Wellington, June 24 : One of the largest known dinosaurs, a titanosaurid, once roamed New Zealand about 80 million years ago, as is evident from the discovery of a vertebra bone in a stream bed in Hawke's Bay in New Zealand.
According to a report carried out in the website www.stuff.co.nz, this was the first evidence that titanosaurids once lived in New Zealand.
Though the bone was found in 1999, it has recently been identified as coming from the giant plant-eating sauropod group known as the Titanosauroidea.
Titanosaurids were widespread globally and lived during the Cretaceous period, between 83 and 65 million years ago. They had small heads, a long neck and tail, and a large body. They were up to 45 metres in length and weighed up to 50 tonnes.
Dr Wiffen found the bone during a routine fossil-hunting trip in a tributary of the Te Hoe River west of Mohaka in northern Hawke's Bay. It was not known if the fossil was from a juvenile or an adult.
According to her, fossil-hunters liked to explore streams after heavy rain as water could expose previously hidden fossil-bearing boulders.
"I saw a partly exposed concretion (sedimentary rock) about the size of a rugby ball in the stream bank. I dug it out and asked a colleague to break it open with a hammer," Dr Wiffen said about the discovery.
"I immediately saw a bone structure inside that looked different from the bone of a marine reptile. To be honest, it's a fairly non-descript and incomplete bone. It is heavily eroded and that's because it must have been transported in a riverbed for some time before it was buried," she added.
Storms would have carried the bone down stream to what would have been a coastal lagoon or estuary 80 million years ago.
At home in her garage, Dr Wiffen painstakingly removed surplus rock and sediment with acetic acid and abrasion tools similar to those used by a dentist.
She took the bone to Dr Ralph Molnar, a recognised dinosaur expert, at the Queensland Museum in Australia.
"Straight away he became quite interested and he thought it might be a tail bone from a titanosaurid," she said.
Dr Molnar had the bone examined by other vertebrate paleontologists who confirmed his initial views.
"It shows that New Zealand had the full range of dinosaurs. The titanosaurid would have lived several million years after Zealandia (the New Zealand continent) split away from Gondwanaland," said Dr Campbell.