7 Jul 2017

Exploring the words of 'Earth's diary'

From Nine To Noon, 10:06 am on 7 July 2017

Fossils are the words and strata (layers of sedimentary rock or soil) are the pages of "Earth's diary", says palaeontologist James Crampton. He's joining local iwi Ngai Tuhoe on a hunt for evidence of dinosaur fossils in Te Urewera.

Life on earth has been around 4 billion years, but around 600 million years ago 'complex life' evolved, scientists generally believe.

It's still up for debate whether this evolution was inevitable or a chance coincidence, but we do know that we are living on and ourselves part of a 'microbe planet', Crampton says.

"What we see as life – the kauri trees and the people and the chimpanzees – is just this tiny little icing on the cake of life."

"99.9 percent of the life that's ever lived is extinct now."

Some say biodiversity has been increasing massively over millennia and others disagree, he says.

"So we said 'Let's look at snails and clams in New Zealand that we have this amazing database of and see what they show."

What they found was more or less constant diversity in the last 50 million years.

Layers of strata (sedimentary rock or soil) are like the pages of a diary with each layer preserving the fossils that were living at the time and the fossils are like the words on the page, Crampton says.

"It's an imperfect diary, but it's still remarkably good."

For some groups the fossil record is very good, for some it's not, he says.

"Your chances of being preserved as a dinosaur are very low, whereas your chances of being preserved as a mollusc are much higher."

Many believe there have been five big mass extinctions in the history of life on earth, but there's disagreement about where they were caused by.

Although it's commonly thought that an asteroid of estimated 10km-wide asteroid took out the dinosaurs, some scientists believe it was massive volcanic eruptions of a scale we can't imagine today which caused the extinctions.

Crampton thinks it was likely an unfortunate coincidence of the two.

"We know that there'd been huge eruptions going on in India, then oh dear, an asteroid came in, as well."

So what do we know about the dinosaurs that were once here?

Until 100 million years ago what we now know as New Zealand was just a little slice on the side of Gondwanaland – "a giant southern continent made up of Australia, and Antarctica, Africa and South America.

When we started drifting away 100 million years ago to become what we are today, there were some dinosaurs on this land, including long-necked sauropods, armoured Ankylosaurus and other two-legged carnivores.

So far the only confirmation we have of this is thanks to one or two bones found by amateur palaeontologist Joan Wiffen. Crampton says.