12.8: Key Points
- Page ID
- 42152
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- The Cambrian Explosion marks the rapid rise of animal diversity and the first widespread appearance of hard body parts.
- Burrowing and bioturbation in the Cambrian transformed seafloor ecosystems and indicate increased animal mobility.
- Cambrian fauna included trilobites, brachiopods, and early echinoderms dominated early Paleozoic oceans.
- The Great Ordovician Biodiversification Event (GOBE) produced major increases in species-level diversity.
- The end-Ordovician mass extinction was driven by global cooling and glaciation on Gondwana. It was the first of Earth's five mass extinctions.
- Early Paleozoic tectonics shifted Laurentia’s east coast from a passive margin to an active subduction zone.
- The Taconian Orogeny formed the first Appalachian Mountains during the early Paleozoic. The area went through two more events, the Acadian Orogeny during the middle Paleozoic and the Alleghenian Orogeny during the late Paleozoic.
- Major marine transgressions (Sauk, Tippecanoe, Kaskaskia, Absaroka) repeatedly flooded North America.
- Silurian innovations included the evolution of jaws and the first land plants and arthropods.
- The Devonian is the “Age of Fishes,” with major diversification of placoderms, acanthodians, and lobe‑finned fish.
- Lobe‑finned fish such as Tiktaalik represent transitional forms leading to the first tetrapods.
- Arthropods were the first animals to colonize land, evolving book lungs and tracheae.
- Plants transformed Earth’s surface through weathering, soil formation, and the evolution of vascular tissues.
- The Late Devonian mass extinction was driven by forest expansion, nutrient runoff, and widespread ocean anoxia. It was the second of Earth's five mass extinctions.
- Late Paleozoic climate swings included a major ice age followed by warming, alongside mountain building (Alleghenian, Sonoma) and the setup for the Permian–Triassic extinction. It was the third of Earth's five mass extinctions.
- Tetrapods diversified on land during the Carboniferous and Permian, giving rise to amphibians, reptiles, and early synapsids such as Dimetrodon and therapsids.
- Vast Carboniferous forests and high oxygen levels fueled the rise of giant arthropods and the first flying insects, which underwent a major adaptive radiation.
- The end-Permian mass extinction driven by massive CO₂ release, global warming, ocean stagnation, and euxinia was the most severe extinction in Earth’s history and reshaped life on land and in the oceans.