Astrum Space - The Bizarre Creatures that Lived on Earth Before the Dinosaurs | Astrum Sleep Space

Episode Date: August 26, 2025

How did Earth become habitable? Join us on a journey through time. 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. Earth is the place we call home. It's where we work, eat, sleep and go about our daily lives. But how well do we really know it? We like to think of Earth as the blue marble, a stable, temperate world, hospitable to life.

but that's really just a snapshot of a dynamic and evolving planet. If we zoom out on the cosmic timeline, we discover that our home would have been unrecognizable to us at most other times in its history. So let's see if we can reconstruct what Earth might have looked like in the distant past. Let's imagine that alien scientists, who have never seen Earth as it is today, visited at various stages in its development. depending on when these visitors arrived, they would have formed completely different ideas

about the kind of planet Earth was. What would they have seen 4.5 billion years ago? Two billion years ago, half a billion years ago. I'm Alex McColgan, and you are listening to the Astrum podcast. Join me today as we recreate Earth's ancient past and imagine what the planet might have looked like at various points in time. But before we dive into any of that, here's something that not only helps me sleep, but also helps support the channel. Mantis sleep masks are designed to create a blackout effect, making sure you receive the best sleep possible. They come in a range of different variants, from their original sleep mask to their pro for comfort and breathability. However, if you

love listening to these podcasts, there's also a sound version which will help you fall straight to sleep. Use my link in the description and the code Astrum at checkout to receive 10% of your next order. Now, before we start, a little disclaimer. To answer these questions, we'll need to draw on some models that not all our scientists agree on. Traveling into the extremely distant past always carries some error bars. Some of the science we're pretty sure about. Other things are still being debated. So, as we indulge our imagination, let's keep in mind that some of these claims are still being developed and rigorously questioned, as they should be. But to the best of our current knowledge, this is what our planet could have been like.

As long as we're going into the past, we might as well go way back. Let's start 4.5 billion years ago. It's not the very beginning, but pretty close to it. At this time, the Earth is basically a hot, viscous ball of molten rock, and I doubt our alien visitors will want to hang around for very long. The Earth is still young, not even 100 million years old yet, which in planetary terms is an infant. Earth's thin atmosphere is made mostly of hydrogen and helium, most of which is stripped by

the solar wind, since the Earth hasn't yet formed a magnetic field. As a result, the young planet has little protection from the sun's cosmic rays, and the planet is a hotbed of radiation. Earth is also constantly being bombarded with asteroids and comets, which add to its mass, a process called accretion. Just imagine a big ball of chewing gum that you keep adding to with fresh wads of gum, and you'll get the idea. So not only is the young Earth hot and gooey, it's also growing.

But these are not the only impacts the planet has to contend with. In the recent past, there was a cataclysmic event in which a protoplanet collided with the Earth, resulting in the formation of our moon. If our alien visitors were to see Earth in this state, would they see its potential? I'm unsure I would at this stage. But despite these ominous beginnings, the seeds of change are taking root. Riding aboard these imbound Asteroids is a special compound that will play a crucial role in Earth's history, water. While not all of Earth's water comes from these meteors, scientists believe much of it does. According to this theory, hydrogen ions in the solar wind impact these meteors, ejecting

oxygen atoms under their surfaces, thereby producing water. These frequent impacts seed much of the young planet's water. Then, as the planet cools, heavier elements, sink towards the Earth's center, and lighter compounds, such as water, rise to the surface. Volcanic eruptions spew other gases like carbon dioxide, ammonia, and additional water vapor into the atmosphere. Eventually, all of this accumulating water vapor will lead to the formation of Earth's oceans and its mature atmosphere. So, even if Earth is a dangerous place to be at the moment, our alien visitors might see some untapped potential and come back to Earth once it's had a bit more time in the oven. Let's imagine that the scientists returned to Earth

2.5 billion years ago to see if anything has changed. Two billion years have passed, and instead of a molten planet, they find what our scientists call the pale orange dot. Earth has developed a solid crust and magnetic field, which has retained a method methane-rich atmosphere with a distinct pale orange haze, very much like Saturn's Titan. Earth also has vast oceans of liquid water formed from rainfall. Looking upward, our alien scientists see a terrifyingly huge moon overhead, far closer than it is today. Here's a fun fact. The moon has slowly been drifting away from Earth for the past 2.5 billion years and is still moving away from us at the rate of 3.8 centimeters per year.

This drift will eventually stop, but not for another several billion years. But 2.5 billion years ago, the moon is much, much closer, and this proximity leads to far stronger tidal forces in the oceans. While this snapshot of Earth is probably more Earth-like than the previous snapshot, To me, it almost feels more alien than before. Earth must have looked like a barren dream world, a lot closer to a surreal Salvador Dali painting than the teeming planet we know today.

Being experienced in the field of astrobiology, our alien scientist takes some blue-green water samples and find the cause of this orange haze, photosynthesizing bacteria called cyanobacteria. They are excited to find that Earth has developed, developed life. These primitive bacteria are living in communities in shallow water, which in turn have released oxygen into the atmosphere in an event called the Great Oxidation. As part of this transformation, the Earth now has a protective ozone layer, which shields life from the most

harmful effects of solar radiation. Without any competitors, the cyanobacteria reigns supreme. Using solar energy, they are converting carbon dioxide and water into nutrients, seeding the atmosphere with oxygen as a byproduct. Bacteria are now the uncontested rulers of planet Earth, and they have permanently altered their atmosphere in ways that make our current way of life possible. Enthusiastic for Earth's future, our alien scientists decide to come back to Earth 650 million years ago. And boy, what a difference 1.9 billion years makes. The planet is now in its cryogenian period, at a time scientists call snowball Earth. According to these models, Earth is completely frozen over. Think of the last Pleistocene Ice Age, only a lot colder. In fact, all of the Earth's surface

and half of its total ocean water are frozen solid. The earth has become so cold that temperatures at the equator are similar to those in modern-day Antarctica. While the scientists aren't sure what triggered this downshift in global temperatures, some theories include a major volcanic eruption that spewed ash into the atmosphere, a vast reduction in greenhouse gases due to photosynthesizing life forms and Melankovic cycles. Of course, it was quite likely a combination of factors that amplified this global cooling. Interestingly enough, underneath all this glacial ice is a single supercontinent called Panotia, centered on the South Pole.

However, given the vast glacial cover, our alien visitors are having trouble discerning land from ocean. As a side note, don't confuse this supercontinent with Pangaea. Plate tectonics will eventually break apart Panotia and reform that later supercontinent in a few hundred million years, but let's not get ahead of ourselves. Our space visitors land and wander around the vast, endless glaciers, amazed that this frozen landscape was once covered in molten rock. At first, they think the harsh climate might have wiped out Earth's fledgling life, but that life has proven remarkably resilient. Cyanobacteria remain in the ocean, perhaps clustered around

hot hydrothermal vents, much like the black smokers that are currently at the Mid-Atlantic Ridge. There are also newly evolved microbial life forms, such as red algae. Complex, multicellular life remains elusive, but the fact that life has found a way to survive the planet's harshest freezing events so far is a testament to its staying power. At this point, I'd like to imagine our alien visitors having an argument among themselves. The youngest and most temperamental of the group is having a tantrum. First a lava ball, then a barren bacterial playground, and now a ball of ice, it exclaims. Why do we keep coming back here?

But the eldest of the group puts an arm, tentacle, or articulated limb of our preference around its younger comrade. Patience, the wise alien tourist says to its impertinent partner, I have a feeling this planet is in for some major shake-ups. Let's come back in another few hundred million years. I think it will be worth the trip. So, giving the planet time to change, our alien scientists decide to come back during the Devonian period 360 million years ago, and they are shocked by what they see. The planet has thawed completely, where temperature is generally warmer than those of the present day. Scientists estimate that the tropical sea surface temperatures range from 30 degrees Celsius to 21 degrees Celsius later in the Devonian, a temperature

drop that coincides with diminishing CO2 levels due to increasing plant growth. The supercontinent has broken up and formed multiple continents, the largest of which is Gondwana, covering the South Pole and much of the southern hemisphere. Gondwana, Inc. much of what is modern-day Africa, South America, Antarctica, Australia and India, so it's pretty big. But the most dramatic change our visitors notice is that life has already undergone the Cambrian explosion, a rapid expansion of biological diversity that filled the seas with all sorts of complex life. The oceans are now teeming with trilobites, clam-like brachio pods, and complex marine vertebrates. such as fish. Among the more fearsome specimens are dungliosteus, a massive, armored fish 10 meters in length,

and Titanicthus, another giant with a taste for smaller prey, like krill-like zooplankton. Given the presence of these fish that look like great white sharks crossed with armored submarines, our alien scientists decide not to go for a swim, despite the invitingly warm waters. Meanwhile, plants have completely transformed what was once barren continental crust. With no large herbivores in existence, vegetation grows unchecked into dense, sprawling forest, which have produced a layer of stable, nutrient-rich topsoil. But these trees would look very unusual to us. They are vascular plants.

Related to today's thorns and some conifers, there is also an enormous tree-loyal. like fungus called prototaxites, which stand some eight meters tall. Very likely, these mysterious tree-like structures are fruiting bodies of far larger subterranean organisms which haven't been preserved. A few marine species have even evolved limbs and are beginning to walk on land, such as Ichiostega, a rather charming, four-legged vertebrate that looks like a modern amphibian, whose stout limbs and lungs allow it to navigate swamp-like habitats. As our alien visitors leave the Devonian period Earth, they finally have a sense of the ecological diversity and temperate climate that will follow. The once molten planet turned pale orange dot turned giant snowball now somewhat resembles the blue marble we know today. Of course,

other big changes are yet to happen. A mass extinction event will soon decimate marine life and eventually lead to greater complexity among the land animals that adapt. Temperatures will again plunge, setting off the late Paleozoic Ice Age, before rebounding to warmer temperatures again, and complex life will continue evolving in remarkable ways. Among the new species will be amphibians and some giant reptiles you might have heard about called dinosaurs. I wonder when our alien scientists will visit next, how far in the future will they be? meet us? Will they exchange some intergalactic travel tips with our future descendants? I guess we'll have to leave that chapter of Earth saga for another day. That's all we have time for today. I hope

you enjoyed this journey of planetary evolution. If you like what you've heard, please feel free to follow us for more podcasts on other fascinating space topics. But for now, I'm Alex McCulligan, and this has been Astrom. All the best, and see you next time. You said this place was steps from the Water. We just haven't found the steps yet. How much did we save? Enough. Enough to get lost. Or you could book a stay with Hilton. Welcome to your oceanfront room. Just steps from the water. The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay. Hilton for the stay. to build up your team to handle the growing chaos at work, use Indeed sponsored jobs. It gives

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