Late Triassic facts for kids
Quick facts for kids Late Triassic |
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|---|---|
| ~237 – 201.4 ± 0.2 Ma | |
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Map of Earth 220 million years ago during the Late Triassic Epoch
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| Etymology | |
| Chronostratigraphic name | Upper Triassic |
| Geochronological name | Late Triassic |
| Usage information | |
| Celestial body | Earth |
| Regional usage | Global (ICS) |
| Time scale(s) used | ICS Time Scale |
| Definition | |
| Chronological unit | Epoch |
| Stratigraphic unit | Series |
| Time span formality | Formal |
| Lower boundary definition | First appearance of the ammonite Daxatina canadensis |
| Upper boundary definition | First appearance of the ammonite Psiloceras spelae tirolicum |
The Late Triassic is the third and final epoch of the Triassic Period. It lasted from about 237 million years ago to roughly 201.4 million years ago. Geologists study rocks from this time, called the Upper Triassic series, to understand how early reptiles lived and how the first true dinosaurs conquered the land.
This epoch is famous for two major events. First, the very first dinosaurs, such as Coelophysis and Plateosaurus, grew and spread across the world. Second, the epoch ended with one of Earth's biggest extinction events. This event changed the planet forever and allowed dinosaurs to become the dominant land animals during the Jurassic Period.
Contents
What Is the Late Triassic Epoch?
The Late Triassic is a time division used by geologists and paleontologists. It sits between the Middle Triassic and the Early Jurassic. During this time, all modern continents were stuck together into one giant supercontinent named Pangea.
The word "Triassic" comes from the Latin word trias, which means three. In 1834, a German scientist named Friedrich August von Alberti noticed three distinct rock layers across Germany. These layers included colourful sandstone, limestone packed with shells, and coloured clays. The Late Triassic corresponds mainly to the upper layer of clay and sandstone, known as the Keuper.
Geologists split the Late Triassic into three smaller time periods called ages:
- The Carnian Age (237 to 227 million years ago)
- The Norian Age (227 to 208.5 million years ago)
- The Rhaetian Age (208.5 to 201.4 million years ago)
How Do Scientists Date Late Triassic Rocks?
Scientists use fossils to tell how old different rock layers are. These special fossils are called index fossils.
For a long time, researchers used ammonites. Ammonites were sea creatures with coiled shells related to modern squid and octopuses. They changed rapidly over time, which helps scientists date marine rocks very accurately. The start of the Carnian Age is marked by the appearance of the ammonite Daxatina canadensis.
Scientists also use tiny, tooth-like fossils called conodonts. Conodonts were parts of eel-like creatures that lived in the sea. The start of the final age, the Rhaetian, is defined by the first appearance of the conodont Misikella posthernsteini.
On land, paleontologists track animal history using land-vertebrate time zones. These zones help scientists compare dinosaur and reptile fossils found in places like North America, South America, and Europe.
Life on Land in the Late Triassic
Before dinosaurs ruled the planet, other fascinating reptiles filled the land. Earth was full of strange creatures that shared habitats with early dinosaurs.
The Rise of the First Dinosaurs
The first dinosaurs evolved during the Carnian Age, roughly 233 million years ago. Early dinosaurs were agile and walked on two legs.
Some of the most famous Late Triassic dinosaurs include:
- Herrerasaurus: One of the earliest meat-eating dinosaurs, found in Argentina. It was fast and had sharp teeth.
- Eoraptor: A small, two-legged omnivore that was only about 1 metre (3.3 feet) long.
- Coelophysis: A slender carnivore that hunted in packs across North America.
- Plateosaurus: A large, long-necked plant-eater that reached up to 8 metres (26 feet) long.
Crocodile Relatives and Other Land Reptiles
Even though dinosaurs were spreading, they were not the top predators yet. Relatives of modern crocodiles, called pseudosuchians, dominated the ecosystems:
- Rauisuchians: Giant, four-legged carnivores with massive skulls. They sat at the top of the food chain.
- Aetosaurs: Heavy, plant-eating reptiles covered in bony armor plates that looked like giant walking armadillos.
- Phytosaurs: Long-snouted predators that lived in rivers and hunted like modern crocodiles.
- Dicynodonts: Sturdy, tusked plant-eaters that belonged to the mammal-like reptile group.
The First Mammals and Pterosaurs
The Late Triassic was a time of major new beginnings. The first true mammals appeared during this epoch. They were tiny, furry, nocturnal animals that looked like modern shrews. They ate insects and hid from large predators.
In the air, pterosaurs evolved. These were the first flying vertebrates. They had light bones and skin wings supported by a single long finger. Pterosaurs flew over rivers and coastlines hunting for fish and insects.
Life in the Late Triassic Oceans
The oceans of the Late Triassic were vast and full of dangerous predators. A single giant ocean called Panthalassa covered most of the Earth.
Giant Marine Reptiles
Reptiles returned to the seas and grew to enormous sizes:
- Ichthyosaurs: Marine reptiles shaped like modern dolphins or tunas. Giant species like Shonisaurus grew over 15 metres (50 feet) long.
- Nothosaurs: Long-necked sea hunters that had paddle-like feet and sharp teeth for catching fish.
- Placodonts: Heavy reptiles with flat, tough teeth used to crush clams and shellfish.
Fish, Ammonites, and Reef Builders
Bony fish, called neopterygians, expanded rapidly during this epoch. These fish are the ancestors of modern ray-finned fish.
Ammonites floated through the waters, feeding on small creatures. On the sea floor, modern-style stony corals began building colorful reefs. Clams, snails, and sea lilies also formed underwater communities.
Climate and Environment Across Pangea
Because all the land was joined into Pangea, the climate was unusual compared to today.
Dry Climates and Giant Deserts
The center of Pangea was extremely hot and dry. Huge red deserts with shifting sand dunes stretched across entire continents. There were no ice caps at the North or South Poles. The difference in temperature between the equator and the poles was much smaller than it is today.
Many rocks from this epoch are red sandstones and mudstones. These show that dry seasons were long and intense. Mud cracks and ancient soil layers prove that water holes frequently dried up under the sun.
The Carnian Pluvial Episode: A Huge Wet Period
Around 234 million years ago, the dry climate suddenly changed. Scientists discovered that Earth experienced a rainy period called the Carnian Pluvial Episode.
Huge volcanic eruptions in western North America released greenhouse gases into the air. This caused global warming and triggered heavy rainfall around the world. The wet climate lasted for about two million years.
This humid phase transformed plants and forests. Thick conifer forests and ferns spread widely. Paleontologists believe this rainy period helped early dinosaurs spread quickly because new plants provided plenty of food for plant-eating species.
Extreme Monsoons and Wildfires
Pangea had powerful weather seasons. During parts of the year, massive monsoons brought stormy winds and heavy rains to coastal areas. During the dry season, droughts were severe.
Scientists have found fossil tree trunks with fire scars dating back to the Late Triassic. These scars prove that widespread wildfires swept through forests during hot, dry spells.
The Triassic–Jurassic Mass Extinction
The Late Triassic ended with one of the most severe extinction events in Earth's history, around 201.4 million years ago.
What Caused the Extinction?
The main cause was massive volcanic activity. The supercontinent Pangea began to tear apart, opening up the Atlantic Ocean.
As the land tore open, a huge volcanic area formed called the Central Atlantic Magmatic Province (CAMP). These volcanoes erupted vast amounts of lava for roughly 500,000 years.
These eruptions caused massive environmental problems:
- Huge clouds of carbon dioxide entered the atmosphere, causing extreme global warming.
- Toxic gases and sulfur dioxide led to acid rain.
- The oceans warmed and became acidic, which harmed creatures with calcium shells.
- Ash and soot temporarily blocked sunlight, causing sudden cold spells before warming took over.
Which Animals Survived and Which Disappeared?
About 76% of all living species died out during this extinction event.
Groups that disappeared or suffered heavy losses included:
- Giant rauisuchians and aetosaurs completely died out on land.
- Phytosaurs vanished from rivers and lakes.
- Most marine reptiles, such as nothosaurs and placodonts, disappeared.
- Conodonts in the ocean died out entirely.
- Many coral reefs, clams, and ammonite groups were severely damaged.
Groups that survived included:
- Dinosaurs survived easily, possibly due to their insulating feathers and efficient breathing systems.
- Small mammals survived by hiding in burrows and eating insects or seeds.
- Crocodylomorphs (ancestors of true modern crocodilians) lived through the crisis.
- Pterosaurs continued flying in the skies.
With their large competitors gone, dinosaurs quickly took over the empty habitats. At the start of the Jurassic Period, dinosaurs grew to massive sizes and ruled the planet for the next 135 million years.
Summary of the Late Triassic
The Late Triassic was an exciting time of change on planet Earth:
- It lasted from 237 to 201.4 million years ago.
- Continents were combined into the supercontinent Pangea.
- The first true dinosaurs and mammals evolved during this epoch.
- The climate was mostly dry and warm, interrupted by the rainy Carnian Pluvial Episode.
- A massive extinction caused by volcanic activity ended the epoch and began the reign of giant dinosaurs.
Related Pages
In Spanish: Triásico Superior para niños
- Triassic
- Pangea
- Dinosaur
- Carnian Pluvial Episode
- Triassic–Jurassic extinction event
- Jurassic
