Today – 1/18Today – 1/18

• Critter in the news / weather report

• Reading background

• End of the dinosaurs (?)

• First writing assignment

Possible test question

Peter Ward and Roger Smith in Gorgon want:

A. To learn how mammals survived the end-Permian extinction event

B. Evidence of dinosaur ancestors

C. To determine if the Permo-Triassic extinction was sudden or gradual

D. All of the above

Administration:

“Get to know you” form worth 2 pts XC

Ross’ OH in Gould-Simpson 205

Turiasaurus

End of the Jurassic, 145 Ma

100+ feet long! Almost 100,000 lbs!

sauropod - member of clade Sauropoda

Other super-giants like Brachiosaurus and Seismosaurus more closely related to each other than to Turiasaurus

Last time:

Biostratigraphy – Principle of faunal succession

Mammal-like reptiles of the late Permian*

Mass extinctions

http://darkwing.uoregon.edu/~millerm/meander.html

/www.uky.edu/AS/Geology/howell

Meandering river

Braided streams

Meandering v. braided stream:

Braided streams: networks of interconnected channels that form where there is a large sediment supply, large fluctuations in flow levels, erodable banks

Meandering river: think of large single channel slowly winding its way across a gently sloping plain. E.g. Mississippi R. Banks stabilized by well-established vegetation

Carbon atom

Carbon Isotopes

All carbon atoms have 6 protons98.9 % of carbon atoms have 6 neutrons, called C-121.1 % have 7 neutrons, called C-13Plants prefer C-12Scientists measure ratio in rocks, try to explain observationsStable isotopes, not radioactive like C-14

Features of the P-T carbon isotopic excursion

Ubiquitous – global, all kinds of rocks including limestone, paleosol nodules, kerogen, and vertebrate teeth!

Means that something big happened and that this can be used to find the boundary anywhere rocks deposited across the right time span are exposed

So fast and so extreme that it cannot be explained by volcanism or other “normal” processes

www.kent.ac.uk/physical-sciences

USGS

Methane hydrate mechanism:

Enormous amounts of natural gas are stored in solid H2O (ice – but not quite the ice we are used to) cages at the bottom of the sea and under permafrost. This methane is enriched in C-12!

Methane is a powerful greenhouse gas so release of some would initiate warming, perhaps starting a positive feedback

Proposed causes of dinosaur extinction

Out-competed by smarter, egg-eating mammals

Disease

Falling sea level

Volcanically driven climate change

Asteroid strike! (had been written off by 1980 because no crater had been found)

1980 - Walter and Luis Alvarez discover

iridium rich clay layer

www.physast.uga.edu/~jss/

www.geology.ucdavis.edu/~cowen/HistoryofLife/ktbits.gif

http://www.lpl.arizona.edu/SIC/

Location of the Chicxulub crater - site of the K-T impact!

www.windows.ucar.edu/earth/images/chicxulb.gif

Chicxulub - “tail of the devil”

Animation of Chicxulub crater formation

Evidence for K-T impact

World-wide clay layer with iridium, shocked quartz, spherules, and carbon

65 Ma tsunami deposits ringing the Caribbean

Chicxulub crater

It was a BIG explosion!

Asteroid or comet was 10 km (6 mi) across

Moving at 75,000 km/hr (45,000 mi/hr)

5 billion times the energy of Hiroshima

World-wide forest fires, tsunamis, acid-rain, year-long “nuclear winter”

At least 75% of all species went extinct, including 90% of all plankton

http://www.lpl.arizona.edu/impacteffects/

Asteroid 1950-DA, March 16, Asteroid 1950-DA, March 16, 28802880

Unlike the K-T impact that killed the dinos, the cause of the P-T extinction is still the subject of vigorous debate!

http://jan.ucc.nau.edu/~rcb7/

X

Pangea

Tethys

Sea

The blue planet, 260 Ma

http://dsc.discovery.com

Siberian Traps

Proposed causes of P-T extinction:

Final assembly of Pangea – changes ocean currents, climate

Volcanism – Siberian traps flood basalt, Chinese explosive volcanism. Release CO2, causes warming, promotes ocean anoxia by weakening currents, lowering O2 solubility, and melting gas hydrates.

Impact

Combination

Insert pic of AC

Petrified tree? AC shot from above! With inset of teeth

What fossils tell us about dinosaurs

How they looked - size, shape, skin How they behaved - diet, locomotion, social life, as parentsPhysiology - thermal regulation, growth patternsHistory of life - speciation and extinction, relationships among groupsEnvironmental reconstruction, rock ages geochemistry, paleogeography, interaction between physical and biological worlds

www.dinoland.dk

web.ukonline.co.uk/conker/

← Griffin inspired by Protoceratops? ↓

www.oum.ox.ac.uk/geolcoll.htm

1677 – Robert Plot publishes first known description of a dinosaur bone. However, he mistakes it for the femur of a giant human!

www.lhl.lib.mo.us/events_exhib/exhibit/ex_paper_dino.shtml

1815 – William Buckland finds Megalosaurus jaw

home.uchicago.edu/~shburch/dinopaper.html

1830’s – Meet Meg, plus the happy water lizard

1831

1833

1836 – Gideon Mantell discovers the teeth of Iguanodon

www.lhl.lib.mo.us/events_exhib/exhibit/ex_paper_dino.shtml

Iguanodon – notice the sprawling legs1842 – Richard Owen defines the “Dinosauria”, which

translates as “terrible lizards”

Depiction by Owen circa 1850

Benjamin Waterhouse Hawkins’ 1853 dinosaur reconstructions being prepared for display in the Crystal Palace, Hyde Park, London

http://www.ric.edu/rpotter/cryspal.html

www.simondevlin.com

www.owen.k12.ky.us/trt/beverly/Megalosaurus_files/frame.htm

http://www.healthstones.com/dinosaurdata/dinodata.html

Nicholas Steno – “Father of stratigraphy”

Second half of the 1600’s

Said fossils were remains of organisms

Principle of Original Horizontality – rock layers laid down horizontally, any deviation from this due to later disturbance

Law of Superposition – lower layers are older, upper layers are more recent

Early 1800’s geology comes alive!

1795 – Theory of the Earth by James Hutton: how rock layers form, hot inside, old, uniformitarianism, natural selection

1815 – Geologic map by William Smith: biostratigraphy

1830-1833 – Principles of Geology by Charles Lyell: stratigraphy

1859: On the Origin of Species by Darwin

Archaeopteryx – London specimen, found 1861

Taphonomy - the study of how fossils get preserved

How sedimentary rock deposits are formed and how dead animals get in themHelp us understand ancient ecosystemsHelps us understand biases in the fossil recordSome organisms and parts of organisms rarely preserved

www.fossilhut.com

Solnhofen specimen - 60’sBerlin specimen - 1877www.sonoma.edu/users/g/geist/bio.html

www.cmnh.org

paleo.cc/paluxy/livptero.htm

Pterodactylus kochi

leute.server.de/frankmuster/P/Pterodactylus.htm

www.hayashibara.co.jp/html/shinka/

Ichthyosaur from Holzmaden

www.urweltmuseum.de/Englisch/shop_eng/fossilienverkauf_eng.htm

www.johnsibbick.com/prehist-pages/pre-p-20.asp

www.breckminerals.com

Brief history of bird origins debate

Archae has teeth, hand claws, and a bony tail like dinos; but feathers like birds

1926 Heilmann decides birds did not descend from dinos because dinos lack wishbones (since found)

1964 Deinonychus discovered

1972 Walker suggests birds descended from an ancestral crocodilian

www.dinosoria.com

Deinonychus

www.amherst.edu/~pratt

Connecticut Valley dinosaur tracks described by Edward Hitchcock 1836 - 1858

Ichnology: study of trace fossils

1856 - Joseph Leidy publishes first description of North American dinosaur

fossils

Hadrosaur “duckbill”

www.dinosaursinart.com

Stegosaurus stenops

Stegosaurus ungulatus

www.dinosaursinart.com

Allosaurus fragilis

1878 - Iguanodon mass grave found in Belgium

http://digitalidesigns.net/

Brontosaurus, now called Apatosaurus

Ornithischia - “bird-hipped”

Saurischia - “lizard-hipped”

1889 - 1892 Hatcher finds 32 ceratopsians

www.geo.uw.edu.pl

www.amnh.org

Torosaurus Pentaceratops

www.peabody.yale.edu

http://homepage.mac.com

Western Diamondback Rattlesnake

Komodo Dragon

Pangolin

Rhinoceros skin

www.petinfo4u.com

Ceratosaurus - first (1884) really good carnivore skeleton

Charles Knight - the first great dinosaur illustrator

1902, 08 - Tyrannosaurus rex found at Hell Creek, Montana

by Barnum Brown

1910 - new kinds of hadrosaurs

Roy Chapman Andrews - the real Indiana Jones

Franz Nopcsa

Portions of the 1947 Zallinger

mural at Peabody

Museum, 110 ft wide by 16 ft

high

Two kinds of fossils:

Body fossils: preserved body parts such as bones, shells, eggs, skin impressions

Trace fossils: preserved marks on the planet left by activity of ancient organisms such as footprints, nests, toothmarks, coprolites, fossil regurgitates. Trace fossils are especially important because they tell us about behavior!

How to fossilize a bone:

Death followed by burial

Permineralization – pore spaces in the bone are filled with minerals precipitated from groundwater

Replacement –original material is replaced by other minerals. Rare in bones, common in wood. Complete permineralization and replacement = petrification.

10,000 years minimum fossilization time

www.mackenzieltd.com

Sedimentary rocks

Igneous rockswww.neldamsbakery.com

Sedimentary Sedimentary Rocks Record Rocks Record EnvironmentEnvironment

A = Sandstone (beach environment)B = Shale (shallow marine environment)

C = Limestone (deeper marine environment)

Sedimentary rocks – accumulations of fragments of pre-existing rocks lithify OR minerals precipitate from aqueous solution

Marine transgression – sea level rises

Stratigraphic column resulting from a

marine transgression

Stratigraphic column resulting from a

marine regression

sandstone

silty shale

limey shale

limestone

silty shale

limestone

sandstone

limey shale

Sedimentary Rocks Record Environment

Sediments come from eroding mountains

Sediments sort by weight, so sand deposited at beaches, nearshore: makes sandstone

Mud / clay deposited offshore: makes shale (too fine-grained to see individual grains)

Calcite precipitated by marine organisms. Deposited in deeper waters where influx of terrestrial material is low: makes limestone

Sedimentary Rocks Record Environment

Sandstone and shale can also be formed from desert dunes, lake, river and floodplain, and delta deposits

Most dinosaurs found in river, especially floodplain deposits

A distinctive set of strata is called a formation

www.oceansofkansas.com

Western Interior Seaway – 80 Ma

www.wvup.edu/ecrisp/fieldstudiesinutah.html

Morrison Formation

rainbow.ldeo.columbia.eduGondwana

Laurasia

Morrison Formation

Late Jurassic, 154-145 MaCovers 1.5 million km2 western NA – outcrops in 13 states and 2 provinces of CaSeasonally dry, especially in the south. Wetter and swampy (coal beds) in the north All kinds of plants and animals – conifers, ginkos, cycads, horsetails, frogs, fish, salamanders, pteros, mammals, dinos, probably mostly from riparian areas. Perennial water sources even in arid areas.

www.colostate.edu

www.rainbow.ldeo.columbia.edu

http://en.wikipedia.org

www.neiu.edu/~awroblew/

Hell Creek Formation

Hell Creek Formation

Latest Cretaceous, 67-65 MaMontana, N and S Dakota, WyomingK-T boundary, “fern spike”Rockies rising to west, huge amounts of sediment being shed into WIS, forming all kinds of great deposits – estuaries, tidal inlets, tidally-influenced fluvial channels, fluvial channels, alluvial plains, lacustrine basins, and coal swamps. Probably all related to a huge delta a la the Mississippi

So how do I find a dinosaur?

Get a geologic maps

Colors represent a combination of age and type of rock exposed at surface

Find an outcrop on non-marine, Mesozoic sedimentary rocks, go there

Geologic Map of Arizona

Clades: how we think about relatedness in this class

Derived character: a feature of an organism that has changed from the ancestral condition. “Evolutionary novelties”

Primitive character: a feature of an organism that has not changed from the ancestral condition

Clade: a group of organisms that share derived characters

A clade is a group of organisms that are more closely related to each other than they are to any other organisms

Dinosaur

“A reptile-like or bird-like animal with an upright posture that spent its life on land”

Evolutionary novelties (shared derived characters): advanced mesotarsal ankle, femur with ball, pelvis with hole for femur ball. Allowed upright posture with legs under the body, not sprawled to side. This allowed high levels of activity!

Three of more pelvic (sacral) vertebrae

Phylogenetic tree = family treeOlder

Younger--

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-Tim

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