Georges Cuvier Charles Lyell To study evolution means to dig in the past The science of past organims is paleontology greek palaews old logos science Paleontology deal with fossils lat fodere to dig ID: 911621
Download Presentation The PPT/PDF document "2. The discovery of the past" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
2. The discovery of the past
Georges Cuvier
Charles Lyell
To study evolution means to dig in the past.
The science of past organims is paleontology (greek:
palaews: old, logos: science)Paleontology deal with fossils (lat. fodere = to dig)
Early paleontology mainly described ancient life within the Linnean frameworkModern paleontology tries to reconstruct ancient life. It links therefore ecology and taxonomy.
Mary Anning (1799-1847)
Richard Owen (1804-1892)
Slide2How do animals fossilize?
Taphonomy (Greek:
tafos: burial; nomos: law)
Living organism
Death
Remains
Exposed remains
Buried remains
Stratinomy
Decomposition
Decay
Bleaching
Delayed burial
Immediate burial
Ginkgo biloba
Ginkgo adiantoides
Much less than 1% of all organisms fossilize
Coral fish
Coral fish from Jura
Fossil
Mineralization
Bioerosion
Slide3A fossil forest in Dorset, England formed by fossilized bacteria around old tree stumps.
Fossilized Cyanobacteria (stromatolit
e
s) from South Africa
A mammoth coprolith (fossilized excrements)
A fossilized dinosaur footprint from New Mexico
Slide4From B. Ziegler: Allgemeine Paläontologie. Thieme, 1975.
Immediate and delayed buriages
Slide5Hard body materials
Soft body materials
What fossilizes?
Substance Examples
Calcite (CaCO3) Octocorallia Bryozoa Brachiopoda Polychaeta
Ammonita Belemnita EchinodermataAragonite (CaCO3) Hydrozoa GastropodaCalciumphosphate Vertebrata (Ca5(OH)(PO4
)3) Trilobita CrustaceaOpal (SiO2.H2O) Radiolaria Diatomea Porifera
Chitin Algae Fungi Arthropoda Cnidaria Priapulida Annelida
Cellulose Plantae Tunicata
Soft tissues very seldom fossilizeExceptions areFast drying out in very arid climates
Permanent
f
rozen
Preservation in amber or asphalt
A feathered Dinosaur:
Sinosauro-pteryx
Slide6Vertebrata
Echinodermata
Tentaculata
Arthropoda
Cnidaria
Porifera
BranchiotremataAnnelida
Flagellata
Ciliata
Cephalochordata
Echiurida
Tunicata
Chaetognatha
Plathelminthes
Pentastomida
Nematoda
Tardigrada
Onychophora
Pogonophora
Sipunculida
Rhizopoda
Ctenophora
Mesozoa
Sporozoa
Without hard skeleton
With hard skeleton
Hard skeleton infrequent
Fossils
Fossils
Unknown
Unknown
Rare
Rare
Unknown
Unknown
Rare
Unknown
Rare
Unknown
Rare
Unknown
Unknown
Unknown
Often
Often
Often
Often
Often
Often
Some taxa often
Some taxa often
Some taxa often
Some taxa often
Often
Mollusca
Often
How complete is the fossil record?
Slide7Under what conditions do organisms fossilize?
Volcanic ashes
Anaerobic conditions
(moorlands)
River sediments
Moisture gradient
Nutrient rich soils
Probability of fossilization
Salinity gradient
Slide8How complete is the fossil record?
Neogene Iberian mammals
The completeness of the fossil record P
T can be calculated from the probability R that a fossil species is preserved at least in one geological layer:
Species level: 77%
Genus level: 91%
SCI: Quotient of consistent to inconsistent nodesRCI: Relative completeness index
GAP: Gap excess index
Divergence time inferred from cladogram
Divergence time inferred from fossils
Benton MJ, Willis MJ, & Hitchin R. 2000. Quality of the fossil record through time. Nature 403: 534-537.
Alba DM, Jordi A, Moya-Sola S. 2001. Completeness of mammalian fossil record in the Iberian neogene. Palaeobiology 27: 79-83
Slide9Continental drift
Alfred Lothar Wegener (1880-1930)
The tectonic plates
(from David Sanfwell, Scripps Inst. Oceanography)
Evidence for plate tectonics:Fit of coastlinesDistribution of mountainsContinuity of fossils
Continuity of geological featuresIsostasy: Earth acts like a fluid
From Press et al.. 2004. Understanding earth, http://www.whfreeman.com/presssiever/con_index.htm?99iex
Slide10From
C. R. Scotese
:
http://www.scotese.com/future.htm
Continental drift
Slide11How to match phylogeny and plate tectonics
Slide12Relative dating methods
Relative dating uses geological strata to infer whether fossils are older or younger than a given
stratum
Layer 1
Layer 2
Layer 2
Time
Older
Younger
Stratigraphy
Morphological primitivism
Fossil dating
Slide13Absolute dating methods
Radiometric dating
Most minerals which contain radioactive isotopes are in igneous rocks.
The dates they give indicate the time the magma cooled.
Potassium 40 is found in:
potassium feldspar (orthoclase) muscovite amphibole glauconite Volcanic rocks Sometimes in sediments
Uranium may be found in: zircon urananite monazite apatite sphene Volcanic rocks
Carbon 14 is used for bones
Slide14How to use radiometric dating?
The Rb/Sr System
b
-decay
= 1.42 x 10
-11
a
-1, t1/2 = 4.8 x 1010
a
P
t
: Amount of daughter atoms through decay
Total
Original
Decay
86
Sr is an isotope that is
not radioactive
not radiogen
Slide15Modified from Andy MacRae: Radiometric Dating and the Geological Time Scale. http://www.talkorigins.org/faqs/dating.html
Raw data
Recognition of unique events to subdivide time
Radiomtric dating of layers
Calibrating geological
time
Stratigraphy
Relative time scale
Absolute time scale
Geological
time scale
Radiometric dating
Slide16Fission track
Dendrochronology
Fission Tracks (FT) are micrometer-sized, linear damage tracks that occur in insulating minerals and that are caused by the spontaneous fission of heavy, unstable nuclides (mostly 238U in natural minerals).
Dendrochronology analyses tree-ring growth patterns.
Slide17History of the earth
Nicolas Steno (1638-1686)
Steno founded
stratigraphy
by stating thatgeological layers are horizontal and superposed.
Deeper layers are older.The Red Rock Canyon, California
Slide18The geological time scale
Eon
Era
Period
Age at Base (Mya)
Duration (Mya)
Phanerozoic
Cenozoic
Quaternary
1.6
1.6
Tertiary
65
63.4
Mesozoic
Cretaceous
140
75
Jurassic
205
65
Triassic
250
45
Paleozoic
Permian
290
40
Carboniferous
355
65
Devonian
410
55
Silurian
440
30
Ordovician
510
70
Cambrian
540
30
Proterozoic
Neoproterozoic
Ediacaran (Vendian)
630
90
Cryogenian
850
220
Tonian
1000
150
Mesoproterozoic
1600
600
Palaeproterozoic
2500
900
Archean
3800
2950
Hadean
4550
750
Slide19History of palaeontology: http://en.wikipedia.org/wiki/History_of_paleontology
History of earth: http://wiki.cotch.net/index.php/History_of_the_EarthRadiometric dating details: http://www.tulane.edu/~sanelson/eens211/radiometric_dating.htm
Geological time scale: http://en.wikipedia.org/wiki/Geologic_time_scale
Today’s reading