Triassic facts for kids

Quick facts for kids Triassic
251.902 ± 0.024 – 201.4 ± 0.2 Ma PreЄ Є O S D C P T J K Pg N
A paleomap of Earth as it appeared 225 Ma during the Norian Age of the Late Triassic Epoch
Chronology
Triassic graphical timeline -255 — – -250 — – -245 — – -240 — – -235 — – -230 — – -225 — – -220 — – -215 — – -210 — – -205 — – -200 — Pz Mesozoic Permian Triassic Jurassic ET Middle Late Induan Olenekian Anisian Ladinian Carnian Norian Rhaetian       ← Triassic–Jurassic extinction event ← Scleractinian corals & calcified sponges ← Carnian pluvial episode ← Manicouagan impact ← Coals return ← Full recovery of woody trees ← Smithian–Spathian boundary event ← Permian-Triassic extinction event Subdivision of the Triassic according to the ICS, as of 2024. Vertical axis scale: Millions of years ago
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Period
Stratigraphic unit	System
Time span formality	Formal
Lower boundary definition	First appearance of the conodont Hindeodus parvus
Lower boundary GSSP	Meishan, Zhejiang, China 31°04′47″N 119°42′21″E / 31.0798°N 119.7058°E / 31.0798; 119.7058
Lower GSSP ratified	2001
Upper boundary definition	First appearance of the ammonite Psiloceras spelae tirolicum
Upper boundary GSSP	Kuhjoch section, Karwendel mountains, Northern Calcareous Alps, Austria 47°29′02″N 11°31′50″E / 47.4839°N 11.5306°E / 47.4839; 11.5306
Upper GSSP ratified	2010

The Triassic is an exciting geologic period that lasted for about 50.5 million years in Earth's history. It is the very first chapter of the great Mesozoic Era. This ancient time began around 251.9 million years ago, right after the end of the Permian Period. It ended around 201.4 million years ago when the famous Jurassic Period began. Scientists consider the Triassic to be a time of incredible comebacks and brand-new beginnings for living things.

Before the Triassic started, our planet went through a terrible crisis called the Permian–Triassic extinction event. This huge disaster wiped out most living plants and animals on land and in the oceans. Because so many creatures died out, the ancient biosphere had plenty of open space for new life. Over millions of years, clever survivors multiplied, changed, and developed into brand-new kinds of animals.

The Triassic is especially famous because it is the period when the very first dinosaurs appeared on Earth. It was also the time when the earliest flying reptiles took to the skies and furry mammals first evolved. Land ecosystems were largely dominated by ancient reptiles, particularly an amazing group called archosaurs. In the waters, unusual sea monsters swam, while bizarre giant amphibians guarded lakes and rivers.

Throughout this entire period, all the world's land was joined together into one gigantic supercontinent named Pangaea. Surrounding this giant land was a massive global ocean. The interior of the continent was baking hot, dry, and filled with massive sandy deserts. By studying ancient rocks, geologists and paleontologists can piece together what this wild, prehistoric world looked like.

How the Triassic Period Got Its Name

The name Triassic comes from the Greek word trias, which means a set of three or a triad. A German geologist named Friedrich Alberti chose this name in 1834. He noticed that rocks from this time in southern Germany always occurred in three very distinct layers.

The bottom layer is called the Buntsandstein, which means colorful sandstone full of reddish and striped rock. The middle layer is known as the Muschelkalk, a type of limestone that contains lots of fossilized sea shells. The top layer is called the Keuper, which is made of colorful clay and mud deposits. Together, these three layers told scientists that an entire unique age of Earth had taken place here.

• 

  Early Triassic sandstone (Buntsandstein) near Stadtroda, Germany

• 

  Middle Triassic Muschelkalk (shell-bearing limestone) near Dörzbach, Germany

• 

  Late Triassic Steigerwald Formation and overlying Hassberge Formation in Schönbuch, Germany

Time Divisions of the Triassic Period

Scientists who study the geologic time scale divide the Triassic Period into three main parts called epochs. These three epochs are the Early Triassic, the Middle Triassic, and the Late Triassic. Each epoch represents a different phase of recovery and animal evolution across the ancient globe. Rocks formed in these times are called Lower, Middle, and Upper Triassic rocks.

The three epochs are further split into smaller slices of time called faunal stages. The Early Triassic contains the Induan and Olenekian stages. The Middle Triassic contains the Anisian and Ladinian stages. Finally, the Late Triassic contains three stages: the Carnian, the Norian, and the Rhaetian. Each stage is recognized by special index fossils found in rock layers around the world.

What Did the Earth Look Like During the Triassic?

230 Ma continental reconstruction

During the Triassic, planet Earth looked completely different than it does on modern world maps. All the continents that we know today were smashed together into one giant landmass called Pangaea. This enormous C-shaped supercontinent stretched all the way from the North Pole down to the South Pole. It was centered right over the equator, making the center of the land very hot.

Pangaea was divided into two huge regions. In the north lay Laurasia, which included what is now North America, Europe, and parts of Asia. In the south lay Gondwana, which contained modern South America, Africa, India, Australia, and Antarctica. A huge gulf called the Tethys Ocean curled into the eastern side of Pangaea. The rest of the planet was covered by one single, colossal body of water called the Panthalassa Ocean.

Because all the land was connected, animals could walk across enormous distances without hitting ocean barriers. However, deep inside the supercontinent, conditions were harsh and dry. Huge subduction zones bordered the giant landmass where ocean crust slid deep underneath the continental edges. Over millions of years, tectonic forces slowly stretched the crust, preparing to break Pangaea apart.

Continents on the Move

View of the Tethys area during the Ladinian stage (230 Ma)

The supercontinent shifted, tilted, and slowly rotated over tens of millions of years. Deep underground, stretching tectonic forces pulled on the thick continental crust. Great cracks began to appear across regions where modern oceans now sit. Places like eastern Canada and western Europe began pulling away from each other along deep rift valleys.

In the southern half of Pangaea, pieces of crust that we call Cimmerian land blocks moved northward. As these pieces drifted across the ancient ocean, the older Paleo-Tethys waters shrank, while the new Neo-Tethys ocean opened behind them. Along what is now the eastern coast of Australia, mountain-building took place during the Hunter–Bowen orogeny. In South America, underground volcanic activity produced rich felsic igneous rocks along active margins.

Towards the very end of the Triassic, Pangaea began to split in a dramatic way. Immense cracks ripped across the land where North America, South America, Africa, and Europe met. Molten rock flooded up from deep inside the Earth through massive fractures. This gigantic volcanic zone was the Central Atlantic magmatic province, signaling the birth of the Atlantic Ocean.

Sydney, Australia lies on Triassic shales and sandstones. Almost all of the exposed rocks around Sydney belong to the Triassic Sydney sandstone.

Ancient Oceans and Changing Sea Levels

The ancient global ocean, Panthalassa, was truly immense, covering more than two-thirds of the planet's surface. Beneath its waters, tectonic plates like the Farallon plate, the Izanagi plate, and the Phoenix plate moved slowly across the globe. Along ocean boundaries, underwater trenches swallowed oceanic crust while undersea ridges erupted new sea floor.

Compared to other times in Earth's history, the global eustatic sea level during the Triassic was fairly low. At the start of the period, sea levels were roughly similar to modern sea levels. As time went on, water levels crept upward, rising up to 50 meters higher during the warm Carnian age. Later in the period, the waters dropped back down dramatically, exposing shallow coastlines. Because there were no giant ice sheets at the poles, these sea changes were caused by undersea volcanic activity shifting the shape of ocean basins.

Climate and Weather Patterns

The climate of the Triassic Period was mostly hot, dry, and arid across large parts of the world. Because Pangaea was so enormous, cool ocean breezes could not reach far inland. Instead, the middle of the continent was covered in vast, scorching deserts. Rocks from these desert areas formed bright red beds made of iron-stained sandstone and salty evaporite minerals left by dried-up lakes.

Earth had no freezing polar ice caps during the Triassic Period. Instead, areas near the North and South Poles were moist, green, and pleasantly temperate. Lush forests grew near the poles, providing wonderful homes for ancient reptiles, amphibians, and unusual trees. The extreme temperature difference between the giant baking landmass and the surrounding cool ocean created wild seasonal weather. This caused powerful seasonal storms known as the Pangean megamonsoon.

Heat Waves and Wet Spells

The Early Triassic was the hottest time in the entire Phanerozoic Eon. Enormous volcanic eruptions from the Siberian Traps had pumped massive clouds of greenhouse gases into the atmosphere. This made tropical regions so blisteringly hot that many animals simply could not survive near the equator. Over several million years, temperatures swung between scorching heat spikes and cooler episodes.

During the Late Triassic, a truly remarkable weather change occurred called the Carnian Pluvial Event. Around 234 million years ago, giant volcanic eruptions triggered sudden warming that filled the skies with moisture. For nearly two million years, heavy rains poured across the dry landscapes of Pangaea. This sudden wet spell transformed desert environments into lush green wonderlands. It helped kick off an evolutionary explosion for brand-new groups of plants and animals, including the dinosaurs.

Prehistoric Plant Life

Plants on Land

An Early Triassic Australian landscape including Pleuromeia (central foreground) as well as horsetails, Dicroidium trees (prominently on right), as well as the temnospondyl amphibian Bulgosuchus (foreground) and an erythrosuchid reptile (background left). Art by Michael Rothman

Plant life on land had to rebuild itself after the end-Permian extinction. In the Early Triassic, strange spike-moss relatives called lycophytes took over empty landscapes. A famous plant from this time was Pleuromeia, an unbranched, tree-like plant that grew up to two meters tall. Because the world was recovering from disaster, tough plants like these thrived before thicker forests returned.

As the climate stabilized, great forests spread across the supercontinent. In the southern regions of Gondwana, a famous tree called Dicroidium became very common. It belonged to an extinct group known as "seed ferns" that produced seeds instead of simple spores. In the northern regions, ancient relatives of Ginkgoales spread widely, alongside towering cone-bearing trees. These included primitive conifers such as the Voltziales and the extinct family Cheirolepidiaceae.

Another remarkable group of seed-bearing plants was the Bennettitales, which looked a bit like modern palm trees or cycads. These tough, woody plants first became common in the Late Triassic and remained important across the Mesozoic. Thick groves of horsetails grew along sunny riversides, providing plentiful meals for plant-eating animals.

The Mystery of the Missing Coal

One of the strangest puzzles in geology is the Early Triassic "coal gap." Coal forms when thick layers of dead swamp plants build up and turn to stone over millions of years. In rocks from the first several million years of the Triassic, scientists find virtually no coal deposits anywhere on Earth.

Scientists think the great Permian extinction completely wiped out the delicate swamp forests that normally made peat. At the same time, the climate became too hot and dry for swampy wetlands to survive. It took millions of years for new wetland plants to evolve, adapt, and build up thick plant layers again. Only in the Middle and Late Triassic did coal-forming swamps finally return to our planet.

Plankton in the Oceans

Tiny microscopic life in the ocean also changed dramatically during the Triassic. Before this time, ancient red and green algae called Archaeplastida and photosynthetic cyanobacteria ruled the open seas. During the Triassic, new kinds of tiny floating plant life took over the surface waters. These new plankton groups used a special cellular evolution process called secondary endosymbiosis. They formed the base of a completely rebuilt marine food chain, feeding billions of tiny sea animals.

Animals of the Triassic World

Middle Triassic marginal marine sequence, southwestern Utah

Life in the Seas

After the end-Permian disaster, life in the oceans had to start almost from scratch. In the Early Triassic, new kinds of modern corals appeared, building small, patchy reefs. These reefs were much smaller than modern coral reefs, but they provided safe homes for sea creatures. Along the sea bottom, burrowing clams and bivalves rapidly multiplied, while spiral-shelled worm-tubes called Microconchids coated underwater rocks.

One of the greatest success stories of the Triassic seas was the return of the ammonites. These free-swimming mollusks had spiral shells and tentacled arms like an octopus. Although almost all ammonites died out during the Permian extinction, a single surviving family multiplied and spread across the entire globe. Millions of ammonites filled the waters, serving as prey for bigger hunters and leaving behind beautiful fossil shells.

Insects on Land

Insects did exceptionally well during the Triassic Period. During the Middle Triassic, many new families of water-dwelling insects evolved, filling ancient rivers and lakes. This was a crucial time for the evolution of Holometabola, the large insect group that undergoes complete metamorphosis. Ancestors of beetles, flies, wasps, and other familiar modern bugs buzzed through the warm Triassic air and crawled across prehistoric forests.

Fish of Rivers, Lakes, and Seas

Birgeria

In the aftermath of the Permian disaster, surviving fish spread quickly throughout the world's oceans and rivers. Because swimming animals could travel across connected waterways, many fish species developed a widespread cosmopolitan distribution. Primitive lobe-finned fish known as Coelacanths reached their greatest diversity during the Early Triassic.

Ray-finned fish, called Actinopterygians, experienced a massive population boom. The earliest ancestors of teleosts—the modern bony fish that make up most fish species today—appeared during this period. Fierce predatory fish like Saurichthys and Birgeria hunted other fish in shallow seas. Some of these ocean hunters grew more than 1.2 meters long with long, needle-filled jaws. In freshwater rivers and lakes, ancient lungfish like Ceratodus crunched through hard-shelled prey with thick tooth plates. Meanwhile, early shark relatives known as Hybodonts ruled both salt and fresh waters with tough, sharp fins.

Giant Amphibians

Reconstruction of the Triassic amphibian Mastodonsaurus

While modern amphibians are usually small creatures like frogs and salamanders, Triassic amphibians were absolute giants. The top amphibian predators were the Temnospondyli, an ancient group of heavily armored, flat-headed creatures. Most temnospondyls lived in rivers, swamps, and lakes, acting like prehistoric salamander-alligators.

Some of the largest temnospondyls belonged to a group called the Stereospondyli. A monster named Mastodonsaurus grew between 4 and 6 meters long, sporting enormous jaws with long, sharp tusks. It spent its days lurking underwater, waiting to snatch unwary fish or land animals that came down to drink. Other amphibian families, like the needle-snouted trematosaurs and the broad-headed metoposaurs, filled waterways across Pangaea.

At the same time, the very first ancestors of modern Lissamphibians began to show up. Tiny proto-frogs hopped around riversides during the Early Triassic. However, these small modern amphibians stayed relatively rare throughout the Triassic, waiting for their turn to take over after the giant temnospondyls faded away.

Land Reptiles and the Archosaurs

The Archosaur Revolution

Reptiles took full advantage of the open world following the Permian extinction. The most important reptile group of the Triassic was the Archosauromorpha. Over millions of years, these animals radiated into an unbelievable variety of shapes and sizes. Early archosauromorphs included bizarre long-necked reptiles called Tanystropheidae. The famous genus Tanystropheus had a stiff neck that was actually longer than its entire body and tail combined, which it used to snap up fish from rocky coastlines.

Other early branches included the gliding Sharovipterygidae, which stretched skin membranes between their back legs like living gliders. Plant-eating groups like rhynchosaurs and Allokotosauria wandered the plains in large herds. The allokotosaur Shringasaurus was a bulky, 4-meter-long plant-eater that grew two curved horns on top of its head, looking like a prehistoric reptile bull.

Fierce carnivores called Archosauriformes walked with more upright legs and carried curved, serrated teeth. Early predators like the big-headed Erythrosuchidae sat firmly at the top of the food chain in the Early Triassic. From these fierce hunters came the true archosaurs, which quickly split into two major branches:

• The bird-line archosaurs, called Avemetatarsalia, which produced the first flying pterosaurs and true dinosaurs.
• The crocodile-line archosaurs, called Pseudosuchia, which included ancient relatives and ancestors of modern alligators and crocodiles.

Throughout most of the Triassic, the crocodile-line pseudosuchians were the undisputed kings of the land. They were much more common and diverse than the early dinosaurs. Some pseudosuchians, like the aetosaurs, were heavily armored plant-eaters covered in bony plates. Giant meat-eaters, often called "rauisuchians," grew up to 6 meters long and hunted with massive jaws. One famous example was Postosuchus, a terrifying apex predator that stalked Late Triassic North America.

• 

  Tanystropheus, a long-necked tanystropheid

• 

  Proterosuchus, a crocodile-like early archosauriform from the Early Triassic

• 

  Staurikosaurus, one of the earliest dinosaurs, a member of the Triassic family Herrerasauridae

• 

  Postosuchus, a rauisuchid which was an apex predator in parts of Late Triassic North America

• 

  Plateosaurus was one of the largest of early sauropodomorphs, or "prosauropods", of the Late Triassic

• 

  Coelophysis was one of the most abundant theropod dinosaurs in the Late Triassic

The First Dinosaurs and Pterosaurs

During the Carnian age of the Late Triassic, the very first dinosaurs made their appearance. Unlike the giant dinosaurs that came later, early dinosaurs were fast, two-legged creatures of modest size. Meat-eaters like Herrerasaurus and the slender, agile Coelophysis chased down lizards, insects, and small animals. Coelophysis was between 1 and 2 meters long and hunted in agile packs.

Plant-eating dinosaurs also got their start during the Late Triassic. Early long-necked herbivores known as Sauropodomorpha spread across cooler regions of the supercontinent. A famous example is Plateosaurus, which could grow up to 8 to 10 meters long and rear up on its powerful hind legs to munch leaves from tall trees. Even so, dinosaurs remained a minor part of the world's ecosystems throughout the Triassic Period.

Up in the air, another group of avemetatarsalians developed powered flight for the very first time among animals with backbones. These were the pterosaurs. Early pterosaurs had long tails, toothy jaws, and wings made of skin stretched along an elongated fourth finger. They swooped through the air, catching fish and insects along coastal lagoons.

Fantastic Sea Reptiles

Marine vertebrate apex predators of the Early Triassic and Anisian (Middle Triassic)

While dinosaurs were taking their first baby steps on land, reptiles made a huge splash in the oceans. Several groups of land-dwelling reptiles moved back into the water, transforming into remarkable marine hunters. The Sauropterygia group included paddling pachypleurosaurs and predatory nothosaurs, which swam with four flippers like modern seals. One unusual relative, Atopodentatus, used a hammerhead-shaped jaw lined with tiny teeth to scrape algae from undersea rocks.

Another famous group was the placodonts, chunky marine reptiles with broad, flat teeth made for crushing tough clam shells. Later in the period, the very first long-necked plesiosaurs began swimming through the waves.

The undisputed champions of Triassic waters were the ichthyopterygians, or ichthyosaurs. These streamlined reptiles looked like reptilian dolphins, with dorsal fins, paddle-like limbs, and powerful tails. While early ichthyosaurs were small, by the Middle and Late Triassic they evolved into absolute ocean giants, reaching lengths of over 15 to 20 meters.

Other Triassic Reptiles

The Triassic was home to many other fascinating reptiles that lived alongside the archosaurs. The very first true turtles appeared during the Norian age, including primitive species like Proganochelys. These early turtles had hard shells, but unlike modern turtles, they could not pull their heads inside their armor and still had small teeth in the roofs of their mouths.

Small lizard-like reptiles called Sphenodontia scampered through the underbrush, hunting insects and worms. Another important group was the drepanosaurs, strange tree-dwelling reptiles that looked a bit like chameleons. They had grasping feet, sharp finger claws, and even claw-tipped tails to help them climb through high tree branches.

Synapsids and the Origin of Mammals

Before the Triassic, mammal relatives called therapsids had ruled the land. Although many died in the end-Permian extinction, three main groups survived into the Triassic: the tusked plant-eating dicynodonts, the predatory therocephalians, and the dog-like cynodonts.

In the Early Triassic, a pig-sized dicynodont named Lystrosaurus became the most abundant land vertebrate on Earth. Digging for roots with its strong beak and tusks, it survived in huge numbers across the recovering planet. Carnivorous cynodonts like Cynognathus served as fierce predators with specialized biting teeth and muscular jaws.

• 

  Lystrosaurus was a widespread dicynodont and the most common land vertebrate during the Early Triassic, after animal life had been greatly diminished

• 

  Cynognathus was a carnivorous mammal-like cynodont from the Early Triassic.

As the period wore on, bigger and faster archosaurs pushed therapsids out of top predator and large herbivore roles. This event is sometimes called the "Triassic Takeover." Instead of giving up, cynodonts adapted by shrinking in size. They moved into the shadows, hunting insects under the cover of darkness.

Living a nocturnal life required these small creatures to stay warm in the chilly night air. Over generations, they developed warm-blooded metabolisms, sensitive whiskers, and insulating fur coats. By the Carnian age of the Late Triassic, these advanced cynodonts gave rise to the very first true mammaliaforms—the direct ancestors of modern mammals.

Famous Fossil Treasure Troves

Fossils from the Triassic Period are preserved in special rock beds around the world called lagerstätten. These unique sites contain fossilized bones, shells, and sometimes even soft tissues preserved in astonishing detail.

Two famous Early Triassic sites are the Guiyang biota in China and the Paris biota in Idaho, USA. Both of these sites show that ocean life bounced back from the Permian extinction much faster than scientists used to believe. Just over one million years after the catastrophe, complex communities of fish, mollusks, and sea predators were already flourishing.

Another famous site is Monte San Giorgio, located near Lake Lugano on the border between Italy and Switzerland. During the Middle Triassic, this area was a quiet, warm marine lagoon protected behind offshore reefs. The bottom waters of the lagoon had no oxygen, which prevented dead animals from rotting or getting eaten by scavengers. Paleontologists have uncovered thousands of perfectly preserved fossils here, including hundreds of complete skeletons of fish, sea reptiles like Neusticosaurus, and the strange long-necked Tanystropheus.

The Triassic–Jurassic Mass Extinction

The mass extinction event is marked by 'End Tr'

The Triassic Period came to an abrupt, violent close around 201.4 million years ago. A massive disaster known as the Triassic–Jurassic extinction event struck life on Earth, wiping out roughly half of all living species. It was especially harsh on ocean animals. Mysterious eel-like creatures called conodonts vanished forever, along with almost all marine reptiles except for ichthyosaurs and plesiosaurs. Clams, sponges, and ammonites suffered devastating population crashes.

On land, the disaster completely changed the balance of power. Almost all the mighty crocodile-line pseudosuchians—including the giant rauisuchians and armored aetosaurs—were wiped out. Crocodile-like phytosaurs living along rivers died out completely. Giant temnospondyl amphibians and large mammal-like dicynodonts also disappeared from most ecosystems.

Skull of a Triassic Period phytosaur found in the Petrified Forest National Park

What Caused the Great Extinction?

Scientists have investigated several possible causes for this great extinction event. For a while, some researchers thought a giant meteorite collision might be responsible. A huge ancient impact crater at Manicouagan Reservoir in Quebec, Canada, was studied carefully. However, modern radioactive dating showed that the Manicouagan space rock struck Earth about 214 million years ago—roughly 13 million years before the Triassic actually ended.

Today, scientists know the true culprit was massive volcanic activity. As Pangaea began tearing apart, enormous cracks opened along the seam between modern North America, Europe, and Africa. This created the Central Atlantic Magmatic Province, unleashing millions of cubic kilometers of bubbling lava.

These eruptions pumped titanic amounts of carbon dioxide and sulfur into the atmosphere. The gases triggered rapid global warming, deadly ocean acidification, and sudden weather disruption. Millions of plants and animals could not handle the rapid changes to their environment and died out over a relatively short period of time.

The Stage is Set for the Jurassic

Although the end-Triassic extinction was terrible for many species, it opened the door for one special group: the dinosaurs. Small and medium-sized dinosaurs survived the environmental chaos much better than the bulky pseudosuchians. With their chief competitors and predators gone, dinosaurs suddenly had an empty world full of possibilities.

As the Triassic gave way to the Jurassic Period, dinosaurs expanded into every ecological niche imaginable. They grew larger, multiplied rapidly, and spread across the entire globe. The tough, dry world of the Triassic had forged hardy, adaptable creatures that went on to rule planet Earth for the next 135 million years.

See also

In Spanish: Triásico para niños

• Geologic time scale
• Dinosaur
• Permian
• Jurassic
• Pangaea