Teeth from Diamantinasaurus

Transcript: Episode 11: Hidden Vultures and Sauropod Teeth

This is a transcript of Episode 11 – Research Journal: Hidden Vultures and Sauropod Teeth.

Travis Holland 0:07
Welcome to Fossils and Fiction, a podcast exploring cultural and scientific ideas about dinosaurs.

Hi, I’m Travis Holland. This episode is another in the research journal format. I speak with two researchers who have recently published papers and a new evidence about the diversity of ancient life in Australia. First up is Dr. Ellen Mather from Flinders University, speaking about the redescription of a long-known eagle, as instead being from an extinct species of vulture. Secondly, we have Dr. Stephen Poropat, who reports on a trove of sauropod teeth from Winton, Queensland.

Ellen Mather 1:14
I’m Dr. Ellen Mather, from working at Flinders University paleontology lab. So this research was part of my PhD project, which was looking at fossil eagles from Australia we’re specifically looking at I’m describing and determining the taxonomy of species that hadn’t been formally described yet. And so it’s been pretty good to get this out and formally published so the world can know a bit more about the, our extinct fauna and also looking forward to getting the rest out as well.

Travis Holland 1:50
Could you tell me about your vulture?

Unknown Speaker 1:53
This vulture actually has quite a storied history. So species itself was originally described back in 1905, by an ornithogolist in Queensland called Charles Walter de Vris. And he named it they came from a fossil that was found in northern South Australia, distal humerus along the Warburton River, and he named it Taphaetus lacertosus, which means powerful grave Eagle. Now, over the course of the 20th century, other paleontologists started looking at this fossil and thinking maybe this isn’t an eagle, maybe it’s a vulture. But for the most part, these are just suggestions rather than actual in depth study. And so my research really wanted to go into detail and confirm whether or not this was actually the case.

Travis Holland 2:42
Great. And so what did you actually do you reevaluated the fossil itself, and then found some other evidence as well?

Ellen Mather 2:49
at the time, we couldn’t get direct access to the fossil. So the Queensland Museum was kind enough to allow us to scan the original fossils. So we could look at the scan data and compare it for that. But we also were fortunate enough to identify more material of this species that came from the Wellington case in New South Wales, which the Australian Museum leant to us. And so this material included two fragments of distal humeri identical to the fossil from the Warburton River, and also a metatarsal. So the lower leg bone about that that was the right size that we’d expect for this, the same species. Under normal circumstances, this discovery would have just in a reassignment of its taxonomic affinities, and not resulted in a name change. So it would still be Taphaetus. But the thing is that de Vris actually made a bit of a mistake when he named it that you’d actually use the name to pay to us about five or 10 years prior for another species. And under taxonomic rules, you can’t use the same name multiple times for different things that kind of makes things a bit of a mess when you’re trying to understand how they’re related to each other. So the name of Tahaetus was effectively invalid. So we had to come up with a new name.

Travis Holland 4:12
What was the new name? Do you want to explain that a little bit? .

Ellen Mather 4:14
Yep, so the new name we gave the species was Cryptogyps lacertosus. So keeping the species name but giving it a new Genus name. So Cryptogyps, literally translated means hidden vulture. So we chose this name to reflect how this species had been sort of hiding in plain sight as an eagle for over a century.

Travis Holland 4:34
What implications do you think it has for realizing that there were vultures in the Australian landscape during the Pleistocene, rather than just just the Eagles?

Ellen Mather 4:43
So it definitely has us reinterpreting like the biodiversity of large birds of prey in Australia. So we now know that during the Pleistocene, there were there were a much more diverse group, but it also has broader implications as well for our ecosystems function back then. So vultures are wherever they’re found, play pretty vital roles in ecosystems as scavengers. So they help consume and break down carcasses rapidly. And they also prevent the spread of diseases from they also prevent the spread of disease. So as you can imagine, when vultures are removed from an environment, that means that carcasses tend to persist in the environment for much longer, you get diseases spreading much, you get diseases becoming much more widespread in ways that they wouldn’t have previously. And you also get other species becoming, you also get other species that will now try to fill that niche that vultures were occupying. And that can result in ecosystems, or restructuring and rebalancing as populations shift and dynamics are altered.

Travis Holland 5:57
What do you think the environment looked like when these falters were roaming the landscape?

Ellen Mather 6:02
So at the time, the Australian environment would have been pretty ideal for a vulture. So you’d have lots of megafaunal animals roaming around, you’d have Diprotodon, so you’re getting loads big megafaunal animals that could have provided these carcasses for vultures to survive on interestingly, and so we’d have these vultures, we’d also have most of the modern fauna around back then too, so there would still be the Wedge Tailed Eagle, there’d still be our kangaroos. So in some ways, the modern fauna is just a slightly is really just the reduced aspect of the Pleistocene fauna.

Stephen Poropat 6:53
My name is Dr. Steven Poropat. I am currently a postdoctoral researcher at Curtin University. But while I was doing this research, I was an adjunct at Swinburne University of Technology. And I’m also a research associate with the Australian Age of Dinosaurs Museum in Winton Central Queensland.

Travis Holland 7:15
Right, would you tell me, I’ll give some background on the Winton Formation and what’s been found there so far?

Stephen Poropat 7:23
Yeah, so the Winton Formation is a rock unit that is between about 101 to 93 million years old, across its full extent. In Winston, the rocks tend to be towards the upper end of that, about 98 to 95 or 94 million years old. And these, the rocks that formed the Winton Formation were deposited on a very flat floodplain. And so you know, Winston today is quite flat 95 to 98 million years ago, it was probably just as flat as it is now. But instead of being scrubby grassland this deposit was actually formed when Winton was covered in forest. The dominant trees forming the canopy would have been conifers, so relatives of modern day bunya, cowrie and hoop pines. But then in the understory, there would have been flowering plants like angi- or angiosperms, they would have been ginko. There would have been cycads and ferns, no grass whatsoever, because it hadn’t evolved yet. And yeah, just and horsetails were the other dominant plant group that lined the waterways, so fossils of all those different plants have been found in the Winton area.

But in addition to that, of course, there are multiple lines of evidence to suggest that animals were there as well. We often find freshwater bivalves so related to modern day unioide bivalves, we find evidence of freshwater turtles, freshwater crocodiles, well are crocodile relatives anyway, they’re not true crocodiles. And there have been two species named to this point one’s called Isisfordia duncarni fromIsisford, the other is Confractosuchus soroktonis from near Winston and that one’s particularly notable because it was found with a dinosaur in its belly. So it was predating on or at least eating small bodied dinosaurs. And in addition to that, of course, you’ve got lungfish tooth plates, so lungfish still live in Queensland today but in a very restricted area I think it’s the Murray River now – you know 95 million years ago they were Australia wide and we find that to plates in many many fossil deposits and Winton is no exception. Additional to that you have the occasional bony fish in the freshwater deposits there’s a possible – there’s definitely a lizard but what type of lizard it is, we’re not sure it’s either related to modern day goannas or its designers or it’s [unknown] related to mosasaurs the older really big ocean going live sense of the Mesozoic or Cretaceous period.

But of course then dinosaurs what I think most people want to hear about. And yet, there are at least four different groups of dinosaurs represented in the Winton area. In addition to all the fossils that I’ve talked about that to this point. We have theropod dinosaurs, primary among them being Australovenator wintonensis, a megaraptorid found near Winton in 2005. We have ankylosaurs, so armoured dinosaurs, very rare evidence of them a few teeth and a few other bones that haven’t been described yet. Ornithopods, mostly known from their footprints, rather than any fossil evidence beyond the one that was found inside Chookie, or Confractosuchys. The most common dinosaur fossils found by far are those of sauropods. big, long net herbivorous dinosaurs that were evidently dominant in this area 95 to 98 million years ago.

Travis Holland 10:52
Yeah, so all that plant life forms a rich variety of food for some of those saw reports, and particularly, I think Diamantinasaurus, one of the ones that from the area.

Stephen Poropat 11:07
That’s right.

Travis Holland 11:08
And this particular research paper that we’re going to talk about today, you found a range of teeth are assembled in a series of teeth, I think from from the from the region, including some from Diamantinasaurus. Tell us about the teeth.

Stephen Poropat 11:22
Yeah, so basically, before 2000 or 2017, rather than out of 2017 2019. Before 2019. We didn’t have any definitive sauropod tastes that we could point to a say, Yes, this is a Sauropod tooth from the whole the Winton area. And that was despite the fact that over the past 20 years now we were 17 years then, the Australian Age of Dinosaurs Museum had excavated probably close to three dozen sauropod sites across the region. So to not find any teeth from sauropods was really unusual. And the main reason for that is that, like reptiles today, especially crocodiles, sauropods would have continually replaced the teeth in their jaws throughout the course of their lifetime. They didn’t just have baby teeth, or milk teeth, and then adult teeth like we do. They, as soon as the truth wore out, it would be lost, shed, and they’d replace it. In some sauropods, it’s not unusual to see six replacement teeth per socket lined up ready to go. In other sauropods, you might only see one or two lined up ready to go, they’re using their teeth for longer and replacing them less often. So there were many reasons that we thought we should be finding them, but we just weren’t. And then had this one site, which we called the Mitchell site. In 2019, we found a dozen teeth throughout the entire dig season, which was about three weeks in duration. And then a follow up dig to the same site in 2021, produced another five from the same site.

What those teeth also provided us with, of course, was a search image, go through the collections that have been assembled to that point, and see if we could find anything that looked like the teeth that we were finding at the Mitchell site, which were undoubtedly sauropod, and sure enough, from the original Diamantinasaurus site, which was called the Matilda site. So it produced the skeleton of Diamantinasaurus that bears the name also the skeleton of Australovenator that bears the name of the best skeleton of that animal so far. And there was a bit of jaw with two teeth lodged in it that came from that site, that looked as if it had possibly been chewed up and eaten by a carnivorous dinosaur or a crocodile. And there was also an isolated tooth as well from that site that had been ambiguous until that point. But we realized when we saw these other teeth, it’s got to be from a sauropod. So all of a sudden, we had a few teeth that were probably part of that same individual, the original Diamantinasaurus, and another tooth that was actually found because those were found in 2005, or somewhere between 2005 2010, because the Matilda was dug for five years in a row. But even before that, a site that produced another specimen of Diamantinasaurus that was only recognized as such in 2016, there was a tooth from there too. And it was even better than the ones that came from the Matilda site. So he was associated with us a Diamantinasaurus skeleton nicknamed Alex. So we had teeth from two individuals of Diamantinasaurus, in addition to all these teeth coming out of the Mitchell site. And basically, what that has enabled us to do is say that all of these tastes look very similar to one another. And if they don’t all belong to Diamantinasaurus, they at least belong to a very close relative thereof. So there’s another sauropod from the Winston area called Savannasaurus. There’s one from Eromangah called Australotitan, and there’s another one called Sarmientosaurus from Argentina. All four of them are part of a group of sauropods that are called Diamantinasaurians. We named that group last year because we recognised it as including those animals. And so these teeth are clearly from a Diamantinasaurian, in the case of the Winton ones most likely Diamantinasaurus or Savannasaurus.

Travis Holland 15:11
Where do that where does that group fit within the broader sauropod [inaudible]?

Stephen Poropat 15:20
So, I guess the sauropods that be most familiar to people are things like Diplodocus or Apatosaurus or Brontosaurus. Those are a group that’s very separate from the sauropods we’re talking about. The big group that they belong to is called Macronaria, which just means big nostrils because the only forms in that group have been nostrils things like Giraffatitan and Brachiosaurus have got big nostrils on their on their heads. If you walk a little bit further up the tree, you take this one branch that goes away from those sorts of sauropods, and then radiates in – in the latest Cretaceous, you have a group called titanosaurs. So by the time you hit about 90 million years ago, until the extinction of dinosaurs 66 million years ago, titanosaurs are the only sauropods you find anywhere in the world. And Diamantinasaurus and its relatives are right at the base there on the ground floor of Titanosauria, they are very sort of, we would we don’t use the term primitive, but it’s an easy way to understand their basal titanosaurs.

Travis Holland 16:23
Right. So what are the implications then of the work being able to characterize these teeth finally, and and add them to collections or recognize them as part of those specimens?

Stephen Poropat 16:35
Two big things from my perspective, one relates to you know, what primative Titanosaur teeth look like. And the second, of course, relates to the position of Diamantinasaurians in their ecosystem. So advanced titanosaurs are derived titanosaurs, they have much narrower crown teeth than Diamantinasaurians did. So they tend to be concentrated right to the front of the mouth, they seem to have been replaced really rapidly, because they’re very narrow. They’re not using too many resources to actually make each individual tooth so they’d wear down and be replaced really rapid fire. Diamantinasaurians weren’t doing that. They were they had much more robust teeth. And they presumably then would have replaced them much more slowly, because they would have been quite energetically costly to produce and to replace. And it would seem that they needed to be robust based on what these sauropods were eating. So it’s quite possible that they’re eating very different foods to the derived titanosaurs. Because derived titanosaurs, some of them are clearly specialized for browsing very low to the ground. You see them with sort of squared off muscles, all the teeth forming a row along the front of the mouth. They’re browsing very low to the ground, but Diamantinasaurus and its relatives don’t seem to have been doing that. So one of my co authors PhD candidate Tim Frauenfelder from University of New England in Armidale he looked at the microwear on the sauropod teeth from the Mitchell site, because five of the 17 teeth that were found to the end of 2021 had wear facets on them. So that is part of the tooth where the tooth has been grinding against and adjacent to the tooth in the opposite jaw or against the food that the animals eating. Because sauropods didn’t chew, they just snipped and swallowed, but the teeth still abraided against each other and against whatever they were eating as they were procuring it. And so he looked at the wear facets, and basically was looking for what we call pits, gouges and scratches. Pits and gouges tend to represent bits of sediment or grit being rubbed between teeth. And he found very few of those: in low browsing animals you find a lot. So we can pretty much rule out a very low browsing habit for Diamantinasaurians. So they’re probably feeling at least a meter above the ground. And based on the lakes of their necks and everything else we can put together to reconstruct their feeling envelope, they could possibly reach as high as 10 meters above the ground surface. And so plants within that window, anything could be on the menu, as far as the actual foodstuffs themselves are concerned. Because he found plenty of scratches on these teeth. They were eating something that was somewhat hearty and abrasive. So whether they were stripping bark, or occasionally taking a fresh conifer cone shoots or something like that fruiting bodies from cycads. We don’t know what we will need in future to test this hypothesis, of course, is definitive gut contents in a sauropod. And it’s actually been reported before even though we haven’t finished the research on it, but we do have a sauropod that has got contents preserved from the Winton area. And if we can establish what species that is what’s in its gut, we may well be able to test the interpretations we’ve made based on the teeth.

Travis Holland 19:56
Right. So lots of lots of interesting information coming out there. And I guess they do expect there to be some more of significant finds in the future from Winton and nearby?

Stephen Poropat 20:07
Absolutely. Some of the unpublished stuff that’s in the pipeline, in and of itself will blow people away. I’m hoping there are two main projects that I’m working on a present that including that specimen with the gut contents that will alter our understanding of these sauropods even more, or if not alter, and at least enhance it. And yet, every time we go out into the field, we’re heading out in a matter of four weeks or so we could find something truly groundbreaking pardon the pun.

Travis Holland 20:39
Look forward to more news coming out of the Australian Age of Dinosaurs and the associated institutions. Thanks for joining us.

Stephen Poropat 20:46
Thank you very much. It was it’s been a pleasure.

Travis Holland 20:58
Thanks to Dr. Ellen Mather and Dr. Steven Poropat for their time. If you’re enjoying Fossils and Fiction, we welcome your comments and feedback on social media. Or please consider rating us on your favorite podcast app. Thank you for listening to the Fossils and Fiction podcast produced by me, Travis Holland, with the support of Charles Sturt University. The podcast theme music is Sonora by Quincas Moreia via the YouTube Audio Library. Find more content on our social media channels, Twitter, Facebook, YouTube, Instagram, and Tiktok show notes are available on the website fossilsfiction.co. You can subscribe to the podcast on all major podcasting platforms.

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