Paleoenvironment of Utah:Fading the Mists of Time

Late PermianPangea SupercontinentLaurasia and GondwanalandTethys SeaCutler and Kaibab Limestone

Permo-Triassic ExtinctionMost devasting mass extinction 90-95% of marine species died out75% of vertebrate families went extinct, synapsids heavily hitCasualites: Trilobites, Tabulate and Rugose Corals, Pareiasaurs, Cordaites Causes: Many! Severe climatic fluctuations, Siberian traps, Oceanic OverturnSeen at Capital Reef NP

TriassicPangea begins to break upAdaptive radiation of flora and faunaArchosauromorphs become dominant vertebratesUtah = 5-10 degrees North of the Equator

TriassicEarly (240 Ma):MoenkopiShinarump Conglomerate

Late (215 Ma):ChinleUpper Triassic

Triassic PaleoclimateGlobally warmer by 6C, with little latitudinal variationNo polar ice capsClimatic Shift from warm and moist to hot and dryLarge landmass = interior continental desert with high seasonalityUtah: semiarid to subhumid climatePaleosols of Moenkopi record MAP 300-400mm and MAT 13-23C desert shrub or dry woodlandsPaleosols of Lower Chinle record MAP 700-900mm, but up to 1400mm and MAT 18C open forest (Petrified Forest)Paleosols of Upper Chinle record MAP 400-600mm and MAT 29C desert shrub or dry woodlands

Triassic Flora and FaunaFlora: seed ferns, cycads, conifersFauna: Archosauria: Dinosaurs!Climatic warming mirrored in floral and faunal turnovers MassospondylusCeolophysisCycad

JurassicPangea breaks up into North America, Eurasia, and Gondwana as the North Atlantic Sea opensTethys Sea closedSpread of Dinosaurs

JurassicNavajo Sandstone Widespread Coastal DunesGreat Navajo sand sea spreads across interior of Western North America.Epicontinental seaway present = Some shallow marine excursionsLate Jurassic uplift to the West causes stream direction to reverse, expanding deposition of dinosaur fossil-bearing Morrison FmNamibian Desert, SW Africa

Jurassic PaleoclimateGlobally warm and moist climate, prevailing up to the polar regions

Southwestern North America: Arid Coastal DesertThicknesses of annual depositional cycles within the Navajo Sandstone indicate strong near-equatorial, north-westerly winds Mountains to the West enhanced wind strength, and cast a rain shadow, allowing active dunes to extend very close to the palaeoequator.

Jurassic Flora and FaunaConifers: most diverse, majority of tall treesCycads, tree ferns and gingkosAge of DinosaursPterosaursFirst mammalsMorganucodonGingko

CretaceousBreak-up of Pangea into present day continents completeDinosaurs continue terrestrial dominanceRadiation of Angiosperms

CretaceousMancos Shale Marine shale, overlain by shallow marine sandstones and fluvial deposits.

The Western Interioris the site of an encroaching epicontinental seaway from the north. Mountain building orogenies to the West

Cretaceous PaleoclimateGlobally warm and moist climate Tropics 9-12C warmer than today, Deep Ocean 15-20 warmer than today

Increased Sea level = Epiconinental Seaways

Extensive tropical ocean stabilized global climate, gentle temperature laditudinal gradient

Weaker global winds

Cretaceous Flora and FaunaAngiosperms diversify, dominant Late Cretaceous coevolution with insectsAge of DinosaursBirds

Far different oceanic and atmospheric circulation, arid climate in UtahCold high latitudesTropical Tethys Sea, with rice and diverse faunaVast stretches of lowland on Pangea had homogeneous floras and faunas, low diversity of land reptiles, cosmopolitan marine species, gymnosperm forests-complex and diverse ferns and conifersCordaites: mangrove-like swamp treesTraps: sulfates into atmosphere, decrease global tempsThen warmingOceanic overturn=hypercapnia, carbon-dioxide had accumulated = poisoningLife began to rediversify after the great Permo-Triassic extinction and warm-water faunas spread across Tethys. Similar to Permian Pangea begins to split Late Triassic, due to rifting in eastern NA, Europe and North America, leading to North Atlantic OceanThe supercontinent of Pangea, mostly assembled by the Triassic, allowed land animals to migrate from the South Pole to the North Poletetrapods disperse widely (faunas similar worldwide)Early: A broad fluvial and shallow marine depositional system (the Moenkopi Formation) covers much of the southern Western Interior. -fossil ripples, playa deposits=ephemeral lakesLate: The Chinle fluvial system covers much of the Western Interior. Chinle rivers are sourced in remnant highlands of the Appalachian Mountain system.

Poles instead warm and moistmore ideal climateMuch of the rainfall was predominantly convective in character, often focused over the oceans and leaving major desert expanses on the continental areas. Yellow=evaporitered=calcreteRed-bed sandstones and evaporites

Plants of this age include: precursors of the Ginkgo tree and Maidenhair fern, cycads with pollen bearing cones, and early conifers. Archosauria = Triassic laid foundations for radiation of dinosaurs, pterosaurs (winged reptiles), and crocodiles (ultimately birds) Due to shift in climate to warmer conditions:S. Hemisphere Seed ferns replaced by Northern-style confer-dominated floras = dominant herbivores died out, replaced by first herbivorous dinosaursCoelophysis was a long-necked, bipedal, carnivorous dinosaur of the late Triassic. a herding theropod About 9 ft (3 m) long, it was light, fast, and agile. From western USA. Massospondylus was an early herbivore about 13 feet (4 m) long and 3 feet (1 m) tall. It had a long neck, very long tail, a small head, peg-like teeth, and large, five-fingered hands with a large thumb claw. Massospondylus may have been able to use its hand for grasping in addition to walking. Ferns and subtropical varieties found as far north as 60 degrees rich floras in Greenland and AntarcticaGreen=coal, blue=bauxiteGingko=living fossil, only extant member of grouphuge Diplodocus and the meat-eating Allosaurus. Stegosaurus had stiff bony plates along its back. Camptosaurus (plant-eating and beaked) could walk on its two hind legs. Near PriceSouthern Atlantic ocean open, australia and antarctica still attachedHadrosaurs, t-rex, triceratopsCret. Angio. Include magnolia, beech, fig, willow, palm