Tag Archives: terror bird

Episode 304: Animals of the Paleogene

Thanks to Pranav for suggesting this week’s topic, animals of the Paleogene, the period after the Cretaceous! Thanks also to Llewelly for suggesting the horned screamer, now one of my favorite birds.

Further watching:

Southern Screamers making noise

Horned Screamers making noise

Further reading:

The Brontotheres

Presbyornis looked a lot like a long-legged goose [art by Smokeybjb – CC BY-SA 3.0]

The southern screamer (left) and horned screamer (right), probably the closest living relation to Presbyornis:

Megacerops was really really big:

All four of these illustrated animals are actually megacerops, showing the variation across individuals of nose horn size:

Uintatherium had a really weird skull and big fangs:

Pezosiren didn’t look much like its dugong and manatee descendants:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’re going to look at some strange animals of the Paleogene period, a suggestion from Pranav. Pranav also suggested the naked mole-rat that we talked about in episode 301, but I forgot to credit him in that one.

As we talked about in episode 240, about 66 and a half million years ago, a massive asteroid smashed into the earth and caused an extinction event that ended the era of the dinosaurs. The geologic time period immediately after that event is called the Paleogene, and paleontologists study this era to learn how life rebounded after the extinction event. We’re going to learn about a few animals that evolved to fill ecological niches left vacant after dinosaurs went extinct.

These days, mammals fill a whole lot of these ecological niches, so it’s easy to assume that mammals have been successful for the last 66 million years. But while that’s true now, birds were incredibly successful for a long time. Basically for millions of years after the non-avian dinosaurs died out, it was dinosaurs 2.0 as the avian dinosaurs, better known as birds, spread throughout the world and evolved into some amazing organisms.

This included terror birds, which we talked about in episode 202. They lived in South America, except for one species from North America, and evolved really soon after the dinosaurs went extinct, appearing in the fossil record about 60 million years ago. They lasted a long time, too, only going extinct around 2 million years ago.

The earliest known terror bird was about three feet tall, or 91 cm, but its descendants became larger and more fearsome until they were apex predators throughout South America. The biggest species grew up to ten feet tall, or three meters, with a massive beak and sharp claws on its toes. It couldn’t fly but was a fast runner. You would not want a terror bird chasing you.

Lots of other birds evolved throughout the Paleogene, but most of them would look pretty familiar to us today. Paleontologists have found fossils of the ancestors of many modern birds, including penguins, hummingbirds, and parrots, which shows that they were already specialized some 25 or 35 million years ago or even more. In the case of penguins, we have fossils of penguin ancestors dating back to the late Cretaceous, before the extinction event. Those ancient penguins could probably still fly, but it didn’t take too long to evolve to be a fully aquatic bird. The species Waimanu manneringi lived around 62 million years ago in what is now New Zealand. It resembled a loon in a lot of ways, with its legs set well back on its body, and it probably spent much of its time floating on the water between dives. But unlike a loon, it had lost the ability to fly and its wings were already well adapted to act as flippers underwater.

Another bird would have looked familiar at first glance, but really weird when you gave it a second look. Presbyornis lived between about 62 and 55 million years ago in what is now North America, and it lived in flocks around shallow lakes. It was the size of a swan or goose and mostly shaped like a goose, with a fairly chonky body and a long neck. It had a large, broad duckbill that it used to filter small animals and plant material from the water and its feet were webbed…but its legs were really long, more like a heron’s legs.

When the first Presbyornis fossils were found in the 1920s, the scientists thought they’d found ancient flamingos. But when a skull turned up, Presbyornis was classified with ducks and geese. It wasn’t very closely related to modern ducks and geese, though. Researchers now think its closest modern relation is a South American bird called the screamer. Llewelly suggested the horned screamer a long time ago and now that I have learned more about these birds, I love them so much!

The screamer looks sort of like a goose but has long, strong legs and a sharp bill more like a chicken’s. It lives in marshy areas and eats pretty much anything, although it prefers plant material. It has two curved spurs that grow on its wings that it uses to defend its territory from predators or other screamers, and if a spur breaks off, which it does pretty often, it grows back. The screamer mates for life and both parents build the nest together and help take care of the eggs and chicks when they hatch.

The horned screamer has a long, thin structure that grows from its forehead and looks sort of like a horn, although it’s not a horn. It’s wobbly, for one thing, but it’s also not a wattle. It grows throughout the bird’s life and may break off at the end every so often, and it’s basically unlike anything seen in any other bird. Maybe presbyornis had something similar, who knows?

The screamer gets its name from its habit of screaming if it feels threatened or if it just encounters something new or that it doesn’t like. The screaming is actually more of a honking call that sounds like this:

[screamer call]

People sometimes raise screamers with chickens to act as guard birds. It can run fast but it can swim faster, and it can also fly although it doesn’t do so very often. Although it’s distantly related to ducks, its meat is spongy and full of air sacs that help keep it afloat in the water, so people don’t eat it. It is vulnerable to habitat loss, though.

One organism that evolved early in the Paleogene was grass. You know, the plant that a whole lot of animals eat. There are lots and lots of different types of grass, not just the kind we’re used to mowing, and as the Paleogene progressed, it became more and more widespread. But it wasn’t as ubiquitous as it is now, so even though the ancestors of modern grazing animals evolved around the same time, they weren’t grazers yet. The word graze comes from the word grass, but ancient ancestors of horses and other grazing animals were still browsers. They ate all kinds of plants, and didn’t specialize as grazers until grasses really took off and huge grasslands developed in many parts of the world, around 34 million years ago.

Because the Paleogene lasted so long, between about 66 and 23 million years ago, there’s literally no way we can talk about more than a few animals that lived during that time, not in a single 15-minute episode. We’ve also covered a lot of Paleogene animals in previous episodes, like paraceratherium in episode 50, the largest land mammal known. It probably grew up to about 16 feet tall at the shoulder, or 5 meters, and taller if you measured it at the top of its head. Other examples are moeritherium, an ancient elephant relation we talked about in episode 18, the giant ground sloth that we talked about in episode 22, and the ancient whale relation basilosaurus that we talked about in episode 132. Patrons also got a bonus basilosaurid episode this month. But I’m pretty sure we’ve never talked about brontotheres.

Brontotheres first appear in the fossil record around 56 million years ago and they lived until at least 34 million years ago. All animals in the family Brontotheriidae are extinct, but they were closely related to horses. They didn’t look like horses, though; they looked a lot like weird rhinoceroses, although remember that rhinos are also related to horses. They were members of the odd-toed ungulates, along with tapirs and the gigantic Paraceratherium.

Fossil remains of brontotheres have been found in North America, a few parts of eastern Europe, and Asia, although they might have been even more widespread. The earliest species were only about three and a half feet tall at the shoulder, or about a meter, but later species were much larger. While they looked a lot like rhinos, they didn’t have the kind of keratin hose horns that rhinos have. Instead, some species had a pair of horns made of bone that varied in shape and size depending on species. The horns were on the nose as in rhinos, but were side-by-side.

Brontotheres developed before grasslands became widespread, and instead they were browsers that mostly ate relatively soft vegetation like leaves and fruit. Grass is really tough and animals had to evolve specifically to be able to chew and digest it. In fact, the rise of grasslands as the climate became overall much drier around 34 million years ago is probably what drove the brontotheres to extinction. They lived in semi-tropical forests and probably occupied the same ecological niche that elephants do today. This was before elephants and their relations had evolved to be really big, and brontotheres were the biggest browsing animals of their time.

Brontotheres probably lived in herds or groups of some kind. They were widespread and common enough that they left lots of fossils, so many that they were found relatively often in North America even before people knew what fossils were. The Sioux Nation people were familiar with the bones and called them thunder horses. When they were scientifically described in 1873 by Othniel Marsh, he named them after the Sioux term, since brontotherium means “thunder beast.”

Two of the biggest brontotheres lived at about the same time as each other, around 37 to 34 million years ago. Megacerops lived in North America while Embolotherium lived in Asia, specifically in what is now Mongolia. Megacerops is the same animal that’s sometimes called brontotherium or titanotherium in older articles and books.

Megacerops and Embolotherium were about the same size, and they were huge, although Embolotherium was probably just a bit larger than Megacerops. They stood over 8 feet tall at the shoulder, or 2.5 meters, and were more than 15 feet long, or 4.6 meters. This is much larger than any rhinos alive today and as big as some elephants. Their legs would probably have looked more like an elephant’s legs than a rhinoceros’s.

Brontothere nose horns weren’t true horns, since they don’t seem to have been covered with a keratin sheath, but they were formed from protrusions of the nasal bones. They might have been more like ossicones, covered with skin and hair. Megacerops had a pair of nose horns that were much larger in some individuals than others, and scientists hypothesize that males had the larger horns and used them to fight each other.

But this can’t have been the case for embolotherium. It had even bigger nose horns that were fused together in a wedge-shaped plate sometimes referred to as a ram, but they contained empty chambers inside that were a continuation of the nasal cavities. They wouldn’t have been strong enough to bash other embolotheriums with, but they might have acted as resonating chambers, allowing embolotherium to communicate with loud sounds. All individuals had these nose horns, even juveniles, and they were all about the same size, which further suggests that they had a purpose unrelated to fighting.

At about the same time the brontotheres were evolving, another big browsing animal also lived in what are now China and the United States. Two species are known, one in each country, and both stood about 5 feet tall at the shoulder, or 1.5 meters. It looked sort of like a brontothere in some ways, but very different in other ways, especially its weird skull, and anyway it was already big around 56 million years ago when brontotheres were still small and unspecialized.

Scientists aren’t sure what uintatherium was related to. It’s been placed in its own genus, family, and order, although some other uintatherium relations have been discovered that share its weird traits. Most scientists these days think it was probably an ungulate.

Uintatherium’s skull was extremely strong and thick, which didn’t leave a whole lot of room for brains. But what uintatherium lacked in brainpower, it made up for in sheer defensive ability. It had huge canine teeth that hung down like a sabertooth cat’s fangs, although males had larger fangs than females. Males also had three pairs of ossicones or horns on the top of the skull that pointed upwards. One pair was on the nose, one pair over the eyes, and one pair almost on the back of the skull. They could be as much as 10 inches long, or 25 cm, and paleontologists think that males wrestled with these horns the same way male deer will lock antlers and wrestle.

Uintatherium lived in the same habitat and probably ate more or less the same type of plants that later brontotheres did. They went extinct around the time that brontotheres evolved to be much larger, which suggests that brontotheres may have outcompeted uintatherium.

We’ll finish with one more Paleogene mammal, Pezosiren. It was only described in 2001 from several incomplete specimens discovered in Jamaica in the 1990s, and it lived between 49 and 46 million years ago.

Pezosiren was about the size of a pig, although it had a longer, thicker tail compared to pigs. It wasn’t any kind of pig, though, and in fact it was distantly related to elephants. It was the oldest known ancestor of modern sirenians. Pezosiren is also called the walking siren, because it still had four legs and probably spent at least part of the time on land, although it could swim well. Scientists think it probably swam more like an otter than a sirenian, propelling itself through the water with its hind legs instead of its tail.

Pezosiren was probably semi-aquatic, sort of like modern hippos, and already shows some details specific to sirenians, especially its heavy ribs that would help it stay submerged when it wanted to. It ate water plants and probably stayed in shallow coastal water. At different times in the past, Jamaica was connected to the North American mainland or was an island on its own as it is now, or occasionally it was completely submerged. About 46 million years ago it submerged as sea levels rose, and that was the end of Pezosiren as far as we know. But obviously Pezosiren either survived in other areas or had already given rise to an even more aquatic sirenian ancestor, because while Pezosiren is the only sirenian known that could walk, its descendants were well adapted to the water. They survive today as dugongs and manatees.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 202: Terror Birds and Pseudotooth Birds

Let’s find out about some gigantic birds this week! Thanks to Pranav and Richard for the suggestions!

Further reading:

Exceptionally preserved fossil gives voice to ancient terror bird

Antarctica yields oldest fossils of giant birds with 21-foot wingspans

Look at that beak! Llallawavis scagliai:

Big birdie!

A red-legged seriema and an unfortunate snake:

Another big birdie!

Toothy birdie!

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’re going to learn about some gigantic extinct birds! Pranav wants to hear about Phorusrhacidae, also known as the terror bird. Something called a terror bird is definitely going to be interesting. My brother Richard also tweeted me about some huge extinct birds called pelagornithids, so we’ll talk about them too. Both birds were huge and successful, but extremely different from each other.

Phorusrhacidae is the name for a family of flightless birds that lived from about 62 million years ago to a little under 2 million years ago. Flightless birds may make you think of ostriches and penguins and dodos, but remember that Phorusrhacids were called terror birds. They were carnivores and many of them were enormous.

Most terror birds lived in South America, with one species known from southern North America. A few newly discovered bird fossils from Africa and Europe may have been close relations of terror birds, but palaeontologists are still studying them.

Various species of terror bird ranged in size from about 3 feet tall to 10 feet tall, or 1 to 3 meters, and had long, strong legs that made them fast runners. The terror bird also had a long, strong neck, a sharp hooked beak, and sharp talons on its toes. The beak was strong but the jaw muscles were relatively weak. Researchers think that it ambushed prey and chased it down, then either kicked it to death with its sharp talons or held it down with its feet and stabbed it to death with its beak. Smaller species may have grabbed its prey and thrown it back down with enough force to injure, stun, or outright kill the animal. It may have swallowed small prey whole and regurgitated pellets made up of compressed fur and bones, the way many modern carnivorous birds do today.

Although the beak was strong, it was also hollow. This would have made it weigh less, which meant that the bird could move its head more quickly. Some researchers think that it might also have acted as a resonant chamber, and that the bird could clap its beak closed to make a loud noise to communicate with other terror birds. It had excellent hearing and vision, but a poor sense of smell.

Many details of what we know about terror birds come from a single specimen discovered in 2010 in Argentina. The bird lived around 3 million years ago and stood four feet tall, or 1.2 meters. It was described in 2015 and is named Scaglia’s magnificent bird. I am not going to attempt to pronounce its scientific name [Llallawavis scagliai], but I’ll put it in the show notes along with a picture. Almost the entire skeleton is preserved in stunning detail, including details that hardly ever preserve, like the tiny bones that help the eye focus. Studies of the tiny ear bones and other details of the ear indicate that its hearing was most acute at low frequencies, which meant it would have been good at hearing footsteps. It also probably had a deep voice.

The terror bird had wings, but they were small and probably only used for display. The wings did have claws, though, and may have been used to fight other terror birds over mates or territory. Young terror birds of some species might have been able to fly, although adults certainly couldn’t.

The earliest known terror bird, Paleopsilopterus, lived about 60 million years ago in what is now Brazil. It was relatively small, only about three feet high, or 1 meter. It evolved only a few million years after the non-avian dinosaurs went extinct, and its descendants became larger and more fearsome until they were apex predators throughout South America.

Kelenken, for instance, grew up to ten feet tall, or three meters, and had an enormous beak, 18 inches long or almost 46 cm. It lived in what is now Argentina around 15 mya. It’s the tallest terror bird known but it was more slenderly built than others so was probably a faster runner. It was only discovered in 1999.

Brontornis, however, was the one that puts the terror into terror bird. It grew over 9 feet tall, or 2.8 meters, but it was massively built. It probably wasn’t a very fast runner and would have definitely been an ambush predator. Most likely it hid among trees or other tall vegetation, and when an animal came too close, BOOM! THERE’S A TERROR BIRD! RUN! TOO LATE, ARGH!

Titanis lived in parts of North America, with fossils found in Texas and Florida. It probably stood a little over eight feet tall, or 2.5 meters, although we don’t have any complete skeletons so can only estimate its actual size compared to other species of terror bird. You may find information online that says Titanis lived as recently as 10,000 years ago in Florida, and that it used the claws on its wings like hands to help catch prey. Both these things are wrong, unfortunately. The fossil bones found in the Santa Fe River in Florida had washed out of their original location and were mixed in with much more recent bones, and there’s no evidence that any terror bird used its wings like hands. Terror birds were descended from birds that could fly, not descended directly from dinosaurs, so its wings were still highly modified for flight.

Titanis lived in North America about five million years ago. But how did it get to North America from South America before the Isthmus of Panama formed around three million years ago? Before then, a big stretch of ocean separated the two continents. Researchers think it island-hopped, as the tops of mountains and hills in what is now Central America first emerged from the ocean as sea levels dropped, forming islands. Volcanoes also formed islands in the area. Titanis may have traveled to these islands by swimming or rafting during storms.

Terror birds went extinct after the Isthmus of Panama opened up when sea levels lowered. This connected North and South America, which allowed animals from North America to cross into South America and vice versa. The Andes Mountains also formed about this time and changed the climate of much of South America. Forests became open savanna where terror birds wouldn’t have been able to hide to ambush prey. Climate change combined with increased competition from saber-toothed cats and other North American predators probably led to the terror birds’ extinction.

There are no descendants of terror birds living today, but its closest living relations are probably the seriema birds, the red-legged and the black-legged seriema. Both live in South America and both are carnivorous birds that eat small animals like rodents, lizards, snakes, and even other birds. When it catches an animal, it beats it against the ground until it dies. It will also sometimes eat fruit and eggs.

The red-legged seriema stands a little over three feet tall, or a meter, with long legs, long neck, and long tail. It’s mostly brown and gray and it has a fan-shaped crest low down on its forehead, just above the bill. The gray-legged seriema looks very similar but is mostly gray. The seriema also has a sickle claw on each foot that it uses to cut pieces off its dead prey so it can swallow them more easily.

The seriema can fly, but it prefers to walk or run. It can run up to 15 mph, or 25 km/h. It builds its nest in low bushes so it can just hop up onto the nest instead of having to fly. It’s also aggressive and will attack animals much larger than it is, driving them away from its nest or chicks. Farmers sometimes catch young seriemas and tame them, then allow them to patrol the farmyard to catch rats and snakes and drive away larger predators.

Next, let’s learn about a different giant extinct bird, Richard’s suggestion. Unlike the terror bird, pelagornithids could fly. They’re sometimes called pseudotooth birds because they had teeth, but they weren’t real teeth. They were pointy projections of the jaw bones that grew along the edges of its beak and were covered with keratin. Pelagornithids evolved around the same time as the terror bird, around 62 million years ago, and didn’t die out until about the same time as the terror bird, around 2.5 million years ago.

And like the terror bird, pelagornithids were huge, but in a different way than terror birds. They were sea birds that may have superficially resembled modern albatrosses, but they were much larger. The largest living albatross has a wingspan of about 11 1/2 feet, or 3.5 meters, but the largest known pelagornithid had a wingspan estimated at up to 21 feet, or almost 6.5 meters. Its wings were narrow and pointed like albatross wings are.

Researchers think that the pelagornithid probably mostly ate soft-bodied animals like squid and other cephalopods, because its teeth were not very strong. It probably scooped its prey up from the water while flying, like many modern seabirds do, although it could probably also sit on the water and dip its long, strong beak down to catch anything that swam too close. Its bones were too delicate for diving. It may have had a throat sac like a pelican too. It was probably white or gray in color and its wings and tail were probably black, which is the most common coloration for sea birds of any kind.

It had short legs but enormously long wings, so long that it probably couldn’t flap them. Its strongest muscles were the ones that held the wings out straight. It was definitely a bird, of course, but it was proportioned more like a flying reptile, Pteranodon, even though they weren’t related. You know what that means, of course. Convergent evolution! Researchers think the pelagornithid spent almost all its time soaring on ocean breezes, scooping up cephalopods and fish to swallow whole, and that Pteranodon probably did the same. These days, modern albatrosses fill that particular ecological niche, and the albatross has many similarities to the pelagornithid too.

Pelagornithids of various species were found throughout the world, from the Arctic and Antarctic to the tropics. It was extremely successful and unlike the terror bird, which was restricted to land, it could travel as far as it liked as long as it had a breeze to keep it aloft. It evolved soon after the non-avian dinosaurs went extinct and didn’t die out until the beginning of the Pleistocene. What happened then? Why aren’t these enormous birds still flying around?

The Pleistocene, of course, was the ice age, or more properly the ice ages. Its onset resulted from a lot of factors, including the movement of continents that changed ocean currents radically. Once the changes started, they accelerated quickly. As more water froze and became massive glaciers that weighted down entire continents, sea levels dropped and more land was exposed, including the Isthmus of Panama that connected North and South America. This would have radically changed the air currents that pelagornithids used to travel around the world, from nesting sites to feeding sites and back. It also drove many sea animals to extinction as their environments became too cold or too warm for them to adapt to, or the water where they lived just dried up completely.

The one place where pelagornithids couldn’t go was across continents. They needed constant sea breezes and lots of water where they could catch prey, and steep cliffs near water to nest on. As the ecological changes of the Pleistocene became more pronounced, pelagornithids had more and more trouble surviving, and finally they went extinct. Modern albatrosses, gulls, and cormorants expanded at the same time to fill the ecological niche left open by the pelagornithid.

While there are no living descendants of pelagornithids, researchers tentatively think they’re most closely related to living ducks, geese, and swans. Since most pelagornithid fossils are badly damaged and fragmented, so that we only have one or two bones preserved from any given animal, it’s hard for scientists to make conclusions as to what they were most closely related to. Hopefully more and better fossils will be found soon so we can learn more about these gigantic birds!

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us and get twice-monthly bonus episodes for as little as one dollar a month.

Thanks for listening!