Fossils trigger row down under

Think about New Zealand and you may imagine the rolling mountains not islands submerged in the sea...
19 January 2009


A breaking wave on the ocean


Think about New Zealand, and you may imagine the rolling mountains featured in Lord of the Rings, or the nasal voices of Flight of the Conchords. But you may not imagine the islands submerged in the sea...

However, there's evidence to suggest that New Zealand was in fact buried in the ocean around 25 million years ago, although a recent discovery by scientists from University College London, the University of Adelaide and the Museum of New Zealand now challenges that idea.

The scientists, led by Marc Jones, have discovered an 18 million year old fossil of a lizard-like reptile, known as a Sphenodon.  Back in the time of the dinosaurs, Sphenodons were found all over the place, but today they exist only as a distant ancestor, the New Zealand tuatara lizard, an endangered species found on 35 islands around the country's coastline.

Previously, the oldest known Sphenodon fossil was around 34,000 years old, but this new specimen is much more ancient, dating back around 19 to 16 million years ago- back in the Early Miocene era.

New Zealand is thought to have broken off from a huge land mass called Gondwanaland - this is the huge supercontinent that broke up to make most of the continents in our Southern hemisphere, including Antarctica, Australasia, Africa and South America.  It split off around 82 million years ago, carrying animals and plants, including the Sphenodon ancestors of the tuatara lizards.

Now some scientists think that New Zealand  - or Zealndi as it was then - was completely submerged underwater around 22 to 25 million years ago. But the discovery of this fossil, and others besides, suggest that at least enough land remained above sea level to support their survival. There simply isn't enough time for the species to have recolonised the islands if they had been completely washed out.

And it also shows that the ancestors of the tuatara were a hardy bunch, as they managed to survive an 8 degree drop in temperature around 14 million years ago. Sounds chilly!


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