1	Mid Paleozoic: Silurian, Devonian
2	Earth in the Silurian ~ 443 to 417 ma Geography & Climate North pole- a vast ocean South pole- a supercontinent (Gondwana) Tropics/Sub-tropics- Laurentia-Baltica-Avalonia Were converging, Ocean basins closing Stable, warm climate
3	Continents & Oceans: Silurian The Setting: Taconian Orogeny ended Seas transgressing, encroaching eastward Shallow seas cover an immense region No major volcanic activity Collision- Caledonian Orogeny
4	The Caledonian Orogeny 2^nd major orogenic event of Phanerozoic Collision between Laurentia & Baltica Mountain building Caledonian belt of Britain and Norway = northern Appalachian-E. Greenland Causes sedimentation –identical on two sides of Atlantic Most of Ireland, Wales, northern England, Scotland & Norway Appalachian belt 1^st of multiple plate collisions that continued from Early Silurian through to the Late Devonian
5	Position of Continents Cambrian through Devonian Paleomap Project by Christopher Scotese
6	Silurian Rocks Silurian seas were dominated by carbonate sedimentation Include evaporite deposits & reef formations Extensive in NY, OH, western Canada Michigan Basin circular area created by subsidence Up to 1500 meters of dolomite rock, minor rock salt and anhydrites Large organic reefs of chiefly coral & stromatoporoid
7	Life of the Silurian: Marine Early Silurian seas- low diversity of animals Late Silurian- life had recovered, and complex marine ecosystems had developed Major phyla returned different families & orders dominated
8	Silurian Marine Invertebrates Filter Feeders Brachiopods- abundant pentamerids Bivalves, incl. freshwater Crinoids- widespread Graptolites- index fossil for Siliurian stages Monograptus uniformis -marksSilurian-Devonian boundary Grazers Gastropods Scavengers Trilobites- scarce
9	Silurian Trilobites
10	Silurian Predators Nautaloids- declining Eurypterid “sea scorpion”- top predators. Fish: Jawless & jawed 1st fish with jaws- acanthodians Sea Spider Sea Stars
11	Silurian Terrestrial Life 1^st vascular plants!!! Basis of terrestrial ecology since their appearance Have tubes for transporting water & nutrients through tissues Cooksonia- Simple leafless stalks with sporangia @ tips Baragwanathia, 1^st lycophyte
12	Silurian Terrestrial Life 1^st Terrestrial Animals!!! Arthropods Millipedes, centipedes, spider-like Tragonotarbid
13	Earth in the Devonian ~ 417 to 354 ma Geography & Climate Uniform, warm climate 2 supercontinents, Gondwana and Euramerica A vast ocean covered the rest of the Earth North America & Europe collided raise Appalachian Mountains of eastern North America Followed by great volumes of sediment deposition
14	Continents & Oceans: Devonian The Setting: Early Devonian is marked by a widespread unconformity Regression exposed continents to erosion Middle Devonian- KaskaskiaTransgression Marine deposition resumes Severe cratonic deformation- arch & basin warpings Continued subsidence of MI Basin Collision-Acadian Orogeny
15	The Acadian Orogeny 1. Began ~430 to 425 ma Continued for 40 ma 2. Avalonian arc and Baltica collide with Proto-North America Avalonia sandwiched between eastern Canada & Baltica 3. Created Northern Appalachian mountains. 4. Created Euramerica, a supercontinent 5. Iapetus Ocean floor was subducted, and volcanism ensued
16	The Acadian Orogeny: Terranes 2 Major Exotic Terranes Accreted to Laurentia Iapetus Ocean terrane- Accreted to Laurentia Metamorphosed Found in Maine, New Hampshire, Vermont, & Connecticut Avalonian terranes All of Rhode Island's foundation rock, parts of eastern Maine, Massachusetts, Connecticut, South Carolina Also found in New Brunswick, Newfoundland and Nova Scotia, Morocco, Portugal, Spain, Ireland, Wales, southern England and the northern coasts of France, Belgium, Holland and Germany
17	Position of Continents Cambrian through Devonian Paleomap Project by Christopher Scotese
18	Devonian Rocks Granite & regional metamorphism from the Acadian Orogeny “the Red continent” Devonian Red beds (iron oxidation) Eastern Grenland, nw Eurupoe- Old Red Sandstone Same as American Catskill Redbeds Carbonate rocks, reefs Black shales associated with Late Devonian Glaciation Glacial deposits, Gondwana
19	Life of the Devonian: Marine Marked by complex marine ecosystems Brachiopods- spirifers dominant Bivalves, gastropods Trilobites- scarce Ammonoids Fish- great diversity
20	Devonian Land Animals 1^st tetrapods, or land-living vertebrates!!! Ichthyostega – 1^st fossil tetrapods found & described (1932) Acanthostega– fish with fingers; may have been 1^st land tetrapod Sinostega pani , China, 2002. 354 ma 2 main Groups of Tetrapods 1. Amphibians 2. Amniotes (have 2 subgroups) a. Synapsids (incl. mammals) b. Sauropsids (incl. reptiles)
21	Age of Fish Acanthodians- abundant First true sharks Placoderms Dunkleosteus- “Dinichthys”- Largest predator in late Devonian seas. Reached 40 ft Ray-finned fish- 99% of modern fishes from this group lobe-finned fish- ancestor of amphibian & us!
22	Devonian Terrestrial Plants Early D: primarily small plants ~ up to 1 meter tall, lack true leaves/roots Late D: ferns, horsetails & seed plants 1^st trees & 1^st forests Lycophytes (club mosses) Sphenophytes (horsetails) Ferns progymnosperms Archaeopteris-true wood pteridosperms (seed ferns)
23	Devonian Mass Extinction 2^nd severe extinction event of Phanerozoic 70% of marine invertebrates wiped out. Pentamerids disappear completely. Ammonoids devastated. Decline in trilobites/gastropods Reef communities decimated Typical Devonian fish, incl. armored jawless fish and placoderms go extinct. Caused by Gondwanaland glaciation Returned to polar position
24	End Mid-Paleozoic