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

2. 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.

3. Silurian – Devonian Major Events

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

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

6. The Age of Fishes
Jawed Spiny Acanthodians

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

8. 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

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

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

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

12. Proliferation of Reefs

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

14. Silurian-Devonian Coral Reefs

15. Ecological Zonation of Coral Reefs

16. Reef Facies
Devonian Reef Complex, W. Australia

17. Modern-day Reef Environment

18. Silurian Reef
Thorton Quarry,
South of Chicago

19. Late Devonian Extinction Another Cool Down?

20. 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