Dinosaur teeth unveil our Jurassic past

But first, a new study has used advanced analysis of fossilised teeth to uncover amazing details about what the group of long-neck dinosaurs called sauropods ate, where they lived, and how they might have moved around during the Jurassic, 200 million years ago. Daniela Winkler at Kiel University is one of the scientists behind it…

Daniela - We wanted to find out how the sauropods, so the long-necked dinosaurs that were the largest creatures that ever walked on the Earth, how they lived together in certain environments. And if they fed on the same stuff, so they were in competition with each other, or if they actually split the resources they found, to co-exist in these environments.

Chris - So you're saying as a group, different members of the group would eat one thing, different members would eat another, and therefore everyone’s a winner because you’re not conflicting or competing for what you’re trying to exploit?

Daniela - Right, that’s the idea. We want to know if different species have their specific taste for different plants, so they don’t compete.

Chris - And how can you work that out, given these things were around tens of millions of years ago?

Daniela - We look at the best-preserved fossils we have from sauropods - and that’s their teeth. Teeth are made of the hardest material in the body and are super well-preserved in the fossil record. They’re so well-preserved that they even show tiny, tiny scratches - tiny wear marks that stem directly from the contact with the food. When they chew, they slightly wear their teeth, and how they wear their teeth depends on what they ate. The whole pattern gives us a very distinct idea of what kind of plants they ate, and also in what kind of  environment they actually lived, because other stuff in the environment is also interacting with the teeth. For example, dirt, grit and dust may settle on plants, especially if it's a very dry environment. The sauropods couldn't help but also munch on the dirt that’s on the plant, and that leaves additional small scratches.

Chris - Are they in competition, or are they actually going for as diverse a range of foodstuffs as they can get?

Daniela - So we found that when we analysed these three very different environments, one in nowadays United States of America, one in today's Portugal, and one in Tanzania in Africa, the really cool finding we got was there's this one group of dinosaurs, they're called Camarasaurids. One of the famous dinosaurs is the Camarasaurus. I guess many people maybe have heard about it already. The Camarasaurus was around both in Portugal and also in the US, and we found that it had a super, super narrow diet range it fed on. So it was super selective. It had a very, very distinct wear. And that is super uncommon, because imagine we are analysing fossils, they may have been deposited. So maybe these animals died over the course of hundreds of thousands of years, so they are not all from the same exact time mark. But these Camarasaurids, they showed such consistent wear on their teeth, that we think that they were very, very, very specialised on a specific diet, and that they even followed this preferred food source seasonally. So if it was not available in their habitat anymore, they might have migrated.

Chris - Doesn’t being so fussy make them highly vulnerable?

Daniela - Very likely. So I think that had made them sort of vulnerable. And we see that their specific, very narrow diet also differed slightly between the United States and Portugal. Because in Portugal, there was another species of sauropods around, the Pterosaurs. They seem to have preferred the same food sources as the Camarasaurids, and so the Camarasaurids had to slightly shift their food to avoid competition with the Pterosaurs. They seem to have been better in the competition so that they could force Camarasaurids into this other diet.

Chris - It’s an amazing window into the past, what you've unlocked here, isn’t it? The other intriguing thing you mentioned was that the dirt and dust that's on the plant material also imparts almost like a fingerprint, tooth wear pattern. So you're also seeing past climate, dust, dryness, and so on. Are there any intriguing possibilities emerging from that? Or are you seeing things that we've previously not had an opportunity to study through that?

Daniela - Yes, definitely. We found that the sauropods from Tanzania showed a very, very different wear pattern compared to all other species in our study. We were kind of surprised by that, because they are from a group called Brachysaurids, so very tall, very long-necked animals feeding probably in the canopy, so in the high trees. It was kind of surprising that they were so different in Tanzania. So we looked a bit into the available climate record, and we actually found that there was a huge desert belt very close to the area where our dinosaurs lived. It's very likely that sand was basically blown onto the plants, and they had to munch on it when they fed. They couldn't really avoid it, and it's something we see today in the African savannah, for example. That's exactly what we found in the dinosaurs from Tendaguru in Tanzania. So it's really cool if we have these different methods that help us to better reconstruct the past environment and climate.