Earth History GEOL 2110 The Paleozoic Era Part 4A: The Silurian and Devonian Periods Time of Fish, Amphibians and Forests

Major Concepts Biodiversity on the seafloor continued in Silurian and Devonian times. Ammonites replaced Nautiloids; Bony fish diversified to skeletal fish. Land began to be populated with burrowing animals, spiders, scorpians and later amphibians Spore-bearing vascular plants took root in the form of club moss, ferns, horsetails and seed ferns. The proliferation of coral reefs caused restricted basins wherein great thickness of limestone and evaporites were deposited.

Silurian – Devonian Major Events

Marine Biodiversity Recovers from Ordovician Extinction Trilobites get big and defensive 1’ Spirifer Brachiopods Thick-walled, “winged” Brachs

Marine Biodiversity Recovers from Ordovician Extinction Coiled Ammonoid Cephalopods Replace Straight Nautiloids

The Age of Fishes Jawed Spiny Acanthodians

Invasion of the Land Vascular Plants take Root Lycopsids (Club Moss) Rhynia – leaf-less tubes Sphenopsids (Horsetail) Psilophyton –Rooted , strong bundled stalks

Invasion of the Land Late Devonian – Seeded Plants and Trees Plants colonize the land! Late Devonian Seed Fern Stumps, Catskill Mtns, NY Modern-day spore tree fern as existed in the Late Devonian Fossilized Seeds from a Seed Fern

Invasion of the Land Vascular Plants take Root Plants colonize the land! Invasion of the Land Vascular Plants take Root

Invasion of the Land Bugs and Slimy Creatures Follow Plants colonize the land! Devonian centipede claw and head Devonian compound insect eye Millipede fossil

Invasion of the Land Bugs and Slimy Creatures Follow Plants colonize the land! Invasion of the Land Bugs and Slimy Creatures Follow

Proliferation of Reefs

Silurian-Devonian Coral Reefs Huge reefs in the Silurian and Devonian, made of: Tabulate Chain Coral Sponges Rugose Corals Heliophyllum Hexagoneria

Silurian-Devonian Coral Reefs

Ecological Zonation of Coral Reefs

Reef Facies Devonian Reef Complex, W. Australia

Modern-day Reef Environment

Silurian Reef Thorton Quarry, South of Chicago

Late Devonian Extinction Another Cool Down?

Part 4b: Stratigraphy and Tectonics of Silurian and Devonian Periods Next Lecture The Paleozoic Era Part 4b: Stratigraphy and Tectonics of Silurian and Devonian Periods