,” said Dr. Daugherty.

They live, and live it up. “We know there are females that are still reproducing in their 80s,” said Dr. Daugherty. At the Southland Museum and Art Gallery in Invercargill, New Zealand, a captive male tuatara named Henry, a local celebrity that had been nasty and unruly for decades until a malignancy was removed from his genitals, mated with an 80-year-old female named Mildred, and last year became a first-time father — at the age of 111.

In every way, tuataras are late bloomers and passionate procrastinators. They don’t reach sexual maturity until age 15 to 20. A female needs two or three years to grow a clutch of eggs internally, and takes another seven or eight months after mating before she finally lays those fertilized eggs. Then the eggs incubate in the ground for yet another year before a brood of finger-size baby tuataras will finally hatch. By comparison, the incubation time for the average North American lizard is only four to six weeks. “If these were plants, most lizards would be like weeds, and the tuatara like a sequoia,” said Dr. Daugherty. For all the nobility of the comparison, the tuatara’s stately pace is also its Achilles’ heel, he added. That’s why the reptile today is found only on diligently monitored islands away from the New Zealand mainland, protected from mammals like rats, pigs or stoats that within months could reduce every sequoia equivalent and its seedlings to so much sawdust.

The New Zealand tuatara, or Sphenodon, is the sole surviving member of a reptilian order that once was as widespread and species-rich as are today’s other three reptilian clans — the crocodilians, the snakes and lizards, the turtles and tortoises. Among the tuatara’s unusual reptilian traits are the relatively simple structure of its heart and lungs, the somewhat froggy style of its gait and the absence of any sort of male intromission organ, or penis. A male tuatara manages as a male bird does, by pressing his cloacal opening against the female’s.

The tuatara also has a unique approach to mastication. As Neil Curtis and colleagues at the University of Hull in England have shown through computer simulations, the tuatara slides its single row of lower teeth across a groove between a double row of upper teeth, shearing the food, said Dr. Curtis, “like a pair of scissors.”

New Zealand’s breakaway land mass proved an ideal tuataran sanctuary, for it lacked any terrestrial mammals that would dig up the reptile’s slow-cooking eggs or pick off the adolescents before they had a chance to breed. Without mammalian predation pressure, the tuatara life cycle became ever more protracted. The carnivorous reptile thrived, feasting on wetas, worms, nesting seabirds and the occasional baby tuatara, and the population climbed to densities far higher than would be seen for a calorically needier meat-eating mammal.

The edenic age ended some 900 years ago, with the arrival of the first Polynesians and their happenstance co-travelers, the rats. Then came pigs, dogs, cats, goats, Europeans. By the 19th century almost no tuataras survived on the New Zealand mainland.

Today maybe 50,000 survive and are considered a national treasure. A vast majority live on Stephens Island, a mecca for herpetologists, where tuatara densities reach more than 1,000 reptiles per acre and where the animals devote considerable effort to defending their little bit of turf, especially the males and especially during mating season.

“They have crests they can inflate, to make them look big, and they stand very tall and start mouth-gaping at each other,” said Dr. Godfrey. “If one male doesn’t get the message, it will escalate into a physical fight.” They tear at each other’s crests and toes, they trade parasites. “During mating season, you can see the bright orange patches of mites on their necks,” said Dr. Godfrey. “It’s quite spectacular.”

They fight for land and fertile females, and if they must fight to the death, well, they are tuataras: they can do it in cold blood.

Other adorable New Zealand species: