1 / 25

Applications of the palaeontology: - study of the evolution - interpretation of spatial distribution of ancient organis

Applications of the palaeontology: - study of the evolution - interpretation of spatial distribution of ancient organisms (palaeobiogeography datation of the rocks (biostratigraphy) interpretation of ancient environments (palaeoecology) reconstruction of palaeoclimates.

laken
Télécharger la présentation

Applications of the palaeontology: - study of the evolution - interpretation of spatial distribution of ancient organis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Applicationsof the palaeontology: • - study of the evolution • - interpretation of spatial distribution of ancient organisms • (palaeobiogeography • datation of the rocks (biostratigraphy) • interpretation of ancient environments (palaeoecology) • reconstruction of palaeoclimates. • Most of these applications need other disciplines: geology, • sedimentology, geomorphology, geochemistry, astronomy, • magnetostratigraphy, archaeology, etc.

  2. Fossilisation is a transfer of material from the biosphere to the lithosphere. In long term, weathering of rocks may return this material to the biosphere. Events of the fossilisation: death before and after burial.

  3. Palaeontology and Earth history – evolution

  4. C B A Time

  5. Palaeontology and palaeobiogeography Mesosaurus

  6. NEW ZEALAND MOA KIWI TUATARA

  7. Palaeontology and Biostratigraphy a Several fossils indicate relative ages. Trilobites (a) are Palaeozoic in age. Nummulites (b) are Eocenic in age. Ichthyosaurs (c) belong to the Jurassic and Cretaceous. b 0.5 cm 1 cm c 20 cm

  8. Geological Time Line

  9. CORES Marine sediments Palaeontology provides biostratigraphic, palaeoenvironmental and palaeoclimatic data. In particular, microfossils are very useful for isotopic analyses (O18/016) on their skeletal parts. Diatoms Coccolithophores Foraminifers

  10. Palaeontology can help magnetostratigraphy and vice versa. Magnetostratigraphy summarizes the variations of the polarity of the magnetic field of the Earth. Thus, from the recent to the past, several chrons with different polarity (normal and reversed) have been recognized. Each chron can be controlled by biostratigraphy and radiometric datings.

  11. Palaeontology and (Palaeo)ecology a Most fossils are good environmental markers. Rudists (a) are reef-builders in ancient tropical seas. Agrichnia (b) fossil traces indicate marine deep-water bottoms. Some gastropods (c) are typical of lagoons. c b

  12. LIVING FOSSILS Lake sturgeon Ginko biloba Limulus

  13. Palaeontology needs the knowledge of the present-time environment and organisms in order to transfer these data in the past.

  14. Palaeontology highlights the morphological analogies of the organisms that live in similar environments in order to interpret the palaeoenvironments.

  15. Pollution markers?

  16. Palaeontology and (Palaeo)climate a Some fossils indicate well defined climatic conditions. Wooly mammoths (a) and penguins (b) are Typical of cold conditions. Organic builders corals (c) indicate warm conditions. After Roberts (1998) b 1 cm c

  17. 18O/16O Emiliani (1955) Foraminifers are single-celled mostly marine organisms. Those with calcareous (CaCO3) shell provide good material for oxygen isotopes analyses. 18O/16O shell === 18O/16O water 18O ► heavier isotope 16O ► lighter isotope

  18. Interglacial phase Decrease ice volume Increase of m.s.l. No variations of 18O/16O in sea-water and shells Glacial phase Increase ice volume Decrease of m.s.l. increase 18O content in sea-water and shells

  19. Milankovitch’s theory Orbital variations produce climatic changes. Actually, the variations of positions of the Earth with respect to Sun determine climatic changes. Precession of polar axis 23,000yrs Axial tilt (obliquity) 41,000yrs Eccentricity of Earth orbit 100,000-400,000yrs This produces variations of solar radiations in different seasons and latitudes.

  20. Scenario 1 – sea ingression Marine biotopes increase producing the development of marine life. Terrestrial biotopes decrease. Terrestrial life declines. Scenario 2 – sea regression Terrestrial biotopes increase. Terrestrial life develops. Marine biotopes decrease. Marine life declines.

  21. Marine terraces

  22. Fossils give a relative chronology, that can helped by radiometric datings. These datings can give a numeric age to the stratigraphic units. The chemical properties of an element are related to the number of protons of the nucleus of the atom. The atomic weight of the element is related to the neutrons number. Thus, the same element can present atoms with different atomic weight (isotopes). These isotopes can stable or unstables. The latter produce alpha particles (2 neutrons + 2 protons) and emit/capture electrons, originating stable isotopes of other elements. The process of radioactive decay of a progenitor radionuclide to a descending nuclide (descending daugther) occurs trough a half-life typical of each isotope. t = 1/ λ loge (D/P + 1) Knowing the initial ratio between parent (P) and daughter (D), it is possible to determine their ratio in the sample. Thus, on the basis of the half-life and the decay constant (λ) it is possible to obtain the radiometric age of the sample. )

  23. Pollens and spores Changes of floral scenarios RISOLUZIONE: 50 anni TIME RANGE: milioni di anni Dendrochronology Thickness of the rings RISOLUZIONE: stagionale TIME RANGE: 500-770 anni BP

More Related