IRA FLATOW, host:
This is TALK OF THE NATION/SCIENCE FRIDAY. I'm Ira Flatow.
A little bit later in the hour, we'll talk with marine biologist and undersea explorer Sylvia Earle. But first, perhaps you heard last week about the new species of ancient crocodile found in Patagonia and dubbed Godzilla for its hefty size and T. rex-like snout. And last month marked the debut of a new birdlike dinosaur, a cousin of Velociraptor, the oldest of its kind ever found in South America. With its long winglike forelimbs, could this new dinosaur settle once and for all that debate over whether the earliest birds were direct descendants of dinosaurs like these? Well, we'll talk about it. We're going to start this hour with dinosaur news, and if you'd like to join our discussion, give us a call. Our number: 1 (800) 989-8255, 1 (800) 989-TALK. And as always, you can surf over to our Web site at sciencefriday.com, and I suggest you go there now, because we have a photo of one of the dinosaurs up there that we're going to be talking about when you click on this hour's program.
Let me introduce my guest, Peter Makovicky is an assistant curator of paleontology at the Field Museum in Chicago, Illinois. He joins us today from his office there.
Welcome to the program.
Dr. PETER MAKOVICKY (Assistant Curator of Paleontology, Chicago Field Museum): Thank you, Ira. Thanks for being--for inviting me on.
FLATOW: You're welcome. Let's first talk about this incredible-looking Godzilla crocodile from last week's Science. It really does look like a cross between a T. rex and something that would slither around in the water.
Dr. MAKOVICKY: Yeah. This animal, which is named Dakosaurus, is quite unique. It belongs to a family of exclusively marine crocodiles called teleosaurs that lived during the age of dinosaurs. And the strange thing, as you noted, is its skull. All other teleosaurs have a very long, thin skull and sort of snaggleteeth in it, adapted for biting fish or catching fish. This animal, on the other hand, looks like it went for substantially larger prey and had the equipment to do so.
FLATOW: Huge teeth on this thing.
Dr. MAKOVICKY: Yeah, very large teeth and very massive jaws. The jaws are relatively short, which gives them sort of a more powerful bite, and they're much more massive, so they're clearly designed to really damage some poor, hapless victim.
FLATOW: Wow. Did it have the other parts of the body that look like a present-day crocodile, the four limbs, the giant tail behind it?
Dr. MAKOVICKY: Yeah, well, the teleosaurs are, as I said, exceptionally adapted for marine environments. So they'd actually converted their limbs into paddles. Over evolutionary time, their legs had actually become paddles. So they would probably have been pretty useless on land. And they also evolved a fin along the back end of the tail, sort of similar to what you'd see in an eel or a sort of long fish like that.
FLATOW: So it is a true crocodile, then?
Dr. MAKOVICKY: It's a more primitive lineage of crocodile than the ones that are around today. The animals we have around today, called the eusuchians or Crocodilia, are a little more derived. This is an evolutionary side branch that sort of emerged in the Jurassic period and sort of became this radiation of marine predators, if you will.
FLATOW: Right. But it does have this head that really, as we say, with a full set of teeth in it, a head that could have been a Tyrannosaurus rex. It did have this head that's more like a land reptile than what we would have thought fish--the sort of thing that lived in the water, like it looks like this thing did.
Dr. MAKOVICKY: Yeah, absolutely. It's a very surprising head, especially since teleosaurs are not uncommon fossils, and quite a few of them have been found, and they all seem to have this very sort of conserved pattern of having this long, very narrow snout with snaggleteeth for catching fish. And then to find this guy with an extremely different skull shape, clearly adapted for something else, is quite something.
FLATOW: Yeah. Is this an evolutionary period here, then? Are we seeing transitions possibly with this kind of animal?
Dr. MAKOVICKY: What I think you see is really a result of this radiation. As I said, the teleosaurus sort of--during the age of dinosaurs, a lot of different reptile groups with land-living ancestors sort of reinvaded the watery environment and the seas. And so you had plesiosaurs and ichthyosaurs, and you also have this lineage of crocodiles, the teleosaurs, doing it. And I think simply that as they invaded what was essentially a new environment, a lot of new habitats and niches opened to them and so some of them became specialized fish-eaters, at least the majority of them, but then now we actually have found these guys who evolved in a slightly different direction to become sort of macropredators. They preyed on probably the other marine reptiles that were around at that time.
FLATOW: Right. Let's talk now about something different, the discovery that you reported, a new species of dinosaur in Argentina that was the subject of a Nature--a paper in Nature last month. Tell us about this dinosaur and what makes it so unusual.
Dr. MAKOVICKY: This dinosaur is quite remarkably different from the animal I just talked about. It's first of all much smaller. It's sort of about the weight of a rooster and then has slightly longer legs and a head and, of course, a very long tail, as most dinosaurs do. And it's about five feet long, as I sort of intimated, and it's a rather fast animal, very long hind limbs, very lightly built. And it belongs to the same family as Velociraptor. The family is known as the Dromaeosauridae. And the interesting thing about this animal is that it's sort of the best evidence we have so far for the presence of this family, Dromaeosauridae, on the continents of the Southern Hemisphere. Up till now, their distribution seemed to be exclusively on the Northern Hemisphere.
FLATOW: And so this really looks like it might have been--did it have feathers and things like that that would put it in the bird family?
Dr. MAKOVICKY: Well, the animal has a lot of very birdlike features of its skeleton. For example, it has a very massive and hollow wishbone. It has very long forelimbs that are almost winglike in its proportions, and it shares with birds a number of other features in the hip region and in the hind limbs. So it is very birdlike. The rocks we found it in unfortunately don't preserve any of the soft tissues of the animal. So we don't have direct evidence of feathers in this animal. But it's a very close relative of some animals that have been found in China, other Dromaeosaurs, that have been found in fossil layers that do preserve very beautifully the soft integument of these animals, and those have feathers. So pretty much in the same way if we were to reconstruct sort of the australopithecine Lucy, we'd put hair on it, 'cause it's a mammal like us and it has hair; we'd put feathers on this animal, too.
FLATOW: And so what's so significant about finding it in South America?
Dr. MAKOVICKY: Yeah. Well, during the Jurassic period, the time in which, for example, Dakosaurus lived, and the preceding part of the age of dinosaurs, all the continents of the world were gathered together in one large supercontinent which we call Pangaea. During the last third of the age of dinosaurs, the Cretaceous period, these continents started splitting apart, first into a northern and a southern land mass and then subsequently more into the configuration we see today. And so because most of the--if not--well, actually all the Dromaeosaurs we knew until now occurred in the Cretaceous and on northern continents. Most of the evidence suggested that these animals were, in fact, evolving in the Cretaceous after the continents split apart. Now that we have very good evidence that there's a southern branch of this family, we can surmise that Dromaeosaurs, in fact, have a much older evolutionary history. They must have been around in the Jurassic period. Their common ancestors were distributed on all continents, and then in the Cretaceous, once the continents split, then you had them evolving into two separate lineages, the northern ones that led to Velociraptor and the more familiar animals we know and then a southern lineage that led to Buitreraptor.
FLATOW: So there was a split there?
Dr. MAKOVICKY: Yeah.
FLATOW: Yeah, you have--put another branch on the family tree.
Dr. MAKOVICKY: So to speak, yeah.
FLATOW: So--but this dinosaur didn't fly. You know, it's not like a turkey that might have feathers and flap its wings but not get off the ground?
Dr. MAKOVICKY: Actually that's only domestic turkeys, since we're talking about Thanksgiving.
FLATOW: Right. I...
Dr. MAKOVICKY: Wild turkeys will fly.
FLATOW: They do in my back yard.
Dr. MAKOVICKY: Yeah. And they're quite the sight to see taking off...
Dr. MAKOVICKY: ...almost like a helicopter.
Dr. MAKOVICKY: The reason we think this animal didn't fly is basically that although, as I mentioned the forelimbs are very long, they're not quite the same length in proportion to the body as in, for example, Archeopteryx, the earliest known bird. They're close to that but not quite. So, you know, another 10, 15 percent and we'd be there.
But most of the sort of the anatomy, that is the shape and direction of the shoulder girdle that would allow a winglike beat to the forelimb, the muscle attachment area on the shoulder and on the wishbone is as well-developed if not better than in some of these early birds. So...
Dr. MAKOVICKY: ...certainly a lot of the hardware, the evolutionary hardware, if you will, that would have been required for the evolution of flight was shared by this animal as well as the earliest birds.
FLATOW: And in the final minute or so that we have there, let's talk a bit about this week in science. Researchers were reporting on the first grass-eating dinosaurs, that they found evidence in the dung of dinosaurs that they ate grass.
Dr. MAKOVICKY: Yeah, that's quite a substantial and important study, because grasses so far have really only been known from the Cenozoic; that is, from the period after the age of dinosaurs. But recent work based on DNA studies--that is, the relationships of grasses elucidated from their genetic material--suggests they might, in fact, be older and would have been around alongside the dinosaurs. So in this very neat study, the scientists--it was a team of Indian and Swedish scientists actually--looked for a new source of information. They went to fossilized dung of large sauropods, Titanosaurs, animals that looked sort of like Brachiosaurus but were somewhat younger in the geological record. And there they found little crystallizations called phytoliths which grasses deposit in their stems and which are fairly unique in their shape and size for grasses ...(unintelligible).
FLATOW: So it tells us more about what grasses were growing at that time...
Dr. MAKOVICKY: Yeah.
FLATOW: ...if anything else.
Dr. MAKOVICKY: And it turns out that quite a few of the modern families of grasses were there alongside the dinosaurs, and they apparently ingested some of them, although from the remains of the dung, it looks like the dinosaurs were sort of fairly liberal as to their choice of food. They kind of ate pretty much any kind of plant they could get at.
FLATOW: Could it be that they--so now we have to look at a little bit of the biology that was going on at that time. That's interesting.
Dr. MAKOVICKY: Yeah, absolutely. The interesting thing about grass is, of course, that grasslands are now one of the main biomes of our world, and those don't show up till much later...
Dr. MAKOVICKY: ...because grasses are adapted to dry, cold climates. So the question now is, where and what environments were they living in during the much warmer and wetter, you know, time of the dinosaurs?
FLATOW: Well, Dr. Makovicky, we're going to have to leave it there and come back to that question and answer it later, 'cause we've run out of time. I want to thank you for taking time to join us today.
Dr. MAKOVICKY: All right. Well, thanks for having me on, Ira.
FLATOW: You're welcome. Peter Makovicky, assistant curator of paleontology at the Field Museum in Chicago.
Short break. When we come back, we're going to be joined by--well, you know her, Sylvia Earle. So she needs no introduction. She'll get one after this break. Stay with us.
I'm Ira Flatow. This is TALK OF THE NATION/SCIENCE FRIDAY from NPR News.
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