ExtinctZoo - Why Evolution Keeps Making The Same Animals

Episode Date: August 6, 2025

Beneath Germany’s shale, workers uncovered fossils that shouldn’t exist...or at least it would seem so. Instead what was found was proof of evolutions strangest (but perhaps most logical) habit.

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on April 30th, the powerful vocals of Demi Lovato on May 17th, and the signature Southern Country Rock of Eric church on July 19th. Tickets on sale now at yamava Theater.com, only at Yamava Resort and Casino, celebrating its 40th anniversary. You in? Must be 21 to enter. In Germany's Posidonia Shale, workers have been quarrying rock for centuries, turning ancient seabed into roof tiles and tabletops. But sometimes their tools hit something unexpected, hitting not rock, but the preserved remains of creatures. And sometimes those creatures are ones that shouldn't exist. At least,

it would seem like that. The formation dates to the early Jurassic, so about 183 million years ago, when this part of Germany was covered by a warm, shallow sea. And already in the early 19th century, quarry workers were finding strange skeletons embedded in the stone. And during the latter half of the century, as industrial quarrying expanded, the rate of discovery exploded. And ultimately, thousands of different specimens emerged from the rock, and what they

revealed would challenge our fundamental understanding of how evolution works. You see, what they found were reptiles, marine reptiles, ones that had died over 100 million years ago. And that's cool and all, but what really made paleontologists do a double-take was the fact that these ancient reptiles looked almost exactly like dolphins, not similar, not reminiscent, almost exactly the same. These were the ichthyosaurs. The resemblance was uncanny and went way beyond surface details. Their bodies were perfectly streamlined, wider at the front and tapering to a crescent tail, which is the optimal shape for cutting through water at high speeds.

And as it would so happen, this is also the body plan that dolphins possess. And apparently, some species could hit 40 kilometers or 25 miles per hour, which requires more than just a good body shape. It needed the whole package. Rigid torso for efficient force transfer, paddle-like limbs, and a tail built for powerful propulsion. And guess who also has that? Yep, that's right, dolphins. Even their coloration followed the same pattern that we see.

Dark above, light below. a camouflage technique called countershading that makes them harder to spot. I mean, honestly, if you were to somehow bring back an ecthosaur and ask them on what it was, they'd almost certainly say a dolphin. But here's the kicker. Ectheosaurs were reptiles and dolphins are, well, obviously mammals. They're about as related as you are to a turtle. And like dolphins, ectheosaurs breathe air with lungs.

But they'd have been doing it since the Triassic, having come to existence around 250 million years ago. They even gave birth to live young in the water, and we have fossils of mothers with babies emerging tail first, which is exactly the same as we see in modern whales and dolphins, which is done to prevent drowning. But ectheus horse went extinct 90 million years ago, and they took their body plan and design with them, and for 40 million years, nothing quite like them existed in the oceans. But then, mammals decided to return to the water, and something very strange happened. Using a completely different blueprint, a furry, four-legged land animal, evolution built the same animal again. Now, the early whale ancestors, and thus dolphin ancestors, looked nothing like ectheosaurs.

Pachy Cetus was basically a wolf that liked to fish, and ambelocetis was like a furry crocodile with legs built for walking and swimming. But generation by generation, as these mammals became more and more aquatic, they started looking less like their ancestors and more like those long dead reptiles. And by the time true dolphins evolved in the legacy, the transformation was complete. Evolution had built the icthosaur from scratch, using a mammal. But how does nature create what essentially looks to be the same animal twice, especially when separated by millions of years and starting from completely different ancestors?

Well, what those German quarry workers stumbled upon was evidence of one of evolution's strangest habits, but also perhaps the most logical, convergent evolution, which is what happens when natural selection keeps reaching for the same solution to the same problem, regardless of what it's working with. And this would seem odd at first glance, as mutations in evolution are supposed to be completely random. And as Stefan J. Gold famously argued, if you replay the tape of life, you would get completely different results. Except, you don't. Play the tape in Australia, and you'd likely still get at least one marsupial that looks like a wolf. Play it in Europe, and you'll also probably get

another mammal that looks like a wolf. Different starting points, same ending. And this isn't some rare quirk, it happens constantly at every scale, in every environment. I mean, if you want to see convergent evolution in action, you don't even need fossils or far-flung islands. Just go to your garden on a summer evening, because as you watch carefully, you might spot will look to be a tiny hummingbird hovering at the flowers. I mean, it moves like a hummingbird, feeds like hummingbird, and even sounds like a hummingbird, with its characteristic hummingwings. There's just one problem. If you're in Europe or Asia, it can't be a hummingbird, as they only live in the Americas. What you would be seeing is the macroglossum still a terum, also known as the hummingbird hawk moth. With a wingspan of just

40 to 45 millimeters, it's much smaller than any actual hummingbird. But the way it moves, identical. It hovers in front of flowers, wings beating up to 85 times per second, producing that distinctive hum. It's proboscis, a hollow tube that extends from its body, looks shockingly similar to a hummingbird's beak, and reaches deep into the same tubular flowers that the birds also prefer. The moth has even evolved similar metabolic adaptations, with thoracic temperatures reaching above 45 degrees Celsius or 130 degrees Fahrenheit during flight, which is near the absolute limit for insect muscle activity, mimicking the hummingbird-like extreme metabolic strain. But here's where it gets really strange. The moth doesn't just look like a hummingbird, it sees like one too. They have a trichromatic visual

system that's even more precise than honeybees at distinguishing colors, and their food preference is also based on visual identification, just like hummingbirds. They've even converged on similar daily activity patterns, feeding most actively during the warm hours when nectar production peaks. Yet despite these seemingly endless similarities, if you peek under the hood, everything is different, a lot different. Hummingbird flight muscles attach directly to the wing bones, contracting to create each wing beat, while moth flight muscles attach to the thorax itself, i.e. the upper torso, deforming the entire body segment with each beat, with the thorax literally changing shape 85 times per second.

Hummingbirds have tongues that are forked pumps that lap nectar, while the moth has a proboscis, which inflates with hemo-limth pressure like a biological party horn. So same flower, same hovering, same basic appearance, but completely different machinery. But convergent evolution doesn't always involve completely separate evolutionary paths, and in those cases, the appearance, behavior, and even machinery, all pretty much converge at one point. Take Madagascar. This almost Texas-sized island broke away from Africa about 160 million years ago. And even though it is separated by 400 kilometers or 250 miles of straight ocean, certain mammals were able to make their way over through random chance by oceanic dispersal, where they then evolved in isolation.

And today, if you walk through a forest in Madagascar, you might spot a small spiny mammal that rolls into a ball when threatened. And when looking at it, any reasonable nature-loving person would say, oh look, a hedgehog. And if they did, they'd be a hundred. percent wrong. Meet the Greater Hedgehog Tenric, a creature that looks so similar to a hedgehog that a fool natural is for decades, hence the name. It's similar in size to an actual hedgehog, being about nine inches or 23 centimeters long, it has the same defense strategy, rolling up into an impenetrable ball of spines, has the same diet, snuffling around at night for insects and other

invertebrates, and the same habitat preferences, from forests to gardens. But Greater Hedgehog Tenericks aren't hedgehogs, despite the name. And in fact, they're not even close. In the grand family tree of mammals, Tenric sat on a branch with elephants, artvarks, and manatees, the Afrotheria, an ancient group that evolved in Africa when it was still an island continent. And on the flip side, hedgehogs belonged to Laurasia Theria, along with trues, moles, carnivorans, ungulates, and others. And these two lineages split over 100 million years ago, when the dinosaurs were still roaming the earth. So, how did evolution create the same animal twice? Well, it again started with the same problem, being a small mammal in a world.

of predators. You need defense or you're not exactly some big threatening creature, and so the solution become a spiky ball, of course. But the details reveal the different paths taken. Hedgehog spines are hollow modified hairs made of keratin, while tenorick spines are solid keratin, not hollowed. Hedgehogs have 36 teeth arranged in a specific pattern, while tenorics have a different pattern, and even their reproduction is different.

As tenrics do something, almost no other placental mammal does. You see, females have a cloaca, a single opening for reproductive, did not. digestive and urinary systems, which is unlike almost every other mammal, but is like birds and reptiles, as this was the original trait among our ancestors. But here's the really wild part. Tenricks are not a species, or even a genus. It's a family, officially known as the Tenrecaday. And the Tenrecaday, i.e. Tenrics, didn't stop but making just a hedgehog. You see, Madagascar's no native rodents, no native cats, or many other mainland mammal groups. So Tenricks diversify to fill all those empty niches. There are tenures.

tenurics that look like shrews, the shrew-tenrics, tenricks that look like otters, tenricks that look like mice, and so on. It's almost like evolution was given a single mammal type and told to recreate an entire ecosystem with just that. And remember, besides niches, convergent evolution also just happens because of problems, so to speak. And some problems are shared across ecosystems regardless of where they are. Take forest, for example. They all have a universal problem, and that's that trees are tall, and the ground is, well, dangerous. In some, So if we're a small mammal living in the canopy, climbing down one tree and up another isn't just exhausting, it's basically a death wish.

So how do you get from one tree to the next without becoming someone's lunch? Well, according to four different groups of mammals on four different continents, the answer is simple. The ground is lava, so glide. In Australia, sugar gliders, also known as Pataris, Brevisips, solved it first, or at least we used to think it did as we thought sugar gliders were one species. But recent studies have revealed that what we call sugar gliders are actually. three different species that look essentially identical, which we only figured out were different

species by looking at their literal genome. And these marsupials, weighing about 115 to 140 grams, developed a potassium, a membrane stretching from wrist to ankle, which they used to glide. And they're pretty dang good at it, too, being able to glide 50 meters or more in one jump, steering with their limbs and making precision landings on vertical tree trunks. And then meanwhile, in North America, flying squirrels and it penantly invented the same solution. The southern flying squirrel, Glaucomus Volens, is also a small little guy and has what looks like the same wing membrane. But if you look closer, you'll see the morphology is slightly different, as is their gliding

style. They can gain lift while gliding and reach distances of 90 meters when launching from trees. And just before landing, they pull off an aerobatic move that would make even stunt pilots jealous, jerking their tail up to rotate their body vertical, and then landing, head up with all four feet, absorbing the impact on cushioned pads. But both of these animals pale compared to the engineering marvel that is the Calugo. These Southeast Asian oddities took one look at the other gliding mammals and said, Amateurs.

As the Sunda Calugo doesn't just have membranes between its limbs, it also has membranes between every finger, every toe, tail, and even nails, essentially just creating one giant body wing. And when extended, it looked less like a gliding mammal and more like a furry kite that someone brought to life. And unsurprisingly, with such engineering ingenuity, they can glide over 100 meters with a loss fewer than 10 meters in altitude, meaning its glide ratio even approaches that of certain aircrafts, despite weighing many times more than the other gliders,

being more akin to a small cat in size. And the really clever part is that recent studies have found that longer glides actually results in softer landings. So in other words, they're not just better at gliding, they're also better at touching down. And then finally, among our small fuzzy gliding friends, there is the anomalor, also known as the scaly-tailed squirrels. which looked at the other gliders and decided to add its own innovation.

Scales in the tail that worked like climbing spikes, giving extra grip on smooth bark after landing. Because apparently, regular gliding wasn't a flex enough. But with this all said, not every animal wants to fly, and some don't even want to see the sky, let alone be in it. And if you want to see what real evolutionary constraints look like, go underground. Here, the rules are pretty much absolute.

No light, limited oxygen, soil in your eyes, ears and nose, and a movement that requires pushing through solid matter. So while the surface might allow for some creativity, down here, there's only one way to survive, apparently, and that's to become a mole. You see, Europe and America have the true moles, the Tulpa, while Africa has the golden moles, the Chryso-Cloridae, and then Australia has marsupial moles, the Notre-Rictes.

Three continents, three completely different starting points with lineages separated over 160 million years, and yet put side by side, and you need counterintelligence to tell them apart. Get it, a mole. Anyways, the convergence evolution checklist here is almost completely comic in its completeness. Slingrical body? Check.

No visible neck? Check. Tiny eyes covered with skin? Check. No external ears? Check. Powerful digging claws? Check.

Dense adorable fur that lies flat in any direction? Check. I mean, even their biochemistry has converged. With all of them evolving hemoglobin that works better in low oxygen environments. But just like we've seen in other examples, they also developed their own course. I mean, the European mole evolved something that sounds like a thriller movie. The sixth finger. Not a modified finger, but an entirely new digit evolved from a wristbone, giving them a wider

digging surface. And then in a similar, but not so similar direction, some species of golden mole evolved massive inner ear bones that let them detect vibration through sand, essentially turning their skulls into seismometers, allowing them to sense prey moving several meters away through solid ground. In the marsupial mole, well, it doesn't even bother permanent tunnels. At just 12 to 16 centimeters long, and 40 to 60 grams in weight, it literally swims through sand, using an up and down stroke like a subterranean Michael Phelps, with the sand collapsing behind it, leaving no trace. So again, three different continents and three basically identical solutions.

But if you thought having four different gliders and three different moles is bad, wait until you hear about evolution's most blatant case of self-plagiarism. Crabbs. Or rather, all the things that aren't crabs, but decide to become them anyway. There's actually a word for this, carcinization. It's the tendency of crustaceans to evolve in a crab-like forms, and it happens so often that biologists have given up on being surprised. Now, true crabs, a brachyura, evolved the crab designed once in its ancestor,

i.e. having a flattened body, folded tail, sideways walk, and the whole shebang. And it was obviously a good design, over 7,000 species good. But apparently that wasn't enough, as evolution kept making more crabs from non-crab starting material. King crabs? Not crabs. They are hermit crabs that gave up on borrowing shells and evolved their own crab disguise. And you can still see their hermit heritage in their twisted asymmetrical abdomens, a remnant from their shell-dwelling ancestors. And they're not the only hermit crabs that have undergone some crabifying, with coconut crabs being another offender, except they took it to an extreme,

not only evolving into a crab, but also leaving the ocean and becoming the world's largest land arthropod. And this is by no means the end of it. Porcelain crabs, also not crabs. despite looking exactly like them, with them be more close related to squat lobsters. But evolved such a perfect crab impression that they even copied the sexual dimorphism patterns of true crabs. Him, also not a crab. And there are even other non-crabbs that become furry crabs. Seriously. I mean, meet the hairy stone crab.

So this all begs the question. Why does everything want to be a crab? And the answer is because in certain environments the crab body plan is simply optimal. The flat body lowers the center of gravity, perfect for stability and waveswept rocky shore. In the folded tails, another piece of engineering brilliance. You see, lobsters and shrimp have this long muscular tail, which they use for what's called the caridoid escape reaction. Basically, when they panic, they shoot backwards through the water like organic jet skis.

And this is fast and all, but it's also expensive, etabolically speaking, and requires keeping a lot of vulnerable equipment hanging off your back end. And so crabs were just like, nah, to all of that. Instead, they tucked their tails under their bodies, armored them up, and freed themselves from having to maintain escape muscles which they rarely used, ones which can also be taken advantage of. And then there's the sideways walking, which sounds goofy until you realize it's a genius evasion strategy. You see, most ocean predators are built for forward propulsion, basically being similar to torpedoes, only being able to move in a straight line. So crabs moving sideways by default makes

it that much more difficult to catch them. And the claws, well, they're kind of self-explanatory, being basically Swiss army knives turned appendages, weapons, tools, and eating utensils, all in one package. And again, this body plant is so effective that even terrestrial crustaceans adopt it, like the coconut crab which I mentioned earlier. The nightmare fuel, which is the world's largest land arthropod, that can both climb trees and crack coconuts with claws that generate forces approaching 3,300 newtons, which is more than the bite force in most dogs, by the way. So what does all this tell us about convergent evolution?

Well, two things. Rules are rules, and don't fix what ain't broke. For example, if you want to move officially through water, the law of fluid dynamics dictate the optimized body shape. If you want to glide, aerodynamics determine your wing loading. And if you want to dig, soil mechanics constrain your form. And then, of course, chemistry adds its own rules. I mean, there are only so many ways to build a light-detecting molecule,

so eyes converge in the same design over and over again. And even something as specific as echolocation evolves separately in bats, dolphins, some shrews, and even certain birds. Because, if you need a quote-unquote sea with sound, the physics of sonar don't offer many options. And remember, ultimately natural selection dictates the thought of the first of the final output, which over time will always lead to the optimal solution considering the circumstances, to which they're not an infinite amount. And this is why convergent evolution is everywhere.

It's not that evolution lacks imagination, it's that physics, chemistry, and ecology define a limited solution space. When different lineages face the same challenge, they often find the same answer, not because they're related, but because it's the only answer that works. And the implications of this are kind of crazy if you think about it. I mean, if the physics we observe is universal, and as far as we know, it is, then evolution might be weirdly predictable. Not in the details, obviously, but in the broad strokes, kind of. I mean, picture an alien planet with oceans, which let's just assume is also water. The fast swimmers there won't look like dolphins because they're copying Earth, they look like dolphins because fluid physics behave

the same way everywhere. And if they have a forest-like ecosystem, something might glide between trees using membranes. And if they have an underground ecosystem, the diggers will probably have reduced eyes and be tubular in shape. I mean, heck, If the conditions are right, they'll probably even have crabs. After all, the universe really does seem to have a thing for them. And this is what makes convergent evolution and natural selection so interesting. All these different lineages, separated by millions of years, or vast spaces, and they keep arriving at the same solutions, because those are the best solutions.

It's both beautiful and limiting at the same time. All this magnificent diversity of life, and yet we're all constrained by the same rules. Makes you wonder, if humans ever go extinct, there's a chance for another highly intelligent species on our planet. Thanks for watching, and until next time, on the list. Enjoy more ways to save at Ralph's, like low prices in every aisle. And when you download the Ralph's app, you can clip and save more with digital coupons every week. Plus, you can earn fuel points to save up to $1 per gallon at the pump.

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