Please enable JavaScript.
Coggle requires JavaScript to display documents.
Geologic History and the Evolution of life - Coggle Diagram
Geologic History and the Evolution of life
Vocabulary
Eon: The largest units of geologic times.
Eras: What eons are subdivided into (smaller units of time).
Period: What eras are subdivided into.
Period: What eras are subdivided into.
Mass extinction:The extinction of many species on Earth within a short period of time.
Land Bridge: A bridge that connects two continents that were previously separated.
Geographic Isolation: The separation of a population of organisms from the rest of its species due to some physical barrier, such as a mountain range or an ocean.
Responses to change
-All species of organisms depend on the environment for their survival. If the environment changes quickly and species do not adapt to the change, they die.
There have been several mass extinction events in Earth's history.
-Gas and dust from volcanoes can block sunlight and reduce temperatures causing climate change.
Sudden changes in the fossil record represent times when large populations of organisms died or became extinct.
-Scientists hypothesize that a meteorite impact might have caused the mass extinction that occurred when dinosaurs became extinct.
-Evidence for this impact is in a clay layer containing the element iridium (which is very rare on Earth's rocks) in rocks around the world.
-When environments change, some species of organisms are unable to adapt, so they become extinct.-However, other species adapt to environmental changes.
-Land Bridges: When continents collide or when sea level drops, landmasses can join together. Over time, organisms move across land bridges and evolve as they adapt to a new environments.
-Geographic Isolation: The movements of the tectonic plates or other slow geologic events can cause geographic areas to move apart. When this happens, populations of organisms can become isolated. Separated populations of species can evolve in different ways as they adapt to different environments.
Precambrian Time
life has been evolving on Earth for billion years.
The oldest fossil evidence of life on Earth is in rocks that are about 3.5 billion years old.
The oldest fossil evidence of life on Earth is in rocks that are about 3.5 billion years old.
The oldest fossils of multicellular organisms are about 600 million years old.
These fossils are rare, and early geologists did not know about them.
They hypothesized that multicellular life first appeared in the Cambrian period.
Time before the Cambrian was called the Precambrian time.
Scientists have determined that Precambrian time is nearly 90 percent of Earths history.
The rare fossils of multicellular life forms in Precambrian rocks are form soft bodied organisms different from organisms on Earth today.
Precambrian life led to a sudden appearance of new types of multicellular life forms in the Cambrian period.
This sudden appearance of new, complex life forms, such as trilobites, were the first to have body parts.
Move evidence of trilobites is in the fossil record. Scientists hypothesize that some of them are distant ancestors of organisms alive today.
Developing a Geologic time line
Geologists organize Earth's past by developing a time line of Earth's past called the geologic time scale. Time units on the geologic time scale are thousands and millions of years long-much longer than the units we use to organize events in our life.
Eons are the longest units of geologic time. Eons are subdivided into smaller units of time called eras.
Eras are subdivided into periods. Periods are subdivided into epochs.
Hundreds of years ago, when geologist began developing the geologic time scale, they chose the time boundaries based on what they observed in Earth's rock layers.
Different layers contain different fossils.
Older rocks contained only fossils of snail, relatively simple life-forms.
Younger rocks contained these fossils as well as fossils of other, more complex organisms, such as dinosaurs.
While studying the fossils in rock layers, geologists often saw abrupt changes in types of fossils within the layers.
Sometimes, fossils in one rock layer didd not appear in the rock layes right above it. It seemed as though the organisms that lived during that period of time had disappeared suddenly.
Geologists used these sudden changes in the fossil record to mark divisions in geologic time.
Due to the fact that the changes did not occur at regular intervals, the boundaries between the units of time geologic times are irregular.
Essential questions
What was the geologic time scale development? The geologic time scale was developed after scientists observed changes in the fossils going from oldest to youngest sedimentary rocks.
What are some causes of mass extinctions? I learned that some causes of mass extinctions are climate change and meteors.
How is evolution affected by environmental change? To begin with, change in an organism's environment forces the organism to adapt to fit the new environment, eventually causing it to evolve into a new species.