When did dinosaurs first appear?
Dinosaurs first appeared about 230 million years ago during a time called the Triassic Period. This period lasted from about 252 to 201 million years ago and was the first part of the Mesozoic Era, also known as the "Age of Dinosaurs."
Back then, the Earth looked very different from today. Instead of separate continents, there was one giant landmass called Pangaea. This supercontinent was surrounded by a vast ocean and had a hot, dry climate with large deserts. There were no polar ice caps, and plant life mainly consisted of ferns, cycads, and conifers.
The first dinosaurs were small, lightweight, and fast. Many of them walked on two legs, allowing them to move quickly and escape predators. Unlike the giant dinosaurs that came later, these early species were not the rulers of their time. They had to compete with other reptiles, such as crocodile-like creatures called pseudosuchians, which were dominant predators.
Some of the first dinosaurs included Eoraptor and Herrerasaurus.
Eoraptor, whose name means "dawn thief," was a small, bipedal (two-legged) dinosaur that grew up to 3 feet (1 meter) long. It had sharp teeth and claws, suggesting it was a meat-eater.
Herrerasaurus was slightly larger, about 10 feet (3 meters) long, and one of the first known theropods—a group of dinosaurs that later gave rise to famous predators like Tyrannosaurus rex.
Though dinosaurs were not yet the dominant animals of the Triassic, they were beginning to evolve and adapt, paving the way for their incredible success in the Jurassic and Cretaceous periods.
The rise of the dinosaurs – The Jurassic Period (201-145 million years ago)
The Jurassic Period was a time of great change, marking the true rise of the dinosaurs as the dominant creatures on Earth. After surviving the mass extinction at the end of the Triassic Period, dinosaurs began to grow larger, stronger, and more diverse than ever before. This period saw the emergence of many famous dinosaur species, from enormous plant-eaters to powerful carnivores.
Giant herbivores rule the land
During the Jurassic, plant-eating dinosaurs became some of the largest creatures to ever walk the Earth. These dinosaurs, called sauropods, had long necks to reach the tallest trees and massive bodies to store food.
Brachiosaurus, one of the tallest dinosaurs, could grow up to 85 feet (26 meters) long and weigh as much as 80 tons. Unlike some other sauropods, it had long front legs, allowing it to reach higher branches than its plant-eating rivals.
Diplodocus, another famous sauropod, had a very long neck and tail and could whip its tail as a defense against predators.
These massive dinosaurs spent their days munching on ferns, conifers, and cycads, which covered much of the Jurassic landscape.
Fearsome carnivores take over
With plant-eaters growing larger, meat-eating dinosaurs (carnivores) also evolved to become stronger and more efficient hunters.
Allosaurus, one of the most fearsome Jurassic predators, was a large theropod (meat-eating dinosaur) that grew up to 35 feet (10.5 meters) long. It had sharp, serrated teeth and powerful claws, making it a dangerous hunter.
Unlike the later T. rex, which had small arms, Allosaurus had long, muscular arms with large claws, helping it take down prey.
Other Jurassic carnivores included Ceratosaurus, which had a horn on its snout, and Torvosaurus, a huge predator that could challenge even the biggest plant-eaters.
The first flying reptiles take to the skies
The Jurassic also saw the rise of the first flying reptiles, known as pterosaurs. Although they weren’t dinosaurs, they lived alongside them and were the first vertebrates (animals with backbones) to develop powered flight.
Pterosaurs, like Pterodactylus, had large wings made of skin and muscle, allowing them to glide through the air while hunting for fish and insects.
Some pterosaurs, like Dimorphodon, had sharp teeth and could catch prey while flying.
Later in the Jurassic, pterosaurs evolved into larger species, some with wingspans as wide as 20 feet (6 meters).
A changing world
During the Jurassic, Earth’s landmasses were still connected but slowly breaking apart. The supercontinent Pangaea began splitting into Laurasia (the northern landmass) and Gondwana (the southern landmass). This change created new environments, including vast forests, swamps, and coastal areas, giving dinosaurs new places to thrive.
The Jurassic Period set the stage for the Cretaceous, when dinosaurs would reach their peak of diversity. From gigantic plant-eaters to deadly predators and flying reptiles, the Jurassic truly was the golden age of dinosaurs.
Dinosaurs at their peak – The Cretaceous Period (145-66 million years ago)
By the Cretaceous Period, dinosaurs had adapted to all kinds of environments. Some species were small and fast, while others were gigantic and powerful.
Small but smart: The raptors
One group of dinosaurs that thrived during the Cretaceous was the dromaeosaurs, or "raptors." These dinosaurs were fast, smart, and often had feathers!
Velociraptor was small but deadly, about the size of a turkey. It had sharp claws on its feet and may have hunted in packs, making it a fearsome predator.
Other raptors, like Deinonychus, were larger and could take down much bigger prey.
Some of these dinosaurs, over time, evolved into birds, which still exist today!
The kings of the cretaceous: Large meat-eaters
The Cretaceous also saw the rise of some of the largest and most powerful carnivores ever.
Tyrannosaurus rex, one of the most famous dinosaurs, was a massive predator, growing up to 40 feet (12 meters) long and weighing nearly 9 tons. It had huge, bone-crushing jaws and was likely both a hunter and a scavenger.
Spinosaurus, the largest known carnivorous dinosaur, could grow over 50 feet (15 meters) long and may have been semi-aquatic, hunting fish in rivers and lakes.
These mighty hunters dominated their territories, ruling over other dinosaurs in their ecosystems.
New plant-eaters appear
Many new herbivorous (plant-eating) dinosaurs appeared during the Cretaceous, feeding on the diverse vegetation that had started growing.
Triceratops, one of the last dinosaurs before extinction, had three large horns and a bony frill on its head. It may have used these features for defense or fighting rivals.
Ankylosaurus was a tank-like dinosaur covered in armor, with a massive clubbed tail to defend itself from predators like T. rex.
Hadrosaurs (duck-billed dinosaurs), such as Parasaurolophus, could make loud sounds using their hollow crests, possibly for communication.
These herbivores had to adapt to a changing world, as new plants like flowering plants, trees, and grasses started growing. These plants provided new food sources for dinosaurs and helped reshape the prehistoric landscape.
A changing world
As the Cretaceous Period progressed, Earth’s environment kept shifting. The continents continued to move apart, creating new islands and oceans. This led to changes in climate, food sources, and competition between species.
Dinosaurs continued to flourish until 66 million years ago, when a catastrophic event changed everything.
The Cretaceous: The peak of the dinosaurs
The Cretaceous Period was the most diverse and exciting time for dinosaurs. From giant predators like T. rex and Spinosaurus to tough plant-eaters like Triceratops and Ankylosaurus, dinosaurs had taken over nearly every environment on Earth.
Though this was their last chapter, dinosaurs ruled the planet for over 160 million years—far longer than humans have existed.
The beginning of the end
Near the end of the Cretaceous, a giant asteroid struck Earth in what is now Mexico's Yucatán Peninsula. This event triggered massive wildfires, tsunamis, and a dramatic climate shift, leading to the extinction of most dinosaurs.
However, some small dinosaurs survived and evolved into birds, meaning that, in a way, dinosaurs still live on today.
The 5 most famous dinosaurs and why they are so popular
Many would list these five dinosaurs as the most famous, This is what makes them special.
1. Tyrannosaurus rex (T. rex) – The king of dinosaurs
Why is it famous?
T. rex was one of the largest meat-eating dinosaurs ever, growing up to 40 feet long!
It had huge, sharp teeth (some as big as bananas!) and a powerful bite.
It appears in many movies, including Jurassic Park.
Even though its arms were tiny, T. rex was a strong and fearsome predator.
2. Triceratops – The three-horned herbivore
Why is it famous?
Triceratops had three big horns and a large bony frill on its head, making it look cool and unique.
It was one of the last dinosaurs before the big extinction.
It may have used its horns to fight off predators like T. rex.
Scientists have found many fossils, making it one of the most well-known dinosaurs.
3. Velociraptor – The smart and fast hunter
Why is it famous?
Velociraptors were small but super fast (as fast as a cheetah!).
They were very intelligent and may have hunted in packs like wolves.
In Jurassic Park, they were shown as terrifying, smart hunters (though the movie made them bigger than they actually were).
Scientists discovered Velociraptors had feathers, making them look more like birds than lizards.
4. Brachiosaurus – The giant long-necked dinosaur
Why is it famous?
Brachiosaurus was one of the tallest dinosaurs, with a long neck to reach tree leaves.
It was a gentle giant, only eating plants.
It’s famous for its scene in Jurassic Park, where it peacefully eats from the trees.
Its size made it one of the most iconic dinosaurs from the Jurassic Period.
5. Stegosaurus – The spiky-backed dinosaur
Why is it famous?
Stegosaurus had large, bony plates on its back and a spiked tail for defense.
It looked unlike any other dinosaur, making it one of the most recognizable.
Its brain was very small for its body size, which makes it an interesting fact!
It lived during the Jurassic Period, walking alongside big predators.
Dinosaurs today?
Even though the big dinosaurs are gone, their relatives are still here—birds! That’s right, chickens, eagles, and parrots are distant cousins of dinosaurs.
Fun dinosaur facts
The longest dinosaur was Argentinosaurus at over 100 feet - as long as 4 school buses.
The fastest dinosaur might have been Ornithomimus, running up to 40 mph.
Dinosaur fossils have been found on every continent, even Antarctica.
Microraptor, one of the smallest dinosaurs, was about 1-2 feet (30-60 cm) long and had wings for gliding.
Triceratops had three sharp horns and a frilled shield on its head to protect itself from T. rex.
Tyrannosaurus rex had a bite force of over 12,000 pounds per square inch (PSI)—strong enough to crush a car.
Every bird alive today, from pigeons to eagles, is a distant relative of dinosaurs.
More than 1,000 species of dinosaurs have been discovered so far.
Dinosaurs were some of the most amazing creatures to ever live on Earth. Even though they disappeared millions of years ago, scientists still discover new fossils and learn more about them.
