Prehistoric Earth
Geologic Time
Time ______
Earth’s ______is divided into time units based on:
• Major ______events
• Major ______forms
• Mass ______
-______- longest time subdivision based on the abundance of certain types of ______
-______- 2nd longest time ______based on major worldwide changes in types of fossils. (______, Mesozoic, & ______)
-______3rd longest time subdivision based on types of life that existed ______.
-______- smallest time subdivision characterized by differences in ______life.
Organic Evolution
-The fossil record shows that species have changed over geologic ______.
-______changes can affect an organism’s survival.
-Organisms that can not adapt ______or ______will not survive.
Species
Ø Group of organisms that normally ______with other members of their group.
Ø Reproduction is the key to the ______of a ______.
______Selection
Ø A process by which organisms with characteristics that are suited to a certain environment have a better chance of ______& ______.
Ø Genetic ______can help or destroy a species’ survival.
Earth’s History
v Pre______Time
Ø ______is about 4.5 billion years old.
Ø ______portion of Earth’s history (88%) including the Hadean, ______, & Proterozoic Eons.
Ø Very few ______are found that date back to 4 billion yrs ago.
Ø Earth was a ball of ______for at least a billion yrs.
Primitive Atmosphere
• Atmosphere started out as a lightweight mixture of ______& ______, which drifted out into space.
• It was replaced by large amounts of ______, Carbon dioxide, Sulfuric acid, & small amounts of Water Vapor (from ______.)
• Eventually the Earth ______and the rain formed the ______oceans.
Precambrian Life
• The first organisms to form on Earth (3.5bya) were ______that lived in the ______oceans feeding on sulfur chemicals.
• Cyanobacteria used ______for photosynthesis to make food & produce ______.
• Fossils of cyanobacteria are called ______.
• Over millions of years, the levels of Oxygen increased in the ______& ______.
• Current Atmosphere = 79% ______, 20% Oxygen, 1.0% ______, Water Vapor CO2 & other
v Paleozoic Era (______mya to 248 mya)
Paleozoic Life
• ______animals populate the oceans at the beginning of the Paleozoic Era. ______are the most abundant.
• Prehistoric ______fishes become the most abundant organism during the ______of the Paleozoic.
• ______take control at the end of the Paleozoic.
• ______& cone-bearing plants (Gymnosperms) grow on land.
• Early forms of ______first appear on land near the end of the Paleozoic.
Paleozoic Geology
• ______forms near the end of the Paleozoic.
• The largest ______in Earth’s history kills 90% of all marine life & ______of land species (Permian Period.)
v Mesozoic Era (248 mya to ______mya)
Mesozoic Life
• Reptiles (Dinosaurs) most ______organism on Earth.
• Reptiles are the 1st ______to live entirely out of the water.
• The 1st ______appear during the Triassic Period
• The 1st ______evolve from dinosaurs during the Jurassic Period.
• The 1st flowering plants (______) evolve during the ______period.
Mesozoic Geology
• Pangaea breaks apart into ______& Laurasia during the early Mesozoic.
• The 2nd largest ______in Earth’s history kills many marine & land species including the dinosaurs.
• Many factors could have led to the ______:
• Plate Tectonics causing ______changes
• ______Asteroid hit the Earth
• Blocking out of the ______
• ______temperatures
• ______
v Cenozoic Era (65 mya to ______)
Cenozoic Life
• ______become the most dominant organism on Earth.
• 3 groups of mammals evolve:
§ ______
§ Marsupials
§ ______
§ The largest of the mammals becomes ______during the Cenozoic.
§ Homo sapiens appear about 140,000 years ago (according to the fossil record) and becomes the most dominant/______animal.
Fossils
Principle of Superposition
Ø In ______rock layers, the oldest layers of rock are on the bottom.
Ø Rock layers can be ranked by ______age.
Forming Fossils
Ø An organism must be ______quickly to form a fossil.
Ø Hard parts dissolve to leave ______.
Ø A ______is formed when a mold fills w/ sediment or minerals.
Ø Thin ______films remain in the shapes of dead organisms.
Fossil Type / Description______ / hollow impression of a living thing in rock after it rots away
______ / solid mineral deposit that filled a mold, leaving a copy of the living thing
______ / an impression in rock made by a living thing during its life activities
______ / plant or animal tissue replaced by minerals
Whole ______ / an entire plant or animal encased and preserved in ice, sap, or another material
______ / remains of tracks, burrows, eggs + eggshells, nests, droppings, etc
Dating Fossils
______Decay
• Some ______are unstable and decay into other isotopes & particles.
• Decay is measured in ______, the time it takes for half of a given isotope to decay.
Radiometric Ages
• The ratio of the parent isotope to daughter product can be used to determine the ______age of the rock.
• Living organisms less than ______years old can be dated using Carbon-14.