BIO 2| GEOLOGICAL TIME SCALE Flashcards
- is a record that depicts Earth’s history and, at the same time, the order of life from 4.6 billion years ago to the present.
Geologic Time Scale
- distinguishes Earth’s history based on life-forms that existed at certain times since the planet’s formation.
- The majority of these life forms are discovered as fossils, which are the remains or evidence of an organism from the geologic past that have been preserved in silt or rock.
Geologic Time Scale
Carbon-14 is known as radioactive isotope of carbon. It is continuously produced in the upper atmosphere as repercussion of cosmic ray bombardment. Carbon-14 can be used to date events on the process known as radiocarbon dating. The half-life of carbon 14 is only 5, 730 years, and thus, it can be used to date events from pre-historic times including recent geologic history.
Carbon Dating
- known as radioactive isotope of carbon.
- is continuously produced in the upper atmosphere as repercussion of cosmic ray bombardment.
Carbon 14
The half-life of carbon 14 is?
5,730 years
When “eras” are grouped together, this will create the longest geologic subdivision called an “____.” marked by differences in life forms and can vary from continent to continent.
Eon
When “periods” are compacted together according to their characteristics, this geologic division will comprise the so-called “era.” Marked by major changes in the fossil record.
Era
Is a basic unit of geological time during which a specific kind of rock system is produced. Based on types of life existing at the time
Period
Shortest subdivision; marked by differences in life forms and can vary from continent to continent.
Epoch
order of geologic time
eon
era
period
epoch
2 division of eons
precambrian
phanerozoic
3 division of precambrian
hadean
archean
proterozoic
3 eras
paleozoic
mesozoic
cenozoic
“Age of Invertebrates”
Paleozoic
“Age of Reptiles”
Mesozoic
“Age of Mammals”
Cenozoic
periods of paleozoic (7)
Cambrian
Ordovician
Silurian
Devonian
Missippian (Carboniferous)
Pennsylvanian (Carboniferous)
Permian
period of mesozoic (3)
Triassic
Jurassic
Cretaceous
periods of cenozoic (3)
Paleogene (Tertiary)
Neogene (Tertiary)
Quaternary
epochs of Paleogene (3)
Paleocene
Eocene
Oligocene
epochs of Neogene(2)
Miocene
Pliocene
epochs of Quaternary (2)
Pleistocene
Holocene
we are living in what eon, era, period, and epoch?
Phanerozoic Eon
Cenozoic Era
Quaternary Period
Holocene Epoch
Earliest span of time
Precambrian
Everything since
Phanerozoic
More than 85% of earth’s history falls under this supereon, from 4.6 billion years ago to 540 million years ago.
PRECAMBRIAN EON
The solidification of the earth’s continental and oceanic crust
HADEAN EON (4.6-4 BILLION YEARS AGO)
The evolution of earth’s first life forms
ARCHEAN EON (4-2.5 BILLION YEARS AGO)
The appearance of multi-celled animals and the gathering of land masses to form continents
PROTEROZOIC EON (2.5 BILLION YEARS AGO-541 MILLION YEARS AGO)
This is the most recent among the eras of the Phanerozoic Era; this era marks the age of mammals and the first human evolution.
CENOZOIC ERA (66 MILLION YEARS AGO-NOW)
This era marks the beginning of dinosaurs, mammals, birds, and plants due to mass extinction.
MESOZOIC ERA (252 MILLION YEARS AGO)
The explosion of diverse marine life and the largest mass extinction of marine organisms
PALEOZOIC ERA (541 MILLION YEARS AGO)
541 MILLION YEARS AGO TO PRESENT
PHANEROZOIC EON
means ‘ancient life.’ The oldest animals on Earth appeared just before the start of this era in the Ediacaran Period, but scientists had not yet discovered them when the geologic timescale was made. Life was primitive during the Paleozoic and included many invertebrates (animals without backbones) and the earliest fish and amphibians.
Paleozoic (541-252 million years ago)
- Land animals hadn’t evolved yet.
- Marine life flourished.
major groups of invertebrates first - Most appeared.
- Protective shells and exoskeletons evolved. Many unique and unusual invertebrates, which looked nothing like the animals of today, swam in the Cambrian seas.
CAMBRIAN PERIOD (541-485 MILLION YEARS AGO)
Dickinsonia costata
precambrian eon
- The most iconic invertebrates trilobites, a group of arthropods ranged in size from a small coin to a tire. Crinoids, also known as sea lilies, lived attached to the seafloor, filtering plankton out of the water with their feather-like arms.
- The first vertebrates (animals with backbones) were primitive, jawless fish that first appeared near the end end of the Cambrian Period.
CAMBRIAN PERIOD (541-485 MILLION YEARS AGO)
a group of arthropods ranged in size from a small coin to a tire.
trilobites
also known as sea lilies, lived attached to the seafloor, filtering plankton out of the water with their feather-like arms
Crinoids
The first vertebrates
primitive, jawless fish
Haikouichthys ercaicunensis
CAMBRIAN PERIOD (541-485 MILLION YEARS AGO)
- Trilobites and crinoids were still around. Many new marine invertebrates with shells evolved at this time and replaced Cambrian forms.
- The first corals appeared, but they were not widespread. Algae and sponges dominated reefs. Jawless, armored fish were common.
ORDOVICIAN PERIOD (485-444)
- Marine predators such as sea stars
and nautiloids existed. - Coral reefs consist of sponges,
bryzoans and cyanobacteria.
ORDOVICIAN PERIOD (485-444)
- The first land plants appeared.
They were similar to mosses and other plants without deep roots or leaves.
ORDOVICIAN PERIOD (485-444)
- A MASS EXTINCTION ended the
Ordovician Period when ~80% of species living in the shallow seas became extinct!
Abundant glaciers caused sea level to drop. - The survivors were the agnathans characterized by: lack of jaw, being armored and having no fins. This group consists of the hagfishes and lampreys.
ORDOVICIAN PERIOD (485-444)