UNIVERSITY OF CALGARY  SPRING 2010 GLGY 209-20  INTRODUCTION TO GEOLOGY I
GEOLOGIC  TIME  SCALE <ul><li>There are four eons: </li></ul><ul><li>PHANEROZOIC  (visible life forms); </li></ul><ul><li>...
Evaluation of the Geological Time <ul><li>Studying the Biblical chronology, the Irish Bishop  James Ussher   concluded in ...
Radioactive Decay <ul><li>Some of the isotopes are stable, other not. </li></ul><ul><li>An unstable isotope nucleus can be...
Radioactive Decay Series Radioactive decay series between Uranium 238 and Lead 206. There are eight alpha and six beta dec...
Half-Life <ul><li>The half-life of a radioactive element represents the time it takes for one half of the atoms of the ori...
Half-Life principle
Half-time Resolution
GEOLOGIC  TIME  SCALE
Explaining the fossil record. Theory of evolution
Living World Hierarchy <ul><li>Karl Linnaeus yielded the first hierarchy of the living world. </li></ul><ul><li>In the 7 t...
Hierarchy as Proposed by Linnaeus <ul><li>Linnaeus belief: “…  if God created the World it is possible to understand God’s...
Grouping Animals by Similarity
Species Names _ Binominal <ul><li>Linnaeus established the first system of species naming, which is defined as binominal: ...
Linnaeus Change of Opinions <ul><li>Linnaeus abandoned his principle of the unchangeable species. He brought the argument ...
Cuvier’s Catastrophism <ul><li>Baron Georges Leopold Cuvier (1769-1832) is often remembered for the establishment of the  ...
Cuvier’s Data & Interpretations <ul><li>Cuvier discovered remains of quadrupeds to species now living in the Quaternary se...
Jean-Baptiste Lamarck  (1744-1829)  <ul><li>In 1861 Darwin wrote about Lamarck:  </li></ul><ul><ul><li>“ Lamarck was the f...
Intraspecific Variability <ul><li>J.-B. Lamarck  had to face a formidable challenge by studying invertebrate fossils: the ...
It Started with a Voyage <ul><li>Charles Darwin was a young naturalist at the board of H.M.S. Beagle in a five year voyage...
First Hand Biological Data <ul><li>Darwin made systematical observations on the Galapagos Island finches noting that “… on...
First Hand Geological Interpretations <ul><li>Darwin made quite accurate interpretations about the atol formation. </li></ul>
A New Definition for Evolution <ul><li>Evolution can be shortly described as “ descent with modification ”. </li></ul>
The First Release <ul><li>The most important work of Darwin has been published in 1859. </li></ul><ul><li>Four editions ha...
Alfred R. Wallace <ul><li>Wallace is nowadays regarded as a coauthor of the evolutionary theory.  </li></ul><ul><li>In 185...
EMERGENCE OF LIFE ON EARTH
CHON <ul><li>The dominant elements in the life forms today are: </li></ul><ul><ul><li>Carbon; </li></ul></ul><ul><ul><li>H...
Earth’s early atmosphere <ul><li>Alexandr Ivanovic Oparin (1896-1980) postulated that it is possible that CHON molecules c...
<ul><li>Oparin model was one in which the Earth’s original atmosphere was a reducing one, without much free molecular oxyg...
Isua Supercrustal Group <ul><li>The Greenland Isua Supercrustal Group contains some of the oldest sedimentary rocks on Ear...
Experimental confirmation <ul><li>Miller and Urey experiment (1953) demonstrated the possibility that simple elements can ...
Miller and Urey experiment <ul><li>They started their experiment considering that all the gases in the Earth’s primordial ...
Polymerization <ul><li>Monomers were not enough. </li></ul><ul><li>Examination of the simplest life forms on the modern Ea...
Polymerization
Polymerization <ul><li>Combining the simple CHON molecules into larger molecules would result in the formation of polymers...
Metabolism <ul><li>Simple “alive” organisms existed before they were packed into cells, which are extremely complex struct...
Metabolism
Other kinds of metabolism <ul><li>Aerobic photoautotrophy  (oxygenic photosynthesis) – higher algae and plants; huge amoun...
Hadean times conditions <ul><li>Craters at the surface of the Moon, Mercury, Venus, demonstrate the existence of a severe ...
Hadean times conditions <ul><li>The early oceans at the Earth’s surface were probably boiled repeatedly during the primord...
Nature of data <ul><li>Data from fossils. </li></ul><ul><li>Data from mineralogical composition of the rocks. </li></ul><u...
The oldest life forms
Stromatolites - generalities <ul><li>The first stromatolites were discovered in the New York State, in the surroundings of...
Organic nature of the stromatolites <ul><li>The organic nature of the stromatolites was demonstrated long time after based...
Schreiber Beach  Cryptozoon
The first Precambrian fossils Eosphaera
The living stromatolites <ul><li>Living stromatolites were discovered in a salty lagoon of western Australia – the Shark B...
Fossil & living stromatolites <ul><li>A stromatolite is best studied in polished sections. </li></ul>
Stromatolite morphology
Stromatolite characteristics <ul><li>Accretionary organo-sedimentary structures; </li></ul><ul><li>Thinly layered, megasco...
Stromatolite persistence
Stromatolite fossil record <ul><li>Fig Tree Formation of South Africa 3.1 to 3.5 billion years old. </li></ul><ul><li>Just...
Stromatolite evolution <ul><li>Stromatolites occurred in the Archean times. At the beginning of their evolution the distri...
Stromatolite evolution <ul><li>Stromatolites represent the living witness of the evolution’s evolution. </li></ul><ul><li>...
Isolated cells <ul><li>Early Archean of western Australia (Pilbara Craton). </li></ul><ul><li>Apex Chert is a lithological...
Apex Chert cyanobacteria <ul><li>Some of the cells from the Apex Chert show folded filament with cell-like structures made...
Strelley Pool Chert cyanobacteria <ul><li>The chain-like structure is similar to that of the modern purple bacteria. </li>...
Earth’s rusting <ul><li>Approximately 2.0  billion years ago a major phenomenon happened on Earth. </li></ul><ul><li>Oxide...
Prokaryote diversification <ul><li>The first Precambrian fossils were discovered in the Gunflint Formation of southern Ont...
 
Prokaryote <ul><li>Eukaryote cells are much more complex than the prokaryotes.  </li></ul>
First eukaryotes <ul><li>The first eukaryotes were discovered in the Bitter Springs Formation of Australia. </li></ul><ul>...
Eukaryotes - examples <ul><li>Bangiomorpha </li></ul><ul><li>Filamentous thallus, similar to those of the modern red algae...
Eukaryotes - examples <ul><li>Torridonophycus </li></ul><ul><li>Algal microstructures escaping from a bag-like structure (...
Eukaryotes - examples <ul><li>Melanocyrillium </li></ul><ul><li>Shows similarities with the modern group of testate amoeba...
Kingdoms  <ul><li>Bacteria  (Prokaryotae, Procaryotae, Monera); prokaryotic cells (lacking a nucleus and nuclear membrane)...
Ediacara Hills (southern Australia).
Precambrian Time Scale
Ediacara Animals <ul><li>Animals imprints from Ediacara Hills are all metazoans. They document the transition from the uni...
Ediacara dominant fossils <ul><li>Parvancorina </li></ul><ul><li>Size: 1-2.5 cm; </li></ul><ul><li>Shield-shaped front end...
Ediacara dominant fossils <ul><li>Tribrachidium </li></ul><ul><li>Unknown affinities; </li></ul><ul><li>2-5 cm; </li></ul>...
Ediacara dominant fossils <ul><li>Dickinsonia </li></ul><ul><li>1-100 cm; </li></ul><ul><li>Segmented, head, tail (segment...
Ediacara dominant fossils <ul><li>Charnia </li></ul><ul><li>0.15-2 m; </li></ul><ul><li>Strong similarities with the moder...
Ediacaran Animals Today? Living sea-pens from offshore NW Australia.
Ediacara  dominant  fossils
Spriggina  Case <ul><li>A worm-like animal of the Ediacara fauna presents an extraordinary feature. </li></ul><ul><li>In t...
Spriggina  Case <ul><li>Approximately 3 cm long. Australia, then Russia. </li></ul>
Controversial Way of Life <ul><li>Seilacher & McMenamin suggested that the animals of Ediacara all lived in symbiotic rela...
Vendoza Controversy <ul><li>Seilacher & McMenamin emphasized the dissimilarities between Ediacara-type and modern organism...
Ediacara Fauna Extinction <ul><li>Ediacara fauna appeared approximately 630 M.y. ago and developed for about 50 M.y. </li>...
Interpretation dynamics
Aspidella  case <ul><li>0.1-5 cm; </li></ul><ul><li>Canada, 1872; </li></ul><ul><li>Originally was considered a pseudofoss...
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209 20 12

  1. 1. UNIVERSITY OF CALGARY SPRING 2010 GLGY 209-20 INTRODUCTION TO GEOLOGY I
  2. 2. GEOLOGIC TIME SCALE <ul><li>There are four eons: </li></ul><ul><li>PHANEROZOIC (visible life forms); </li></ul><ul><li>PROTEROZIC (early life forms); </li></ul><ul><li>ARCHEAN (oldest rocks); </li></ul><ul><li>HADEAN (no rock record). </li></ul>
  3. 3. Evaluation of the Geological Time <ul><li>Studying the Biblical chronology, the Irish Bishop James Ussher concluded in 1654 that the Earth has been created in the year 4,004 BC. </li></ul><ul><li>Georges Louis Leclerc, Comte De Buffon estimated the age of the Earth at about 75,000 years. His major work, Les Epoques de la Nature has been published in 1778. </li></ul>
  4. 4. Radioactive Decay <ul><li>Some of the isotopes are stable, other not. </li></ul><ul><li>An unstable isotope nucleus can be transformed spontaneously into an isotope with a stable nucleus configuration. </li></ul><ul><li>This process is known as radioactive decay . </li></ul>
  5. 5. Radioactive Decay Series Radioactive decay series between Uranium 238 and Lead 206. There are eight alpha and six beta decay steps.
  6. 6. Half-Life <ul><li>The half-life of a radioactive element represents the time it takes for one half of the atoms of the original unstable parent element to decay to atoms of a new and more stable daughter element . </li></ul>
  7. 7. Half-Life principle
  8. 8. Half-time Resolution
  9. 9. GEOLOGIC TIME SCALE
  10. 10. Explaining the fossil record. Theory of evolution
  11. 11. Living World Hierarchy <ul><li>Karl Linnaeus yielded the first hierarchy of the living world. </li></ul><ul><li>In the 7 th edition of his book ‘ Systema Naturae ’ (Lat.: Systema Naturae: Creationis telluris est gloria Dei ex opere Naturae per Hominem solum ) Linnaeus postulated that species are real & unchangeable entities . </li></ul>
  12. 12. Hierarchy as Proposed by Linnaeus <ul><li>Linnaeus belief: “… if God created the World it is possible to understand God’s wisdom by studying his creation .” </li></ul><ul><li>His best known student Daniel Solander was Captain James Cook’s naturalist in his voyages around the world. </li></ul><ul><li>Kingdom > Class > Order > Genus > Species </li></ul>
  13. 13. Grouping Animals by Similarity
  14. 14. Species Names _ Binominal <ul><li>Linnaeus established the first system of species naming, which is defined as binominal: </li></ul><ul><ul><li>Name of the Genus + Name of the Species </li></ul></ul>
  15. 15. Linnaeus Change of Opinions <ul><li>Linnaeus abandoned his principle of the unchangeable species. He brought the argument of the plant hybridization. </li></ul><ul><li>The process of creating new species was not regarded as open-ended. He believed that all the new occurred species came from the primae species , namely those from the Garden of Eden. </li></ul>
  16. 16. Cuvier’s Catastrophism <ul><li>Baron Georges Leopold Cuvier (1769-1832) is often remembered for the establishment of the comparative anatomy and vertebrate paleontology as sciences. </li></ul>Vertical section of the cavern at Gaylenreuth in Franconia, from George Cuvier's Essay on the Theory of the Earth.
  17. 17. Cuvier’s Data & Interpretations <ul><li>Cuvier discovered remains of quadrupeds to species now living in the Quaternary sediments of the Paris Basin. </li></ul><ul><ul><li>At lower levels are present extinct species of elephant , hippopotamus , rhinoceros or mastodon or close relatives of those genera . </li></ul></ul><ul><ul><li>Still lower in the stratigraphic column, the bone debris belongs to the extant mammal genera and they are quite rare at the base of the Tertiary deposits. </li></ul></ul><ul><ul><li>Cuvier concluded that during the history whole populations of quadrupeds have been exterminated. </li></ul></ul><ul><li>He also observed that the strata with terrestrial mammal bones are sandwiched between strata bearing typical marine fossils. </li></ul><ul><li>Therefore, recurrent flooding by the sea must have been an agency involved in the successive extinction. </li></ul>
  18. 18. Jean-Baptiste Lamarck (1744-1829) <ul><li>In 1861 Darwin wrote about Lamarck: </li></ul><ul><ul><li>“ Lamarck was the first man whose conclusions on the subject excited much attention. This justly celebrated naturalist first published his views in 1801. . . he first did the eminent service of arousing attention to the probability of all changes in the organic, as well as in the inorganic world, being the result of law, and not of miraculous interposition”. </li></ul></ul>
  19. 19. Intraspecific Variability <ul><li>J.-B. Lamarck had to face a formidable challenge by studying invertebrate fossils: the large number of specimens of the same species. </li></ul><ul><li>Practically, he had to explain and to transform in systematic language the morphologic variability of various species. </li></ul>
  20. 20. It Started with a Voyage <ul><li>Charles Darwin was a young naturalist at the board of H.M.S. Beagle in a five year voyage around the world. </li></ul><ul><li>His extensive observations on the South American mammal faunas as well as from the faunas of the Pacific Islands (distribution of living species on isolated islands) could be best observed by the heretical idea of transmutation . </li></ul>
  21. 21. First Hand Biological Data <ul><li>Darwin made systematical observations on the Galapagos Island finches noting that “… one might really fancy that …one species had been taken and modified for different ends ”. </li></ul>
  22. 22. First Hand Geological Interpretations <ul><li>Darwin made quite accurate interpretations about the atol formation. </li></ul>
  23. 23. A New Definition for Evolution <ul><li>Evolution can be shortly described as “ descent with modification ”. </li></ul>
  24. 24. The First Release <ul><li>The most important work of Darwin has been published in 1859. </li></ul><ul><li>Four editions have been published during his lifetime. </li></ul>
  25. 25. Alfred R. Wallace <ul><li>Wallace is nowadays regarded as a coauthor of the evolutionary theory. </li></ul><ul><li>In 1855 he published an article about the evolution of species from one another. </li></ul><ul><li>He lacked Darwin’s strong arguments. </li></ul>
  26. 26. EMERGENCE OF LIFE ON EARTH
  27. 27. CHON <ul><li>The dominant elements in the life forms today are: </li></ul><ul><ul><li>Carbon; </li></ul></ul><ul><ul><li>Hydrogen; </li></ul></ul><ul><ul><li>Oxygen; </li></ul></ul><ul><ul><li>Nitrogen. </li></ul></ul><ul><li>Sulfur and phosphorus are present in smaller amounts. </li></ul>
  28. 28. Earth’s early atmosphere <ul><li>Alexandr Ivanovic Oparin (1896-1980) postulated that it is possible that CHON molecules could have been formed before life begun to give rise to the first cells. </li></ul><ul><li>A starting point of Oparin’s model was the fact that the plant cells are too complex to have been formed without a long process of inorganic evolution. </li></ul>
  29. 29. <ul><li>Oparin model was one in which the Earth’s original atmosphere was a reducing one, without much free molecular oxygen. </li></ul><ul><li>CHON molecules could be accumulated in a reducing atmosphere. </li></ul><ul><li>“Primordial soup” was not alive! </li></ul>Earth’s early atmosphere
  30. 30. Isua Supercrustal Group <ul><li>The Greenland Isua Supercrustal Group contains some of the oldest sedimentary rocks on Earth (3.8 – 3.7 billion years). </li></ul><ul><li>Rare oxides and carbonates, which do not form layers! </li></ul><ul><li>Graphite levels indicate organic origin. </li></ul>
  31. 31. Experimental confirmation <ul><li>Miller and Urey experiment (1953) demonstrated the possibility that simple elements can react chemically to form simple organic CHON molecules. </li></ul><ul><li>They obtained seven aminoacids (e.g., glycine, alanine, etc) – organic compounds . </li></ul>
  32. 32. Miller and Urey experiment <ul><li>They started their experiment considering that all the gases in the Earth’s primordial atmosphere were hydrogenated: H 2 , CH 4 , NH 3 , H 2 O vapors. </li></ul><ul><li>Energy was produced by lightning and ultraviolet radiation. </li></ul>
  33. 33. Polymerization <ul><li>Monomers were not enough. </li></ul><ul><li>Examination of the simplest life forms on the modern Earth, mycoplasmas, present a part of DNA and several hundreds of complex molecules. Mycoplasmas are parasitic. </li></ul><ul><li>An ordinary bacterium has thousand of complex molecules, including approximately 500 kinds of RNA. </li></ul>
  34. 34. Polymerization
  35. 35. Polymerization <ul><li>Combining the simple CHON molecules into larger molecules would result in the formation of polymers, a necessary step in the development of the life forms on Earth. </li></ul><ul><li>Example: Cellulose (carbohydrate polymer) is formed by repeating the glucose monomeric unit (C 6 H 12 O 6 ). </li></ul><ul><li>MOLECULES DO NOT FOSSILIZE. </li></ul>
  36. 36. Metabolism <ul><li>Simple “alive” organisms existed before they were packed into cells, which are extremely complex structures. </li></ul><ul><li>The metabolism of the primordial organisms was probably very simple: fermentation (more energy is required than it is produced) or anoxygenic photosynthesis (copious amount of glucose are produced but the process depends of the hydrogen sources, which are available only locally). </li></ul>
  37. 37. Metabolism
  38. 38. Other kinds of metabolism <ul><li>Aerobic photoautotrophy (oxygenic photosynthesis) – higher algae and plants; huge amounts of hydrogen are produced. </li></ul><ul><li>Aerobic heterotrophy (respiration) – characteristic to the animals (much more energy is consumed than produced. </li></ul>
  39. 39. Hadean times conditions <ul><li>Craters at the surface of the Moon, Mercury, Venus, demonstrate the existence of a severe meteoritic bombardment in the early history of the Earth. </li></ul>
  40. 40. Hadean times conditions <ul><li>The early oceans at the Earth’s surface were probably boiled repeatedly during the primordial meteorite bombardment. </li></ul><ul><li>The craters on the terrestrial planets can be used for stratigraphy purposes. </li></ul>
  41. 41. Nature of data <ul><li>Data from fossils. </li></ul><ul><li>Data from mineralogical composition of the rocks. </li></ul><ul><li>Chemical fossils as results of the organic activity. </li></ul>
  42. 42. The oldest life forms
  43. 43. Stromatolites - generalities <ul><li>The first stromatolites were discovered in the New York State, in the surroundings of Saratoga, in the early 1880s. </li></ul><ul><li>The name of stromatolites was given long after. </li></ul><ul><li>Originally they were named Cryptozoon . </li></ul>
  44. 44. Organic nature of the stromatolites <ul><li>The organic nature of the stromatolites was demonstrated long time after based on the discoveries from southern Ontario. </li></ul><ul><li>Cryptozoon structures were discovered in a point known as Schreiber Beach by Stanley A. Tyler (University of Wisconsin). </li></ul>
  45. 45. Schreiber Beach Cryptozoon
  46. 46. The first Precambrian fossils Eosphaera
  47. 47. The living stromatolites <ul><li>Living stromatolites were discovered in a salty lagoon of western Australia – the Shark Bay. </li></ul>
  48. 48. Fossil & living stromatolites <ul><li>A stromatolite is best studied in polished sections. </li></ul>
  49. 49. Stromatolite morphology
  50. 50. Stromatolite characteristics <ul><li>Accretionary organo-sedimentary structures; </li></ul><ul><li>Thinly layered, megascopic, calcareous; </li></ul><ul><li>Produced by the activity of mat-building communities of mucilage secreting microorganisms; </li></ul><ul><li>Consist mainly of photoautotrophic prokaryotes (e.g., cyanobacteria) </li></ul>
  51. 51. Stromatolite persistence
  52. 52. Stromatolite fossil record <ul><li>Fig Tree Formation of South Africa 3.1 to 3.5 billion years old. </li></ul><ul><li>Just like in the Gunflint Formation of Ontario, the fossils were found in stromatolitic structures. </li></ul>
  53. 53. Stromatolite evolution <ul><li>Stromatolites occurred in the Archean times. At the beginning of their evolution the distribution is patchy. </li></ul><ul><li>They are ubiquitous in the Proterozoic, when the lived in all the environments: streams and rivers, lakes and ponds, seas and oceans. </li></ul><ul><li>Major reduction in frequency at the Precambrian/Cambrian boundary. </li></ul>
  54. 54. Stromatolite evolution <ul><li>Stromatolites represent the living witness of the evolution’s evolution. </li></ul><ul><li>Precambrian times: if not broken, don’t fix it! </li></ul><ul><li>Cambrian to Quaternary: extraordinary diverse morphological changes. </li></ul>
  55. 55. Isolated cells <ul><li>Early Archean of western Australia (Pilbara Craton). </li></ul><ul><li>Apex Chert is a lithological unit in a volcano-sedimentary formation. </li></ul><ul><li>Earliest cyanobacteria debris. </li></ul>
  56. 56. Apex Chert cyanobacteria <ul><li>Some of the cells from the Apex Chert show folded filament with cell-like structures made of carbon. </li></ul><ul><li>Similar to modern iron bacteria. </li></ul>
  57. 57. Strelley Pool Chert cyanobacteria <ul><li>The chain-like structure is similar to that of the modern purple bacteria. </li></ul>
  58. 58. Earth’s rusting <ul><li>Approximately 2.0 billion years ago a major phenomenon happened on Earth. </li></ul><ul><li>Oxides formed in vast amounts (Banded Iron Formation = BIF). </li></ul><ul><li>They document a huge increase in the molecular oxygen in the Earth’s atmosphere. </li></ul>
  59. 59. Prokaryote diversification <ul><li>The first Precambrian fossils were discovered in the Gunflint Formation of southern Ontario. </li></ul><ul><li>Ex: Gunflintia and Huronipora . </li></ul>
  60. 61. Prokaryote <ul><li>Eukaryote cells are much more complex than the prokaryotes. </li></ul>
  61. 62. First eukaryotes <ul><li>The first eukaryotes were discovered in the Bitter Springs Formation of Australia. </li></ul><ul><li>Age: approximately 770 m. y. </li></ul><ul><li>Cell arrangement suggests meiotic cell division. </li></ul><ul><li>Chemical fossils: 1.8 billion years. </li></ul>
  62. 63. Eukaryotes - examples <ul><li>Bangiomorpha </li></ul><ul><li>Filamentous thallus, similar to those of the modern red algae; </li></ul><ul><li>Primitive holdfast attached to the seafloor, allowing the alga to rise upward towards the sunlight. </li></ul><ul><li>Age: ~ 1.2 billion years; </li></ul><ul><li>ST: Proterozoic-Quaternary. </li></ul>
  63. 64. Eukaryotes - examples <ul><li>Torridonophycus </li></ul><ul><li>Algal microstructures escaping from a bag-like structure ( acritarch ), which helped them to survive the dry climate, cold, etc). </li></ul><ul><li>Clorophyte . </li></ul><ul><li>Age: ~ 0.9 billion years. </li></ul><ul><li>ST: Upper Proterozoic-Quaternary. </li></ul>
  64. 65. Eukaryotes - examples <ul><li>Melanocyrillium </li></ul><ul><li>Shows similarities with the modern group of testate amoebas. For this reasons it is included among the earliest animals. </li></ul><ul><li>Organic, sometimes with agglutinated particles. </li></ul><ul><li>Age: ~ 0.8-0.9 billion years. </li></ul><ul><li>ST: Upper Proterozoic-Quaternary. </li></ul>
  65. 66. Kingdoms <ul><li>Bacteria (Prokaryotae, Procaryotae, Monera); prokaryotic cells (lacking a nucleus and nuclear membrane). </li></ul><ul><li>Protoctista (Protista); single eukaryotic cell (with nucleus and nuclear membrane); include foraminifera and radiolaria. </li></ul><ul><li>Animalia (Animals); heterotrophic multicellular eukaryotes (phyla subdivided by cell organization level, symmetry, feeding structures, segmentation, presence of vertebrae or notochord…). </li></ul><ul><li>Plantae (Plants); autotrophic multicellular eukaryotes (algae or aquatic plants and tracheophytes or vascular terrestrial plants). </li></ul><ul><li>Fungi ; (as endoliths in fossil record) heterotrophic eukaryotes with chitinous resistant fungal spores. </li></ul>
  66. 67. Ediacara Hills (southern Australia).
  67. 68. Precambrian Time Scale
  68. 69. Ediacara Animals <ul><li>Animals imprints from Ediacara Hills are all metazoans. They document the transition from the unicellular to multicellular forms of life. </li></ul><ul><li>Ediacaran animals generally present a simple structure, being soft-bodied animals (there is not a trace of skeleton). </li></ul><ul><li>They are worm-like animals (flatworms, segmented worms), coelenterates and some totally unknown types. </li></ul>
  69. 70. Ediacara dominant fossils <ul><li>Parvancorina </li></ul><ul><li>Size: 1-2.5 cm; </li></ul><ul><li>Shield-shaped front end; </li></ul><ul><li>Central axis and weak traces of segmentation; </li></ul><ul><li>Up to 10 pairs of possible appendages with distinct set of growth stages; </li></ul><ul><li>Interesting orientation: head shield(?) facing the direction of water current (feeding strategy?). </li></ul>
  70. 71. Ediacara dominant fossils <ul><li>Tribrachidium </li></ul><ul><li>Unknown affinities; </li></ul><ul><li>2-5 cm; </li></ul><ul><li>Disk-shaped with three raised arms and raised borders; </li></ul><ul><li>Triradial symmetry. </li></ul>
  71. 72. Ediacara dominant fossils <ul><li>Dickinsonia </li></ul><ul><li>1-100 cm; </li></ul><ul><li>Segmented, head, tail (segmented worm?); </li></ul><ul><li>No gut or other internal organs have been found; </li></ul><ul><li>The tail(?) occurs only in the mature specimens. </li></ul>
  72. 73. Ediacara dominant fossils <ul><li>Charnia </li></ul><ul><li>0.15-2 m; </li></ul><ul><li>Strong similarities with the modern sea-pens; </li></ul><ul><li>Bilateral symmetry; </li></ul><ul><li>Feather-shaped frond with a series of side branches. </li></ul>
  73. 74. Ediacaran Animals Today? Living sea-pens from offshore NW Australia.
  74. 75. Ediacara dominant fossils
  75. 76. Spriggina Case <ul><li>A worm-like animal of the Ediacara fauna presents an extraordinary feature. </li></ul><ul><li>In the (probably!) anterior part of its body there is a portion which apparently presents a thickened tissue. </li></ul><ul><li>First evidence of cephalization . See also Parvancorina . </li></ul>
  76. 77. Spriggina Case <ul><li>Approximately 3 cm long. Australia, then Russia. </li></ul>
  77. 78. Controversial Way of Life <ul><li>Seilacher & McMenamin suggested that the animals of Ediacara all lived in symbiotic relationships with algae in their tissues as the modern corals do today. </li></ul><ul><li>Practically the animals of Ediacara-type could get nutrients from the activity of the photosynthetic symbiotic algae. </li></ul>
  78. 79. Vendoza Controversy <ul><li>Seilacher & McMenamin emphasized the dissimilarities between Ediacara-type and modern organisms. </li></ul><ul><li>They also proposed to include the animals of Ediacara into a distinct systematic category: Vendoza . </li></ul><ul><li>The name comes from Vendian , the terminal Neoproterozoic in Russia. </li></ul>
  79. 80. Ediacara Fauna Extinction <ul><li>Ediacara fauna appeared approximately 630 M.y. ago and developed for about 50 M.y. </li></ul><ul><li>It represents the first adaptative radiation of the multicellular organisms. </li></ul><ul><li>Fossil record is patchy. </li></ul><ul><li>Last record : in Ireland some about 510 M.y. </li></ul>
  80. 81. Interpretation dynamics
  81. 82. Aspidella case <ul><li>0.1-5 cm; </li></ul><ul><li>Canada, 1872; </li></ul><ul><li>Originally was considered a pseudofossil; </li></ul><ul><li>Reexamined after the Ediacara discovery; </li></ul><ul><li>Originally classified as jellyfish; </li></ul><ul><li>Anchoring system of Charnia ? </li></ul>

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