MESOZOIC EVENTS Ch 13 Mesozoic f 1290pg 368

MESOZOIC EVENTS Ch. 13

Mesozoic

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MESOZOIC f 14_01_pg 406

Mesozoic Key Events • Breakup of Pangea • Expansion of Atlantic Ocean, while Pacific shrank. • Deposition of Clastics along America’s East Coast (Triassic) • Formation of Earth’s present ocean basins • Formation of Gulf of Mexico (Late Jurassic and Triassic) • Evaporite deposition resulting in the formation of Salt Domes (Oil Exploration)

Mesozoic Key Events “Continued” • Deposition of chalk deposits from epicontinental seas (Cretacious) • Sedimentary deposits occurred in the Cordilleran Orogenic Belt along the west coast (Late Triassic) • Morrison Formation, known for dinosaur remains, formed from epicontinental seas out west around the Cordilleran. (Middle Jurrassic) • Western North America Subjected to 4 Orogenies (Sonoma, Nevadan, Sevier, and Laramide – Rocky Mtns)

Breakup Of Pangea f 13_01_pg 374

Breakup Of Pangea • 4 Stages – Stage 1: Rifting and volcanism along normal fault systems (Triassic) – Stage 2: Opening of narrow oceanic tracts between Southern Africa and Antarctica (Late Triassic). – Stage 3: Atlantic rift began to extend northward (Jurassic – Cretaceous) – Stage 4: Separation Complete (Cenozoic)

Breakup Of Pangea Stage 1 (Triassic) – North America separated from Gondwana • South Africa, India, Australia, Antarctica – Mexico separated from South America – Eastern border of N. America separated from Africa

Breakup Of Pangea Stage 2 (Late Triassic) – Africa and India separated – Large outpourings of basaltic lavas

Breakup Of Pangea Stage 3 (Jurassic – Cretaceous) – Eastern end of Tethys Sea closed (predecessor to Mediterranean Sea) – South America split away from Africa.

Breakup Of Pangea Stage 4 (Cenozoic – Beginning) – North America (Laurentia) separated from Northern Europe/Russia (Baltica) – Australia separated from Antarctica

Triassic Paleography “ 200 -251 ma” f 13_02_pg 376

Jurassic Paleography “ 145 -200 ma” f 13_07_pg 379

Cretaceous Paleography “ 65 -145 ma” f 13_12_pg 384

Mesozoic in Eastern North America • Tectonics characterized by the opening of the Atlantic Ocean (Tensional Forces) and Deposition of Sediments. – Nonmarine Sediments: Poorly sorted, coarse grained, unweathered feldspar. • Triassic (200 -251 mya) – Erosion of Appalachian Mountains – Fault zones created due to tensional forces – Volcanism associated with initial breakup of pangea. • 3 Lava Flows – Gulf of Mexico Formed precipitating gypsum and salt to thicknesses exceeding 1000 meters. • Louann: Famous Salt dome on the Gulf Coast

Erosional Depositional Episodes f 13_04_pg 377

Gulf Coast Evaporite Deposites f 13_08_pg 380

Gulf Coast Salt Dome Formation f 13_09_pg 380

Mesozoic in Eastern North America “Continued” • Jurassic (145 -200 mya) – Transgressive/Regressive Sequences – Evaporite Conditions Ended • Cretaceous (65 -145 mya) – Time of high sea level and epicontinental seas – Deposition of large volumes of sediment – Extensive Carbonate reefs – Chalk Deposits

Mesozoic in Western North America • Tectonics characterized by the closing of the Pacific Ocean (Compressional Forces) and Active Subduction Zone along West Coast. • 4 Orogenies that progressed from the west to the east – Sonoma, Nevadan, Sevier, Laramide • Triassic (200 -251 mya) – Sonoma Orogeny: Volcanic and Greywacke deposits – Eastern Cordillera: Shallow marine sandstones and limestones – Arizona’s Painted Desert and Petrified Forest National Park.

Thrust Faults f 13_23_pg 390

Sonoma Orogeny “Permian-Triassic Boundary” f 13_14_pg 385

Mesozoic in Western North America “Continued” • Jurassic (145 -200 mya) – 3 Orogenies: Nevadan, Sevier, & Laramide(Rocky Mtns) – Sundance Sea: Epicontinental Sea which formed the Sundance Formation. – Morrison Formation: Dinosaur bone deposits, formed after the Sundance Sea regressed. • Cretaceous (65 -145 mya) – – – Erosion of the Cordillera Advance of marine waters and sedimentation Dakota Group: Sandstone Formation Volcanic Material Niobara Formation: Carbonate Formation Fossil-Fuel Deposits (Colorado, Nebraska, Wyoming)

Sundance Sea “Jurassic” f 13_27_pg 392

Sevier Orogeny “Mid Jurassic to Early Cenozoic” f 13_22_pg 390 East of Sierra Nevada Mountains

Cretacious Tectonic Features “Western U. S. ” f 13_30_pg 393

MESOZOIC LIFE Ch. 14

MESOZOIC LIFE – KEY CONCEPTS • A warm climate was the major factor in the diversity and distribution of fauna and flora. • Advent of Angiosperms (Flowering Plants) • Giant Marine Predators • Advent of giant gliding reptiles. • Earliest known true bird – “Archaeopteryx” Jurassic • Dinosaurs appeared during the Triassic Period. • Mammals evolved from mammal-like reptiles during the Triassic. • Mammals initially mouse-sized but evolved to size of dogs by Cretacious. • Mass extinction event at the end of the Cretaceous – Large Meteor.

Influences On Climate • Configuration and dimensions of the oceans and continents. • Development and location of mountain systems. • Changes in snow, cloud, or vegetative cover. • Carbon Dioxide content of atmosphere. • Location of the poles and equator. • Gas from volcanoes. • Astronomic factors – changes in Earth’s tilt/orbit

Mesozoic Paleoclimates • Warming of Climate during Triassic & Jurassic – Causes • • Orogenic Events formed Mountains Paleogeography: Continents located around the equator Increase in proportion of ocean water to land Increase in carbon dioxide in atmosphere – Evidence • Evaporite/Clastic deposits • Coal Deposits on every Continent • Marine organisms

Mesozoic Paleoclimates • Cooling of Climate during Cretacious – Causes • Regressive sequences • Paleogeography – Land masses had moved toward the poles – Evidence • Extinction of fauna and flora – Tropical Cycads • Increase in conifers and angiosperms • Oxygen isotope ratios indicated a drop in temperature

Mesozoic Paleography A: Triassic B: Jurassic C: Cretacious f 14_02_pg 408

Mesozoic Invertebrates • • • Bivalves (Pelecypods) Corals Echinoderms Nautiloids Ammonoids • • • Belemnites Gastropods Radiolarians Forams Insects

Mesozoic Vertebrates • • • Ray-Finned Bony Fish Amphibians Dinosaurs (Land-based & Flying) First Turtles Marine Reptiles Lizards Snakes Birds: Archaeopteryx Mammals – Prototherians: monotremes – Therians: marsupials & placental

Mesozoic Sea Plants • • Phytoplankton Dinoflagellates Coccolithophorids Silicoflagellates and Diatoms

Mesozoic Land Plants • Spore-bearing ferns • Gymnosperms (Nonflowering) – Cycads, Seed ferns, conifers, ginkgoes • Angiosperms (flowering) – Birch, Sycamore, magnolia, holly, palm, maple, walnut, beech, poplar, willow, sassafras

Dinosaurs f 14_25_pg 421

DINOSAURS 2 Groups 1. Saurischia (Lizard-hipped) 2. Ornithischia (Bird-hipped) The 2 groups distinguished based on hips and teeth.

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A. Saurischia (Lizardhipped) B. Ornithischia (Birdhipped) f 14_19_pg 418

DINOSAURS f 14_17_pg 417

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Dinosaurs – Warm or Cold Blooded? • Dinosaur Posture – Erect, Bipedal • Microscopic Structures of Bone – Richly vascular • Isotope analysis showed results similar to warm-blooded vertebrates • Proportion of predators to prey

Dinosaurs – Feather Covering? • Theorized due to close relationships between birds and dinosaurs • Problems with feather preservation

Flying Reptiles

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Marine Reptiles

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Birds

ARCHAEOPTERYX “Jurassic” f 14_49 a_pg 438

Mammals

MAMMALS • Mammals and their closest relatives appear in fossil record the same time as dinosaurs, in Late Triassic. • Mammals were very advanced therapsids synapsids. • True mammals (Mammalia) found from Late Triassic onward.

MAMMALS Three Groups Monotremes: the last surviving egg-laying mammals. Rare and surviving only in Australasia Marsupials: reproduce by young born live but very poorly developed, which then suckle and grow within a pouch. Dominate Australasia, common in South America, present in early Cenozoic Europe and North America Placentals: stay in the womb until more developed, fed by a placenta. The dominant group in the Americas, Africa, and Eurasia.

MAMMALS • Most Mesozoic mammals very small (shrew-to-house cat sized, with a few badger-sized forms in the Cretaceous); mammals only become large AFTER extinction of nonavian dinosaurs. • Oldest were fairly small. But by Middle and Late Jurassic, there were already some specialized mammals: Burrowers Paddle-tailed, web-footed fish eaters

MAMMALS Major Groups • Prototheria (monotremes): platypus and echidna • Eutriconodonta (monotremes): tiny to opposum-sized to badger-sized • Allotheria (monotremes): Rodent-Like • Metatheria (marsupials): similar to opossums • among largest mammals of the Mesozoic (badgersized) • Eutheria (placentals): many were herbivorous, omnivorous, and insectivorous

Late Triassic f 14_50_pg 438

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Late Cretaceous f 14_53_pg 439

Plants

PLANTS • Plants at the dawn of the age of dinosaurs were very different from those of the modern world: not so much of what was there as what wasn't. • There was no grass, no grain, no fruit, no flowers. But by the end of the Mesozoic, these were present.

PLANTS SPORE PLANTS • Liverworts • Mosses • Clubmosses • Ferns, • All of these were present in the Mesozoic. • For most of the Mesozoic the dominant ground cover was ferns, and tree ferns were fairly important trees in the Triassic and Jurassic.

PLANTS GYMNOSPERMS • Cycads, once widespread, but now more common in the tropical regions. Look something like palms and something like pineapples, • Ginkgoes, trees that were widespread in the Mesozoic and Cenozoic but now limited to a single species • Conifers, highly diverse tree-and-shrub sized species including: Pines Araucarians Cypresses, including junipers, Redwoods, sequoias, and dawn redwoods, Spruces, and Cedars

PLANTS ANGIOSPERMS (Flowering Plants) • Jurassic to Early Cretacious GRASSES • Cretacious

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DINOSAUR EXTINCTION f 14_63_pg 444

Dinosaur Extinction • Causes – – Extraterrestrial Event “Large Meteor” Volcanism Paleoclimates Combination • Evidence – Extraterrestrial • Iridium • Shocked Quartz – Volcanism • • Thickness if the iridium layer Acid Rain – Sulfuric Acid Temperature Decline Antimony & Arsenic Deposits, which are rare in meteorites

Irridium Layer f 14_62_pg 444

Irridium Deposits f 14_64_pg 445

Shocked Quartz f 14_65_pg 445

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THE END