Episode 346: The Rhinoceros!

Thanks to Mia for suggesting the black rhino this week! We’ll also learn about other rhinos and their relations, including a mystery rhino.

Further reading:

Photos suggest rhino horns have shrunk over past century

The Blue Rhinoceros – In Quest of the Keitloa

A rhino with a very small third horn:

Some rhinos have really big second horns [photo by David Clode and taken from this site]:

The “blue rhinoceros,” or keitloa, as illustrated in the mid-19th century:

Show transcript:

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

This week we’re going to talk about an animal I can’t believe we haven’t covered before. Thanks to Mia for suggesting the rhinoceros, specifically the black rhino! We’ll also learn about a mystery rhino.

We’ve talked about elephants lots of times, hippos quite a few times, and giraffes a couple of times, but pretty much the only episodes where we discussed a rhinoceros were 5 and 256. Episode 256 was mostly about mammoths, although we talked very briefly about the woolly rhinoceros, while episode 5 was about the unicorn and didn’t actually specifically talk about the rhino. So after almost 350 episodes of this podcast, one of the most amazing animals alive is one we literally haven’t learned about! Let’s fix that now.

Most people are pretty familiar with what a rhinoceros looks like. Basically, it’s a big, heavy animal with relatively short legs, a big head that it carries low to the ground like a bison, and at least one horn that grows on its nose. It’s usually gray or gray-brown in color with very little hair, and its skin is tough. It eats plants.

The rhinoceros isn’t related to the elephant or the hippopotamus. It’s actually most closely related to the horse and the tapir, which are odd-toed ungulates. The rhino has three toes on each foot, with a little hoof-like nail covering the front of each toe, but the bottom of the rhino’s foot is a big pad similar to the bottom of an elephant’s foot.

The rhino’s nose horn isn’t technically a horn because it doesn’t have a bony core. It’s made of long fibers of keratin all stuck together, and keratin is the same protein that forms fingernails and hair. That makes it even weirder that some people think a rhinoceros horn is medicine. It’s literally the same protein as fingernails, and no one thinks of fingernails are medicine. The use of rhinoceros horn as medicine isn’t even all that old. Ancient people didn’t think it was medicine, but some modern people do, and they’ll pay a whole lot of money for part of a rhino horn to grind up and eat. Seriously, they might as well be eating ground-up fingernails. (That’s gross.)

Because rhino horns are so valuable, people will kill rhinos just to saw their horns off to sell. That’s the main reason why most species of rhino are so critically endangered, even though they’re protected animals. Sometimes conservationists will sedate a wild rhino and saw its horn off, so that poachers won’t bother to kill it. A 2022 study determined that the overall size of rhino horns has shrunk over the last century, probably for the same reason that many elephants now have overall smaller tusks. Poachers are more likely to kill animals with big horns, which means animals with smaller horns are more likely to survive long enough to breed.

The species of rhinoceros alive today are native to Africa and Asia, but it used to be an animal found throughout Eurasia and North America. It’s one of the biggest animals alive today, but in the past, some rhinos were even bigger. We’ve talked about Elasmotherium before, which lived in parts of Eurasia as recently as 39,000 years ago. It had long legs and could probably gallop like a horse, but it was the size of a mammoth. It also probably had a single horn that grew in the middle of its forehead, which is why it’s sometimes called the Siberian unicorn.

We’ve also talked about Paraceratherium before. It was one of the biggest land mammals that ever lived, and while it didn’t have a horn, it was a type of rhinoceros. It lived in Eurasia between about 34 and 23 million years ago, and it probably stood about 16 feet tall at the shoulder, or 5 meters. The tallest giraffe ever measured was 19 feet tall, or 5.88 meters, at the top of its head. Paraceratherium had a long neck, possibly as much as eight feet long, or 2.5 meters, but it would have held its neck more or less horizontal most of the time. It spent its time eating leaves off of trees that most animals couldn’t reach, and when it raised its head to grab a particularly tasty leaf, it was definitely taller than the tallest giraffe, and taller than any other mammal known.

While rhinos are famous for their horns, not every rhinoceros ancestor had a horn. But because rhino horns are made of keratin and not bone, we don’t always know if an extinct species had a horn. Most of the time the horns rotted away without being preserved. We do know that some ancient rhinos had a pair of nose horns that grew side by side, that some had a single nose horn or forehead horn, that some had both a nose horn and a forehead horn, and that some definitely had no horns at all.

The rhinos alive today have either one or two horns. The Indian rhinoceros has one horn on its nose, and the closely related Javan rhino also only has one horn. The Sumatran rhino has two horns, as do the white rhino and the black rhino. Sometimes an individual rhino will develop an extra horn that grows behind the other horn or horns and is usually very small. This is extremely rare and seems to be due to a genetic anomaly. There are even reports of rhinos that have four horns, all in a row, but the extra ones, again, are very small.

Mia specifically wanted to learn about the black rhino. It and the white rhino are native to Africa. You might think that the white rhino is pale gray and the black rhino is dark gray, but that’s actually not the case. They’re both sort of a medium gray in color and they’re very closely related. It’s possible that the word “white” actually comes from the Dutch word for “wide,” referring to the animal’s wide mouth. The black rhino has a more pointed lip that looks a little bit like a beak.

One interesting thing about the black and white rhinos is that neither species has teeth in the front of its mouth. It uses its lips to grab plants instead of its front teeth, and then it uses its big molars to chew the plants. The white rhino mostly eats grass while the black rhino eats leaves and other plant material.

A big male black rhino can stand over 5 1/2 feet tall at the shoulder, or 1.75 meters, and is up to 13 feet long, or 4 meters. It can weigh as much as 4,000 lbs, or 1,800 kg. This sounds huge and it is, but it’s actually smaller than the white rhino, which is the biggest rhino alive today. A big male white rhino can stand over 6 1/2 feet tall at the shoulder, or 2 meters, can be 15 feet long, or 4.6 meters, and can weigh up to 5,300 lbs, or 2,400 kg. These are really really big animals. Nothing much messes with the rhino because it’s so big and heavy, its skin is so tough, and it can do a lot of damage with its horn if it wants to. The rhino doesn’t see very well, but it has good hearing and a good sense of smell.

The nose horn is always the bigger one in species that have two horns, and in the black rhino it can grow quite long. One nose horn was measured as being over 4 1/2 feet long, or 1.4 meters, although most are only about 20 inches long, or 50 cm. The rear horn, which grows roughly over the eyes, is about half the length of the front horn, and is sometimes no more than a little bump. But some black rhinos found in South Africa have a rear horn that’s at least as long as the front horn, and sometimes longer, and that brings us to our mystery rhino.

A rhino with this trait is referred to as a keitloa, a word taken from the Tswana language spoken in the area. In the 19th century, the keitloa was referred to by European colonizers as the blue rhinoceros. The blue rhino wasn’t blue, but it was considered quite rare and different from the ordinary black rhino. It was supposed to be bigger and and even more solitary than the black rhino.

Until 1881, many scientists thought the keitloa was a separate species of rhino from the black rhino, which it otherwise resembled. In 1881, though, a study of black rhinos and blue rhinos determined that they were the same species. A century later, in 1987, scientists found that black rhinos with better access to water grew larger horns than black rhinos living in dryer areas.

There are a number of subspecies of black rhino recognized by scientists, some of them still alive today and some driven recently to extinction. Some people still think that the keitloa may be a separate subspecies of black rhino. That’s one of many reasons why it’s so important to protect all rhinoceroses and their habitats, so we can learn more about these amazing animals.

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 for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 050: Tallest Animals

We’re discovering which animals are the tallest this week! This episode includes our first dinosaur!

Sauroposeidon proteles:

Giraffes:

Bop bop bop have at thee!

Paraceratherium (I couldn’t find one that I liked so I drew one, along with a giraffe and ostrich to scale):

Ostrich running:

I SAID DON’T @ ME

A fine day at the ostrich races. I could not make this stuff up if I tried:

Show transcript:

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

This week we’re looking at tall animals. Is the giraffe the tallest mammal that’s ever lived? Is the ostrich the tallest bird? And what about tall dinosaurs?

I don’t talk about dinosaurs much in this podcast because there are so many good podcasts devoted specifically to dinosaurs. I recommend I Know Dino. It’s family friendly and goes over the latest dinosaur news without talking down to listeners or dumbing down the information.

Four-footed animals are usually measured at the shoulder, since some animals hold their heads low, like bison, while others hold their heads high, like horses. But we’re talking about tall animals today, and that includes animals with long necks. So the measurements here are all from head to toe, with the head and neck held in its natural standing position.

Let’s start with the real biggie, the tallest dinosaur ever found.

In 1994 a guy named Bobby Cross noticed some fossils weathering out of the ground at the Oklahoma correctional facility where he worked as a dog trainer. As he always did when he found fossils, he called the Oklahoma Museum of Natural History. They sent a team to take a look. The team found four vertebrae, but they were just so big—around four feet long each, or 120 cm—that at first they thought they must be fossilized tree trunks.

Sauroposeidon proteles was probably closely related to Brachiosaurus, but was even bigger and taller. Sauroposeidon stood 60 feet tall, or 18 meters, and its neck alone was 39 feet long, or 12 meters. Its body and legs were relatively short and stocky. We don’t have a complete skeleton, just the four vertebrae found in southeastern Oklahoma, and a few vertebrae from two other individuals found in Montana and Texas. A trail of giant footprints in Texas may be a Sauroposeidon track too. But for sauropods, neck vertebrae are the most valuable fossils because they tell so much about the animal.

Sauroposeidon’s neck bones were massive, but they were lighter than they look due to tiny air sacs in the bones, like those in bird bones. The air sacs in bird bones actually contain air that flows through the lungs, called pneumatic bones, which provides the bird with more oxygen. A CT scan of the Sauroposeidon fossils—at least the portions of the fossils that would actually fit in the CT scanner—revealed that sauroposeidon’s vertebrae were constructed in the same way that bird bones are. We know that pterosaurs and theropods had pneumatic bones, so it’s not too surprising that at least some sauropods did too.

Sauroposeidon lived around 110 million years ago, during the Mesozoic era, specifically during the early to mid Cretaceous. The sea level was much higher then than it is now, so Sauroposeidon lived near the coast. It ate plants, and like many birds, it also swallowed stones to help it digest those plants, called gastroliths. Paleontologists have found lots of sauropod gastroliths associated with fossil animals. Unlike mammals, which chew their food before swallowing, sauropods swallowed it whole and the plant material was broken up in a stomach or gizzard-like structure. That’s why its head is so small relative to its body, and how it could eat enough plants to keep such an enormous body going. It probably ate literally a ton of food every single day.

We know a lot about sauropods, and since sauroposeidon appears to be structurally typical of other sauropods, just really big, it’s a safe bet to assume it was like other sauropods in many ways. It probably nested in groups and laid about two dozen eggs at a time in big nests on the ground. We don’t have any sauroposeidon eggs, but they probably wouldn’t have been all that big, maybe about the size of a football. Babies would have grown rapidly and were full grown in ten to twenty years. Sauroposeidon migrated in herds throughout the year, traveling from nesting grounds to new grazing grounds. While it lived near the ocean, it would have had to be careful about walking on soft ground. An animal that tall and heavy can get mired in mud easily. Paleontologists have actually found fossils of sauropods that died standing up, unable to climb out of a muddy hole after sinking in soft ground.

Giraffes are the tallest living animals today, with the tallest recorded giraffe, a male, measuring 19.3 feet, or 5.88 meters. That’s pretty darn tall, about 1/3 the height of sauroposeidon. Giraffes are related to deer and cattle, and live in the savannahs and forests of Africa, where they eat tree leaves that are much too high off the ground for other animals to reach. Female giraffes and their young make up loose groups, while males form groups of their own. While giraffes can kick hard enough to kill lions, when males fight over females, they use their necks. A male will swing its head at another male, and the two will tussle back and forth bopping necks together. As a result, male giraffes have thicker, stronger necks than females. Males are also usually taller than females.

The giraffe not only has a long neck and long legs, it has a long tongue that it uses to grab leaves that are juuuust too far away. The tongue is about 18 inches long, or 45 cm. A giraffe at Knoxville Zoo licked my hair once. The giraffe’s upper lip is also prehensile, and is hairy as a protection from thorns. Because of all the thorns it encounters, giraffe skin is surprisingly tough. The giraffe has large eyes that give it good vision, and it also has keen hearing and smell. It can close its nostrils to protect them from dust, sand, insects, and—you guessed it—thorns. So many thorns. And giraffe fur contains natural parasite repellents, which also makes giraffes smell funny.

All this is pretty awesome, but we’re not done with giraffe awesomeness. Giraffes have skin-covered horns called ossicones. Females and males both have ossicones, although males also have a median lump at the front of the skull that’s not exactly an ossicone but is sort of like one. Some females also have this median lump. Ossicones are made of cartilage that has ossified, or turned boney, and they’re covered in skin and hair, although since males use their ossicones in necking fights, they tend to rub all the hair off and have bald ossicones.

The only other animal alive today that has ossicones is the okapi, a close relative of the giraffe, but giraffe ancestors once had all kinds of weird ossicones. Xenokeryx amidalae, for instance, which lived about 16 million years ago in what is now Spain, had two ossicones over its eyes, and a third sticking up from the back of its head that was T-shaped. The name amidalae comes from the character Padme Amidala in Star Wars: The Phantom Menace, if you remember that weirdly shaped headdress she wore.

Because giraffes are so tall, they have some physical adaptations that are unique among mammals living today. A giraffe has the same number of neck bones as all other mammals except sloths and manatees, which are weird, but the vertebrae are much longer than in other mammals, almost a foot long, or 28 cm. The giraffe can also tilt its head right back until it’s just about in line with the back of the neck. I’m picturing everyone listening tilting their heads back right now, and hopefully you notice how the back of your neck curves when you look up. Also, please don’t wreck your car because you’re looking up while driving. The giraffe’s circulatory system is really unusual. Its heart is enormous and beats around 150 times per minute. The jugular veins, which are the big veins that carry blood up the neck to the brain, have valves that keep blood from running backwards when a giraffe lowers its head to drink.

Giraffes can walk, and giraffes can run, but they don’t have any other gaits. They can’t trot or canter, for instance. Even humans have more than two gaits, because we can skip. Despite its height, a giraffe can really move. It can run over 30 miles per hour, or about 50 km per hour, and keep it up for several miles. It has cloven hooves. Because a giraffe’s body is so heavy and its legs so long and thin, it has specialized ligament structures in its legs that keep them from collapsing. Horses also have this structure, which also helps the animal sleep while standing.

Oh, and the giraffe doesn’t eat leaves all the time. It spends a lot of the day just standing around chewing its cud.

There used to be a mammal that stood almost as tall as the giraffe at the shoulder. Paraceratherium orgosensis went extinct around 23 million years ago, and it’s not even related to the giraffe. It’s a member of the rhinoceros family. Like sauroposeidon, we don’t have a complete skeleton of paraceratherium, so its size is an estimate based on the proportions of closely related animals whose sizes we do know. It probably stood 18 feet high at the shoulder, or 5.5 meters, and while its neck was probably around 7 feet long, or a little over 2 meters, it probably held it forward like a rhino instead of up like a giraffe, so it didn’t add much to the animal’s overall height.

In episode 32 we learned about the giant moa, a flightless bird that once lived in New Zealand. It was probably the tallest bird that ever lived, with big females 12 feet tall, or 3.6 meters. But the tallest living bird is the ostrich. It also lives in Africa and is famous for being flightless and for being able to run really fast. In fact, it’s not only the tallest bird alive, it’s the fastest. It can run over 40 miles per hour, or about 70 km per hour, and it uses its large wings as rudders and even to help it brake. With its head raised, a big ostrich can be nine feet tall, or 2.8 meters.

There are a lot of differences between ostriches and most other birds. Most birds have four toes, for instance. The ostrich has two, one large toe with a hoof-like nail, and a smaller outer toe with no nail at all. All other living birds secrete urine and feces together, but the ostrich secretes them separately the way mammals do. And while most male birds don’t have a penis, the male ostrich does. And the ostrich has a double kneecap. Not only is that unique to birds, it’s unique to everything. No other animal known, living or extinct, has a double kneecap. Researchers have no idea what it’s for, although one hypothesis is that it allows a running ostrich to extend its legs farther, and another hypothesis is that it might protect tendons in the bird’s leg.

The ostrich eats plants, seeds, and sometimes insects. Like Sauroposeidon and many other dinosaurs and birds, the ostrich swallows small rocks and pebbles to help digest its food in its gizzard. The gizzard contracts, smashing the gastroliths and plants together to help break up the plant material the way mammals would chew it.

Ostrich eggs are the biggest laid by any living bird, about six inches long, or 15 cm. Females lay their eggs in a communal nest.

Ostriches are farmed like big chickens, for their feathers, meat, and skin for leather. Ostriches are also sometimes ridden and raced with special saddles and bridles. But ostriches aren’t easy birds to manage. They can be aggressive, and they can kill a human with one kick.

To wrap things back around to dinosaurs, some researchers think many fast-running dinosaurs used their feathered forelimbs the way ostriches use their wings, to help maneuver and possibly to help keep unfeathered portions of the body warm at night. During the day, when it’s hot, ostriches keep their wings raised so that their unfeathered upper legs can release heat into the atmosphere, but at night they cover their upper legs to retain heat. It’s just another link between birds and their long-distant ancestors, the dinosaurs.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. 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 whatever platform you listen on. We also have a Patreon if you’d like to support us that way.

Thanks for listening!