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  1. 1. INDEX -The first cell. -How are eras and periods formed? -The eras. -What are fossils? -How are fossils formed? -How fossils help us? -History of a spider. -The triasic bird. -Life started in the sea. -Ceratites. -Plants fossils. -Model of an primitive rat. -Head and body of a primitive rat. -The symmerodonta.
  2. 2. THE FIRST CELL   Since living things first appeared on the planet, they have changed to adapt to the conditions of their enviroment  We call this biodiversity. This is one example of the first cell, a bacteria.
  3. 3. The bacterias evolutionated and reproduct. In this way appeared lots of species. The appeared the cells. Their join together and form firsts organisms.
  4. 4. How eras and periods formate? We dont know when life appeared in the planet, but we have an idea of the periods and eras thanks to the fossils, that helped scientist to separate the rests of the bodys and the footprints in different millions of years. Fossils also related the eras to different epochs of appearing and desapearing of the several species.
  5. 5. The eras . There are five eras: Archaic : 5.000 millions of years ago the Earth is formed , but there is no life. Primary : 2.600 years ago appeared firsts molluscs. Secundary: 240 millions of years lived the dinosaurs. Terciary: 65 millions of years ago firsts mammals were born. Cuaternary : 2 millions of years ago the men has appeared.
  6. 6. What are the fossils? Fossiles are the body, or footprints of this living thing, mineralized and converted in stone. The footprints can be excrements, tracks, or evrything that show us the activity of a living thing. e Here we can see one axample.
  7. 7. How fossils are formed? The fossils can be formed in different ways. Here is the more common one: 1.First, the body is burried under the mud. 2.Years later, there are just the bones under the layers of mud converted in sedimentary rocks. 3.Past some millions of years the sedimentary layers of rock have moved and the bones have mineralized. 4.Then, the layers bagan to move and the fossil comes to light.
  8. 8. How fossils help us? Fossls a a very important data about the history of our planet. It helpes us in many ways: Reconstruct an important part of the history of life because scientists have learned about the characteriatics of many extinct organisms. Obtain information of the history of Earth: we can know when an organism appeared and when it extinct. Make a calendar of the history of Earth, to divide it in eras and periods.
  9. 9. History of a spider. This was a spider caught in the resine of a tree. It is called ambar. The ambar conserved the body of the spider perfectly, so we can see the animal in the same conditions than when it died. A lot of other insects were caught in this tipe of resine, so we have a small part of many millions of years ago.
  10. 10. The triasic bird. The skelet of this triasic bird was found after millions of years . It is very important because it conserved some of its feathers. Thanks to that we know a dinosaur put the first bird egg. And that responds the questions ``who was first, the egg or the chicken´´. Today we know that it was the chicke.
  11. 11. LIFE STARTED IN THE SEA There are a lot of theories about how life started, but all them says that life started in the sea. This is why we have found lots of fossil shells and bacterias in the sea.
  12. 12. Ceratites. The Ceratites is an extint genus of the ammonite cephalopod that lived in marine habitats in what is now Europe, Asia and North America during the triasic. It is named Horn Stone because of its form. All other different species of its family have the same form.
  13. 13. Some plants get incrusted in the stone .When the plant discompaund s it leaves the siluet of its leaves on the rock . PLANTS FOSSILS
  14. 14. This plant is very similar of its ancestor a primitive fern . The leaves are identic to the primitive plant . That give us the idea that this plant hasnt evolutionated practically nothing.
  15. 15. This is the model of the skeleton of a rat found after a lot of time.
  16. 16. THE HEAD AND THE BODY OF A PREHISTORIC RAT This is part of the restant body of a prehistoric rat. It was found in Timor Oriental, and it was 40 times bigger than a normal rat. This kind of rats desappeares 1.000 years ago, but scientists say the species was born in prehistory.
  17. 17. Symmetrodonta This fossil was found in South America and it is procedent of a family of mammals characterized for the triangular molars. The scientists say that although there were many individuals, there are few fossils.
  18. 18. And this was how the biodiversity expanded, and the evidence the fossiles that left us.
  19. 19. This presentation was made by : NATALIA HERNANDEZ SOSNOWSKA & GABRIELA CAROLINA STANCU