DINOSAURSEXTINCTION GEOL 1066
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This 15 page Class Notes was uploaded by Max Bruen MD on Tuesday October 13, 2015. The Class Notes belongs to GEOL 1066 at Louisiana State University taught by J. Schiebout in Fall. Since its upload, it has received 28 views. For similar materials see /class/222778/geol-1066-louisiana-state-university in Geology at Louisiana State University.
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Date Created: 10/13/15
Geology 1066 Dinosaurs Catastrophes and Extinctions What are dinosaurs Are there ying dinosaurs Marine Dinosaurs Not all ancient animals Not plesiosaurs Two orders of Mesozoic reptiles The upright non sprawling reptiles 1842 Richard Owen coined the term dinosaur Life span 160 million year span From 22865 million years Our species has had around 5 million years Earth is 305 billion years old Why study dinosaurs Accessible science Fascination of kids aliens we can meet As the cause of a major extinction humans can bene t from looking at extinction causes results and recoveries Where did dinosaurs live All continents Preeminence of Asia and Western North America An estimated 825 of all genera of dinosaurs that lived have been found as fossils Fossils and Collecting Fossil remnant or trace of past life naturally preserved in the earth s crust Fossilization of the actual animal Preserves soft parts 0 Freezing o Pickling o Mummif1cation O Distillation Preserves hard parts 0 O O 0 Original apatite is the mineral in bone Permineralization Recrystallization and replacement Casts and molds Fossilization of traces Ichnofossils trace fossils Gastroliths gizzard stones Coprolites fossil dung Eggs and nests Tracks Gnaw mark Field collecting Surface search quarrying J acketing Screening Taphonomy Science of the laws of burial 0 What happens from death to discovery Biases ofthe fossil record the fossil record is poor but deserving Biased toward hard parts animals with hard parts 0 000 O Preburial disarticulation scavenging weathering dissolution Transport sorting Burial upland animals rare mountains and such Post burial dissolution erosion noneXposure noncollecting and preparation damage lose fossils Humans decisions can bias the record we have to study Sample of a depositional Environment Meandering river deposition 0 How a river meanders I Point bar cut bank oxbow lakes I Mississippi River meanders I False River oxbow lake Channel 0 Related deposits 0 Overbank deposits I Levee crevasse splay oodplain Lithostragtigraphy and Biostratigraphy Study of layers of rocks and fossils in the rocks Uniformitarinaism Hutton 17111 century Danish naturalist Steno Basic Principles of stratigraphy the study of layered rocks 0 Superposition in undisturbed strata oldest at bottom youngest at top 0 Original horizontality 0 Original lateral continuity Principles of cross cutting relationships Allows the guring out of a sequence of geologic events Relative and absolute dating Absolute gives an age in years relative refers to position in the sequence of life history Radiometric dating Isotopes have same number of protons and electrons but differ in neutrons and mass Radioactive spontaneously emitting particles or energy by disintergration of nuclei Halflife time for half to decay Carbon 14 Cosmic particles shatter N14 nuclei add a neutron lose a proton to form C14 C14 decays to yield N14 and heat C14 forms a fixed percent ofthe carbon in Carbon Dioxide taken up by living things Once they die no new C14 is added Half life is 5730 plus or minus 30 years Good for 040000 years Source of error Only average decay rates can be obtained Rock freshness weathering and metamorphism Lab accuracy Other sources of absolute ages Varves Tree rings Shell layers William Smith Geologic map of England and Whales Strata contain unique fossil assemblages that can be used for correlation Led to the idea ofbiotic succession What is a good index fossil Marine fossils used for telling the age ofthe strata Need to be spread out and an identifiable range Smaller animals abundant What does finding remains of an animal in a rock mean Animal lived at the same time and place as deposition Same time different place migrated Much earlier reworking Code of stratigraphic nomenclature Rock stratigraphic units 0 Subdivisions of the rocks in the earth s crust distinguished on the basis of lithologic characteristics 0 No concept of time span 0 Formations are mappable bodies of rock 0 Many important dinosaurs sites are in the Morrison Formation for example Biostraigraphic units 0 Bodies of rock strata characterized by fossils contemporaneous with the deposition of the strata Time stratigraphic units 0 Subdivisions of rock considered solely as the record of a specific interval of geologic time Geologic time units 0 Divisions of time distinguished on the basics of the rock record as expressed by the time stratigrapic units I Ex Mesozoic Period 0 Last of three periods in the Mesizoic o In late Cretaceous meet TReX Plate tectonics and climate Effects of mountain ranges 0 Where mountains force air to rise it cools and drops moisture Climate ties 0 Air circulation on a planet without continents but otherwise similar to our own including the side view of air circulation cells and label where wet and dry climate bands would fall on the planet As warm air rises it is cooled and can hold less moisture 0 Water has a moderating affect on climate I It can hold a lot ofheat Continental drift Idea was broached by Alfred Wegener German geophysicist Envisioned a supercontinent that split about 200 million years ago Continents were envisioned as plowing through oceanic crust Evidence Continental shelves fit well Geological features and paleontologic faunas fit 0 Southern paeo oras o Mesosaurs fresh water and estuarine animals in Africa and South America 0 Lystrosaurus index fossil I Terrestrial animal on southern continents o Paleoclimate I Reefs and Permian tillites from glaciations of Gondwanaland are far from the expected areas 0 Apparent polar wandering 0 Ocean oor topography o Roughly about 7 big plates and about 20 small plates I Asthenosphere and lithosphere oat o On pa1tially melted asthenosphere o Oceanic crust and continental crust I Basaltic vs granitic o Basalt is found at mid oceanic ridges 0 Where new crust is formed I Partial melting and or I Weathering I Moves composition nearer granitic Divergent boundaries Mid oceanic ridge basaltic crust formed new ocean crust rifzone Oceanic vs continental volcanoes Basaltic lava is thinner than volcanic crust Convergent boundaries Continent to continent 0 Great mountains like the Himalayas Ocean to ocean 0 Deep sea trench Shear boundaries Neither convergent nor divergent lateral movement like the San Andreas fault Continentality effects What are the effects of high continentality on land In the shallow seas o More changeable on land 0 Climate more extreme in the center of a continent What are the effects of faunas on land and in the shallow sea of uniting several small continents into one large one 0 Change how harsh things are more competition disease Splitting the continent into several smaller ones 0 Less harsh What are the effects of sea level rises on faunas on land 0 Mild situation Effect of regressions 0 Make bigger continent How do continental positions effect latitudinality o Warmer at equator colder at poles 0 Less extreme during dinosaur age What makes climate colder nearer the poles and warmer near the equator vs milder at all latitudes 0 Water currents What arrangements of continents could be devised to increase latitudinality on a hypothetical planet o Continents move position makes a big difference 0 Effects of circumpolar currents o Equatorial circulation Late Triassic through early Jurassic 0 Heat and aridity 0 Strong seasonality I Hand an equatorial dry belt 0 Narrow belts of seasonal rainfall middle and upper latitude dry humid belt Middle and late Jurassic 0 Warm and equable o No polar ice 0 Extensive epeiric seas 0 Less seasonality Last 30 million years of Cretaceous o Deterioration 0 Increased latitudinality and seasonality Evolution Three remarkable forerunners to Darwin 0 Erasmus Darwin I Grandfather of Charles I Believed that new characters could arise to better adapt animals to their habitats but had no good mechanism 0 Cuvier I Founder of comparative anatomy I Recognized some species were extinct I Recognized several distinct body plans instead of a great ladder of being I Believed in catastrophism 0 Did not state that new creations followed each catastrophe as later catastrophists did 0 Migration may have repopulated I Believed species to be immutable 0 Defined them as A species comprehends all the individuals which descend from each other or from a common parentage and those which resemble them as much as they do each other 0 Lamarck I Worked on Paris Basin invertebrates I Inheritance of acquired characters was a widespread idea in Lamarck s time I His idea was that lower forms rise in complexity through an unconscious inner drive new structures arise in response to need I Lysenko a Russian geneticist followed Lamarck and set back Russian science Darwin 0 Studied medicine in Edinburgh 0 Studied to be a clergyman at Cambridge 0 From 18311836 circumnavigated the globe on HMS Survey ship Beagle as its naturalist Alfred Russel Wallace 0 Came up with the idea of natural selection 0 Sent idea to Darwin 0 Published on the Tendency of Varieties to Depart Inde nitely Three tenets of Darwainian Evolution evolution by natural selection Like reproduces like Natural variation occur The best adapted animals survive to pass on their characteristics Gregor Mendal Austrian monk Inheritance behaves as if particulate Charcters assort independently A species An actual or potentially mutually reproducing group of animals reproductively isolated from other such groups The variation on which natural selection acts arises through Mutation Recombination o Mitosis o Meiosis Why are species reproductively isolated Why can t they interbreed with other species Meiosis need to match with chromosomes Possible fate ofa species Survive unchanged Evolve into a new species through time Split into two or more new species Become extinct Linneaus and binomial nomenclature Kingdom phylum class order family genus species The role of type specimens in Linneaus time an din modern classi cation 0 Modern type specimens are the name bearers Nonadaptive evolution Founder effect Genetic drift Gause s Law Law of competitive exclusion 0 Two species that use the same resources in the same way can t coexist long r selection Lots of young Little or no care Most invertebrates rats Kselection Quality not quantity Few young Much energy expended in giving them a good start Tends to have small population Ex elephants Grades clades and cladograms Cladistics 0 Groups to be monophyletic one line 0 More closely related to each other than any other organism Hennig o Founder of Cladistics o A monophyletic group should include an ancestral species and all its descendants 0 Class Reptilia is an example because birds and mammals are excluded 0 Reptiles are a grade not a clade o All descendants should be in same group 0 Based on shared specialized derived traits 0 Not shared primitive traits What is a clade Lineage group With similar genetic heritage What is a grade in the evolutionary sense Group of animals similar in general level of organization Homologous Tracable to a structure in a common ancestor Analogus Functionally similar How do you show relationships on a cladogram Evolution is seen as a system of dichotomous branches in cladograms The evodevo revolution evolutionary development Darwin s Dilemma o The missing Precambrian fossil record Origin of life Four components of life 0 DNA AT G C I Viruses DNA in a protein coat 0 Protein 0 Organic phosphorus compounds 0 Cell membrane Stanley Miller 0 Methane ammonia hydrogen and water vapor with a spark generator 0 Other early atmosphere mixtures also work Fossil Sites Fig tree group in South Africa 0 35 billion year old bacteria Gun int chert Ontario Canada O 19 billion years Prokaryotes Filamentous photosynthesizing bacteria I Lots of oxygen forming I Oxidizing of iron I Banded iron deposits worldwide Earth rusted as iron from the deep ocean oxidized to form banded iron formations Edicara Fauna 0000 Australia Africa South America Russia China Europe Iran North America 630 580 million years Soft bodied impressions of Metazoans in sandstone Possible jelly sh annelid worms coral relatives May represent rapid spread of Metazoans when oxygen reached a threshold Breakthroughs before the Edicara Heterotrophs o Obtained organic molecules from the environment 0 Fed on simpler compounds Autotrophs o Synthesized from inorganic molecules 0 Photosynthesis Prokaryotes 0 Lack definite organelles and organized nucleus 0 Asexual reproduction only Eukaryotes o Organelles start as symbiotic microorganisms 0 Ex photosynthetic bacteria becomes chloroplasts 0 Sex recombination o Multicellularity allows specialization of cells Cynobacterica evolves slowly because widespread huge population asexual Body plans Life modes 0 Sessile o Motile o Planktonic o Nektonic swimming Symmetry o Spherical 0 Radial o Bilateral Coelomate 0 True body cavity Encephalization 0 Having a true head Segmentation 0 Division of body into repeating units 0 Sequential motion 0 Specialization Possible explanations of the Precambrian Cambrian boundary Oxygen rise allows shell secretion Rise of predators but there is little fossil evidence of them until last Cambrian The snowball eart idea suggests some Precambrian times when most of the earth was frozen over End of a snowball earth may have been followed by the Cambrian boundary Support could be an important use of hard parts Some types like brachiopods require a shell for basic body function Burgess Shale Middle Cambrian reef 530 million years old Pikaia 0 Possible chordate Has dorsal nerve cord notochord V shaped muscles in segments Chordate Characters Gill slits Notochord Dorsal hollow Nerve cord Biochemically closest related invertebrates are the echinoderms Phylum Chordate includes subphyla Urchordata and Cephalochordata Urochordates the tunicates o Sessile adults 0 Motile larvae 0 Look roughly like cephalochordates like Amphioxus o Neoteny Retaining larval features into adulthood Vertebrate bone Composed of the mineral apatite Protection water balance salt storage support Divided into Agnatha and gnathostomes o Jaw developed from gill arch 0 Teeth from scaes Ordovician Big predators were eurypterids Devonian Plants and arthropods were on land already Late Devonian First amphibians Time of much mountain building Chondichthyes cartilage fish Osteichthyes Bony fishes Actinoptrygii ray fishes Sarcoptergii Lobe fins including tetrapods Pennsylvanian Permian boundary time First reptiles Amniotic egg 0 Membrane that holds egg in liquid Tetrapods have four classes 0 Amphibian o Reptilia o Aves o Mammalia Skull openings 0 Facilitate jaw muscle action Anapsid o Cotylosaurs and turtles Parapside 0 Upper opening 0 Ichthyosaurs Euryapsida 0 Upper o Plesiosaurs Synapsid 0 Lower o Pelycosaurs therapsids and their descendants Late Paleozoic Two big clades or lineages of land reptiles o Thecodonts a grade and therapsids o Diverge in Permain 0 Last period of the Paleozoic Synapsids vs Retiliaanapsids and diapsids Diapsids 0 Two clades Lepidosaurs snakes lizards archosaurs 0 Share antorbital fenestra 0 Loss of teeth on palate 0 Shape of calcaneum Ornithodira o The noncroc archosaurs Dinosauria Pterosauria 0 Both have erect posture with legs under body The Permian sees the completion of the unification of earth s continents 0 Good time to be a reptile Permian EXtention 95 of marine species Worst extinction since origin of life With supercontinent and no polar ice caps ocean currents didn t stir the depths as much Carbon Dioxide build up Oceanic survivors were the active types 0 Better able to stand Carbon Dioxide stress Others reject the Carbon Dioxide hypothesis and opt for reduced 02 Possibly the Siberian basalt eruptions produced Carbon Dioxide and greenhouse warming Retallack finds shocked quartz and favors an impact