Astrum Space - The Largest Extinction Event on Earth Was NOT Caused By a Meteor | Earth During the Dinosaurs

Episode Date: August 28, 2025

What was Earth-like in the age of dinosaurs?Astrum's newsletter has launched! Want to know what's happening in space? Sign up here: ⁠https://astrumspace.kit.com⁠A huge thanks to our Patreons who help make these videos possible. Sign-up here: ⁠https://bit.ly/4aiJZNF

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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 Theatre.com, only at Yamava Resort and Casino, celebrating its 40th anniversary. You in? Must be 21 to enter. The Earth is 4.54 billion years old, plus or minus 50 million years. That's a lot of birthdays. In that time, Earth has undergone some pretty incredible changes. In a recent episode, we covered 4.2 billion years of that history. history, which saw the Earth transform from a molten ball of lava to a pale orange

wasteland, to a giant snowball, to a flourishing tropical world. But Earth Saga is like a TV drama that keeps taking twists and turns, with some of the most incredible stuff happening in the last 300 million years. So for those of you that were disappointed we didn't cover dinosaurs in part one, well, you might want to stick around. And for anyone just tuning in, here's our premise. Imagine that alien scientists visited Earth at various stages in its development. What kind of planet would they find?

I'm Alex McColgan and you're watching Astrum. Join me today as we continue Earth's saga and imagine how the planet might have looked in its ancient past. First, a reminder. To answer these questions, we'll draw our models that not all scientists agree on, although the job gets easier when our timeline is in the millions rather than billions of years. Not all of the science is settled, and some of these models are still being debated, but to the best of our current knowledge, this is what our planet could have been like. Now, back to the story. Our intrepid alien scientists are fresh off their exciting trip to Earth during the Devonian

period, and are pretty excited about the direction things are headed. Obviously, they need to see what happens next, so they make a return trip 288,000. million years ago. Earth is now in its early Permian period. The biggest geographical change is that the continents of Euramrica and Gondwana have combined into a single landmass called Pangea. The collision of these continents, called the Variscan Orogeny, unleashes powerful tectonic forces that create a mountain range called the Central Pangean Mountains. How tall are they?

Well, Mount Everest is in the right ballpark, as this range is comparable in size to the modern Himalayas. In fact, they are so tall that they have a profound effect on the climate of Pangea. The central Pangean mountains lie just beneath the equatorial rainy belt, and our scientists quickly discover the impact of these giant mountains on the entire continent. South of the range, it is a mega monsoon climate. However, there is a flip side to all this rain. The mountain range, in turn, casts a rain shadow to the north, which creates a huge desert

in Pangea's interior. Basically, when air travels over tall mountains, it moves upward and cools, causing precipitation, so that by the time it crosses the mountains, the air is pretty arid. We see this effect today in the Gobi Desert, which is located in the rain shadow of the Himalayas. Pangaea's formation is a great example of how plate tectonics not only impact the world's landmasses and oceans, but its weather as well. Yet, there are also other factors shaking up the world's climate. During the early Permian, the Earth is still in the latter days of an ice age,

dating back tens of millions of years, an event known as the late Paleozoic Ice House. Our leading theory for this cooling is that the explosion of plant life during the carboniferous raised Earth's oxygen levels and diminished its CO2, leading to a reduction in the greenhouse effect, with Milankovic cycles also likely playing a role. During the late Paleozoic ice house, vast glaciers built up at the poles and in the higher elevations. Yet, by the early Permian, the planet has begun entering a warming trend. The polar ice caps are retreating, but glaciers remain in the ocean.

most of the high elevation mountain ranges. So between the climate disruptions caused by Pangaea and the cooler the normal but warming global temperatures, life forms on Earth have had a lot of adjustments to make. Since our aliens last visited, the formation of Pangaea has produced a vast super ocean called the Panthalacic, or Universal Sea, as well as a smaller ocean called the Paleoetheus. The Panthalassic is so big, it occupies almost 70% of Earth's surface. To gather more information, and, if possible, see what's down there with their own eyes, our aliens enter a submersible and dive in.

As it turns out, the safety provided by said vehicle is much needed. While harmless trilobites and nautilai remain in abundance, Earth's oceans have had some terrifying new inhabitants. Among them is one of the strangest predators ever to patrol the watery depths, Helicoprion, an 8-meter-long shark-like fish with a wall of teeth in its lower jaw, resembling a buzzsaw. Most likely, this wall is an adaptation for tearing apart and sucking soft-body prey. Our aliens have seen some strange creatures during their interstellar travels, but this is definitely one of the strangest.

And honestly, Helicoprion would look utterly alien to us too. I personally have always dreamed of a day when humans discover extraterrestrial life, but until that day comes, our best resource for understanding how life can evolve under various conditions is Earth's own fossil record. Earth was a different planet back then. In our own solar system, moons such as Europa, Ganymede, and Enceladus may have subsurface ocean suitable for strange life forms. Meanwhile, on land, insects have begun to flex some serious muscle. There are all sorts of beetles, including Permocopede and Megynisotera,

an extinct order of giant dragonflies. Just imagine a dragonfly with a wingspan about the size of common seagulls, and you'll have the idea. Another frankly bizarre newcomer is Diplocalis, an early amphibian with a boomerang-shaped head. Look at how fascinating these Earth aliens are, I can hear our extraterrestrial zeno-zoologists say. But by far, the most interesting quadrupede of the early Permian is the Dimetrodon. Although it is often mistaken for a dinosaur in the popular imagination, this 2-4-meter sail-backed predator is actually a synapsid, more closely related to modern mammals than reptiles. Believe it or not, the sail could be an adaptation that predates the transition from exotherms,

or animals that absorb heat from their environment, to endotherms, which regulate temperature internally. You know, warm-blooded creatures like you and me. Vimetrodon's sail contains a network of blood vessels, which allows it to raise its temperature more quickly in sunlight, an early step towards temperature regulation. the planet experiencing all kinds of climactic changes, this ability to regulate temperature would certainly be advantageous. It's a wonderful illustration of how much living organisms can and must change in order to survive. Our planet's climate is like a complex system full of inputs with a biosphere as corresponding

outputs. Planets like ours dictate what sort of life can exist on them. And interestingly, as a planet changes over time. the type of life it can support also changes. Impressed by Earth's development, our alien scientists decide to return in another 100 million years. Unbeknownst to them, they will miss the largest extinction event in Earth's history. I'm not talking about the asteroid that eventually killed off the dinosaurs. A much more catastrophic extinction takes place around 252 million years ago, called the Permian-Turassic extinction event.

Our leading theory is that volcanic eruptions release a huge amount of CO2 into the atmosphere, which raise global temperatures and make the oceans more acidic. This catastrophic event eradicates about 70% of terrestrial vertebrate species and 80% of all marine species, a mass die-off unmatched by any other in the history of the planet. Yet, as devastating as this is in the short term, it would eventually clear the field for a whole lot of evolutionary diversification during the Jurassic and Jurassic. And chief among the beneficiaries is a group of reptiles that would one day rule the planet. Dinosaur.

Our alien scientists returned to Earth during the late Jurassic period, 150 million years ago. Although Pangaea managed to hang around until the early Jurassic, by now it is starting to drift apart due to tectonic movements in the planet's lithosphere. The Earth is made up of about 15 to 20 tectonic plates, which are always moving toward or away from each other at a rate of around 1.5 centimeters a year, which, interestingly enough, is pretty much the same rate as our toenails grow. As plates move away from each other, they open a rift marked by outpouring basaltic lava. So beginning around 200 million years ago, Laurasia breaks away from Godwana, creating two small

smaller supercontinants. In the north, Laurasia contains modern-day North America and Eurasia. To the south, Gondwana includes modern-day South America, Africa, Australia, India, and Antarctica. A narrow body of water called the Tettis Sea is also opening up. It will one day grow into the North Atlantic Ocean as outpouring basaltic lavas at the mid-Atlantic ridge continue to push the landmasses farther apart. Meanwhile, in the south, Antarctica and Madagascar have begun to separate from Africa, opening up the Proto-Indian Ocean.

While the continental land masses still look quite different from how they look today, our alien visitors already have an inkling of where Earth's continental configuration is heading. The climate of the period is scorching hot. Global temperatures are 5 to 10 degrees warmer than they are today, with atmospheric CO2 levels approximately four times greater. What contributed to all this CO2? Very likely, the mass extinction of plants during both the Permian Terracic extinction event and the subsequent die-off called the End Terassic Extinction played hefty roles.

Global temperatures are so warm that ice sheets are unable to form at the poles. Instead, the poles are covered in forests, which likely experience warm summers and cool snowy winters. So little water locked up in glacial ice, sea levels are significantly higher than they are today, with the peak happening right around this time, about 140 meters higher. In terms of flora, gymnosperms such as conifers have become one of the most successful plant types. Some trees, like the extinct Arrocaria Mirabilis, represented by this extraordinarily well-preserved cone, look eerily similar to what you might find today.

This is also a golden age for cycads, palm-like vegetation with woody cylindrical trunks and stiff pinnate leaves. These plants grow heartily in the late Jurassic's expansive tropical and subtropical climate zones. As our alien scientists step out of their ship, they hear an ominous rumbling. Looking over, they spot a pack of towering sauropods. Not just any sauropods either. Suposaurus, one of the most massive terrestrial animals in Earth's history, measuring up to 35 metres long and weighing 40 metric tons. Getting over their initial fright, our alien visitors realized

that these Goliaths are in fact herbivorous grazers, well adapted for reaching high vegetation. But their relief is short-lived. Stalking some of the smaller sauropods is a rangy allosaurus. A formidable species of carnivore nearly 10 metres long, with dozens of needle-sharp, serrated teeth. Luckily, our alien visitors escape their brush with the hungry carnosaur and decide to finish the rest of their tour from the safety of their ship. Once they're in the air, they encounter a feathered Archaeopteryx, an avian dinosaur considered to be one of the first birds.

Archaeopteryx is also sharing the skies with large flocks of non-Avian things. pterosaurs, such as dimorphodon and the crested pterodactyllus. These winged predators are well adapted for catching smaller animals and invertebrates in their toothy, beak-like jaws. But as our alien scientists stopped their expedition for lunch in one of the more sheltered forest glades, it's something small and unassuming emerging from a burrow that catches the zeno-zoologist's interest again. A small furry creature called Tainiolabis.

Teno Labis and other members of the extinct order multiterberculates, named after their unusual teeth, which they'd used to chew in a forward and back grinding motion, are some of the earliest mammals. And while they may look unassuming, our aliens quickly realize there's something different about them, as they observe their sociability in the way that they play with one another. These little rodent-like creatures have highly developed brains, especially compared to pea-brain dinosaurs, And they are warm-blooded, with a useful adaptation called fur to keep them insulated. Little do our alien visitors know the great, great, great descendants of these humble, scurrying

creatures will one day outlive the dinosaurs and dominate the earth. But that chapter will have to wait for a return trip by our intrepid travellers. They are worn out from the scrapes and scares of this trip, but they certainly have an idea of Earth's immense diversity and adaptability. Who knows? They may come back to finish the story another day. I hope you enjoyed this second chapter on Earth's planetary evolution. Are you interested in learning more about Earth's history in future episodes?

Which part of Earth's history would you like to visit if you could? Please let me know in the comments. If you're an alien scientist exploring an ancient planet or a human watching a video about it, sometimes how you explore can be just as important. as what you explore. Having an internet browser that's cluttered with tabs can be a real energy drain, which is why I'd like to talk to you about Opera One, the desktop browser that's the sponsor of today's video. I've never seen a browser that allowed me to organize

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not try out Opera One for yourself by downloading it using my link in the description below. I highly recommend it. Thanks for watching! Did you miss the previous episode about Earth's Past? Check it out here. And a big thanks to my patrons and members for your support. If you want to support the channel too and have your name added to this list, check the links below. I'd really appreciate it.

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