Oldest Tuatara Fossil Lends Weight To A Long History Of Terrestrial Life In NZ
Latest research on the oldest tuatara (Sphenodon) fossils to have been found supports suggestions that the New Zealand landmass, once it had broken away from the super-continent Gondwana, had enough dry land to support early relatives of the tuatara, native frogs, and moa.
The fossil of a lizard-like New Zealand reptile dating back 18 million years has been identified by a team of scientists led by Dr Marc Jones (UCL Cell and Developmental Biology), triggering fresh arguments over whether the continent was fully submerged some 25 million years ago. Today, the endangered New Zealand tuatara (Sphenodon) is a lizard-like reptile that is the only survivor of a group that was globally widespread at the time of the dinosaurs. The tuatara lives on 35 islands scattered around the coast of New Zealand, mainland populations having become extinct with the arrival of humans and associated animals some 750 years ago. The oldest known Sphenodon fossil dates to the Pleistocene era (around 34,000 years old), while the new discovery dates to the Early Miocene some 19 to 16 million years ago (Mya). The fossil, of jaws and dentition closely resembling those of the present-day tuatara, bridges a gap of nearly 70 million years in the fossil record of the group between the Late Pleistocene of New Zealand and the Late Cretaceous of Argentina.
A treasure trove of information about pre-human New Zealand has been found in faeces from giant extinct birds, buried beneath the floor of caves and rock shelters for thousands of years. A team of ancient DNA and palaeontology researchers from the University of Adelaide, University of Otago and the NZ Department of Conservation have published their analyses of plant seeds, leaf fragments and DNA from the dried faeces (coprolites) to start building the first detailed picture of an ecosystem dominated by giant extinct species. Former PhD student Jamie Wood, from the University of Otago, discovered more than 1500 coprolites in remote areas across southern New Zealand, primarily from species of the extinct giant moa, which ranged up to 250 kilograms and three metres in height. Some of the faeces recovered were up to 15 centimetres in length.
Tougher laws are needed to protect scientifically precious fossil beds from being looted and exported to overseas dealers, says palaeontologist Hamish Campbell.
"At the moment, the Antiquities Act is very loose. You can export just about anything and you'll be fined only about $250. It's quite a serious problem - New Zealand has been losing fossils; there must be a constant bleeding"
A combination of geological and biological findings are lending weight to the possibility that the Chatham Islands were under water until three million years ago, and that New Zealands flora and fauna may have evolved in another large island near New Zealand. Traditional thinking is that the islands of New Zealand split from the ancient super-continent Gondwanaland about 85 million years ago, and stayed above the oceans since then. This is challenged by the findings of the multidisciplinary project that has been researching the Chathams, named the Chatham Islands Emergent Ark Survey. The team of biologists and geologists includes Dr Steve Trewick, Senior Lecturer at the Allan Wilson Centre for Molecular Ecology and Evolution. Dr Trewick was part of a team who visited the islands in 2004. Findings include identification of remnants of deepwater limestone from about three million years ago, overlaid by beach deposits of sand, indicating that the Chathams may be much younger than previously thought. A further significant discovery was the previously unmapped formation in the southwest corner of the Chathams, volcanic rocks of a type that erupted and accumulated on the seashore. By using fossils from within the rocks and radiometric ageing, researchers found the formation was deposited between 2.5 million and 4.5 million years ago. The rocks were originally on the seabed, but now form the highest point on the Chathams, indicating that the entire land area was under the sea until uplift about two million years ago raised it to above the water level. Biological findings now coming to hand are compatible with the geological findings, indicating that Chatham Islands birds and plants have been separated from their New Zealand relatives for up to three million years. The final report on the Marsden-funded project is due next year. Participants include staff from Otago, Lincoln and Massey universities and GNS Science.
The remains of some of the most fearsome creatures that walked, crawled and slithered over ancient New Zealand are to be part of a major national exhibition – along with an interesting pile of fossilised vomit.
The display, covering the history of New Zealand fossils and fossil hunting, is being developed by GNS Science to tour museums and science centres next year. Among ancient remains to be displayed are those belonging to moa, dinosaurs, giant penguins, marine reptiles, insects, shells, plants and a pile of fossilised regurgitated squid vomit. GNS Science palaeontologist Hamish Campbell said fossil vomit from bottom-feeding marine predators was regularly unearthed.
"Predators such as squid, octopus, rays, reptiles and even larger fish wolfed down crabs, shellfish and almost anything that moved, ground it up and then vomited or spat out the bits they didn't want."
Palaeontologists have become accomplished at recognising small globs of crushed shell and other debris in the landscape, which can tell scientists the feeding habits of creatures that lived between 85 million and 25 million years ago. Alex Malahoff, GNS Science chief executive, said New Zealand was fortunate to have the best fossil record in the southern hemisphere. Ancient New Zealand was considered to have been a land of fish and birds, but in 1975 Hawke's Bay palaeontologist Joan Wiffen discovered the tail bone of a theropod (a two-legged meat-eater) in a local river bed – putting New Zealand on the world dinosaur fossil map.
Since then, scores of remains – some up to 100 million years old – have been unearthed.