Geologic Time Scale Flashcards
A single eon covers a period of
half a billion years
Paleozoic Era was ______________ years ago
554 million years
Mesozoic Era was _____________ years ago
250 million
Visible life where rapid expansion and evolution of life forms occur and fill the various ecological niches available on Earth.
Phanerozoic Eon
Extinction of over 90% of living organisms including trilobites
Mesozoic Era
6 Mass Extinction Events
- Late Ordovician Extinction Event
- Late Devonian Extinction Events
- Permian-Triassic Extinction Event
- Triassic-Jurassic Extinction Event
- Cretaceous-Paleogene Extinction Event
- (Holocene Extinction)
66-65 mya
Paleocene
It is the subdivision of eons. Spans a several Hundred Millions of years
Eras
Time of Ancient life
Paleozoic
Jurassic period lasted _________________
206-144 million yrs ago.
6 major Periods of Paleozoic Era
- Cambrian
- Ordovician
- Silurian
- Devonian
- Carboniferous
- Permian
Dominated by Sauropods (long necks and tails), and Theropods (bipedal carnivorous Dinosaurs). Feathered dinosaurs first appeared
Jurassic Period
Geologists have divided Earth’s history into a ________________________________________ using significant events in the history of Earth.
series of time intervals
Warm, moist climate conditions contributed to lush vegetation and dense swampy forests. Insects undergo rapid evolution led to such diverse forms of giant cockroaches and dragonflies.
Carboniferous Period
the earliest well developed circulatory system (vascular plants) known as ______________ id found during Silurian Period
Cooksonia
There were extensive shallow epicontinental seas and rocks that are less metamorphosed than Archean age
Proterozoic Eon
Cenozoic era was ___________ years ago.
65 million years
- Wooly Mammoths, Wooly Rhinoceros
- Saber tooth tigers
- Elephants
- H. Habilis
- H. erectus
- Other homo species
Pleistocene
The two major groups of reptiles – diapsids and synapsids dominated this period.
Permian Period
Paleogene Period Epochs
- Paleocene
- Eocene
- Oligocene
Spans hundred million years
Periods
This period brought the emergence of terrestrial life
Silurian
2.5 mya- 12 kya
Pleistocene
As plants move ashore so did other terrestrial organisms. Air-breathing scorpions and millipedes were common during the period.
Silurian period
Extinction of dinosaurs and many other organisms.
Cenozoic Era
Spans ten million of years.
Epochs
Dominated by the dinosaurs (duck billed & horned). Tyrannosaurus Rex is found during this period.
Cretaceous Period
First appearance of organisms with hard parts.
Paleozoic Era
- Ancestral Bats
- Ancestral Elephants
- Cetaceans and Sirenians
- Eohippus (first horse)
- Perissodactyls (odd-toed)
- Artiodactyls (Even-toed)
Eocene
- Rodents
- Condylarths
- Primates
- First Hare/ Rabbits
- Creodonts (catlike & doglike animals)
Paleocene
Largest intervals of geologic time.
Eons
Age of Dinosaurs & Age of Conifers
Mesozoic Era
Diapsids gave rise to the
Dinosaurs
33-23 mya
Oligocene
This period was known as the “age of fishes”.
Devonian Period
The environment was dominated by the therapsids (mammal-like reptiles) and Thecodonts (ancestors of dinosaur)
Triassic Period
Time of Middle Life
Mesozoic
Sharks, fishes and marine Reptiles
Triassic Period
They developed during Devonian Period
Sharks and bony fishes
Age of mammals
Cenozoic Era
Age of reptiles
Mesozoic Era
Period where life was first formed on earth (Archean & Bacteria)
Archean Eon
Periods during Mesozoic Era
- Triassic
- Jurassic
- Cretaceous
Cretaceous Period lasted _____________.
144-65 million years ago.
a system of chronological measurement that relates stratigraphy to time. It is used by geologists to describe the timing and relationships between events that have occurred throughout Earth’s history.
Geologic Time Scale
12 kya- present
Holocene
55-34 mya
Eocene
Almost all marine organisms came into existence as evidenced by abundant fossils.
Cambrian Perios
- Mesohippus and Miohippus
- Mastodons (Mammoth ancestors)
- Parapithecus (New World Monkeys)
- Indricotherium (Largest mammal)
Oligocene
Just before proliferation of complex life on Earth.
Proterozoic Eon
_________________ have distinction of occurring at the highest elevation on Earth – the top of Mount Everest.
Ordovician Rocks
Earth cooled down and was able to support continents and oceans.
Archean Eon
Specific Event happened in Paleozoic Era
The Cambrian Explosion
This period marked the earliest appearance of vertebrates and the jawless fish known as Agnatha
Ordovician
Time of recent life
Cenozoic
Gymnosperms, cycadeoids, cycads, gingkoes, conifers
Triassic Period
Lowland forests of seed ferns, scale trees and true ferns flourished.
Devonian Period
Important event in Cambrian Period is the ability of organisms to secrete ____________________ and __________________ for formation of _________
calcium carbonate and calcium phosphate, shell
Synapsids gave rise to
Mammals
Neogene Period Epochs
Miocene, Pliocene, Holocene
