history of the earth exam 3

Cretaceous Interior Seaway

A Late Cretaceous arm of the sea that effectively divided North America into two large landmasses

Sedimentation in general and evaporites

After erosion of Taconic orogeny, sedimentation returns to dominantly carbonates; evaporites in restricted basins

Antler Orogeny (where, when, what collided, importance)

Antler Orogeny beginning in early Late Devonian; lasts until Carboniferous • Transformation of western Euramerica from passive (no tectonics) to active (convergent) margin for the first time in Paleozoic • Probably collision of a volcanic island arc

Formation of Euramerica

Avalonia rifted from Gondwana in the Early Ordovician and collided with Baltica near the Ordovician-Silurian boundary (480-420 Mya). Baltica-Avalonia was then rotated and pushed north towards Laurentia. The collision between these continents closed the Iapetus Ocean and formed Laurussia, also known as Euramerica.

Devonian black shale basins

Black shale basins from high sea level and greenhouse climate • Possible stratified basins with bottom anoxia and warm water holds less oxygen • Black shales rich in organic matter = oil and gas source rocks

Link between volcanism, CO2, extinction

CO2 levels in ocean increased (hypercapnia) and poisoned marine life (ocean less oxygenated, more acidic) • Support: heavily calcified organisms suffered huge losses; likely unable to form their shells correctly

Caledonian Orogeny

Collisional tectonic event that closed the ocean between Laurentia and Baltica, forming the larger continent, Laurasia. • Gondwana still over south pole

Phosphoria Fm. and its importance

Contains phosphorite which is mined for P; also rich in petroleum and trace met

Destruction of reefs and forests; evidence for this

Corals didn't return until Middle Triassic Forests and plant ecosystems destroyed Coal formation stops Red beds common across boundary fossil dunes and evaporates

Sea level/Absaroka regression

Generally low, plus sea level fall during regression of Absaroka (but not as low as Permian)

why is it named differently in US vs. rest of the world

In North America we have Mississippian (mainly marine rocks) and Pennsylvanian (more terrestrial; with coal). Globally they are subperiods.

Climate on Pangea prior to the extinction and evidence

Large continent = dry interiors; increasingly arid climate

Methane clathrates (methane ice) or burning of coal deposits and how that may have contributed

Methane is a powerful greenhouse gas • Significant amounts stored frozen in ice crystals on seafloor (gas hydrates) • If oceans warm enough, it can release through melting • Global warming catastrophe

What two subperiods are the Carboniferous

Mississippian and Pennsylvanian • Carboniferous was the first modern system, named by Conybeare and Phillips in 1822 • Carboniferous = "coal bearing"— it was the units in England associated with large coal seams

Taconic Orogeny

Mountain-building event that occurred during the Middle Ordovician. Iapetus closed because of taconic orogeny • Caledonian = collision of Baltica and North America • Acadian = collision of Avalonia with North America in Devonian

Tertiary vs. Paleogene and Neogene

Paleogene lake basins and associate formations

Pangea, Panthalassic, Tethys

Panthalassic: super ocean Tethys:seawaywarm water surrounfing pangea

Emissions

Pollutants that are released into the air

Queenston Delta

Queenston Delta: 300 mi wide clastic wedge from erosion of Taconic Orogeny in Late Ordovician

permian sea level

Retreat of ocean and aridity of later Permian • Generally low, plus sea level fall during regression of Absaroka

Alleghanian Orogeny

Series of collisions during late Penn.-Permian • Northwest Gondwana collided with southeastern Laurentia • Began* formation of Pangea • Appalachian, Ouachita, Arbuckle/Wichita, Uncompahgre mountain belts • 1600 km from southern NY to central Alabama

Old Red Sandstone and Siccar Point

Sign of Acadian Orogeny = "Old Red Sandstone" Hutton's unconformity at Siccar Point, Scotland Formed in Acadian Orogeny Silurian marine sediments (tilted) with Devonian nonmarine on top

Sonoma Orogeny continued

Sonoma orogeny has maximum at P-T boundary • Oceanic rocks thrusted on top of eroded structures from Antler orogeny

Thermohaline circulation and ocean conveyor belts (circulating vs. stratified oceans)

Surface currents, namely western boundary currents, are important currents that bring heat and moisture from the equator to higher latitudes. They have the ability to affect weather and long-term climate patterns Deep ocean currents are driven by density differences among water masses These sinking water masses help mix the entire ocean and take gases from the atmosphere to the deep ocean Increased warming of Earth is warming the ocean, which leading to a freshwater lens in the northern and southern Atlantic Ocean This is inhibiting the formation of deep waters, and leading to increased stratification of our oceans Stratification slows and can inhibit ocean mixing, leading to decreased oxygen levels in the deep ocean, warmer surface waters, and intensification of ocean acidification

Restricted basins

The formation of restricted basins isolates seawater from the global ocean and allows the formation of salt deposits, often because restricted basins can have minor connectivity to the global ocean and thus can fill and evaporate many times over result in laminated evaporates

Silurian climate and sea level/Tippecanoe

Tippecanoe (until late Silurian to Early Devonian) = high sea level Melting glaciers = high sea level • High sea level + Laurussia across the equator = lots of warm shallow oceans around palaeoequator

Red beds

Transition from fossiliferous limestones to shales to oxidized (red bed) clastics to evaporites

Calderas

a huge bowl-shaped depression formed when an empty magma chamber collapses after a volcanic eruption Crater Lake

Ocean acidification

decreasing pH of ocean waters due to absorption of excess atmospheric CO2 from the burning of fossil fuels

Two major causes of extinction in geologic past

habitat loss or climate change Causes of habitat loss and climate change in the past were geological • Modern causes include overharvesting, pollution, invasive species

Evaporite and salt deposits

interbedded gypsum and salt (evaporites) on edges of Permian Basin and later in Permian from warm and dry climate • Vast salt beds in Kansas from evaporation of Permian seas; Permian basin evaporites

Effect of humans on biodiversity

pollution invasive species overconsumption/overharvesting

Coral reefs

warm and stable lots of reef development by tabulate and rugose corals BIG ASS scorpions

Permian habitats

warm wet swampy

O2 and organisms

• 35% atmospheric oxygen • Allowed evolution of giant arthropods, like 28" wingspan Meganeura and 8.5 ft Arthropleura

Intermontane basins and deposition

• = basins between mountain ranges • Depositional basins— downdropping to form and sinking during sedimentation allows buildup of thick deposits of sediments

Paleocene-Eocene Thermal Maximum (PETM): what's a hyperthermal, why important

• A hyperthermal: abrupt and intense climatic warming • Part of a series of hyperthermals in late Paleocene and early Eocene • Important as an analog for understanding current global warming • Rates of carbon release ~10x slower than present

Rifting in general

• A rift is a linear zone where the lithosphere is being pulled apart (extensional tectonics) • Can lead to breakup of landmass and formation of new ocean basin with rift as MOR • Has a central valley (graben) with uplifts on one or both sides • Often filled with lakes when continental • Opened Neotethys ocean • Created continent of Cimmeria

Cretaceous-Paleogene Mass Extinction: what groups went extinct, causes and evidence for causes

• AKA K-Pg Mass Extinction or End-Cretaceous Mass Extinction • Used to be called K-T but we don't use Tertiary as a formal time period anymore • Last of the "Big 5" • Strongly linked to asteroid impact • 70-80% decline in marine biodiversity even among successful and well established groups (foraminifera, ostracods, gastropods, cephalopods) • Recovery in Paleogene was rapid radiations of mammals and birds

Sea level/Absaroka-Zuni transition

• Absaroka ends and sea level begins to rise in Zuni Sequence

Rocky Mountains final phase and Black Hills

• Began in Sevier and Laramide orogenies • Cordillera still deforming in Paleogene • Erosion filled basins between mountain ranges • Ogallala aquifer sediments • Black Hills of South Dakota is also part of that latest Laramide orogeny and is the extreme eastern extent of the Laramide

Paleogeography/breakup (rifting) of Pangea

• Breakup of Pangea (rifting) began in Triassic (maybe late Permian) • Continued through Mesozoic

Paleogeography/continued breakup of Pangea

• Breakup of Pangea continues • Gondwana begins to break up with separation of Antarctica/India/Australia from South America/ Africa

Paleogeography/Acadian Orogeny/what collided

• Caledonian orogeny (Baltica + Laurentia) reaches a maximum in late Silurian/Early Devonian • Acadian Orogeny = collision of microcontinent Avalonia with North America in Early-early Late Devonian • Finishes forming continent of Euramerica • Finishes closure of Iapetus Ocean

Rudist reefs and chalk formations

• Carbonate reefs (rudist bivalves) in warm regions • Huge chalk beds (coccolithophore microplankton)

mass extinction causes

• Causes debated • First phase likely related to anoxia, but cause of anoxia debated. Rapid sea level rise? Volcanism? Algal blooms from weathering by land plants? • Second phase also shows signs of anoxia, but may be linked to global cooling/glaciation

Chinle Fm./Dockum Group

• Chinle Fm.: Colored shales with outcrops in Painted Desert of AZ and Petrified Forest NP; known for agate petrified trees (permineralization) and oldest known US dinosaur fossils (Dr. Sterling Nesbitt). Part of Dockum Group in Texas.

PETM and comparison to modern emissions/temperature change

• Comparisons: PETM, Permo-Triassic • Both episodes of significant climatic warming • P/T was the most devastating of the Big 5 • +5-8ºC rise in temperature • ~12000 Gt of C released • Duration of event 20,000 to 50,000 years

cretacerous Paleogeography/continued breakup of Pangea

• Continued rifting of South America and Africa; Australia and India separate from Antarctica • By Late Cretaceous, sea level was very high, creating epicontinental seaways • Large mountain chains in western N.Am. (Sevier and Laramide orogenies; Ancestral Rocky Mountains) in Late Cretaceous

Continuation of Antler Orogeny

• Continuing in Carboniferous • Erosion of Antler highlands deposited sediments next to the mountains— 2 km of sandstone, shale, lavas, ash beds • Now exposed in Nevada and Klamath Mountains of northern California

Basin and Range Province formation

• Created by tension (stretching) of Earth's crust and listric normal faults • Horst (moves up = mountains) and graben (moves down = basin) • Numerous episodes of volcanism

Cyclothems

• Cyclic repetition of marine and nonmarine strata • Repeated transgressions and regressions due to glacial vs. interglacial periods • Characteristic of Pennsylvanian rocks, some in Permian • Very important for correlation of rocks and understanding of Late Paleozoic Ice Age

Cenozoic paleogeography

• Divergence of continents into present-day configurations continues • North America moves south to meet South America • Mid-Atlantic ridge widens ocean between Americas and Eurasia+Africa • India and Australia continue moving north

O isotope paleoclimate signals

• Documented by O isotopes in ice cores spanning the last ~1 myr • Older records from O isotopes in cyclically deposited sediments

Formation of Great Lakes

• Dry lowland depressions in failed midcontinent rift prior to glaciation • Glaciers carved lowlands deeper • Meltwater collected in depressions to form modern Great Lakes starting ~14 Ka • Areas south of Great Lakes dominated by kettles (small glacial meltwater lakes in depressions)

Cenozoic climate

• Earth experienced an overall cooling trend in Cenozoic and glaciers formed at both poles, although they periodically grew and retreated

Big 5 mass extinctions and causes

• End-Ordovician: Climate change (glaciation) reduced shallow shelf habitat. Tectonic/volcanic drivers. • Late Devonian: Complicated. Glaciation and anoxia possibly driven by afforestation of the continents. Possibly invasive marine species. • Permo-Triassic: Climate change (warming), ocean acidification, and reduced shallow shelf habitat driven by tectonics and volcanism. • End-Triassic: Complicated. Possibly warming driven by volcanism; increased aridity • Cretaceous/Paleogene: big damn space rock and likely also volcanism

Carnian Pluvial Event: geologic signs, extinction

• Enormous input of siliciclastic sediments • Anoxia • Change in carbonate factory (shift from high microbial to low metazoan production or cessation of production)

Devonian Major events

• Euramerica (Laurentia + Baltica) subequatorial • Sea level low in Early Devonian • Avalonia incoming

early Gulf of Mexico and evaporites/salt domes

• Evaporites formed from concentration of seawater • Salt domes formed, producing fold and fault structures and traps for oil and gas

Extinction

• Extinction happens all the time (background extinction) • 0.1-1extinctions per million species per year • Current rate may be 100-1000+ times higher • Estimates vary

Paleogene sea level/Tejas transgression and regression/effect on Gulf coastline

• Final Sloss sequence (Tejas) rises to high in Paleogene, but sea level fell as climate cooled

Terrestrial life-- land plants, arthropods

• First vascular land plants (Cooksonia) • First body fossils of fully terrestrial animals: myriapods, arachnids, hexapods

Rocky Mountain foreland basin and Ogalalla Fm

• Foreland basin = an orogenic depositional basin that receives sediments from adjacent source area • Sediments from eroding Rocky Mountains became the Ogalalla Formation • Deposition began between ~60-45 Ma • Now an important aquifer

Closure of isthmus of Panama and its effects

• Formation of land bridge between N. America and S. America which were previously isolated • Blocked west-flowing N. Atlantic Current • Gulf Stream flows NE up to New England = mild climate • Pathway for plants and animals to migrate • Canal built ~100 years ago now separates continents again

San Andreas Fault

• Formed from NW-moving Pacific plate grinding against North American plate • Transform (lateral) plate boundary • Baja California sheared off of N.Am. plate and now rides northwestward with Pacific plate • Where Pacific plate contacts N.Am. plate subduction no longer occurs

Formation of Grand Canyon

• Formed over past ~6 myr • Changes in climate sped up and slowed down rates of erosion • Flow of Colorado River and carving of canyon affected by series of lava dams ~1.8 Ma-500 Ka

Carnian Pluvial Event: effects on dinosaurs and scleractinian corals

• Four episodes of increased rainfall • Multiple C cycle perturbations (negative excursions) • Biotic changes on land and in ocean (ammonoid and conodont extinction; land fauna and flora turnover) • Global warming

What's a cordillera

• From Spanish: little rope • Extensive chain or network system of mountain ranges that run approximately parallel to each other along with plateaus and other intervening features • Western North America and Andes are examples

Glaciation in Antarctic in Paleogene

• Glaciation in Antarctica began ~34 Ma and glaciation in Arctic began ~2.6 Ma • Glaciation at poles requires tectonic movement of plates to isolate polar land masses away from sources of warmth • In Pleistocene (beginning of Quaternary), extensive continental glaciers advanced in northern hemisphere

mississipian paleography

• Gondwana still south-polar/mainly southern hemisphere. • Glaciation in Gondwana (Late Paleozoic Ice Age) • Euramerica across equator and sea level high until late Mississippian (end of Kaskaskia sequence) • Warm shallow seas

Pennsylvanian Period

• Gondwana was still covering south pole and was heavily glaciated (Late Paleozoic Ice Age) • Gondwana moving northward through late Paleozoic to collide with Euramerica • All leading up to formation of Pangea • Siberia and Euramerica colliding to form Eurasia (Laurussia) in late Carb./Perm.

Formation of Washington Scablands

• Gradualism = small changes add up over time • Catastrophism = major change occurs suddenly • Scablands were a result of massive ice age floods south of the Cordilleran ice sheet • Meltwater pooled in a temporary lake the size of Rhode Island • Drained like an overflowing tub into the Columbia River Gorge • Floodwaters carved Grand Coulee Canyon

Coal and distribution of coal in USA

• Great habitat for coal swamps (lowlying warm swampy) • Carboniferous trees were large and very sturdy— lots of bark and other lignin-enforced tissues • Lignin was undigestible by existing fung • Burial of carbon (removal of atmospheric CO2) promoted cooling and rise of atmospheric oxygen north and mid east in the us

Icehouse vs. greenhouse climate states and Earth's climate through time

• Greenhouse: no continental glaciers on Earth; CO2 and greenhouse gases high; temperature high (sea surface temperature ~0-28ºC/32-83ºF) • Most of Earth history • Icehouse/greenhouse mainly driven by tectonic cycles; transitions not well understood

Characteristics of a mass extinction

• High amount of extinction (30%+ of species) • Broad range of habitats or ecologies affected • Global in nature • Short time period/abrupt change • "Considerably higher" than background rates

Proposal of Anthropocene series/epoch and why/what evidence

• Icehouse: continental ice sheets present, but wax and wane through glacial/interglacial cycles; greenhouse gases low; temperature low

Icehouse/Greenhouse

• Icehouse: ice sheets present, but wax and wane through glacial/interglacial cycles; greenhouse gases low; temperature low Icehouse/greenhouse mainly driven by tectonic cycles; transitions not well understood

Importance of rate of change

• If change is slow, organisms can adapt • Natural selection and evolution • If change is rapid, adaptation cannot keep pace • Or change may exceed adaptability

Columbia River flood basalts and western US volcanism

• Intense basaltic lava flows (flood basalts) formed Columbia Plateau in Miocene ~15 Ma • Cascades formed later: Crater Lake erupted ~6 Ka, Mt. Rainier ~2 Ka, Mt. Lassen 1915, Mt. St. Helens 1980

sea level during carboniferous

• Kaskaskia-Absaroka transition at ~M-P boundary

Sevier Orogeny: thin-skinned deformation and thrust sheets

• Late Jurassic to Eocene • Subduction of Farallon Plate under western margin of N.Am. caused thin skin deformation over large belt of land • Mountain building east of Sierra Nevada; classic study area in Nevada and Utah • Dominated by low angle thrust faults with eastward thrusting; faults younger in east

major events of the Silurian

• Late Ordovician: Taconic Orogeny • Closes Iapetus ocean between Baltica and Laurentia -land plants and arthropods diversify -late Ordovician extinction -Tippecanoe and Kaskaskia sequence

Pleistocene ice age

• Low sea level formed land bridge from Siberia to Alaska across Bering Strait • Glaciers carved landscapes • Climate zones shifted southward ahead of ice sheet

Cenozoic tectonics: Alpine-Himalayan orogeny, Mediterranean Basin, Circum-Pacific Orogenic Belt

• Major global tectonic events: • Collision of Africa and India with Eurasia forming the Alpine-Himalayan Orogeny • Crustal flexure related to collision created Mediterranean Basin, which periodically fills and evaporates (evaporite deposition) • As Atlantic Ocean widens, subduction occurs on the rim of Pacific, which creates Circum-Pacific Orogenic Belt • Creates volcanism and mountain-building in Andes, North American Cordillera, Aleutian Arc, Japan, Philippines

Laramide Orogeny

• Maximum in latest Cretaceous into Paleocene • Produced Rocky Mountains • Farallon Plate continues subsiding beneath North America • High-angle reverse faults; classic area in CO, WY, NM • Reactivation of ancient Precambrian normal faults • "Basement-cored uplifts" where mountains are formed as resistant layers of inclined beds surround the central cores

Paleoclimate (Late Paleozoic Ice Age and then changing)

• Most of Europe and N. Am. were warm and tropical with coal deposits forming in swamps • Gondwana was cold, dry, and glaciated • Major climate change in late Permian leading to "the Great Dying" during the Permo-Triassic mass extinction

Newark Supergroup and Palisades

• NY-NJ area has extensive basaltic (gabbro) lava flows from rifting of Pangea within Newark Supergroup • Now called Palisades of Hudson River— may be earliest Jurassic in age by radiometric dating

Sonoma Orogeny

• Permian-Triassic, reaches maximum near P-T • Collision of island arcs with western US

Ocean circulation problems

• Poor ocean circulation due to warming and changed currents (no cold water sink at poles) • Widespread anoxia (gray area at right) • Also disrupts nutrient cycling

What is Basin and Range

• Region arched up during Mesozoic (compression) • Arch subsided and normal faults formed • Uplifted blocks (horsts) formed linear mountain chains and downdropped blocks (grabens) formed basins

Groups that went totally extinct

• Rugose and tabulate corals (all hard corals at the time) • Trilobites • Blastoid echinoderms • Acanthodians • Pelycosaur synapsids, 20 families of therapsid synapsids Reefs and forests disappeared temporarily

Sundance Sea and Sundance Fm

• Sands and silts with marine reptile fossils; formed in Sundance Sea

Characteristics of Permo-Triassic Mass Extinction

• Sea level drop • Reduces shallow shelf photic zone habitat • Cooling or warming • Changes sea level; organisms adapted to climate; oxygenation of ocean can be affected • Anoxia • Impact events • "Impact winter" (disrupt photosynthesis), widespread fires, possibly acid rain

Cretaceous sea level/ Zuni

• Sea level rises in Zuni Sequence (transgression) and reaches high in Late Cretaceous • Zuni transgression creates Western Interior Sea

Late Devonian Mass Extinction: phases, who died

• Second of the "Big 5" mass extinctions in Earth history • Two phases: Frasnian-Famennian and latest Famennian (~20 myr period) • Affected trilobites, brachiopods, ammonoids, conodonts, reef builders • Placoderm fish totally extinct

Glacial/interglacial

• Shorter climate cycles (repeated cooling/warming) driven by variation in Earth's orbit around the sun • Series of glacial/interglacial climate states within icehouse

Glacial vs. interglacial

• Shorter climate cycles (repeated cooling/warming) driven by variation in Earth's orbit around the sun • Series of glacial/interglacial climate states within icehouse • Documented by O isotopes in ice cores spanning the last ~1 myr • Older records from O isotopes in cyclically deposited sediments

Mass extinctions vs. background extinction risk

• Some species have characteristics that make them more at-risk for extinctions. Many have opposite characteristics that make them normally less atrisk. • Mass extinctions break the "rules" of background extinction risk

General Jurassic deposition

• Still many terrestrial areas with alluvial and aeolian deposits and red beds • Eroding mountains along east coast (becoming a coast at that time) • Nevadan Orogeny along west coast • Sundance Sea in mid-late Jurassic • Sundance topped by famous Morrison Fm. in Late Jurassic

Cordilleran accretionary tectonics and exotic terranes

• Subduction zones active along western margin of North America subduct oceanic crust • Fragments of continents and volcanic arcs/islands collided with N. Am. in several episodes of accretion • Identified as exotic accreted terranes when we identify them as parts of somewhere else that got accreted to N. Am.

Permian Paleogeography

• Supercontinent of Pangea • Oceans were Panthalassic and Tethys • Parts of Gondwana still near south pole and glaciated (LPIA) • Pangea moved northward through Permian

History of Quaternary name

• Term is retained from 1700s-1800s when rocks and time were divided into Primary, Secondary, Tertiary, and Quaternary • Primary and Secondary were abandoned relatively quickly in favor of Paleozoic and Mesozoic eras and periods within them

Morrison Fm.

• Terrestrial sands, silts, mudstones formed in swampy river floodplains on top of Sundance Fm. or other formations of same age in different areas. • Rich in dinosaur fossils— the fossil site at Dinosaur National Monument is Morrison Fm

Thrust faults: characteristics

• Thrust faults are a specific kind of reverse fault (dip <45º) • Sign of thrust fault in the field is geometry and older rocks above younger rock

What kinds of sediments are produced by glaciation

• Till: un- or poorly sorted (clay to boulder) size clasts deposited by glacial melting • Erratic: large nonindigenous rock deposited by glacial melting • Stratified drift: well sorted sediments deposited by meltwater flows • Loess: windblown silt (rock flour ground by glacier) • Moraines: mounds of till deposited by glacier

Triassic climate

• Very warm and dry early in period • More temperate later • Pluvial event in Carnian (abrupt shift from arid to humid climate)

Overall contributing causes for Permo-Triassic Mass Extinction

• Volcanic eruptions • Moderate global warming • Methane release catastrophe • Abrupt global warming • Ocean anoxia • EXTINCTIONS

Jurassic climate

• Warm and temperate • Vast seas with warm surface temperatures • No glaciers; coal deposits in Antarctica

Cretaceous climate

• Warm with vast seas and high sea surface temperatures • Subtropical plant fossils found up to 70º north/ south of equator • Cooling began at end of Late Cretaceous

What series/epoch we live in (Holocene)--

• We currently live in the Holocene, but stratigraphers have proposed a new third division, the Anthropocene • Utility of division debated, and appropriate placement of lower boundary debated, but many proposals suggest mid-20th century

permian Basin and Permian reefs

• west Texas, New Mexico, and Guadalupe Mountains of west Texas • 14,000 ft of lagoon, reef, and basin sediments • Basins located between shallow platforms; reefs formed on basin edges of platforms • Reefs: algae and over 250 species of invertebrates • Interbedded gypsum and salt (evaporites) on edges of Permian Basin and later in Permian from warm and dry climate

Siberian Traps volcanism

• ~2,000,000 km3 of flood basalts • Global cooling from ash cloud • Global warming from CO2 release • Possibly burned extensive coal deposits in this area

Big 5 mass extinctions

• ~30-50% of marine families • end-Ordovician • Late Devonian • end-Permian (Permo-Triassic) • Late Triassic • Cretaceous-Paleogene

End-Triassic Mass Extinction: characteristics and cause

• ~76% of all marine and terrestrial species and about 20% of families went extinct Significant impacts: ammonite cephalopods, bivalves, conulariids*, coral reef collapse, land plant turnover, almost all remaining conodonts, last placodonts and giant ichthyosaurs, amphibians, reptiles, synapsids • Set stage (along with Carnian Pluvial Event) for dinosaurs to become dominant land vertebrates in rest of Mesozoic