Okay, but how terrifying were terror birds?

Coming up on this episode of OK, But Birds. Large to gigantic terroberts are about two meters and three meters tall and 100, 120, 150 kilograms. That's huge. Imagine you're standing in a grassland in South America 10 million years ago. The grass is past your knees. It's hot. It smells like dust and like rain that hasn't arrived yet.

Out on the plain, there's a herd of grazers, long necks, slender legs, something between a camel and a horse, but neither. Past them, heavier animals, rhino-shaped, cropping grass with big rodent front teeth. At the tree line, something the size of a bull is standing up on its hind legs, hooking branches down with claws as long as your hand.

Low in front of it, an armored thing roughly the shape and size of a Volkswagen. None of it is familiar because South America spent more than 30 million years as an island. No Panama, no land bridge, just open ocean between this continent and everything else alive on Earth. Which raises the obvious question, something is eating all of that, but what?

It's not. If you pictured a big cat, that's a reasonable guess, and it's wrong. There are no cats here, no dogs, no bears, no hyenas. The entire carnivore and lineage is an ocean away. So evolution led to a different group of organisms filling the role that we typically think of big cats or wolves or bears filling.

And one of the animals that got the job stood 10 feet tall, ran on two legs, wore coarse hair-like feathers, and carried a head the size of a horse's skull with a hooked beak on the front of it. And it was the apex predator of an entire continent for tens of millions of years. Which brings us to the topic of today's episode.

Okay, but how terrifying were terror birds? To help us explore this topic, I'm joined by paleontologist Dr. Federico Dino de Grange. After the break, Dino walks us through what a terror bird skull was actually built to do. Video on. These skulls are nuts. We also get into how many kinds there really were and what these animals looked like alive.

And we talk about what happened when the ocean between North and South America finally closed. Stay tuned. Welcome back to the podcast, everyone. I'm really excited to have Dino here today to talk all about terror birds. Thanks for joining us. Thanks for inviting me. Hi to everyone. Yeah, of course. Well, before we get into the terror part of it all, can you just tell us what a terror bird is and when they lived and where you would have run into one?

Well, a terror bird is a group of cariami forms. Cariami forms were highly diverse during most of the Cenozoic, but they are only represented today by two species, the ceriemas, the black-legged ceriema and the red-legged ceriema. which is the most closely related bird to this family, Forus racidae, the popularly known as terraports.

Most remains actually come from Argentina, from my country. But there are remains from Chile, Uruguay, Brazil, Peru, Colombia, and from the States, Texas and Florida. Oh, cool. I didn't know that there were Texas and Florida fossils. That's really cool. Those remains actually belong to a larger pterovert called Titanis Wild Lady, which is one of the youngest pteroverts known.

Okay. And pteroverts actually live from the Middle Miocene. We are talking about 45, between 45 and 50 million years ago, to actually only... 25,000 years. Wow. And they were characterized by having narrow pelvis, slender high limbs, reduced forelimbs, and... Probably what is the most characteristic feature is the skull.

The skull of a terror bird looks like this. Wow, that's amazing. This is a real-size skull. This is a 3D printing of a terror bird. It's called Andalgalornis. from Catamarca province. And basically, what you can see here is that the beak is quite long, it's narrow, and it's, sorry, tall, and it's tall.

And it's hollow also. Okay. But, What is actually the main feature of a terror bear, of a frutus raci, as we call it here in Argentina, is the lack of cranial kinesis. Cranial kinesis is, I have here a skull of an eagle. It's basically the possibility to flex upward and downward the beak regarding, I don't know if it's possible to see it there, Yeah, we can see it moving a little bit.

Yeah, the upper mandible moves a little bit up and down. Yeah. But one thing I want to ask about that skull that you have. So that's a 3D printed replica of an actual fossil. Is that one of the larger species or is that like medium-sized? Actually, it's a medium-sized. The largest skull known for a bird belongs to a terror bird called Kelenken.

The skull size is about 71 centimeters long. Wow, 71 centimeters. That's like three quarters of a meter long. That's so big. Wow, okay. Well, the name Terrorbird, as I understand it, came from a paleontologist in 1978, and it really stuck. So now, you know, when I teach ornithology, I mentioned the Terrorbirds.

Often my students are like... Can we talk about terror birds? Because it's such a very popular name and it strikes a certain thought into your head. And you've said the popular image does not match the actual fossils. So what's wrong with the picture in people's heads? And tell us a bit more about this name, terror bird.

Based on what we know, based on morphology and isotopes, the terror birds live in spaces with open savannas, spaces with rivers and wetlands and more enclosed areas with small trees and shrubs. Okay, cool. I mean, often when you see a drawing of a terror bird in some setting that an artist has created, they're on grasslands, but it wasn't just grasslands.

There were grasslands, wetlands, and then small trees and shrubby areas as well. Cool. And this goes to the question that you made regarding Larry Marshall. Barry Marshall was the paleontologist that called terror birds based on actually this guy, Andalgalornis. Okay. I mean, that is terrifying. It is terrifying, yes, yes, yes.

It is terrifying. And he actually, he had a point of what they were, should be named terror birds. And this is because we are talking about this animal, Andalgalornis, is about... 140, 1 meter 40 centimeters, 1 meter 50 centimeters tall. That's a medium-sized tero bird. Yeah, medium-sized, a meter and a half.

Medium-sized, about 40 kilograms. That is a medium-sized tero bird. A small-sized tero bird, or at the moment, let's call it for strassets, actually. A small-sized for strassets is about... 90 centimeters tall. Okay. And about 5 to 10 kilograms. Okay. And the really small ones, we think, were maybe capable of clumsy flights.

Oh, cool. Like Ceriemas. Right, yeah. The medium and largest were fully flightless, right? Flightless, yeah. And also they have, compared to these smaller forustracid, medium size and especially large sterobars, have highly reduced forelimbs. Okay. What about the large size? Well, this is where the thing comes, it gets terrorific because actually large to gigantic sterobars are about two meters and three meters tall in 100, 120, 150 kilograms.

That's huge. Yeah. It is huge. It is huge. But Larry Marshall actually thought that these animals were, these animals were fast runners. Tervers were undoubtedly fast runners. But he actually thought at the moment that Tervers killed using their legs. So he, his hypothesis was that Tervers run, pursue praise.

And once they reach the praise, actually they kick the praise in order to, to, to subdue, subdue them. Yeah. Sorry for my English audience. No, you're great. I mean, if we were doing this in Spanish, no one would be able to understand me at all. So you're awesome. And based on this animal, which clearly had like a head that looks terrorific, he thought, oh, these animals had to be like...

very scareful and scary, sorry, scary and terrorific. So the terror birds. And actually it's a name that stuck. It really stuck, yeah. It really stuck because actually he, Marshall, I mean, he didn't consider the small terror birds, which doesn't look so terrorific. If you see this, actually it's a huge skull for a pair, but smaller terror birds, the xylopterines, are actually even smaller.

A skull of a xylopterine is about this size. We have a say here that it's like... All terror birds are foros racids, but not all foros racids are terror birds. I think that's nice, yeah. It's important to notice that actually when Marshall actually named terror birds, named the foros racids as terror birds, terror birds were already known for almost 90 years.

Oh, okay. Interesting. The first Forusracid species thought to be a mammal is actually Forusracos longhissimus, the species that give the name to the family, in 1887. Wow. by one of the main paleontologists of the Argentinian paleontological history, Florentino Meino. And Forus racos actually was one of these gigantic, really large-sized terror birds.

Yeah, I guess it also makes sense that those fossils would attract a lot of attention and someone would want to describe them and try to figure out what they were from because they are quite astounding. You put a terror bird skull through a CT scanner... And ran physics on it. So you've been talking about the kinesis of the skull, the fact that these larger terror birds, their bill doesn't move up the way a lot of other bird bills can.

What did the bite tell you about how these birds actually killed their prey? We use these scans to work on biomechanical 3D modeling using an engineering technique called finite element analysis, for which we had to estimate byte force. We didn't get the byte force from the scans. We had to, using byte data available of extant species, make regressions and estimate byte force.

And we discovered that actually it reverses byte force. But the most interesting thing that we find using this finite element analysis is that servers couldn't do like this. They couldn't grab a break and shake it later. Servers didn't kill using the legs. The legs may work as a tool for pressing the prey against the ground once the terror bear killed it and had to dismember it.

But to kill the prey first, they had to use very precise hatchet-like strikes. So basically the turtle bear was chasing you and once it was close to you, it just opened the mouse and do like... Oh, interesting. It acts like movements in order to kill the prey. This tall beak, which is very tall actually, compared with other birds, it's highly resistant to forces directed upwards.

Okay. I mean, I can understand the original hypothesis about kicking because some contemporary birds of prey, like I think of secretary birds kicking snakes to death. So I can understand thinking that, but it's very cool that it probably was they were using these massive bills to take out their prey.

And what kinds of things were they eating then? I mean, mammals or other birds, all of the above? We think that probably mammals, running mammals, because these clearly terroberts are suit for chasing. Santa Cruz formation is important because actually it's the only place where we can find four species of pterobird.

Okay, so multiple species of pterobird were occurring in the same places, eating different things. Two small species, one medium-sized species, and a large species. Oh, cool. So we know... that based on body size, there is a niche separation. Terra birds were considered as apex predators during the Cenozoid together with crocodiles and marsupials.

And we think that based on this body size, differentiation between these species allow a clear separation of the niche species. From the fossil record then, it seems unlikely that there were any vegetarian terror birds. Like they were all predatory, just predators of different sizes of other things. All predatory.

All predators. So I mean, still, we could, that's still terrifying depending on what size you are. If you're a little mouse, one of the small terror birds would still be pretty scary. In 2010, so there was this nearly complete terror bird skeleton discovered in Argentina and you were able to work out what it could hear.

Can you tell us more about that? That is actually this guy. Oh, cool. Okay. Yeah. It's the most complete skeleton of a terror bird ever found. Oh, cool. My friend who discovered it called me from the outcrops. Oh, really? Oh, that must have been a great phone call. He called me. He was in the outcrops.

taking the skeleton out of the rock. And he called me like, we found the terror bird, we found the terror bird. The skull is so beautifully preserved that allow us to make CT scans. And with those CT scans, we were able to reconstruct the real size brain of a terror bird and the inner ear. Based on inner ear morphology, we know that semicircular canals of the ear, these parts of the ear that are related with spatial orientation and equilibrium, are quite long and slender, indicated fast animal.

The part of the inner ear related with hearing allow us to estimate hearing range, telling us that basically all turverts have low hearing range frequency. Low frequency sounds, yeah. Suffer less modifications during transportation in the air. Right. They are less modified, so you can hear farther. Right, yeah.

Elephants use low-frequency sounds to communicate across really long distances in similar open habitats as maybe terror birds were living in, right? Yes, exactly. So it's important to say here that this doesn't mean that we know exactly what they eat or how was the sound production of terror birds, except if you can hear low-frequency range, obviously you produce low-frequency sounds.

Yeah, it's interesting to think about like what we can and can't infer. I mean, it's frustrating to me as a population geneticist what I like I can't go back and watch what happened. I just have to infer what happened from the genomes of the things I sequence and just like same with paleontology, you can make edifices.

guesses about these things. But it's really cool that just based on the inner ear, you can have a pretty solid hypothesis that these things could run really fast, that they could hear these low frequency sounds, maybe because that was a way to detect prey or maybe because that's how they were communicating like open savanna species.

A few years ago, a bone turned up in Colombia. That might be the biggest terror bird ever found. And it had bite marks on it. Can you tell us a Yeah, actually there are two bones from that area. We published a more recently paper with an even larger terrober than the one that you are mentioning. From the same area in Colombia?

Same area in Colombia. Cool. And these tooth marks indicate us terroberts suffer predation. So there were things eating terroberts. Even the big ones, which is impressive. Even the big ones. But it's important to state that in the area where, in La Venta, the locality where this animal was found, also there are large crocodiles known, fossil crocodiles known.

And those marks are actually from one of those crocodiles. What we don't know if the turban was dead when it was... beaten or it was directly hunted by this grotto what have people been able to figure out about why we don't have terror birds anymore what happened to them We still don't know. Sorry. No, that's, I mean, that's the thing.

I think there are a lot of these outstanding questions and it should motivate more research for sure. Nevertheless, we have some ideas and probably it is a combination of things. One is related to environmental change. Terbers were apex predator, but... Terrapers probably were not any apex predator, were highly specialized predators apex predator and late myosin, early pliocin, great American biotic interchange occur.

Yeah, I was wondering about the great biotic interchange between when North America and South America finally were connected together by the Isthmus of Panama. You had this movement of certain, well, the camelids went down, right? Because camelids evolved elsewhere and then colonized South America. So now you have guanacos and vicuñas and other things.

And some predator mammals also moved into South America, which I was wondering exactly about this. Not only camelids, most jungulates and canids, felids, prosionids, a lot of carnivore placental mamas. So environmental changing, prey, disappearance and competition with another less animal. specialized, let's say, predators, were probably the driving of terrobert extinction.

It is not weird, actually, that our last record of a terrobert, it's one of the smallest species. It's about five kilograms. It's escatornis aterradora, from the very late Pleistocene, a species from the very late Pleistocene of Brazil, which is considered one of these species a terrober that probably were more generalist based on body size.

It was able to reach not only prey, but probably carry on or take advantage of feeding resources that medium to large terroberts were not able to. Yeah, it makes sense that the generalist would maybe survive longer. And it's also interesting that it wasn't just that all these organisms invaded South America where terror birds were, they also seemed to have moved north, right?

That's how they would have crossed the Isthmus of Panama as well. Is there any evidence that any of those canids or cats, ophelid predators that invaded South America preyed directly on terror birds? Would you? There's no evidence from the fossil record. No, we don't have the activity. But maybe, I guess.

Although I wouldn't want to go up against a two and a half meter tall bird with a giant beak that could cut into me. But you never know, I suppose. All right, we've reached the part of the show we call That's BS or That's Bird Stuff, where we give our guests an opportunity to debunk a myth that ruffles their feathers.

So Dino, what do you want to call BS on? I want to call two BS. All right, go for it. One about terror birds and one about serimas, because there are not too many BS about terror birds. But I have read somewhere that actually there are still terror birds in Amazonia. So people, don't worry. There are no terror birds on Amazonia living there somewhere.

I mean, if you want to get lost in Amazonia rainforest, go for it. But don't worry. Probably you will get killed by another thing and not a terror. Not a terror, right? And the other one is about seriemas. Actually, when I was doing my PhD, I was looking to... for serimas. Since they are the most related extant birds to terro birds, to forstracids, I wanted to see how they live.

I wanted to see a living serima, not in zoos, in the natural environment. And And you hear a lot of myths about these beautiful, beautiful, beautiful birds. And amazing, amazing birds, actually. A farmer from there told me that they taste really good with noodles. And they also, serimas, like noodles.

They like noodles. Okay. They like noodles and they taste good. You can cook them with noodles. Okay. And I honestly, I couldn't check any of those. So sorry. And the other one is that they actually like to run. The seriemats are really fast. They can run until up to 40 kilograms an hour. So apparently they like to run faster.

With the cars. So if you go into dirt streets, apparently if you go fast, the Seriemas have this instinct of going and, oh, there's a car, I have to run with it. And sorry, no. That is the myth. It doesn't work. I tried several times and I didn't see any Seriemas. Actually, it's... It took me like a long, they are hard to see here in Argentina.

In Brazil, it's more common, but it took me a long, long time to see several ceremas in the field, in the area where I was. So those, I hope that you enjoy my BS. Yeah, no, myths busted. Don't try to feed ceremas noodles. And if you want to find them, don't drive a car fast because that's not going to attract them.

Well, thanks so much for joining us on the podcast, Dino. It's been really awesome to learn more about Terror Birds. And I appreciate you taking the time to talk to us. Again, thank you for inviting me. It was a pleasure. And if I say some last words... Yeah. I suppose that you are going to use the birth sound here because I have to say it.

Sorry. I have to take this out of my system. For all the people who is hearing this amazing podcast, I have to tell you that terrober, it's not only the best group of vertebrates that they ever live. They are just animals. amazing. They are. They are insane. So you have to use the sound several times.

No worries. No, they're incredible birds and it's been awesome to learn more about them. There were a lot of things today I did not know, so I really appreciate it. Birds are dinosaurs and around here we like our snacks, so we end each episode with a dinosaur nugget. Today's nugget is, terror birds are gone, but their closest living relatives are not.

They're called ceriemas. There are two species, both still walking around South America right now. They're just over two feet tall. They can fly, but mostly don't bother. And they look like a chicken that got stretched. They also still hunt like the family used to. A ceriuma grabs a lizard or a snake, picks it up, and beats it against the ground until it stops moving.

Same continent, same grassland. Roughly 1 20th the size. That's a wrap on this week's episode. Okay, but how terrifying were terror birds? If you like this one, help us out. Leave a rating or a review of five stars, obviously. We'll catch you next time. Byeeee. Okay, But... Birds is hosted by Scott Taylor with production and creative by Zach Karl.

Okay, but how terrifying were terror birds?

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