NOW TEN ELEVEN QUESTIONS……… About how old is the planet Earth? Give your answer in millions of years. 4,560 millions years old. In those early years of the planet, which important chemical was absent from the atmosphere? Oxygen When (how many mya) did life probably first appear? 3,500 mya How do scientists think each of the geologic ages came to its end? Mass extinction The first and the longest geologic age is the Precambrian. What organisms lived then? Bacteria How do paleontologists know which organisms inhabited the Earth all those millions of years ago? Fossils (or molecular evidence) Which old theory was Louis Pasteur able to reject with his experiment? Spontaneous generation Summarise the theory of endosymbiosis, which explains how eukaryotic cells probably evolved. One bacteria hosts another. The two live symbiotically & share essential functions. What is the name of the geologic era in which we live now? Cenozoic What is the picture behind this slide showing? Why so important? Cyanobacteria. Photosynthesisers. Produce oxygen.

A BIG bonus question. Who follows the Blog A BIG bonus question! Who follows the Blog? Tell me whatever you can about this, now famous, dinosaur. Dinocephalosaurus -245 mya -Carnivore -Lived in the seas in what is now China -First evidence of live birth???