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Tuesday, June 5, 2007

Last Survivor Of The Dinosaur Age May Become Extinct Due To Global Warming.

It has survived ice ages, volcanic eruptions and the intrusion of humans on its South Pacific island home, but New Zealand's last survivor of the dinosaur age may become extinct due to global warming.

Mounted with spiny scales from head to tail and covered by rough, grey skin that disguises them among the trees, the tuatara is one of the world's oldest living creatures.

But the lizard-like reptile is facing increasing risk of extinction from global warming because of its dependency on the surrounding temperature which determines the sexes of unborn young while still in their eggs.
"They've certainly survived the climate changes in the past but most of them (past climate changes) have been at a more slower rate," said Jennifer Moore, a Victoria University researcher investigating the tuatara's sexual behaviour.
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"So you wouldn't expect these guys to be able to adapt to a climate that's changing so rapidly."

The sex of a tuatara depends on the temperature of the soil where the eggs are laid. A cooler temperature produces females, while a warmer soil temperature results in male offsprings.

So named by New Zealand's indigenous Maori people because of the spines on its back, the tuatara is the only survivor of its species of reptile that flourished during the age of the dinosaurs, some 200 million years ago.

It can grow up to 50 centimetres (20 inches) and weigh up to one kilogram (2.2 pounds) and like its reptile relative, the turtle, the slow-moving tuatara can live more than 100 years, feeding mainly on insects.

But scientists say its long life span as well as its four-year breeding cycle - relatively slow for a reptile - will make the adaptation process more difficult.

According to Moore, a temperature above 21.5 degrees Celsius (71 degrees Fahrenheit) creates more male tuatara while a cooler climate leads to females.

Already male tuatara on a tiny predator-free island near the top of New Zealand's South Island outnumber females by 1.7 times, Moore explained.

Unique wildlife

Thanks to its geographic isolation, New Zealand is home to a host of unique wildlife, such as the flightless kiwi bird.

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