Highlights of the Phanerozoic: Part 1 – Paleozoic [542 – 251 Ma]

Here’s a few highlights from the history of the Earth and life during the Paleozoic Era, the first Era of the Phanerozoic, which is the fourth Eon in Earth’s history. These events are mainly focusing on North America, and the dates of Periods and Epochs are partially rounded.

PALEOZOIC ERA [542 – 251 Ma]

CAMBRIAN (Є) [542 – 488 Ma]

• Small shelly fauna (spines, spicules from larger organisms) [545-525 Ma]
• Cambrian explosion; dramatic jump in animal biodiversity [525-515 Ma]
  • Trilobites, brachiopods, mollusks, crinoids
  • Chengjiang lagerstätten [520 Ma] and Burgess Shale [505 Ma]
• Saux transgression; quartz-rich sand

ORDOVICIAN (O) [485 – 443 Ma]

• Fauna: trilobites, brachiopods, bryozoan, crinoids, corals, cephalopods
• Shallow marine waters of flooded continents
• Regression in Mid O, transgression (epeiric sea) in Late O
• Late: fungi and plants colonize land, early insects follow
• Taconian orogeny (Appalachians #1)
  • Piedmont terrane and Taconic arc accreted; Queenstown wedge
• *Mass extinction #1* – abrupt ice age, rapid warming
  • 2^nd worst

SILURIAN (S) [443 – 416 Ma]

• Early: populated by low  diversity of animals
• Middle: marine carbonates, shallow seas
• Arthropods on land, first diverse terrestrial ecosystems
• Coral-dominated reefs

DEVONIAN (D) [416 – 359 Ma]

• World climate essentially uniform; milder and more homogeneous
• First amphibians on land; The Age of Fishes
• Seed-bearing vascular plants; armored fish; huge fungi
• Acadian orogeny (Appalachians #2)
  • Avalon terrane accreted (Catskill wedge)
• *Mass extinction #2* – abrupt cooling (Gondwana glaciation)
  • 3^rd worst

CARBONIFEROUS © [359 – 299 Ma]

MISSISSIPPIAN (M) [359 – 318 Ma]

• Age of the Amphibians (into Permian)
• Last widespread carbonate-producing epeiric sea in North America
  • Limestones rich with crinoid fragments

PENNSYLVANIAN (ǁP) [318 – 299 Ma]

• Large coal deposits (rapid global seal level fluctuations), swampy
  • Cyclothems
• First amniotic eggs; foraminifera
• Giant insects, high O₂ levels; more fish
• Alleghenian orogeny (Appalachians #3)
  • Laurasia and Gondwanaland begin to form Pangaea (Pottsville wedge)

PERMIAN (P) [299 – 251 Ma]

• Cooling and drying; coal swamps begin to disappear
• Synapsids—mammal-like reptiles
• Final formation of Pangaea (Alleghenian)
• *Mass extinction #3* – The Great Die Off
  • 1^st worst
  • 90-95% of all marine species die off
  • Eruption of Siberian Traps, flood basalt event
  • Last of Cambrian fauna die off; calcifying marine organisms hardest hit
  • Ocean acidification and anoxia, ozone destruction

Make sure you check out Part 2 – Mesozoic andPart 3 – Cenozoic!