By LOUISE THOMAS



Snakes and crocodiles could have inhabited New Zealand up to 18 million years ago.



Geologists working in a fossil lake near St Bathans, Central Otago, have unearthed a treasure-trove of animal and bird fossils which is set to excite scientists around the world when it is officially announced in Sydney today.



The remains, between 18 and 14 million years old, include snakes, fish, fragments from as yet unidentified mammals and teeth and scutes (bony back plates) of an ancient crocodile.

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It is the first evidence of snakes, and further confirmation of crocodiles, having lived in this country.



Also unearthed were the oldest tuatara bones ever found, eggshells, probably moa, and a piece of New Zealand bat. All these finds are around 16 to 17 million years older than the previous oldest remains.



The geologists, Craig Jones, from the Institute of Geological and Nuclear Sciences, Trevor Worthy, of Palaeofaunal Surveys, Alan Tennyson, from Te Papa national museum, and James McNamara, from the South Australian Museum, will formally announce the findings today at the International Palaeontological Congress at Macquarie University in Sydney.



Mr Jones says the animals lived at a time when the climate was warmer than today's. "But there was a global cooling of around four to six degrees soon afterwards, which may have contributed to some of these animals getting wiped out here.



"Prior to this lake forming, some 15 million years ago, we know New Zealand went through a time of being almost completely submerged. The land area was about 20 per cent of what it is now.



"These fossils are providing a previously unknown snapshot of just who was living here between the drowning of New Zealand and this period of global cooling.



"The animals we have found are very different to the animals we find in New Zealand today, except of course for the recently extinct moas, tuatara and the bats. This points to some substantial changes to New Zealand's vertebrate community since the late Early Miocene, only 15 million years ago."



The find is highly significant, as it shows that many previously undetected animals survived in New Zealand after it separated from Gondwanaland (which broke into Australia and Antarctica) about 82 million years ago.



"It is very exciting stuff," said Mr Jones.



"New Zealand has a very rich late Quaternary [period] terrestrial fossil vertebrate record [up to about 1 million years ago], but we have one of the world's poorest pre-Quaternary records."