Geologic Time Scale Flashcards
What is the first era of the geologic time scale?
Precambrian
The Precambrian era began 542 million years ago and is characterized by the emergence of single-celled organisms.
What significant event marked the end of the Precambrian era?
The rise of more complex animals in the oceans such as Jellyfish
By the end of the Precambrian, the atmosphere was beginning to accumulate oxygen necessary for higher-order animals.
What is the major event that began the Paleozoic Era?
The Cambrian Explosion
This event initiated a rapid period of speciation and a long period of flourishing life on Earth.
What types of organisms were the first to migrate to land during the Paleozoic Era?
Plants
Plants were followed by invertebrates and many other species that appeared and thrived on land.
What was the largest mass extinction at the end of the Paleozoic Era?
Wiped out 75% of marine life and nearly 70% of life on land
This mass extinction event significantly altered the course of life on Earth.
What era is known as the ‘age of dinosaurs’?
Mesozoic Era
Dinosaurs were the dominant species during the Mesozoic Era.
What was the climate like during the Mesozoic Era?
Very humid and tropical
This climate supported the growth of lush, green plants across the Earth.
What significant evolutionary development occurred during the Mesozoic Era?
Birds evolved from dinosaurs
This era saw the emergence of small mammals alongside thriving herbivores.
When did the Cenozoic Era begin?
65 million years ago
The Cenozoic Era continues to the present day.
What major climatic change occurred during the Cenozoic Era?
Cooler and drier climate compared to the Mesozoic Era
This era is characterized as an ‘Ice Age’ with glaciers covering most temperate regions.
What happened to species of life during the Cenozoic Era?
All species of life, including humans, evolved into their present-day form
The Cenozoic Era marks significant evolutionary development for various species.
What eon was believed the formation of Earth occurred?
Hadean Eon
The formation of continents and the rise of prokaryotes.
Archean Eon
Formation of complex cells (Eukaryogenesis).
Proterozoic Eon
Explosion of diversity and emergence of Trilobites.
Paleozoic Era - Cambrian Period
Diversification of marine life and First Land plants appeared.
Paleozoic Era - Ordovician Period
Invasion of land by plants and arthropods and appearance of jawed fish.
Paleozoic Era - Silurian Period
Age of fishes
Paleozoic Era - Devonian Period.
“Coal Age”
Paleozoic Era - Carboniferous Period
First coal swamp forests
Paleozoic Era - Mississipian Period
First Reptiles
Paleozoic Era - Pennsylvanian Period
“The Great Dying” Occurred in?
Paleozoic Era - Permian Period
The Great Dying killed around – of Marine species and – of all land animals.
95%, 50% respectively
Origin of Mammals
Mesozoic Era - Triassic Period
“Age of Dinosaurs”
Mesozoic Era - Jurassic Period
Extinction of Dinosaurs and most large mammals.
Mesozoic Era - Cretaceous Period
First primates, Early Placental Mammals, Modern Birds.
Cenozoic Era - Tertiary Period (Paleogene) - Paleocene Epoch
First Homonids
Cenozoic Era - Tertiary Period (Neocene) - Pliocene Epoch
Modern Humans
Cenozoic Era - Quaternary Period - Pleistocene Epoch
Rise of civilization and agriculture
Cenozoic Era - Quaternary Period - Holocene Epoch
