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Geologic History and The Evolution of Life - Coggle Diagram
Geologic History and The Evolution of Life
Developing a Geologic Timeline
Units in the Geologic Time Scale
In a geological time scale there will always be some type of unit. The longest unit is called an Eon. Currently, earth's eon is the Phanerozoic. Eons also can be subdivided into smaller categories called eras. Eras will later be divided into periods and periods can be divided into epochs.
The Time Scale and Fossils
Geologists have developed a way to use the geological time scale with fossils and earths layers. You see, earth is composed of multiple layers. Geologists then studied that in each corresponding layer there is a specific fossil. So, they labeled they layers according to the geological time scale. For example, on of the oldest layers on earth is the Precambrian which tiny individual fossils are found.
Major Divisions in the Geologic Time Scales
Geologists over the years have discovered many abrupt changes whith fossils and their location in each layer. Sometimes, fossils are found in a specific layer but if you continously go up, they suddenly disapear. Thats hwy geologists have recorded those fossils as abrupt and important changes in history because the existence of the creature suddenly disapear. Because tehse changes didn't occur at regular intervals, the geolocial time scale can be irrelavant because the units are of unequal length. Though, this scale is a working idea and scientists and Geologists are still looking forward to study it and make it more specific and accurate.
Responses to Change
Animals normally change if their environment is suddenly affected. This is because they will have to adapt to a new form of living. These changes can be fundamental because it can extinct a specie if they dont adapt quickly. Thats why its very common for mass extinctions to occur during these types of changes.
Changes in Climate
Usually, animals can die because of their environment. If an environment suddenly changes because of climate or other characteristics, these animals can die if they do not adapt quickly for their survival. If many volcanoes erupt too much pyrclastic ash and other types of gases into the atmosphere, this could block the suns reflection and may affet crops and agriculture near by; this will later lead to mass extinction. Also, a popular example can be Dinosaurs. Scientists hypothesize that Dinosaurs where extinct because of a meteorite impact on earths surface. This is because in the Iridium layer (which is a material that meteorites are composed of) many fossils of Dinosaurs are found. It happens that none of Dinosaurs fossils are found in the other layers which refers that there was a mass extinction in that period of time.
Geography and Evolution
Land Bridges
When sea levels frop or continents collide, a land bridge is formed because two pieces of land are connected. This can help many organisms travel through land and evolve because they will live in a new environment. Through the years, these organisms will adapt and later on evolve to a new creature or just an upgraded versionof themselves.
Geographic Isolation
Geographic isolation is when two populations are isolated or separated from each other because of a physical barrier. These organisms will later evolve by themselves and try new ways to survive by their own. An example can be the Kaibab squirrel and the Albert's squirrel which once belonged to a same specie but where separated.
Precambrian Time
The Precambrian time is a period in time where 90 percent of earth's history was created. Geologists have found multiple singular organisms that are about 3.5 billion years old. They have also found multicellular organisms which are 600 million years old. Those types of organisms are so rare that current geologists thought they didn't exist. The Precambrian time is the time before the Cambrian era.
Precambrian Life
The rare multicellular organisms that were found in Precambrian rocks are actually soft-bodied organism. They are different from todays organism but they became extinct at the end of Precambrian.
Cambrian Explosion
The Cambrian explosion is referred as new complex life forms that appeared after the Precambrian time. These lifeforms evolved into new creatures. They suddenly started to have hard body parts. An example can be the Trilobite fossils. They evolved because they had to adapt to new things; therefore, the hard shells from the trilobites helped them be more preserved and protected from other animals.