Phanerozoic Life Moves to Land
Phanerozoic Objectives
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Provide the approximate time span, geologic changes, and representative organisms of the Phanerozoic Eon, including the Paleozoic, Mesozoic, and Cenozoic Eras.
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Tell the dinosaur story including evolutionary origins, structural features, major taxonomic groups, new avenues of research, and theories for their extinction.
The Precambrian Supereon ended with a variety of oceanic organisms: bacteria, complex single-celled eukaryotes, and multicellular organisms including the first animals.
That leaves a lot of life to come in the Phanerozoic Eon, including the move to land and origin of the vertebrates.
This video introduces the Phanerozoic Eon.
This video introduces Brachiopods and the sources of data for the figure below.
Assuming that the specimens recorded in fossil sheet #1 are older (deeper in the rock strata) than those from fossil sheet #2, hypothesize how the variation in the widths of the Brachiopods of fossil sheet #1 led to the widths observed in fossil sheet #2.
Dinosaurs
The material in this section is background for this week’s Dinosaurs media piece.
Dinosaurs and other large reptiles ruled the Earth’s ecosystems during a portion of the Phanerozoic Eon. This is their triumphant and then tragic story.
In the past few decades, new dinosaur fossil finds have made this group of reptiles even more interesting.
We’ll begin with a general look at the major groups of dinosaurs.
Ornithischians
“Bird-like” pelvis, these herbivores include stegosaurus, hadrosaurs, and triceratops.
Sauropod Saurischians
Herbivorous dinosaurs with a lizard-shaped pelvis. Many were massive, including Brachiosaurus.
Theropod Saurischians
Carnivorous dinosaurs with a lizard-like pelvis, including T. rex and velociraptors. This lineage gave rise to modern birds.
Stegosaurus, an ornithischian herbivore, is one of the best-known dinosaurs. The spiked tail may have been a defense against predators, and the raised plates may have been used for display or possibly cooling.
Evolutionary trees are used to organize different types of dinosaurs.
Brachiosaurus is one of the iconic sauropods, recognizable with its upright stance.
These videos were made at Prehistoric Gardens on the Oregon Coast. A lot of care has gone into the construction of these statues and it is worth a stop while driving highway 101.
Knowledge about dinosaurs continues to change. The next section explores how scientific knowledge can be both tentative and durable.
Check your knowledge. Can you:
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provide the approximate time span, geologic changes, and representative organisms of the Phanerozoic Eon, including the Paleozoic, Mesozoic, and Cenozoic Eras?
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tell the dinosaur story including evolutionary origins, structural features, major taxonomic groups, new avenues of research, and theories for their extinction?
Go back to the Precambrian Page
Go forward to the Tentative & Durable Page
Geologic Time Lecture Guide Contents
The material from this guide and corresponding lecture is assessed on the weekly quiz.
Back to Evolution
Module 7
This Guide
Geologic Time
