CEE 1030 1nd Edition Lecture 24 Fossils Outline of Last Lecture I Weather and climate II Ice Age III Paleoclimatology a Instrumental records b Historical information c Proxy data IV Causes of climate change a Natural causes V Human causes Outline of Current Lecture I Fossil record a Process of fossilization b Preservation potential c Enemies of preservation II Review III Modes of preservation IV Preservation of ecosystems Current Lecture I Fossil record a Remains or traces of once living organisms b Environmental info on habitats in which organisms lived and or died c Ecological info on coexistence and or interactions of species d Process of fossilization i Death ii Burial survive decay and mechanical destruction long enough so some part is buried in sediment iii Diagenesis once buried remains must survive long enough to be found as paleontology many potential fossils are destroyed or altered during lithification metamorphism e Preservation potential i Hard parts vs soft parts soft tissue less likely to be preserved than hard parts These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute II III ii Number of parts organism with more parts is more likely to fall apart iii Population abundance species that was abundant in life is more likely to be preserved iv Depositional environment organism that dies in a place where it is immediately covered by sediment is more likely to be fossilized than an organism that dies in an area of net erosion f Enemies of preservation i Destructive scavenging ii Transport of organism by wind or water iii Slow or delayed deposition of sediment iv Bioturbation organisms burrowing through sediment v Dissolution hard parts such as bones teeth and shells can dissolve from certain pH or chemical factors vi Diagenesis physical and chemical changes during lithification of sediment vii Exposure to be studied a fossil must be found so the rock must be exposed through erosion uplift drilling g Compression fossils i Organism is physically compressed by overlying sediments ii Carbonaceous film preserves outline and surface features iii Reduced to 2D often distorted h Impression fossils i Carbon film in compression fossils is lost only imprint of organism in sediment ii Preservation of morphological detail associated with sediment grain size fine grains have better preservation i Molds and casts i Organism is covered with sediment leaving an impression ii Hard part dissolved away leaving an empty space then mold is filled with sediments or minerals iii Produces replica of organism cast j Other types of fossils i Resin fossil mode of fossilization made from hardened sap Review a Fossilized bone has pore spaces filled with pyrite but some of the original bone remains This is permineralization b Petrified wood is an example of the fossilization process known as replacement Modes of preservation a Body fossil preserved remnants of organism b Ichnofossil tracks burrows or other indications without having the organism itself i Trackway continuous series of tracks or footprints left by a single organism IV ii Coprolites fossilized excrement that can be used to determine the diet and internal organs of extinct organisms iii Burrows where an animal burrows the burrow is flooded and filled with sediment which provides information on behavior Preservation of ecosystems a Taphonomy the study of all processes occurring after the death of an organism until its discovery as a fossil b What proportion of the ecosystem s species is preserved c The preservation of communities i Autochthanous organisms preserved in their original living position ii Allochthonous fossils preserving organisms that were transported prior to deposition d Live dead study a census of organisms living in an ecosystem