Earth’s History Geological time Scale
How do we know about our planet’s history? 8.E.2 Understand the history of Earth and its life forms based on evidence of change recorded in fossil records and landforms. I will explore the geologic timescale of Earth.
Scientist calculate Earth to be 4.54 billion years old. How old is Earth? Scientist calculate Earth to be 4.54 billion years old.
Geologic Time Scale system of chronological measurements used to describe the timing & relationships between events that have occurred throughout Earth's history. Different ages of Earth; ends when a mass extinction beginning when Earth was formed goes to present Using fossils, Paleontologists determine which common organisms fit in which age Chronological= arranged in order of time
Precambrian Era 4600 to 542 million years ago(mya) First era; began with creation of Earth, around 4.6 billion years ago 5 events (creation) 1)sun 2)Earth 3)atmosphere 4)oceans 5) life(simple- bacteria & algae) Organisms became more complex (jellyfish & sea worms) Few fossils- soft bodied & no hard skeleton Extinction-stromatolites and acritarchs (microorganisms)
Paleozoic Era 542 to 251 mya Begins with early invertebrates (lacking a backbone) develops into early vertebrate (fish arachnids & insects amphibians ending with reptiles) Land plants begin to grow (simple mosses & ferns cone-bearing plants ending with seed plants) The Age of Trilobite Pangea formed about 270mya Extinction- most invertebrates & amphibians begin to disappear, 95% of marine species
Mesozoic Era 251 to 65 mya ‘Age of the Dinosaur’ Pangea broke apart about 200 mya. Dominant animals include reptiles & dinosaurs Small mammals & birds appeared Toward end of era more varieties of mammals and flowering plants appeared (life became more diverse) Era ended due to mass extinction of dinosaurs
Cenozoic Era 65 mya- Present Age of Mammals and Humans Mammals – new organisms appeared(more diversity, appearance of humans) & others extinct Flowering plants become more common & diverse
Brain Pop