Geological time scale
The Geological Time Scale is a system of chronological dating that divides the Earth's history into distinct periods of time based on the study of rock layers and the fossils found within them. It is divided into four major divisions: Eons, Eras, Periods, and Epochs.
The largest division of time is the Eon, which is further divided into Eras. The Phanerozoic Eon, for example, is divided into three Eras: Paleozoic, Mesozoic, and Cenozoic.
Each Era is divided into Periods. For example, the Paleozoic Era is divided into six periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.
Each Period is further divided into Epochs, which are the smallest divisions of time in the Geological Time Scale.
The Geological Time Scale allows scientists to understand the history of the Earth and the evolution of life on it. It also helps geologists and other scientists to date rocks and fossils accurately and to correlate them with other rocks and fossils from around the world.
The diversity of animal life on Earth has changed over time, with different groups of animals evolving and going extinct throughout Earth's history. Here are some examples of animals found in each of the major periods of the geologic time scale:
Cambrian Period:-
The Cambrian is known as the "explosion of life" because it saw the rapid diversification of many major animal groups. Some of the animals that evolved during this time include trilobites, brachiopods, echinoderms, and arthropods.
Ordovician Period:-
The Ordovician saw the continuation of many Cambrian animal groups, as well as the evolution of new ones. Some of the animals that evolved during this time include cephalopods, bryozoans, graptolites, and jawless fish.
Silurian Period:-
The Silurian saw the diversification of many marine animal groups, including the first appearance of jawed fish. Some of the animals that evolved during this time include early corals, gastropods, ammonites, and early sharks.
Devonian Period:-
The Devonian saw the emergence of many new animal groups, including the first land animals. Some of the animals that evolved during this time include amphibians, insects, early tetrapods, and placoderms.
Carboniferous Period:-
The Carboniferous saw the emergence of many new terrestrial animal groups, including the first reptiles. Some of the animals that evolved during this time include reptiles, synapsids (early mammal relatives), and insects such as dragonflies and cockroaches.
Permian Period:-
The Permian saw the diversification of many reptile and mammal-like groups, as well as the emergence of some early mammal groups. Some of the animals that evolved during this time include therapsids (early mammal relatives), archosaurs (early dinosaurs), and early turtles.
Mesozoic Era:-
The Mesozoic era saw the dominance of the dinosaurs and the emergence of many modern animal groups. Some of the animals that evolved during this time include birds, mammals, pterosaurs, and marine reptiles such as ichthyosaurs and plesiosaurs.
Cenozoic Era:-
The Cenozoic era saw the diversification and dominance of many modern animal groups, including primates, ungulates, carnivores, and rodents. Some of the animals that evolved during this time include humans, whales, horses, and elephants.
Dominant plants and animals in each of the major periods
Here are some examples of dominant plants and animals in each of the major periods of the geologic time scale:
Paleozoic Era:
Devonian Period: A dominant plant during this time was Archaeopteris, an early tree that grew up to 30 meters tall. A dominant animal was Dunkleosteus, a large armored fish that lived in the shallow seas.
Mesozoic Era:
Jurassic Period: A dominant plant during this time was Cycadeoids, a group of plants related to modern cycads. A dominant animal was Stegosaurus, a large herbivorous dinosaur known for its distinctive bony plates along its back.
Cretaceous Period:-
A dominant plant during this time was the angiosperms, or flowering plants, which rapidly diversified during this period. A dominant animal was Tyrannosaurus rex, a large carnivorous dinosaur that is one of the most famous dinosaurs in history.
Cenozoic Era:-
Paleogene Period: A dominant plant during this time was the palm tree, which grew in tropical and subtropical regions. A dominant animal was Ambulocetus, an early whale ancestor that lived both on land and in water.
Neogene Period:-
A dominant plant during this time was the grasses, which began to spread and diversify during this period. A dominant animal was Megatherium, a giant ground sloth that lived in South America.
Quaternary Period:-
A dominant plant during this time was grasses, which continued to spread and diversify. A dominant animal is Homo sapiens, or modern humans, who have had a major impact on the planet's ecosystems and have become the most dominant species on Earth.
Specifically
Paleozoic Era:
Devonian Period:
A dominant plant during this time was Archaeopteris, an early tree that grew up to 30 meters tall. A dominant animal was Dunkleosteus, a large armored fish that lived in the shallow seas.
Mesozoic Era:
Jurassic Period:
A dominant plant during this time was Cycadeoids, a group of plants related to modern cycads. A dominant animal was Stegosaurus, a large herbivorous dinosaur known for its distinctive bony plates along its back.
Cretaceous Period:
A dominant plant during this time was the angiosperms, or flowering plants, which rapidly diversified during this period. A dominant animal was Tyrannosaurus rex, a large carnivorous dinosaur that is one of the most famous dinosaurs in history.
Cenozoic Era:
Paleogene Period:
A dominant plant during this time was the palm tree, which grew in tropical and subtropical regions. A dominant animal was Ambulocetus, an early whale ancestor that lived both on land and in water.
Neogene Period:
A dominant plant during this time was the grasses, which began to spread and diversify during this period. A dominant animal was Megatherium, a giant ground sloth that lived in South America.
Quaternary Period:
A dominant plant during this time was grasses, which continued to spread and diversify. A dominant animal is Homo sapiens, or modern humans, who have had a major impact on the planet's ecosystems and have become the most dominant species on Earth.
