Notes from Review Fossilization- 2 things in order to have fossils form in sedimentary rock- pressure and water. Most fossils arise because of water and pressure. That is why fossils are preserved best in sedimentary rock. Igneous rocks are formed from volcanic eruptions. Fossils are just any remnant of a living organism that has been left behind when the animal dies. The organic matter of the animal is not a part of the fossil. Cast and molds is where the animal laid down and died and is buried in the sediment. The space where the animal died can become rock that maintains the cast of the animal. It can be 3D. Mineralization is when minerals fill up the empty space instead of sedimentary rock, called per mineralization. Leaves a 3D replica of the animal or plant. Trace fossils leave an impression. Can only get DNA from intact remains. Limit to things that haven’t died a long time ago. The fossil record is limitedto vertebrates, insects with exoskeletons, and mollusks. Only groups with hard parts are more present in the fossil record. Same with plants, the woody stems are more seen in the fossil record. More marine taxa in the fossil record than land taxa. Common stuff is more likely seen in the fossil record. The more recently an organismlived, the more likely that it left fossils. De-extinction Paper - In order for a mass extinction, 56% of taxa go extinct. - It is global, not local. - It happens rapidly, less than 1 million years. - Environmental characteristics that are common in all the extinctions are an increase in CO2. An increase in CO2 is bad because it causes the temperature to increase, example of extinction due to global warming would stuff that lives on top of mountains, polar bears, organisms in ocean. When you warm up the ocean, there is less oxygen in the water. Decrease the ability for the water to carry oxygen, marine life suffocates. Increases acid rain, acidificationof marine and terrestrial environments. CO2 increased at the end of the P extinction due to the volcanoes. CO2 is high in our environment today due to the burning of fossil fuels  anthropocene Actual Paper Information Passenger pigeon, thlyacine, mammoth, blue butterfly, river dolphinWe have DNA for all the species listed above. We can inject the DNA into a similar species. However, should we just bring back the species just because we have the technology to do it? Things to consider: do we have a place to put them, do we know what caused them to go extinct and have we fixed it, risk to humans and other species (danger and socio-economic impacts). The river dolphin is not a good case to bring back because the river is dirty and thereare no efforts to clean it up any time soon. It would go extinct again. (China) The blue butterfly can be brought back because its habitat is available and some has been preserved. It will not have a negative human or socio-economic impact. Thereis even a society to protect the butterfly. Can be brought back. We can go get it if it goes crazy. Thlysine is a marsupial. Went extinct due to hunting and habitat destruction. Need toconsider if it goes crazy, will we be able to go back and get it. Might prey on sheep. Concern that if the thlysine is in the same ecosystem as the Tasmanian devil, will it get the same cancer that the TD has. Not as good as the butterfly, but yes