100 years before the dinosaurs

100 years before the dinosaurs

When we think back millions of years ago, long before recorded history, we usually think about dinosaurs, right? Those big boys are cool, sure, but life on Earth actually existed for billions of years before the first dinosaur chanced onto the scene.

Though, it was very different to what you might imagine. So, come with me on a wild journey from Earth's very first days all the way through to the dawn of the dinosaurs. As with most things, it's a good idea to start at the start.

Around 4.6 billion years ago, dust and gas left over from the Sun's formation bunched together to create colossal space rocks hundreds of miles across. I'm massively simplifying, but these collided with one another over and over and eventually fused to create the Earth, though, certainly not an Earth recognizable to you or me.

No, this early Earth was a hellish, molten world of super heated lava, radioactivity, and regular asteroid impacts. And that was it. For a long, long time. It wouldn't be until almost a billion years later, around 3.7 billion years ago, that things would get interesting.(years before the dinosaurs)

years before the dinosaurs: our planet had cooled significantly

years before the dinosaurs: By this time, our planet had cooled significantly and was near modern temperatures. That doesn't mean it was hospitable though. Largely composed of water with the atmosphere mostly devoid of oxygen, it was an empty world of tumultuous seas and rocky crags.

The only noise you'd have heard was the ceaseless crash of the tide colliding with the shore. That, and the occasional volcanic eruption. creepy. Yet, deep within the waters of this spooky place, something amazing and utterly perplexing happened.

Life was born. We're not exactly sure how, but a miraculous blend of the right processes and ingredients in the Earth's oceans led to extremely simple, single-celled organisms emerging. And some of these organisms produced oxygen. For billions of years our single-celled friends were free to laze around absorbing nutrients and expelling their own byproducts.

What a life. But ever so slowly, they began to change and grow more complex. This would finally come to a head at the start of the Cambrian period, some 538 million years ago. Before the Cambrian, the Earth's landmass had formed one super continent called Robinia. As the Cambrian began however, this would split into several smaller landmasses, the biggest of which was Gondwanaland in the southeast.

But that's not the exciting part. Allow me to introduce you to the Cambrian explosion, the most incredible bio diversification event in the history of our blue planet. Now, when I say explosion I don't mean a big fiery bang. No, this explosion was more metaphorical to describe the sheer number of new creatures that burst onto the scene. Single cells were so last millennia. Now complex life was in vogue.

Most of the basic body forms we see today first appeared at this time, and relatives of crustaceans, molluscs, starfish, and worms developed beneath the waves. Now don't get me wrong, this explosion still took place over tens of millions of years, but considering the lackluster evolution in the billions of years before, this was a monumental event.

years before the dinosaurs: Scientists still argue over the cause of the Cambrian explosion

Scientists still argue over the cause of the Cambrian explosion. Remember I said some of those original, simple organisms started producing oxygen though? Well, one theory is they rapidly multiplied, increasing oxygen levels substantially and allowing for new, more intricate life forms to emerge.

These preyed on lesser life forms and kick started the evolutionary arms race that would go on to define the development of life on Earth forevermore. Regardless of how it happened, the Earth was now perfect for these new breeds of life.

The average temperature was much warmer than it had been, with waters likely to have been around 110 degrees Fahrenheit. This, alongside extra oxygen and carbon dioxide, gave life the opportunity to level up. And level up it did. If you wanna level up your knowledge, why not drop a like and subscribe?

you don't wanna miss out on more awesome videos like this one, do you? All finished? Nice one. Now, where were we? yes, the Cambrian period. Eyes, limbs, mouths, exoskeletons, shells, these adaptations all started around this time.

Though, many of the animals that sported the upgrades were still completely alien looking. Take trilobites. These creepy-looking shelled arthropods could suddenly be found all over the ocean munching on plankton, scavenging on scraps, and hunting other animals.

years before the dinosaurs: first fish

You might recognize them from the abundance of fossils that still remain today. Indeed trilobites were some of the most successful animals to ever live, thriving for hundreds of millions of years. But they weren't the only things that appeared during the Cambrian. The very first fish would also show up. They started out as slimy, lawless eel-looking things.

Crucially, this marked the moment the first true vertebrates evolved. Not that they were exactly impressive in the beginning. Spermatozoon was a weird worm-looking guy that possessed a backbone despite looking utterly spineless. Other animals of the Cambrian were even weirder, like the utterly freakish Robinia, a bottom feeder that looks like it was designed by a child. Or me after a few beers.

It'd use that long beak thing to pick up tiny prey items and place them directly into its mouth, something I wish I had for getting into Principles cans. But with predator and prey dynamics becoming firmly established, one animal needed to stand, or swim, above the rest. This is Anomalous, meaning abnormal shrimp, and it was the top predator of the day.

A little over a foot long, which was huge for the time, this nightmare prawn patrolled the oceans, devouring soft-bodied animals like worms. Now, with such a peerless predator on the prowl, animals were forced to adapt even more to survive. The evolutionary arms race had just been kicked up a notch.

Or at least, it should have been.  around 485 million years ago, just when it looked like everything was coming together and life was steadily advancing, disaster struck. It's still a mystery as to why, but it seems that a dramatic drop in oxygen levels probably caused by volcanic activity led to a mass extinction event. Not everything was wiped out.

years before the dinosaurs: Prototype fish

Some creatures like our old pals the trilobites carried on thriving, but the event was undoubtedly apocalyptic in scale. The Cambrian period was officially over and the Ordovician period was about to begin. The Ordovician has been largely defined by the Great Ordovician Biodiversification Event, aka the GOBE.

over the course of some 30 million years continents shifted, sea levels fell, and oxygen levels in the ocean increased again. The shifted continents created new islands, which birthed segregated habitats for the freshly oxygenated waters around them. Habitats that were ripe for conquering. And life was up to the challenge.

Prototype fish continued to evolve into increasingly more fish-like shapes, though they still had a long way to go before they'd become anything like Nemo. Elsewhere, more nightmarish beasties were emerging. Meet the eurypterids or sea scorpions. Anybody else get a chill when hearing that? These predatory arthropods weren't actually scorpions but are colloquially referred to as such, why?

years before the dinosaurs: why?

years before the dinosaurs: Because of their long spiked tails, grabby claws, and the fact that they're horrifying. Seriously, the earliest Pentecopterus could reach pant-wetting lengths of over 5 1/2 feet. Add these to the list of things I'm glad are long dead. As scary as they were though, they weren't top of the food chain. That honor goes to Cameroceras, a predatory cephalopod related to modern octopuses and squids.

Cameroceras could reach a terrifying 23 feet in length, shell included, and would scour the depths for arthropods like sea scorpions to snack on. Yup, Cameroceras' sharp beak was more than strong enough to crunch through hard exoskeletons and shells, making it top dog in a world filled with armored hors d'oeuvres.

But fauna wasn't the only thing that was changing, flora was about to take over the world. Primitive algae had existed in the seas since the Cambrian, but it was nothing to write home about. That is, until the Ordovician kicked things up a notch.

Algae evolved and spread onto dry land for the very first time as moss. Well, sort of dry land. These early migrators lacked roots and other specialized parts needed to retain water without help, so they dwelled on the edges of waterbodies where it was damp. Despite such humble beginnings though, this was the start of nature's conquest of land.

Not least because plants began absorbing carbon dioxide from the atmosphere and releasing oxygen into it. A journey that would one day lead to the creation of Denny's. The Ordovician period came to an end around 443 million years ago with another mass extinction, this time caused by an ice age.

• Pentecopterus: Early arthropod with long spiked tails and grabby claws, reaching over 5 1/2 feet in length; terrifying but not the top predator.
• Cameroceras: A predatory cephalopod, related to modern octopuses and squids, reaching up to 23 feet in length; top of the food chain, feasting on armored arthropods like sea scorpions.
• Algae Evolution: Primitive algae, present since the Cambrian, evolved and spread onto damp land areas as moss during the Ordovician period.
• Flora's Impact: These early plants absorbed carbon dioxide and released oxygen, setting the stage for the eventual transformation of Earth’s atmosphere and ecosystems.
• Ordovician Mass Extinction: The period ended around 443 million years ago with a mass extinction event caused by an ice age.

years before the dinosaurs: our planet's history

years before the dinosaurs: There's actually been a fair few of them throughout our planet's history. Each one has been utterly devastating, and this was no exception. Beginning 460 million years ago and persisting for the next 40 million years, glaciers enveloped the southern hemisphere, cooling the entire world and crippling marine animal populations worldwide.

Though all the main animal groups survived, their numbers were drastically reduced, and many major species like Cameroceras didn't make it at all. In fact, some 85% of all marine animal species were wiped from existence.

Jeez. Interestingly, some scientists blame this calamity on the success of the new land-dwelling plants. They claim the moss absorbed so much carbon dioxide from the atmosphere that it had a cooling effect on the planet, eventually causing the full-blown ice age. However it happened, one thing is for sure, the Ordovician was over, and the Silurian had just begun.

years before the dinosaurs: 40 million long years after it formed

years before the dinosaurs: 40 million long years after it formed, the ice finally dissipated as CO2 returned to the atmosphere. The melting ice caused sea levels to rise and the climate eventually stabilized, allowing life to expand again. And with the Cameroceras gone, sea scorpions were free to rise to the coveted rank of apex predator.

Thriving more than ever before, they diversified and got even scarier. The Carcinosoma, an unusually massive eurypterid grew to over 7 feet in length. Jeez. Fish too continued to adapt. The first piscine with movable jaw action, made its appearance in the Silurian period. Boy, now we're getting somewhere. Oh, and the very first coral reefs emerged as well.

These formed important parts of diverse new ecosystems and played host to the hardy trilobites and other creatures. Meanwhile, the terrestrial plant life that may or may not have just wiped out most other life on the planet was going from strength to strength. Plants on land began to take on far more complex, recognizable forms, and evolved into vascular, stemmed organisms that could absorb and retain water self-sufficiently.

These plants would form the basis for all modern flora, and with them came the next wave of oxygenation for the Earth's atmosphere. This time, rather than plunging the world into an ice age, quite the opposite happened. The additional oxygen proved enough to support animal life on land. Arthropods began to crawl out of the oceans, with the very first groups probably being myriapods like centipedes and millipedes, and arachnids like scorpions.

These creepy crawlies may have initially only left the water to avoid predators or access new food sources, but the prospect of a whole new environment to conquer proved too good to pass up. See, life was super competitive in the ocean.

years before the dinosaurs: The land however was a new, unconquered playground of opportunities

years before the dinosaurs: The land however was a new, unconquered playground of opportunities. Not that every species that ventured out immediately lost their gills and learned to breathe air. Silurian scorpions still had gills even after moving onto land and had to keep them moist to function. So they wouldn't have strayed too far from the water's edge, at least not at first.

The Silurian period met its end around 419 million years ago with some relatively minor extinction events probably caused by the changing climate. I say relatively minor because unlike others, they didn't bring the entirety of life on Earth to its knees and threaten to make the planet totally lifeless again. They weren't exactly fun though. Regardless, the Devonian period is what followed, and it would prove the most influential period of life since the Cambrian.

For a start, the earliest known sharks evolved, though they were far from the top predators we know today. In fact, they were completely overshadowed by a group of bony fish called placoderms, like this absolute beast, Dunkleosteus. Old Dunkly was the apex predator of the day. At its smallest estimate, it was a little shorter than a male great white shark.

That's three times the size of an adult human. But at its biggest, it was equal to several great whites put together at an astronomic 26 feet. Without a doubt, this was the biggest species alive at the time, and one of the most intimidating fish to have ever lived. Its colossal head housed guillotine like teeth and experts reckon it had a stronger bite than a saltwater crocodile.

For context, saltwater crocs have the most powerful bite of any living creature, but Dunkleosteus had more than double that. I mean, just look at that jaw. Ugh. Fish weren't the only thing getting super-sized either, on land, plants started bulking too. The culmination of all prior evolution, the very first wooded trees sprang up with complex root systems, branches, and height.

years before the dinosaurs: They formed the original forests

years before the dinosaurs: They formed the original forests, which produced a whole load more oxygen for the atmosphere while absorbing huge amounts of carbon dioxide. All this meant the terrestrial ecosystem became even more inviting for new life. And so, finally, the vertebrates took notice.

See, certain species of fish like lungfish had been spending more and more time in shallow waters, and some had even flopped onto land for brief periods. But in the Devonian, everything changed. They evolved. The most interesting representation of this is Tiktaalik, the earliest known vertebrates that could breathe out of the water.

This freaky looking fella had characteristics of fish, amphibians, and reptiles, a bizarre middle ground between the worlds of land and sea. While it still lived mostly underwater, it was capable of clambering onto land when needed. And then we have Ichthyostega, the first of the tetrapods, animals with four fully fledged limbs, like us.

Though they too spent most of their time in the water, the world would never be the same again. Meanwhile, the arthropods that were living on land already started to diversify. Wingless insects and, ugh, spiders developed and spread. For those creatures still confined to the seas though, things were about to get a whole lot worse.

As the Devonian period neared its end, oxygen levels in the oceans began to decline harshly. Without the oxygen to keep them alive, immense swathes of marine creatures died out. The long-lasting trilobites and sea scorpions were decimated, and although some survived, their populations would never recover.

years before the dinosaurs: up to 70% of all invertebrate species died out

years before the dinosaurs: Dominant species like the Dunkleosteus on the other hand were completely eradicated, and up to 70% of all invertebrate species died out. We aren't entirely sure what caused the sudden drop in oxygen, but scientists reckon it probably involved trees.

Now hear me out. Trees in this era reached up to 130 feet tall, so it needed deep systems of roots to support them. But roots don't just anchor plants and absorb nutrients, they also affect the earth around them, altering rocks and creating nutrient-rich soil. The problem? This soil covered the planet so thinly that much of it washed off into rivers and oceans, taking all its nutrients with it.

This fuelled a series of huge algae blooms in the water, and as all this new algae photosynthesized, it removed oxygen from the water. Not good for anything living in there. Man, who knew that plants could be responsible for so many deaths? I'd keep an eye on your succulent if I were you.

And while life underwater was devastated however, the land dwellers continued to thrive, marking a palpable shift in the balance of power. The era that came next, the Carboniferous, showcased the sheer dominance that life on land had cultivated. Starting 359 million years ago, the Carboniferous period saw terrestrial plant life flourish and multiply even more, forming vast jungles and murky swamplands that covered most of the planet.

This incredible amount of foliage caused the oxygen in the atmosphere to reach levels completely unheard of before or since. And it had some crazy effects on the animals of the day. Remember the arthropods that first invaded the land back in the Silurian?

by now they'd had a very long time to evolve and adapt and they were everywhere. When the oxygen in the air skyrocketed, they were given their latest upgrade. See, arthropods take in oxygen through small holes in their body. With more oxygen up for grabs, and huge amounts of available food in the form of these new plants, they grew absolutely enormous....This story continues

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