Monthly Archives: June 2021

Episode 229: Blue Ghosts and Vanishing Sharks

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I got to meet some listeners this week to see the synchronous fireflies, so thanks to Shannon, Diana, Derek, and Autumn for hanging out with me! This week we’ll learn about a different kind of lightning bug as well as a shark mystery!

Derek’s photography, Enchanting Ectotherms

Further reading:

A shark mystery millions of years in the making

I suspect this is a doctored image but it’s gorgeous so here it is anyway, supposedly some blue ghost fireflies:

This is a real photo, no photoshop, taken by Derek Wheaton during our trip. The long line of light in the middle is a blue ghost moving with its light on during a long exposure:

A synchronous firefly on Derek’s hand (photo by Derek Wheaton):

A tiny blue ghost firefly on Derek’s hand (photo by Derek Wheaton):

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. It’s been an amazing week for me because I got to take some people to see our local synchronous fireflies! The fireflies put on a brilliant show for us and the weather was perfect, and it was so much fun to meet Shannon and Diana! Then, two nights later, I also took Derek and Autumn out to see the fireflies. In between, I started research on the blue ghost firefly, since I had originally thought it was just another name for the synchronous firefly, but it’s not. So this week we’re going to learn about the blue ghost firefly, along with some interesting breaking news about a shark mystery.

The blue ghost firefly only lives in parts of the eastern and central United States. In most places it’s rare, but like the synchronous fireflies that all flash together, the blue ghost fireflies are actually pretty common in the southern Appalachian Mountains. The reason why people don’t see them more often is that these days, most people don’t spend much time in the woods at night.

Like other fireflies, the blue ghost lives in forests with deep leaf litter where there’s a lot of moisture in the ground. The female lays her eggs in the leaf litter and when the eggs hatch, the larval fireflies eat tiny insects and other invertebrates like snails.

The blue ghost firefly is different from other firefly species in several ways. First, it doesn’t flash. The male stays lighted up for around a minute at a time while he flies low over the ground watching for a female to light up too. Its glow also appears bluish-white to human eyes, at least in the distance and when it’s really dark out. Up close, it looks yellow-green like other firefly lights. Researchers think it only looks blue because of the way human eyes perceive color in low light.

In the daytime, blue ghost fireflies don’t look like much. They’re small, around 7 mm long, and males are all brown. The females don’t have wings, and in fact they never metamorphose into the adult form and still look like larvae as adults. The female crawls to the end of a twig or blade of grass and glows to attract a mate.

When I was doing my research to learn about blue ghost fireflies, I kept seeing articles comparing its size to a grain of rice. I looked up the average size of a grain of rice, and that’s where I got 7 mm. I didn’t think too much about it.

When Shannon, Diana, and I were watching the synchronous fireflies, we noticed some fireflies that didn’t flash, just stayed glowing while they drifted along low over the forest floor. After I started researching blue ghost fireflies, I realized that was what had seen! So I was especially excited to go back out with Derek and Autumn and confirm it.

Derek works for a nonprofit that breeds endangered fish for conservation projects, which is awesome, but he’s also a photographer, so he brought his camera to try and get pictures and video of the fireflies. His photographs are amazing so if you want to see them I’ve linked to his Facebook page, EnchantingEctotherms, in the show notes. He does a lot of snorkeling so a lot of the animals he photographs are fish or other water animals like turtles and snakes, and he gives information about them in his posts.

Anyway, he wanted to get close-up pictures of a synchronous firefly and a blue ghost firefly, so we all spent some time trying to catch one of each—gently, of course, and without leaving the trail. We didn’t want to hurt ourselves in the dark or disturb the fireflies’ habitat. Derek caught a synchronous firefly first, and it looks like an ordinary firefly that I’m used to, the common eastern firefly, which grows to about 14 mm long. That’s half an inch long. Then, eventually, he also caught a blue ghost. It was so small that at first we thought he might have caught some other beetle by accident, until we looked more closely and saw the telltale head shape of a lightning bug. I took a photo myself and put it in the show notes so you can see just how small it is.

From my own observation, the blue ghosts are much dimmer than other fireflies, which makes sense since they’re so much smaller. The light does look faintly blue-white in the distance, but when it’s closer to you it looks like an ordinary firefly’s light. They do indeed fly very low to the ground while lit up, but they’re also cautious. We had trouble catching one because when we got too close, the firefly would fly down to the ground and put his light out.

Naturally, after photographing our lightning bugs we let them go again. I’m happy to report that the synchronous fireflies have expanded their range a lot since I first stumbled across them about ten years ago, and the blue ghosts seem reasonably common too. They live in a protected area of our local watershed so they’ll be safe and sound forever, hopefully.

This is good, because blue ghosts in particular are vulnerable to habitat loss. Since the female can’t fly, she can’t travel far to lay her eggs. During mating season, some state and national parks in the southern Appalachians close some trails to protect the blue ghost and other fireflies, especially from light pollution from flashlights.

The synchronous fireflies and blue ghosts are only active for a few weeks in June, which is their mating season. We’ll probably be just about at the end of this year’s display by the time you hear this, but if you’re going to be in East Tennessee and want to go out and see them with me next summer, just let me know. As we talked about in episode 180, they only live a few minutes’ walk away from a small parking lot but no one but me seems to know about them.

Next, let’s learn about a shark mystery that’s 19 million years old but that scientists only learned about recently. This month, June of 2021, a team of researchers published results of a shark study in the journal Science. The team had decided to graph the number and diversity of shark species known from the fossil record so they’d have a baseline to compare modern shark diversity to. But they discovered something really surprising.

Nineteen million years ago, there were over ten times as many sharks in the oceans as there are today. They were an important part of the ocean’s ecosystems, especially in the open ocean. And then…they disappear from the fossil record. Over 90% of the world’s sharks died, with shark diversity decreasing by more than 70%. Not only that, sharks never fully recovered from whatever happened.

So what did happen? We don’t know yet. There was a small extinction event called the Middle Miocene extinction peak five million years after the sharks vanished, which researchers think was due to global cooling leading to climate change. The cooling period was caused by a lot of factors, but a big cause was changes in ocean currents and air currents as the continents moved into new positions. Before that, though, the world was comfortably warm for millions of years and the shark population was overall quite stable. Researchers have found no reason why sharks suddenly started dying in such huge numbers, especially in the open ocean instead of in coastal waters.

The leader of the study, Elizabeth Sibert, says that there might have been a climate event of some kind that was disastrous to sharks but that was over relatively quickly, leaving very little evidence behind except for the fossil remains of way more sharks than usual and a lack of sharks afterwards.

Other scientific teams have already started studying the open ocean ecosystem from 19 million years ago and earlier for clues as to what happened, whether other animals were affected, and why sharks never regained their supremacy in the world’s oceans afterwards. That’s how science works: someone makes a discovery and that inspires lots of new studies, which lead to more discoveries. When we do learn more about the great shark die-off of the Miocene, I will keep you posted.

You can find Strange Animals Podcast at That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at 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 if you’d like to support us that way, and don’t forget to join our mailing list. There’s a link in the show notes.

Thanks for listening!


Episode 228: Monkey Lizards and Weird Turtle…Things

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Thanks to Ethan for this week’s topic, two weird animals that developed after the Great Dying we talked about last week!

Further reading:

Monkey Lizards of the Triassic

Placodonts: The Bizarre ‘Walrus-Turtles’ of the Triassic

Drepanosaurus (without a head since we haven’t found a skull yet, but with that massive front claw):

Drepanosaurus’s tail claw:

Hypuronector had a leaf-like tail:

Placodus was a big round-bodied swimmer:

Some placodonts [art by Darren Naish, found at the second article linked above]:

Henodus was the oddball placodont that probably ate plant material:

Show transcript:

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


Last week we talked about the end-Permian mass extinction, also called the Great Dying. This week let’s follow up with a couple of weird and interesting animals that evolved once things got back to normal on Earth. Thanks to Ethan who suggested both animals.


The great dying marks the end of the Permian and the beginning of the Triassic period, which lasted from about 251 million years ago to 201 million years ago. In those 50 million years, life rebounded rapidly and many animals evolved that we’re familiar with today. But some animals from the Triassic are ones you’ve probably never heard of.


We’ll start with a reptile called the drepanosaur. Drepranosaurs are also sometimes called monkey lizards for reasons that will soon become clear. Paleontologists only discovered the first drepanosaur in 1980, Drepanosaurus, and within a few years they recognized a whole new family, Drepanosauridae, to fit that first discovery and subsequent closely related specimens. Drepanosaurs were weird little reptiles that probably looked like lizards in many ways, although they weren’t lizards.


How weird was Drepanosaurus? Very weird. Very, very weird.


It was obviously a climbing animal that probably spent all of its life in the treetops. It had lots of adaptations to life in trees, such as hind feet where all the toes pointed in the same direction and were somewhat curved, sort of like a spider monkey’s hand. That would help it get a good grip on branches. But those hind feet aren’t why it’s called the monkey lizard.


Drepanosaurus and its relatives are called monkey lizards because of their tails. Many monkeys have prehensile tails, which act as a fifth limb and help keep the monkey stable in a tree by curling around branches and hanging on. Drepanosaurus had something similar. Instead of being mobile from side to side like most reptile tails, Drepanosaurus’s tail could mostly only curve downward. Modern chameleons have an even more pronounced downward-curving tail that helps them climb. But the chameleon’s tail is still just a tail. The end of Drepanosaurus’s tail had several modified caudal bones that were probably exposed through the skin. Those modified bones acted as a claw to help the animal grab onto tree trunks and branches. So Drepanosaurus had claws on its front feet, claws on its hind feet, and a claw on its tail. It’s sort of like having five feet.


As if that wasn’t weird enough, let’s talk about those claws on the front feet. It had five toes on each foot, and four of them had ordinary claws. They were sharp but fairly small, about what you’d expect from an animal that grew about 19 inches long at most, or 50 cm. But the second toe on each foot, which corresponds to the pointer finger on a human hand, had a much bigger claw. MUCH BIGGER CLAW. It was as big as its whole hand! Most researchers think it used the claw to dig into rotting wood, insect nests, and bark to find insects and other small animals to eat.


But that’s not all. Drepanosaurus also had a structure called a supraneural bone at the base of its neck, made up of fused vertebrae, that would have made it look like it had a little hunch on its shoulders. While we don’t have a skull of Drepanosaurus, since we only have three specimens so far, this structure is also present in other drepanosaur species where we do have the neck and head, and they all have fairly long, slender necks and birdlike skulls with large eyes. It’s possible that the supraneural bone was the attachment site for special muscles that helped Drepanosaurus extend its neck very quickly to grab insects and other small animals.


Drepanosaurs in general shared many of the traits seen in Drepanosaurus, although with some differences. Many drepanosaurs had opposing toes on the feet that would help them grasp branches and twigs more securely. Most don’t have the giant claw on the front feet although most do have the tail claw. But one monkey lizard doesn’t live up to its name at all.


A little drepanosaur called Hypuronector limnaios, which only grew about five inches long, or 12 cm, had a much different tail from its relations. Its tail didn’t curve downward at all—in fact, it stuck up behind it and was probably not very flexible. Not only was the tail longer than the body and head together, it had long points growing down from the vertebrae, called haemal arches, which made the tail extremely large top to bottom but flattened from side to side.


In other words, its tail looked like a leaf. The drepanosaur could cling to a branch with its tail sticking up, and any nearby predators would probably think it was just another leaf growing from the branch, especially if the tail was covered in green skin. Some researchers speculate that it could have used its tail as a sail to glide from branch to branch too, or it might have acted as a parachute if it had to jump from a branch to escape a predator. Hypuronector’s front legs were longer than its hind legs, unlike other drepanosaurs, which suggests it might have had a flap of skin that helped it glide.


Drepanosaur fossils have been found in parts of the United States and western Europe, but were probably more widespread than that. We still don’t know a whole lot about them, so every new specimen that’s found can give paleontologists lots of new information. Most drepanosaurs resembled weird chameleons with birdlike heads, but they weren’t related to birds or chameleons. We don’t actually know what they were closely related to.


Ethan also suggested placodonts, another reptile that evolved in the Triassic. Don’t confuse them with placoderms, the armored fish that went extinct in the great dying. The “placo” part of both words means tablet or plate. Therefore, placoderms have skin—that’s the “derm” part—covered in plates, while placodonts have flattened teeth, because the “dont” part refers to teeth. That’s why you get braces on your teeth at the orthodontist but you go to the dermatologist for skin problems.


What did placodonts do with their flattened teeth? They used them to crush the shells of shellfish and crustaceans. From that you can infer that they were marine reptiles, and you would be right. The earlier species had big round bodies with heavy bones, which helped them dive to the ocean floor to find food. They lived in shallow coastal waters and had large flattened ribs that helped protect them from injury if currents pushed them into rocks. While the teeth in the back of the mouth were flattened to crush shells, the teeth in the very front of the mouth were sharp and pointed forward to grab prey.


One of the most common early placodonts was Placodus [PLAK-oh-dus], which grew nearly six and a half feet long, or 2 meters. Its long tail was flattened laterally to help it swim and it probably had webbed toes. Since its legs were small and relatively weak considering how heavy its body was, it probably couldn’t get around very well on land, so it would have stayed close to the water. It probably looked kind of like the modern marine iguana, which we talked about in episode 92, but with longer jaws. On the other hand, unlike the marine iguana, placodus had a third eye.


THIRD EYE ALERT! If you remember way back in episode 3, where we talked about the tuatara, we learned a little bit about the parietal eye, or third eye. Parietal eyes are found on the top of a few animals’ heads, including the tuatara, but they aren’t the same as ordinary eyes. They’re very small photoreceptive eyes that can only sense light and dark. In Placodus’s case, researchers think that ability helped it figure out which way was up more easily when it was underwater. If you’ve ever been knocked down by a wave you’ll understand how easy it is to get disoriented underwater.


Placodus and other early placodonts had a ridge of bony scutes on the back to help protect it from predators. In later placodonts those scutes were bigger and bigger until they were more like armor, which added weight to the body and meant that the bones didn’t have to be so dense. This meant that instead of having barrel-like bodies, later placodonts were a little more streamlined. Their bodies were more flattened than round, but still broad across with big plates protecting the back. Their legs were more like flippers.


Does this make you think of something? Something like a sea turtle?


Later placodonts looked a lot like turtles, a classic case of convergent evolution because they weren’t related to turtles at all. If you saw Placochelys, for instance, you’d probably just think it was a weird sea turtle, unless you got a really close look at it. It grew about three feet long, or 90 cm, with a triangular head, a knobby shell, and flippers with clawed toes at the ends. It had a beak like a turtle’s instead of Placodus’s forward-pointing teeth, but unlike a turtle it also had teeth in the back of the mouth. These were still big flat teeth used for crushing shellfish, but like other placodonts the upper teeth grew from the palate, or the roof of the mouth.


Other placodonts would have looked strange to us, like Psephoderma. It grew up to six feet long, or 180 cm, and instead of a single turtle shell, it had two shells. One covered its body from the back of the head down to the pelvis. The other covered its pelvis and was smaller. It had a long tail and a pointy nose.


At least one placodont didn’t live in the ocean and didn’t eat shellfish and crustaceans. Henodus grew about three feet long, or one meter, and lived in brackish water or possibly freshwater. Its shell was twice as broad as it was long. It also had a lower shell, or plastron, on its belly. Its nose was short and squared-off and it had a turtle-like beak, and instead of teeth it had denticles on the sides of its jaws. Some researchers think it was a filter feeder, filtering tiny animals from the water through the denticles, while other researchers think it may have eaten water plants. It might have done both.


There’s a lot we don’t know about placodonts. We don’t know if they laid eggs or gave birth to live young, and we don’t know what exactly they ate. Obviously their teeth were best suited to crushing shells, but we don’t actually know what kind of shellfish they preferred or if they only ate crustaceans or something else. Placodont remains have been found in Europe, the Middle East, and China, but they were probably more widespread than that. During the Triassic, as the supercontinent Pangaea broke up, it created lots of shallow oceans and island chains that would have been ideal for placodonts.


Unfortunately for the placodonts, as the landmasses moved farther apart over millions of years, the shallow seas became deeper. Populations would have become isolated from each other. Eventually placodonts went extinct, probably by a combination of habitat loss and competition from other animals as dinosaurs and their relatives spread throughout the world.


You can find Strange Animals Podcast at That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at 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 if you’d like to support us that way, and don’t forget to join our mailing list. There’s a link in the show notes.


Thanks for listening!

Episode 227: The Great Dying

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It’s another extinction event episode! This one’s about the end-Permian AKA the Permian-Triassic AKA the GREAT DYING.

Further Reading:

Ancient mini-sharks lived longer than thought

Lystrosaurus’s fossilized skeleton:

Lystrosaurus may have looked something like this but I hope not:

This artist’s rendition of lystrosaurus looks a little less horrific but it might not be any more accurate:

Show transcript:

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

It’s time for our next extinction event episode, and this week it’s the big one. Not the extinction event that killed the dinosaurs, but one you may not have heard of, one that almost destroyed all life on earth. I mean, obviously it didn’t and things are fine now, but it was touch and go there for a while. It’s the Permian-Triassic extinction event, or end-Permian, which took place just over 250 million years ago. It was so bad that scientists who aren’t given to hyperbole refer to it as the Great Dying.

Don’t worry, we won’t talk about extinction the whole time. We’ll also learn about some interesting animals that survived the extinction event and did just fine afterwards.

We have a better idea of what happened at the end of the Permian than we have about the earlier extinction events we talked about in episodes 205 and 214. Right about 252 million years ago, something caused a massive volcanic eruptive event in what is now Siberia. Some researchers speculate that the cause of the volcanic eruptions may have been a huge asteroid impact on the other side of the Earth, which was so powerful that it caused magma to move away from the impact like water sloshing in a jostled glass. The magma rose up toward the earth’s crust and eventually through it onto the surface.

The result was probably the largest volcanic event in the last half-billion years and it continued for an estimated two million years. Most of the eruptions were probably pretty low-key, just runny lava pouring out of vents in the ground, but there was just so much of it. Lava covered almost a million square miles of land, or 2.6 million square km. Ash and toxic gases from some eruptions also ended up high in the atmosphere, but one big problem was that the lava poured through sediments full of organic material in the process of turning into coal. Lava, of course, is molten rock and it’s incredibly hot. It’s certainly hot enough to burn a bunch of young coal beds, which added more ash and toxic gases to the air—so much ash that shallow water throughout the entire world became choked with ash.

The carbon dioxide released by all that burning coal caused severe ocean acidification and ocean anoxia—a lack of oxygen in the water. But it gets worse! A lot of lava erupted into the ocean right at the continental shelf, where the shallow coastal water becomes much deeper. This is exactly the place where you find methane deposits in the sediments on the ocean floor. When those deposits were suddenly disturbed by lava flowing into them, all the methane in the formerly tranquil depths was released and bubbled to the surface. Methane is a powerful greenhouse gas, meaning that if a whole lot of it ends up in the atmosphere in a short amount of time, it can cause rapid global warming—much faster than that caused by carbon dioxide. This global warming would have happened after a period of global cooling due to reduced sunlight reaching the earth through ash clouds, which lasted long enough and was severe enough that sea levels dropped as glaciers formed. Then everything heated way, way up. The ice caps melted, which may have led to a stagnation of ocean currents. This in turn would have contributed to the water’s anoxicity and toxicity. The average temperature of the ocean would have increased by almost 15 degrees Fahrenheit, or 8 degrees Celsius. Atmospheric warming may have been as much as 68 degrees Fahrenheit in places, or 20 degrees Celsius. That’s not the average temperature of the world, that’s the temperature increase.

So, basically, everything was terrible and it happened very quickly in geologic terms. A 2018 study found that everything looked pretty much fine for the 30,000 years leading up to the great dying. Some researchers even think the initial extinction event might have taken place over just a few centuries.

Marine animals were affected the most, especially marine invertebrates. Trilobites and placoderms went extinct, eurypterids went extinct, and corals went extinct until about 14 million years later when modern corals developed. Some researchers estimate that 95% of all marine species went extinct.

Things were better on land, but not that much better. At the end of the Permian, life was good on land and it was especially good for insects because of the high percentage of oxygen in the air and the variety of plant life in huge swamps around the supercontinent Pangaea. The largest insects that ever lived were buzzing around in the Permian. This included an order of insects called Meganisoptera, or griffinflies. Griffinflies looked like dragonflies and may be related to them. Some species had a wingspan 28 inches across, or 71 cm. The arthropod Anthopleura, sometimes called the giant millipede, lived in the Permian too. Some species grew six feet long, or 2.5 meters, and were about 18 inches wide, or 45 cm. It looked like a millipede but had even more legs. It probably looked scary, but it only ate plants as far as we know.

Instead of actively breathing the way most vertebrates do, most invertebrates use a passive system to absorb oxygen from the air. This is great when there’s a lot of oxygen. When the level of oxygen drops, though, the largest species can’t absorb enough oxygen to function and die out rapidly. That’s one reason why you don’t have to worry about spiders the size of bears. So all the large invertebrates and a lot of the smaller ones went extinct as oxygen was replaced with carbon dioxide, methane, and other toxic gases in the atmosphere.

The acid rain caused by toxic gases and the reduced sunlight caused by ash in the atmosphere also killed off plants. Forests died, so that the fossil record during and after the extinction event contains massive amounts of fungal spores from fungi that decompose trees. Some researchers think all of the world’s trees died. Forests disappeared for some four million years. Since trees absorb carbon dioxide from the atmosphere and release oxygen, the lack of trees made oxygen levels drop even more.

Animals that depended on forests to survive also went extinct, including about two-thirds of all amphibians, reptiles, and therapsids. Therapsids were proto-mammals and it’s a good thing they didn’t all die out because they eventually gave rise to mammals.

Everything I’ve described sounds so incredibly bad, you may be wondering how anything survived. One stroke of luck was probably the size of Pangaea. That was the supercontinent made up of most of the world’s landmasses all smushed together. Before the extinction event, the middle of Pangaea was probably pretty dry with swampier climates around the edges. After the extinction event, the interior of the supercontinent was the safest place to be.

One of the most common land animals after the extinction event was a herbivore called Lystrosaurus. Lystrosaurus was a therapsid, and it was nothing exciting to look at unless you were also a lystrosaurus. Some species were the size of a cat while some were much larger, up to 8 feet long, or 2.5 m. It had a short snout, a short tail, and a semi-sprawling gait. A lizard walks with its legs stuck out to the sides, while a dog or cat or pig walks with its legs underneath its body. Lystrosaurus was somewhere between the two.

It probably lived in burrows that it dug with its strong front legs. While it had a pair of tusks that grew down from the upper jaw, those were its only teeth. Instead it probably had a turtle-like beak that helped it bite off pieces of vegetation.

Lystrosaurus lived in the central part of Pangaea, in what is now Asia, Antarctica, South Africa, and eastern Europe back when all those areas were all scrunched up close together. It survived the extinction event and expanded its range, and for millions of years it was almost the only big land animal in the world. It had almost no predators because they’d all gone extinct, and it had very few competitors for food because they’d all gone extinct. Lystrosaurus made up 90% of all land vertebrates for millions of years.

How did it survive when so many other animals died out? There are several theories, but the most important factor was probably its lack of specialization. It could survive on any kind of plant instead of needing to feed on specific species of plant. There’s also evidence that it could enter a torpor similar to hibernation where its metabolism slowed way down. This would have been a literal lifesaver during the time when the air and water were toxic and very little plant life survived. Lystrosaurus could hunker down in its burrow for long stretches of time, then come out and find enough food and water to keep it going for another stretch of torpor.

Just imagine the world back then, after the initial extinction event but before the world had recovered—say, a million years after the volcanic activity stopped. Picture a series of gentle rolling hills dotted with grazing animals. It’s peaceful and very open because there are no trees. Grass hasn’t evolved yet so the ground is covered in fern-like plants from the genus Dicroidium, which lives in dry conditions. As you look closer with your mind’s eye, you realize that every single one of those grazing animals—thousands of them visible in every direction—are the same kind of animal that looks sort of like a fuzzy pig with a stumpy lizard tail, clawed feet, and a turtle’s beak. Lystrosaurus, living the good life.

In the ocean, the situation was similar. The shallows were toxic waste dumps of ash where the water had so little oxygen that nothing could survive. But the deeper ocean was still livable for some animals.

For a long time, scientists thought a group of early sharks called cladodontomorphs had gone extinct during the great dying. Their distinctive teeth had been common in the fossil record, but after the extinction event they disappeared. Cladodontomorphs only grew about a foot long at most, or 30 cm, and may have had a weird-shaped dorsal fin that pointed forward. They lived in shallow coastal waters. You know, the worst possible place to be 252 million years ago.

Then palaeontologists found some of those teeth in rocks that were in much deeper water 135 million years ago. It turns out the little sharks had survived the extinction event by moving into the open ocean where conditions were better. And they didn’t just survive, they lasted for another 120 million years.

So let’s break it down. It was probably four million years before trees developed again from different plants. It was some 14 million years before coral reefs could rebuild as modern corals developed after their cousins went extinct. It took 30 million years for terrestrial vertebrates to recover from the great dying and 50 million years for all the ocean’s ecosystems to fully recover. That’s a colossally long time. But it did recover.

So what animals arose once the recovery was well underway? Icthyosaurs. Archosaurs, which eventually evolved into pterosaurs, crocodilians, dinosaurs, and birds. And therapsids that eventually gave rise to modern mammals.

I don’t usually tease the following week’s show, but next week we’re going to learn about some weird and interesting animals that developed in the early to mid Triassic, after the extinction event was over and life started evolving in new directions. As I’ve said in the previous extinction event episodes: no matter how bad things get, there’s always going to be some little animal stumping along out of the carnage to get on with the business of surviving and thriving.

You can find Strange Animals Podcast at That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at 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 if you’d like to support us that way.

Thanks for listening!