geol 110 exam 2

causes of Late Devonian mass extinction

anoxia (related to spread of land plants and weathering)

Origin of jaws

- evolved from bony gill supports by changes in developmental pathways involving hox genes - during evolution of jaws, the first and second pair of gill supports are thought to have been lost, with the third pair persisting as jaws - jaw is clearly homologous to the gill supports because both possess the same bonesq

Tethyan Seaway—when, where?

- circum equatorial - Mesozoic - pangea is rifting apart-> seaway runs thru rifting continents more or less along equator

Caledonian

- continuation of taconic and acadians orogenies - british isles area - collision and suturing of baltica and laurentia - late silurian - early devonian - word originated from before plate tectonics

What are the Geologic (physiographic) provinces of the eastern U.S?

- Coastal Plain (realtively flat line stuff, cretaceous and younger) - Piedmont (hilly area with Fall Line/Zone, represents 1 or more mountain building episodes that have been eroded down, result of taconic orogeny) - Blue Ridge Valley and Ridge (fold belts, Appalachian orogeny, has some late precambrian rock thrust up as a ridge-- this is deep crustal stuff-- it was brought up during alleghanian orogeny) - Plateau - alleghenian, acadian and taconic orogenies

What were the Earliest Burrows? Why were they significant? When did they occur? How can you identify this fauna from Burgess Shale and Edicara fauna?

- Simple burrows and the tracks and trails of undisputed metazoans (many of them deposit feeders)-- called ichnofossils - Precambrian to early cambrian - earliest tracks and trails are thought to have been made by a bilaterally symmetric animal-- like a simple worm - earliest burrows found at the surface of sediment, suggesting that early burrowers could not go deep into sediment yet

What are the Geologic (physiographic) provinces of the western U.S?

- antler orogeny, sonoma orogeny, nevadan orogeny, sevier orogeny

Homologous versus analogous structures—which occur in labyrinthodonts and lobe-finned fish?

- homologous: evolved together, almost identical bone structure - analogous: superficially look like they belong to the same group, same function but different bone structure (ex: bird vs bat wings)

Major reef-building taxa through time AND AS EXAMPLES OF ECOLOGIC REPLACEMENT (LOOK IT UP)

- initial reefs were cyanobacteria, stromatalites -silurian -> sclerosponges - devonian -> barrier reefs -acritarchs were dominante phytoplankton in the paleozoic -Scleractinia became dominant reef builders in Triassic period -ecologic replacement: sclerosponge reefs die out during end of devonian -> habitats are vacant -> after end of devonian, those reefs are replaced by other organisms like crinoids (after competition dies out, a group can explode and fill a niche)

Uralian Orogeny

- initially, Siberia collided with Kazakhstan; resulting continent moved towards Baltica - Permian - produced Ural mountains in Russia east of Moscow

Why was the Calcite Compensation depth (CCD) so shallow during the Early-to-Middle Paleozoic Era?

- lots of limestone deposition on continents when sea level is high -> shallow ccd - this was the situation in early-mid paleozoic -very high sea levels during greenhouse conditions - limestone deposition was on the continental shelf, which was under water -> so CCd was shallow on continental slow - ccd is level in oceans where calcium carbonate dissolves completely - oceans are giant buffer system trying to keep pH within a narrow range to support life - ccd shallows to try and dissolve as much calcium carbonate as it can to counteract the limestone deposits to keep the pH where it is supposed to be - (if calcerous plankton exist (as in Mesazoic) the ccd does not have to shallow as much because the death and dissolution of the plankton helps balance limestone )

preadaptation

- mechanism of rapid evolutionary change related to changes in developmental pathways - the existence of a structure adapted for a particular function or environmental condition that turns out by chance to be adapted for rapid evolution in a different niche

causes of Late Cretaceous mass extinction

- meteor impact :Most widely accepted cause There is a layer of iridium in a sedimentary rock in Gubbio, Italy and other places around the world As you go up thru the Cretacous and approach Iridium layer, there is almost no Iridium present (its not commonly found at earth's surface) Then, there is a huge spike in Iridium Iridium presumably came from a meteor Negative shifts in the carbon isotope curves at the time (towards C12) indicates that photosynthesis basically stopped→ meteor ejecta blocked sunlight - Another possible cause is massive volcanism India moved over the "reunion hotspot" Caused massive eruption Created the Deccan traps-"Large igneous provinces" Massive volcanic eruptions at different intervals Some may possibly be related to mass extinctions

How does the tectonic cycle effect sea level, ocean circulation, and climate?

- movement of continents below atmospheric pressure cells changes climate (continent below a low pressure cell causes rainfall, continent below a high pressure cell causes deserts). - movement of a continent near or over a pole causes the production of glaciers, increasing the latitudinal temperature gradient from poles to the equator while impacting the distribution of terrestrial vegetation, as occurs today. - a super-continent like pangea insulates the earth, slowing radiogenic heat loss from the core and mantle. Eventually, heat builds up enough to cause doming, rifting and breakup of the continent. Seafloor spreading causes mid-ocean ridges-- as these ridges grow in volume they displace water, causing global sea level rise. Increased rifting/ seafloor spreading = increased subduction, which puts more CO2 into the atmostphere thru volcanic activity-- this creates a "greenhouse" atmospheric environment. Warmer conditions also increase hydrologic cycle on land, and increase the energy and rates of circulation of atmospheric convection cells. Also, widespread shallow seas causes decreased albedo. - ^^^ all occured during Mesozoic era

Be able to recognize main dinosaur groups.

- ornithischia: "bird-hipped" , pubis points backwards (pubis and ischium are fused together), includes ceratopsia, ankylosaurs, hadriosaurs (duck-billed), stegosaurs-> all herbivores - saurischia: "lizard-hipped" , pubis points forwards, includes sauropods (long-necked)->herbivores, theropods (T-rex, rapters, allosaurus)->carnivores

nevadan orogeny

- steep angle of subduction causes upwelling of magma and volcanism

Isostacy

- the coupling of uplift and erosion - vertical adjustments of Earth's lithosphere cause portions of Earth's crust to occur at levels determined by their thickness and density - it is like flotation!

Origin of labyrinthodont limbs

- the stubby-limbs of primitive lobe-finned fish may have helped them scoot along shallow bottoms - these limbs were pre-adapted for rapid transition to land by labryinthodonts (early amphibians) - the similarity in bone structure between these 2 groups (homologous) suggests that relatively small changes in developmental pathways could have easily transformed a lobe-finned fish to an amphibian - these genetic changes could have spread rapidly thru relatively small, isolated populations

Alleghenian Orogeny

- third and final episode of uplift in Appalachian region -Gondwana (particularly Africa) collided with eastern and southeastern margin of Laurentia - repeated thrusting of rocks over several hundred kilometers to produce stacks of thrust sheets (each Cambrian to Devonian age) from New York to Alabama - these thrust sheets were eroded and a huge wedge of molasses shed into interior as conglomerates and sandstone - Late Paleozoic -associated with assembly of Pangea

National parks mentioned-major formations present mentioned in class

- yosemite (sierra nevada) - zion (cross bedded sandstones, Navajo) - canyonlands- late paleozoic

causes of End-Permian mass extinction

-90-95% of all marine forms died out; largest mass extinction -Multiple causes-- primary cause probs anoxia and rapid warming caused by massive volcanism in Siberia/ oxidation of methane release from buried sediments

What plankton are responsible for the positive/negative feedback in geologic cycle of carbon?

-Coccolithophorids and other calcerous plankton- volcanism increased CO2 levels in atmosphere-> this CO2 was used up by weathering, lowering earth temp -> these weathering reactions created limestone. The CO2 in the atmosphere is transferred and stored in limestone by coccolithophorids which secrete microscopic platelets of carbonate to produce limestone. - volcanism puts CO2 into atmosphere --> positive - plankton take CO2 out of atmosphere and into rocks --> negative - this is a cycle!!

What was the Edicara Fauna? Why was it significant? When did it occur? How can you identify this fauna from Burgess Shale fauna and earliest burrows?

-Discovered in the Pound Quartzite (fine-grained, hard quartz sandstone) in Edicara Hills, Australia. Its an example of a fossil Lagerstatte, in which soft-bodied taxa that are normally destroyed are preserved. - late Precambrian (before burgess shale) -impressions in sand -Edicara fossils represent a global fauna that predated other known fossils. - Some resembled jellyfish, medusae and sea pens (phylum Cnidaria); this makes sense as it is a very simple and primitive taxa. Others, like the dickinsonia, are more complicated- it was segmented, bilaterally symetric, with diff front and back ends - they are significat because they are hypothesized to be ancestral to all subsequent metazoans, which then diversified during the Cabrian. Others suggest that they are too different from subsequent metazoans, and instead were a distinct offshoot that led only to the cnydarians. - It is suggested that a part of the edicara fauna represented a completely seperate phylum, or perhaps even kingdom, called Vendozoa. These became extinct and were replace by the more familiar and ancestral metazoans. - recently suggested that they were terrestrial organisms, which stems from the interpretation of the entombing rocks as paleosols.

Acadian Orogeny

-Late Devonian - north america (New England) - Acadian and taconic orogenies produced the "Old Red Sandstone" continent -formed Catskills

Antler Orogeny

-Late Devonian (early-mid paleozoic) - island arc off the west coast of North America-> moved eastward -Nevada and Southern California

causes of Late Triassic mass extinction

-Meteor: Maybe related to Manicougan crater-- a meteor crater (with ring like lake around it) Meteor impact caused a bunch of dust to go into atmosphere and block sun-> caused rapid cooling -> "nuclear winter" -Or maybe volcanism: Central Atlantic Mangetic Province As pangea rifts apart, massive volcanism occurs Increase in CO2 changed climate

What was the Burgess Shale? Why was it significant? When did it occur? How can you identify this fauna from Edicara fauna and earliest burrows?

-Mid-Cambrian -Discovered in the Canadian Rockies of British Columbia in the latter part of the 19th cent -example of Lagertaat; fossils preserved as carbon films -based on recent interpretations, of the ancient depositional environments, these fauna lived in the vicinity of a limestone platform in a shallow marine seaway. It is believed that the fauna were rapidly buried by a turbidity current at the base of the platform, which prevented decay - significant because it provides us with significant glimpses of fossil life that are otherwise not often preserved. Many fossils appear to be combinations of animals that are later members of separate, distinct groups (like trilobites and other anthropoids and various worms). The shale also contains many bizarre, other worldly creatures that are so unique they were originally reconstructed upside-down. Burgess shale type faunas were believed to have disappeared from the fossil record by the end of the cambrian. what is believed to be the first chordate, ancestral to fish, in the burgess shale.

Permo-Carboniferous Hercynian Orogeny

-Paleozoic -Massifs of western Europe

Main features characterizing the phyla Cnidaria:

-cnidocysts -includes jellyfish, sea anemones corals, sea fans, and sea whips -possible that some are represented by the Edicara Fauna -radially symmetric animals that possess tissues but no true organs -incomplete digestive tract -Paleozoic corals typically did not produce reef frames, but new taxa of corals (Scleractinia) became dominant reef builders in Triassic period

Main features characterizing the phyla Arthopoda:

-jointed exoskeleton -by far the most diverse phyllum of invertebrate (lacking backbones) -crayfish, lobsters, crabs, shrimp, copepods, barnecals, centipedes, millipedes, spiders, mites, ticks, and insects (and living fossil Horseshoe crab) -chitinous exoskeleton with head, thorax, and abdomen -extinct trilobites lived thru Paleozoic era but became extinct during mass extinction at end of Permian

Main features characterizing the phyla Brachiopoda:

-lophophore (a horseshoe-shaped structure bearing ciliated tentacles around the mouth in certain small marine invertebrates) -"lamp-shells" - clam-like in appearance, consisting of 2 shells or valves typically composed of calcium carbonate, typically articulated by tooth-and-socket structures along a hinge or beak-like area (which is lacking in earlier primitive forms) -Often prominent component of Paleozoic limestones, but declined in diversity and abundance in the Modern Fauna

Main features characterizing the phyla Mollusca:

-muscular foot in bivalves for burrowing -clams, snails, octopuses, squid and modern pearly Nautilus -bilaterally symmetric -present during Paleozoic, but became much more abundance and diverse in Modern Fauna

Main features characterizing the phyla Porifera:

-simplest metazoans, spicules as skeletal elements -sponges or "pore-bearing" animals -lack true tissues or organs -sclerosponges were dominant frame-builders of reefs during first half of the Paleozoic

Main features characterizing the phyla Echinodermata:

-spiny skins -Asteroidea (starfish), Echinoidea (sea urchins and sea biscuits), ophiuroidea (brittle stars), and Holothuroidea (sea cucumbers) - the skeleton is a series of calcerous plates embedded in a skin that articulate with each other superficially with radial symmetry but actually bilaterally symmetric - Sea lillies (Crinoidea) existed in the Paleozoic-- they were basically upside-down starfish on a stick

Modern examples of natural selection:

1) Industrial melanism 2) Sickle cell anemia 3) Antibiotic resistance 4) Vestigial structures

Phyletic gradualism versus punctuated equilibria (fossil record of allopatric speciation)

Phyletic gradualism: selection and variation that happens gradually; you can't see it over a short period of time; Small variations that fit an organism slightly better to its environment are selected for-- a few more individuals with more of the helpful trait survive, and a few more with less of the helpful trait die. Very gradually, over a long time, the population changes. Change is slow, constant, and consistent. Punctuated equilibrium: change comes in spurts. There is a period of very little change, and then one or a few huge changes occur, often through mutations in the genes of a few individuals. Though mutations are often harmful, the mutations that result in punctuated equilibrium are very helpful to the individuals in their environments; the proportion of individuals in the population who have the mutation/trait and those who don't changes a lot over a very short period of time. The species changes very rapidly over a few generations, then settles down again to a period of little change.

Geology of Delaware (highly simplified!)

a. Baltimore Gneiss—ancient continental crust b. Wilmington Complex-remains of volcanic arc c. Wissahickon Formation-trench sediments: graywackes, volcanic rocks, turbidites d. Cockeysville marble-shelf limestones

Effects of the spread of land plants:

a. Diversification of land vertebrates b. Decrease of braided streams c. Increased soil formation and soil profiles d. Possible stimulation of anoxia in Late Devonian oceans as a result of increased weathering and nutrient runoff to the oceans

Hypotheses for the origin of metazoans:

a. Increasing oxygen->Increasing size (surface/volume ratio): decline of banded iron formations (BIFs) allowed oxygen to begin to accumulate in the atmosphere, and levels rose ot about 10% of current level by late neoproterozic. Some of this oxygen diffused into water and into deep ocean environments, where metazoans lived. Increasing oxygen availability would have allowed organisms to grow larger, particularly to maximize surface area (to make its interior closer to the environment for oxygen/co2 exchange during respiration. Primitive organisms have no special respiratory or circulatory systems and can only exchange gases thru body surface. This also explains the appearance of skeletons in the Cambrian-- skeletons would have provided support and muscle attachment for enlarging metazoans. Also, evidence of increasingly advanced burrowing suggests that metazoans were sophisticating-- which would require more advanced nervous systems and musculature-- which would have required more energy and thus more oxygen for aerobic respiration. b. Increasing size->shells->fossils c. Predation->shells->fossils: increasing predation presumably caused some groups to develop skeletons. Skeletons appeared in stages (shown in fossil record) indicating a "biologic arms race" between predator and prey. As predators became more advanced and sophisticated, prey had to adapt or die. However, most marine animals use behavioral responses, not biological/skeletal adaptions, to escape predation. d. Increasing nutrient and food (strontium isotopes): As nervous systems and musculatures became more sophisticated, organisms required more energy-- thus, it is believed that more food must have been available. Animal are open systems that require inputs like food and water in order to survive. Before Neoproterozic, it is possible that photosynthesis levels were low because of low nutrient availability (continents may haven been too small at the time for sufficient weathering and nutrient runoff to occur). Also, up to Neoproterozic, most of phosphorus in oceans may have been precipitated out to form BIFs (dissoveld oxygen -- necessary for marine photosynthesis-- precipitates in the precense of dissolved iron). After most of iron was precipitated out, phosphorus may have become available again. This phosphorus, alongside increasing amounts of land nutrient runoff (possibly from orogeny), may have allowed for marine photosythesis to occur and phytoplankton to flourish. Increasing photosynthesis would have also incresed oxygen levels in atmosphere. e. Reorganization of biogeochemical cycles (fecal pellet production->increasing oxygen): Early metazoans (like flatworms) had incomplete guts (inefficient means of digesting food-- combined mouth/anus). Some metazoans had complete gut (digestive tract with 1 direction of motion)-- these creatures are from taxa that evolved during late Neoproterozic and Cambrian. Complete guts are more efficient with energy use because they allow creatures like worms to combine moving and eating by digesting sediment as they burrow. The energy they saved could then be used for reproduction, population expansion, and thus possibly biotic diversification. would have promoted deeper and more sophisticated burrowing-- this would have used more energy and thus the creatures would require more food, so they would burrow more to find it, and so on; this is a positive feedback loop between evolution and food availability. The appearance of more sophisticated burrowing fauna would have increased the rate of remineralization of dead organic matter-- recycling it back into the water column would have allowed biosphere to continue its explosive radiation. Thus, without advancing burrowing animals, nutrients would have been trapped in sediment, and expansion/diversification may have haulted. f. Snowball Earths: suggested that one or more snowball earths selected for more "fit" metazoans, causing them to evolve; according to this hypothesis, hydrothermal vents provided refuge for creatures during snowball earths, from which survivors could have dispersed and evolved when conditions were favorable again. Modern hydrothermal vents have creatures from taxa characteristic of continental shelves (mollusks, annelids, etc) but the taxa that evolved at the vents have not returned to the shelves, so it is unlikely that vents could have served as refuges in the past. Also, if hydrothermal vents provided shelter, where did the metazoans originate from in the first place g. Hox mutations: Mutations in developmental pathways; Genetic experiments: new body structure, new ways of feeding, new ways of moving h. Multiple causation i. Why were ther no more new phyla after the Cambrian? (PERHAPS BECAUSE OF "GENETIC BAGGAGE"—LOOK IT UP) genetic baggage: all of the major phyla today originates during permian?, but after they appeared they dont really deviate out of the genetic constraints. Each phyllum has it's own basic "ground plan" that they don't deviate from.

What was the origin of skeletons?

a. Oxygen: as oxygen was made more available, metazoans increased in size to increase surface area to increase gas rate exchange-- they would need skeletons to support nervous system and musculature as they grew. b. Increased body size: ^^ c. Predation: increasing predation presumably caused some groups to develop skeletons. Skeletons appeared in stages (shown in fossil record) indicating a "biologic arms race" between predator and prey. As predators became more advanced and sophisticated, prey had to adapt or die. However, most marine animals use behavioral responses, not biological/skeletal adaptions, to escape predation. d. Multiple causation

When were these groups most prominent? Be able to identify photos or figures.

a. Reefs—sclerosponges = stromatoporoids: early paleozoic and late mesozoic b. Gymnosperms (conifers, etc.): late paleozoic -> mesazoic c. Lycopods (coal swamps): mid-cretaceous d. Trilobites: paleozoic e. Crinoids: paleozoic (cambrian/ordovician -> present) f. Scleractinia: triassic-> present g. Cephalopods: paleozoic (ammonites: cretaceous->, ammonoids: late paleozoic, Nautiloids: paleozoic) h. Ostracoderms (jawless fish): early-mid paleozoic i. Placoderms: paleozoic (silurian/devonian -> end of dev) j.. Sharks: devonian-> k. Labyrinthodonts: late paleozoic (mississippian -> pennsylvanian) l. Coelacanths (lobe finned fish): late paleozoic m. Pelycosaurs (sail back reptiles): late paleozoic n. Ostracoderms o. Acritarchs: cambrian -> devonian p. Graptolites (zooplankton): ordovician -> devonian q. angiosperms: mid-cretaceous

Objections to Darwin's theory:

a. The Earth is not sufficiently old for evolution to have occurred (Lord Kelvin) b. How do you get a wholly new structure like a wing or an eye or a wholly new group of organisms? c. The incompleteness of the geologic record; with more work, it would be found that all organisms were created at the same time (Lyell) d. What is the mechanism of inheritance?

Snowball earths

a. explanation of lithologic changes; limitations: runaway glaciation occurred in tropics via positive feedback (caused by increase of earth's albedo). The deposits, diamictites, are poorly sorted ice-rafted debris; the glaciers were not mountain glaciers. Thus, the neoproterozoic glaciers must have been so huge that they extended over continents and large amounts of the ocean-- making the earth look like a snowball. b. criticism of most recent hypothesis-Slushball Earth: for the diamictites to be so thick, it seems the glaciers would need to have grown for a very long time near the equator, yet the hypothesis indicates that glaciers grew and retreated rapidly. Also, sea ice on snowball earth is estimated to be as much as 1/2 mile thick-- this would have slowed the hydrologic cycle by restricting the transfer of water vapor from the oceans to the atmosphere and then back to ice by precipitation-- this would have prevented the growth of ice sheets. Slushball earth hypothesis has much thinner sea ice that would have been subjected to breakup-- breaks would allow the exchange of water vapor, allowing the continuation of the hydrologic cycle and the continued growth of ice sheets. Ice would have reached no further towards the equator than 45 degrees latitude. During slushball earth, photosyntesis continued allowing exchange of oxygen and co2 thru atmosphere and oceans-- this would have allowed decreased atmospheric CO2 levels, which would have increased the possibility of repreated advance and retreat of ice (carbon isotope ratios for the time are relatively normal- so some photosynthesis was occuring). c. True polar wander versus apparent polar wander: true polar wander involves the rotation of the entire crust and mantle as a single unit around the earth's core. Small changes in the distribution of continental masses caused the entire crust/mantle shell to rotate rapidly from the poles to the tropics because of the conservation of angular momentum; the crust/mantle shell would have carried the continents from the poles to the tropics in the process; as magnetized particles solidify in igneous rock, the angle of the particle in relation to polar north tells it's latitude --> used to tell where continents were at certain times and support continental drift --> we cant tell the longitude though; but are the continents moving or is the pole moving?? apparent polar wandering if if the continents move, true polar wandering is if the pole is actually moving (like with snowball earth hypotheses--> crust and mantle rotate above the core --> not really supported anymore)

Mesozoic Era (basically like the Cambrian to Devonian): major features

a. ~250 - 65 myr b. drastic shift from paleozoic fauna-- rise of dinosaurs (and eventually birds/mammals) c. greenhouse conditions d. rise of angiosperms e. pangea rifts (seperated to Gondwana and Laurasia) f. Tethyan Seaway runs along the equator at end of mesazoic (between rifting continents) g. orogenies along west coast of america h. marine diversity increases at end of mesazoic i. diversity in general increased (after permian mass extinction killed 90-95% of life) j. shallow seas --> decreased albedo k. rifting of pangea --> rise in sea level --> shallow CCD l. rifting --> mid ocean ridges --> volcanism --> CO2 put into atmosphere --> greenhouse

Permo-Carboniferous (basically the reverse of Cambrian through Devonian): Major features

a. ~360 - 250 myr (mississipian, pennsylvanian, and permian eras) b. Shift from Cambrian to Paleozoic Faunas c. Mainly icehouse conditions (greenhouse transitioning to icehouse) d. relatively low sea level? e. coal swamps f. assembly of Pangea- orogenies g. rise of the amniote egg (allowed for the further exploitation of the land by certain tetrapods) h. Freshwater clams made their first appearance, and there was an increase in gastropod, bony fish, and shark diversity i. Carboniferous: lobe-finned and spiny fishes -> amphibians; Permian: -> true bony fish j. Carboniferous: giant swamp forests; Permian: forests began to dry out. The mossy plants that depended on spores for reproduction were being replaced by the first seed-bearing plants, the gymnosperms

Early-to-Middle Paleozoic World: Major features

a. ~542 to ~350 myr b. Shift from Cambrian to Paleozoic Faunas c. Mainly greenhouse conditions d. High CO2 e. High sea level (low albedo) f. Lots of volcanism (due to subduction, higher rates of seafloor spreading)-> h. Well-developed oxygen minimum zone h. So black shales often widespread i. Shallow-water limestone deposition widepsread because of high sea level: stromatolites->stromatoporoid reefs j. Shallow water limestone + CO2 ->Very shallow calcite compensation depth (CCD) k. More-or-less circumequatorial seaway l. Sluggish ocean circulation ("Meddies": resembles Mediterranean today) m. No forests until Late Devonian

Main features characterizing the phyla Chordata:

animals possessing at some point in their life: - an axial rod-like notocords for body support -a single dorsal tubular nerve cord -paired gill slits

Causes of Late Ordovician mass extinction

global cooling related to southern hemisphere glaciation

Sonoma Orogeny

northern California (Klamath Mtns)

Convergent evolution

the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.