27 May 2016

Finding dinosaurs in Antarctica

From Nine To Noon, 10:07 am on 27 May 2016
The reconstructed skeleton of a Cryolophosaur at Auckland Museum

Cryolophosaurus at Auckland Museum Photo: Auckland Museum CC BY

More than a hundred years ago on his fatal expedition to the South Pole Robert Falcon Scott and his unlucky team discovered the very first fossils in Antarctica while trekking over the Transantarctic Mountains.

The rocky remains hinted at much warmer past for the frozen continent and more finds since have revealed Antarctica was once covered in dense forest inhabited by all kinds of plants and animals - including dinosaurs.

One of the members of the latest expedition to dig for fossils in the deep south was Australian paleontologist Steven Salisbury from the University of Queensland.

Read an edited excerpt of the interview below:

Let’s talk about the dinosaurs that lived in Antarctica. How many million years ago?

Most of the rocks there that have produced dinosaurs on the peninsula are between 71 and 66 million years old, so at the very end of the age of dinosaurs. Things that have been found down there that give us a bit of insight into the dinosaur fauna from that part of the world, include a very nice partial skeleton of an armoured dinosaur, a type of Ankylosaur. There’s been two or three different types of small two-legged plant-eating dinosaurs called Ornithopods, so about the size of a kangaroo and probably similar body proportions. And a couple of bits of Theropods. Meat-eating dinosaurs. There was a nice partial skeleton found in about 2005/2004. And one bone from a Sauropod dinosaur. One of those big long-necked, long-tailed plant eaters. And that’s pretty much it. Other than the birds and obviously birds being dinosaurs, we can’t rule them out of the whole thing. But most people are really interested in the non-avian dinosaurs and of course that’s what we’re into as well.

The first obvious question is how did the dinosaurs cope with the cold, but actually, was it that cold in this era?

The main thing you have to remember back then, was that Antarctica was connected to Australia. New Zealand was probably starting to pull away, or Zealandia, the big land mass that includes New Zealand and areas to the north of it, it was just starting to pull away at this time but it was probably still connected. The Antarctic Peninsula was probably connected to the southern tip of South America by a chain of islands, so as a consequence of that arrangement of these land masses, there was no circumpolar current in action.

The Southern Ocean didn’t really exist. We had Pacific, Atlantic and Indian Oceans extending down to very high latitudes with much warmer waters than we get today, circulating at different points around the Antarctic coast. So the effect of that would have been that most of the time, with those warmer sea surface temperatures around Antarctica, it would have kept it a lot warmer than it is now. Antarctica doesn’t really start to freeze until the Southern Ocean starts to gain in size. That’s something that doesn’t really start to happen until about 20 million years ago.

So, back during the time when the rocks that we were looking at down there were deposited, it would have been much warmer than it is now. We see evidence of that, not just the types of animals that you find fossils of, so there’s a very rich marine life in the ocean there, but in a lot of areas where we are looking close to what were ancient river mouths, we are finding a lot of plant fossils. We’ve found lots of leaves and various types of these flowering plants. This all indicates that you have temperate forests living not far from where all of these fossils are occurring.

It really starts to paint a quite different picture of what that area was like at around the time all of these animals were around.

There are some theories that the Antarctic dinosaurs could potentially have survived the extinction event, whatever it was, that wiped out dinosaurs in other parts of the globe 65 million years ago. Do you give much credit to that theory?

At the moment there’s no evidence to suggest that any dinosaurs other than birds made it through the extinction event. We had a couple of areas that we looked at down in the peninsula where you see the transition from the end of the age of dinosaurs to the start of the age of mammals, we can actually put our finger on it, in the rocks. As yet we haven’t found anything above that line to suggest that any types of non-avian dinosaurs persisted.

It’s quite amazing, on one side of the hill you can be walking around and you’ll see ammonites and plesiosaur bones and things and on the other side, those animals are gone and things are very different. There’s fish and birds and things, but the non-avian dinosaurs and marine reptiles, the ammonites and things, disappear. It’s exciting to be in a place where you can actually see what happened in the rocks, there aren’t actually a lot of places like that around.

I think it’s a nice idea to imagine, maybe in the remote part of Gondwana, maybe in Antarctica or New Zealand, that some dinosaurs might have persisted, but as yet we haven’t found any bones to suggest that that is the case so at the moment we have to assume as we have for a while that the majority or all of them went extinct at about 65 million years ago.

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