The Mesozic Era

The Triassic Period

Triassic Period ~ 252 - 201 million years ago

The Triassic Period was a time of great change on Earth and can be split into the Early (252 - 247m years ago), Middle (247 - 237m years ago) and Late (237 - 201m years ago) Triassics. It began after the worst-ever extinction event; known as "The Great Dying", it wiped out up to 90% of all species, animals and plants alike.

During the Triassic, Earth had one giant landmass called Pangaea. The environment varied greatly and as it recovered from The Great Dying, conifers reaching 30 metres tall grew in large forests and gave way to ferns in drier regions. As animals recovered, mammal-like reptiles like the Lystrosaurus and the first amphibians evolved in freshwater to live alongside existing Temnospondyls like Mastodonsaurus (something like a modern-day crocodile), and Ichthyosaurs evolved in the seas.

At the same time, Sphenodonts appeared, which would give rise to groups like Plesiosauria. While the Early Triassic was dominated mostly by mammal-like reptiles, the Middle Triassic saw a diverse range of archosaurs appear. These would later lead to dinosaurs, birds, crocodiles, turtles and pterosaurs.

Groups like Aetosaurs, Phytosaurs and the incredible Tanystropheus were quite successful. Pterosaurs appeared during the Middle Triassic and are the earliest known vertebrates to have powered flight. By the Late Triassic, archosaurs dominated the Earth.

The change on Earth during the Triassic period was not limited to plant and animal life. By the end of the Triassic period, Earth experienced another mass-extinction event after massive volcanic activity and Pangea began to break up.

An artists impression of how Pangea looked 225 million years ago.

Pangaea - Some 225 million years ago, Earth's continents formed one large super-continent called Pangaea

An artists impression of a Lystrosaurus. The creature has four legs on the ground and has downward-facing small tusks on its face.

Lystrosaurus - The most common animal in the Early Triassic period; it was roughly the size of a pig.

An artists impression of a Mastodonsaurus. The creature has four short limbs and a large flat head. Similar to modern-day crocodiles.

Mastodonsaurus - A type of temnospondyl that lived during the Late Triassic. It looked like a massive frog, except with a triangular head that reached up to 1.25 metres in length.

An artists impression of an Icthyosaurus. The creature has four flippers, a dorsal fin, a vertical tail and a pointed head with a large jaw full of teeth.

Utatsusaurus - One of the earliest ichthyosaurs which evolved during the Early Triassic period.

An artists impression of a Plesiosaurus. The creature has a long neck with a shorter tail with four powerful flippers.

Plesiosaurus - A marine reptile species of Plesiosauria that lived from the Middle Triassic until the end of the Cretaceous period

An artists impression of a Desmatosuchus. The creature has four legs, a long tail and a short head. It looks like it has armour on its back.

Desmatosuchus - A type of aetosaur that lived during the Late Triassic period

An artists impression of a Rutiodon. The creature has four short legs with a long tail, and a short head with long snapping jaw full of teeth.

Rutiodon - A type of Phytosaur from the Late Triassic period. While they resemble modern-day crocodiles, they have a very different heritage.

An artists impression of a Tanystropheus. The creature has four strong legs with a long tail, and massively long neck with a short head.

Tanystropheus - An archosaur with a neck longer than it's body and tail combined that lived from the middle Triassic period.

An artists impression of a Preondactylus. The creature has large webbed wings attached to its forelimbs and hindlimbs, a short head and a long thin tail.

Preondactylus - An early Pterosaur from the late Triassic period, they lived until the end of the Cretaceous period.

The Jurassic Period

Jurassic Period ~ 201 - 145 million years ago

Spanning 56 million years, the Jurrasic period can also be split into the Early (201 - 174m years ago), Middle (174 - 164m years ago) and Late (164 - 145m years ago) Jurassics. It is also known as the Age of the Dinosaurs.

In the Early Jurassic, Pangaea continued to split into North and South with the northern half broken into North America and Eurasia. The southern half started to split in the Middle Jurrasic and east (Antartica, Madagascar, India and Australia) split from west (Africa and South America). At the end of the Late Jurassic, new oceans, such as the Atlantic, were forming in the spaces between these land masses and mountains rose on the sea floor, pushing sea levels higher.

Marine life such as plesiosaurs and ichthyosaurs had survived extinction and now dominated the seas and oceans. On land, the Early Jurassic saw dinosaurs such as Dilophosaurus, Vulcanodon, Anchisaurus and Scutellosaurus thrive, while Apatosaurus, Brachiosaurus, Diplodocus, Allosaurus and Stegosaurus flourished in the Late Jurassic.

Archaeopteryx, though to be a transitional fossil between non-avian dinosaurs and birds, also evolved in the Late Jurassic.

The end of the Jurassic Period saw several species of dinosaur die out, which would give rise to the Cretaceous period, however this extinction was not as severe as the one at the beginning of the Jurassic period.

An artists impression of land mass on Earth roughly 150 million years ago - Pangaea has split into northern and southern halves.

By the Late Jurassic, Pangaea began to split into northern and southern halves, and the Atlantic Ocean began to form.

An artists impression of a Dilophosaurus. A bipedal creature with two strong backlimbs short forelimbs and a crest on its head.

Dilophosaurus - Lived during the Early Jurassic. Studies have shown that the crests on its skull may have been larger in one sex than the other.

An artists impression of a Vulcanodon. A sauropod with four large, strong legs, a long neck and a long tail.

Vulcanodon - Found during the Early Jurassic, this is one of the earliest Sauropods; a very large qudrupedal herbivorous dinosaur with a long neck and tail, small head and massive limbs.

An artists impression of an Anchisaurus. A quadrupedal dinosaur with four large, strong legs, a long tail, short neck and small head.

Anchisaurus - A herbivorous dinosaur from the Early Jurassic. It was previously known as Megadactylus and Amphisaurus.

An artists impression of a Scutellosaurus. A small, bipedal dinosaur with a long tail and short neck.

Scutellosaurus - A small, lightly-built dinosaur that is one of the earliest representatives of the armoured dinosaurs.

An artists impression of an Apatosaurus. A land dwelling creature with four massive legs, a long tail and a long neck.

Apatosaurus - One of the largest land animals that ever existed; it had an average length of 23 metres.

An artists impression of a Brachiosaurus. A land dwelling creature with four massive legs, a long tail and a long neck.

Brachiosaurus - One of the most famous dinosaurs and for a long time, the largest dinosaur known. It's forelimbs were longer than it's hindlimbs, giving it a steeply inclined neck.

An artists impression of a Diplodocus. A land dwelling creature with four massive legs, a long tail and a long neck.

Diplodocus - Another well-known sauropod, Diplodocus lived alongside predators like Allosaurus in the late Jurassic period.

An artists impression of an Allosaurus. A large bipedal predator with a long thick tail, short forelimbs, short neck and large head.

Allosaurus - A large predator with a big skull and dozens of sharp teeth from the Late Jurassic.

An artists impression of a Stegosaurus. A qudrupedal herbivore with small, sturdy legs, a short tail with spikes attached, small neck and head and spines down it's back.

Stegosaurus - Very famous dinosaur from the Late Jurassic. It had plates down its back andlong spikes on its tail.

An artists impression of an Archaeopteryx. A small magpie-sized creature with wings, tail and small pointed head.

Archaeopteryx - A bird-like creature similar in size to amagpie, though with more in common with dinosaurs than birds. Archaeopteryx is thought to be a transitional fossil between non-avian dinosaurs and birds.

The Cretaceous Period

Cretaceous Period ~ 145 - 66 million years ago

The longest time period in the Mesozic Era, the Cretaceous period last 79 million years and can be divided into the Early Cretaceous (145 - 100m years ago) and the Late Cretaceous (100 - 66m years ago).

While the Early Cretaceous saw the Earth's landmasses essentially look like two large continents, the narrow waterways that were spreading brought great diversity. As the Late Cretaceous started, continents as we know them today had formed, separating the dinosaurs and allowing each to evolve suit their own environment.

The Early Cretaceous saw well-known dinosaurs like Spinosaurus, Giganotosaurus and Iguanodon evolve. In the seas, Plesiosaurus and Ichthyosaurus were eventually joined by Mosasaurus. Although the film was called Jurassic Park, quite a few of the dinosaurs featured were found during the Late Cretaceous such as Triceratops, Tyrannosaurus and Velociraptor.

The end of the Cretaceous Period saw another massive extinction event and though open to debate, it is widely believed and that an asteroid impact is the main culprit. This brought the end of the Age of Dinosaurs as 75% of all plant and animal life was once again wiped out.

An artists impression of land mass on Earth roughly 100 million years ago - Pangaea has split into continents as we know them today, though India id floating in the Indian Ocean and Australia is still connected to Antartica.

At the start of the Late Cretaceous, the continents as we know them today were forming, though India was still floating in the Indian Ocean and Australia was still connected to Antartica.

An artists impression of a Spinosaurus. A bipedal creature with two strong backlimbs short forelimbs with claws and a large crest on its back.

Spinosaurus - One of the largest known carnivorous dinosaurs, it is estimated to have been bigger than Tyrannosaurus or Giganotosaurus and was found in the Early Cretaceous.

An artists impression of a Giganotosaurus. A bipedal creature with two strong legs, a powerful tail, large head with a big jaw and sharp teeth, and small clawed forelimbs.

Giganotosaurus - Weighing approximately 6,000kg, this was a very powerful carnivore.

An artists impression of an Iguanodon. A quadrupedal dinosaur with four large, strong legs, a long tail, short neck and small head.

Iguanodon - A herbivorous dinosaur from the Cretaceous Period. It's thought that it could switch between four legs and two legs as needed.

An artists impression of a Mosasaurus. A large marine reptile with four flippers, a massive tail and head and large teeth.

Mosasaurus - One of the largest mosasaurs, it reached up to 17 metres (56 feet) in length and was found during the Late Cretaceous period.

An artists impression of a Triceratops. A land dwelling creature on four legs with a short tail, large head and large frill on the back on it's head. It had three horns on it's face.

Triceratops - The skull of a Triceratops could reach up to 2 metres in length.

An artists impression of a Tyrannosaurus. A land dwelling bipedal creature with two long strong legs, a powerful tail, very short forelimbs and a large head.

Tyrannosaurus - Probably the most famous dinosaur, it was found during the Late Cretaceous and the largest complete skeleton ever found is almost 13 metres (40 feet) long.

An artists impression of a Velociraptor. A small land dwelling creature with agile legs, a thin tail, a short neck and elongated head. It has massive claws on each limb.

The Mesozoic Era