5 minute read
HERE BE MONSTERS
THE CHATHAM ISLANDS are known for their rugged beauty and for the plentiful marine life that fills the oceans around them. Millions of years ago the marine life was also plentiful, but it was also, quite frankly, terrifying; huge carnivorous reptiles weighing tonnes, devouring prey with rows of razor-sharp teeth, a veritable menagerie of fantastical beasts. Ancient mariners marked unknown oceans with the cautionary phrase ‘Here be Monsters’, and for the seas around prehistoric Chathams it was a fitting warning indeed.
For generations, it was believed that there had never been dinosaurs in Aotearoa New Zealand. Most scholars felt that our landmass was simply too young and no fossils had been found to dispel this belief. All that changed however, after self-taught fossil hunter Joan Wiffen discovered her first dinosaur bone at Mangahouanga, in Hawkes Bay, in 1975.
It is the evidence of the big beasts that captures the wider public’s imagination.
Wiffen, who had served in the air force during WW2 and become interested in natural history from books she bought her children, had made fossil hunting into a family affair, frequently loading up the car to search out rocks encrusted with fish teeth and vertebrae. These were fairly common, small, and relatively recent, but the 1975 find turned out to be a much larger land-dwelling creature, in fact a theropod dinosaur. And while it would be several years before her findings would be completely verified, today the former presence of dinosaurs on New Zealand’s landmass is unarguable because of her work. Since then Joan and her colleagues have found at least three types of carnivorous dinosaurs, three kinds of herbivorous dinosaurs, and a flying reptile.
The finds had a huge impact on the way we viewed our ancient history, and now, finds of dinosaur fossils on the Chatham Islands have had a similar impact on the scientific community.
The recent Chatham Island finds began in 2003 when theropod bones were found on the Islands by Dr Jeffrey Stilwell of Melbourne’s Monash University (Dr Stilwell did his PhD under Otago University associate professor of palaeontology Ewan Fordyce, this country’s leading palaeontologist, so in true Crowded House fashion we can claim some of the glory!).
And his finding was pretty glorious: a 2kmlong, ten metre thick deposit of bones, teeth and claws that has already produced more dinosaur fossils than have been unearthed in mainland New Zealand over the past 25 years. The 70-75 million year old deposit is held in silicified sandstone and conglomerate—now dubbed the Takatika Grit—and contains not just dinosaur bones but marine reptiles, sponges and molluscs, and even ancient plant material, including spectacularly preserved pine cones.
The skeletons are of an ancient species now named Kupoupou stilwelli in recognition of Dr Stilwell and using the Moriori word kupoupou meaning ‘diving bird’.
All those added extras really gets your average palaeontologist’s motor running, but it is the evidence of the big beasts that captures the wider public’s imagination. And what big beasts they were; included in the finds were fossils of the mosasaur, a huge carnivorous reptile that could be between four and ten metres long with a mouth bristling with teeth (yes, we are going to need a bigger boat), and the elasmosaurus, a type of plesiosaur also measuring up to ten metres long with an extraordinarily long neck,
but which thankfully ate mostly crustaceans and molluscs. There were also fossil remains of the theropod, the carnivorous monster that walked upright and is a part of the family of dinosaurs which were the largest carnivore to walk the earth; they are very much what we envision when we think of dinosaurs. The name theropod means ‘beast-footed’, and that pretty much says it all.
How the aquatic and land-based fossils came to be in the same place is probably due to the quaintly named ‘bloated and floated’ process whereby dinosaurs like the theropod would have bloated shortly after dying and been carried by tides before sinking to join their aquatic cousins in eternity. Or in this case until 2003 when Dr Stilwell arrived.
Other, more recent, fossil finds have also helped shed light on the evolution of penguins, in New Zealand waters and beyond. Penguin skeletons found on the Chatham Islands between 2006 and 2011 have provided a link between the known ‘giant’ penguins of the prehistoric era and modern-day birds.
The skeletons are of an ancient species now named Kupoupou
Kupoupou stood about 1.1 metres tall and appears to be the link between the ‘monster penguin’ Crossvallia waiparensis which was virtually human sized, and the modern-day penguins that still swim around us. Work on ascertaining just what that link could be is now underway.
Work is also ongoing to delve deeper into the hidden fossil treasures that the Chatham Islands have yet to offer up; they may be one of the most remote parts of our country, but they may also hold the key to a much greater understanding of our prehistoric past.
