Dino-Bites: When did the Dinosaurs Live?

Humanity has held dominion over the earth for a blink in the cosmic scale. Life has existed on this planet for 3.8 billion years, and we have only been here for around a 100,000 to 200,000 years. Civilization has only been a part of our history for around 5000 years.

The dinosaurs ruled the world for nearly 180 million years.

In that time, the Earth went through tremendous geological change. Continents smashed together and split apart. Mountains rose and fell. Massive inland seas sliced through the land that we stand on now.

Though the world was different, it wouldn’t have seemed alien to us. In fact, life flourished at this time. Conditions allowed the largest land animals to ever exist to thrive for millions of years.

But it wasn’t always a time of giants. The first period of the Mesozoic geological era, the Triassic, had humble beginnings for the dinosaurs.

The Triassic Period:


247 million years ago, all the continents we know now were lumped together into a super continent called Pangaea. The gigantic size of the landmass would have allowed for some harsh climatic conditions that would have effects would linger throughout the entire Mesozoic.

Earth was a greenhouse. Though the sun was cooler, and the days were shorter, the amount of carbon dioxide in the atmosphere was two to ten times higher than it is currently. Even the polar regions on Pangaea were warm. The super continent was also quite flat, with low tectonic activity, at least in the early parts of the Triassic.

The lack of mountains didn’t allow rain clouds to form with frequency, nor were their many inland seas to help condensation and evaporation to occur. Large chunks of the super continent were arid deserts, bordered by conifer forests that took advantage of the few areas with ground water and rainy seasons. No flowering plants existed yet.

A mysterious extinction event wiped out a majority of life on Earth at the end of Triassic 200 million years ago,  which miraculously allowed the dinosaurs to thrive as they entered the Jurassic period.

The Jurassic Period:


The Jurassic saw intense amounts of continental drift as the continents split. Those same vast deserts became gigantic seaways. Life began to diversify as they were separated by the new seas. Rainfall levels rose as the mountains did the same, allowing flora and fauna to flourish.

Once diminutive, Dinosaurs began to grow immense in size. Conditions and evolution allowed vast change in a relatively short time. This gave rise to the sauropods, and the age of giants. Marine reptiles, some immense in size, ruled the oceans, while flying reptiles glided through the air.

Conifers were still the dominant form of plant life as the greenhouse Earth was still a factor. Semi-arid landscapes were still prevalent, though many allowed for longer and more frequent rainy seasons.

The Jurassic was truly the dawn of the golden age of dinosaurs. Though it wasn’t the longest period, it saw the most change.

The Cretaceous Period:


Beginning 145 million years ago, the Cretaceous was the longest, and would see the dinosaurs go through intense amounts of evolution.

The continents continued to split further, and the greenhouse conditions that were so prevalent earlier began to diminish. The Earth became a bit wetter, but arid climates were still the norm, punctuated by rainy seasons.

Flowering plants began to emerge, beginning an evolutionary arms-race that forced dinosaurs to evolve or die. Hardwood trees sprouted up in the late Cretaceous. Large Redwoods not unlike those in modern day California dominated northern forests.

Dinosaur variety continued to grow. Ceratopsians, and Tyrannosaurids emerged in this period, and early avian flightless and flying theropods began their long evolutionary transition to modern day birds.

But then something happened that changed everything.

The K-T Extinction:


Around 66 million years ago, a vast and rapid change occurred that led to the dinosaurs going extinct.

Much of the evidence points to a meteorite impact. A mountain-sized rock smacked into the Earth in what would become the Yucatan peninsula. A 100-teraton explosion blasted debris and immense heat into the atmosphere, super-heating the earth. Creating a pyrosphere of death that baked fauna and started planetary wildfires.

Anything that survived would have to endure a dark, years long winter, as dust and smoke choked the atmosphere.

Miraculously, the survivors of this cataclysm were surprisingly varied. Early mammals, and even some amphibians and reptiles survived. Toothless birds, direct descendants of the theropod dinosaurs, and ancestors to modern birds also survived.

The near total extinction of the dinosaurs is remarkable. They had endured extinction events before with remarkable grace. They saw great change in the 180 million years they dominated the Earth, but it only took one rock to end their reign forever.

Though they may be gone, dinosaurs still have an effect on us now. The decomposition of carbon from decaying plants and animals in the Earth’s crust create the fossil fuels that run our cars, and fuel our world. Birds are everywhere. From the south pole to the rain forests.

We are still learning more about these amazing creatures and the world they lived in. Looking to the past will make a much more fascinating future.

Next on Dino-Bites: What did Dinosaurs Look Like?

(To celebrate the 25th anniversary of the Jurassic Park film franchise, we will be posting a series of short (mostly) articles throughout the month about dinosaurs and the world they lived in.

These “Dino-Bites” will be intended to inform and clarify some newer discoveries, and also dispel some falsehoods in film and other media about these ancient creatures.

All of this leading to the launch of Jurassic World Evolution, and the premiere of Jurassic World: Fallen Kingdom.

So keep your battery charged with us as we dive back in time to the age of dinosaurs!)


Header image credit: Karen Carr for Sam Noble Oklahoma Museum of Natural History

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