<Table> <Tr> <Th> Date </Th> <Th> Gya </Th> <Th> Event </Th> </Tr> <Tr> <Td> 14 Sep </Td> <Td> 4.1 </Td> <Td> `` Remains of biotic life '' found in 4.1 billion - year - old rocks in Western Australia . </Td> </Tr> <Tr> <Td> 21 Sep </Td> <Td> 3.8 </Td> <Td> First Life ( Prokaryotes ) </Td> </Tr> <Tr> <Td> 30 Sep </Td> <Td> 3.4 </Td> <Td> Photosynthesis </Td> </Tr> <Tr> <Td> 29 Oct </Td> <Td> 2.4 </Td> <Td> Oxygenation of Atmosphere </Td> </Tr> <Tr> <Td> 9 Nov </Td> <Td> </Td> <Td> Complex Cells ( Eukaryotes ) </Td> </Tr> <Tr> <Td> 5 Dec </Td> <Td> 0.8 </Td> <Td> First Multicellular Life </Td> </Tr> <Tr> <Td> 7 Dec </Td> <Td> 0.67 </Td> <Td> Simple Animals </Td> </Tr> <Tr> <Td> 14 Dec </Td> <Td> 0.55 </Td> <Td> Arthropods ( ancestors of insects , arachnids ) </Td> </Tr> <Tr> <Td> 17 Dec </Td> <Td> 0.5 </Td> <Td> Fish and Proto - amphibians </Td> </Tr> <Tr> <Td> 20 Dec </Td> <Td> 0.45 </Td> <Td> Land Plants </Td> </Tr> <Tr> <Td> 21 Dec </Td> <Td> 0.4 </Td> <Td> Insects and Seeds </Td> </Tr> <Tr> <Td> 22 Dec </Td> <Td> 0.36 </Td> <Td> Amphibians </Td> </Tr> <Tr> <Td> 23 Dec </Td> <Td> 0.3 </Td> <Td> Reptiles </Td> </Tr> <Tr> <Td> 24 Dec </Td> <Td> 0.25 </Td> <Td> Permian - Triassic Extinction Event , 90 % of Species Die Out </Td> </Tr> <Tr> <Td> 25 Dec </Td> <Td> 0.23 </Td> <Td> Dinosaurs </Td> </Tr> <Tr> <Td> 26 Dec </Td> <Td> 0.2 </Td> <Td> Mammals </Td> </Tr> <Tr> <Td> 27 Dec </Td> <Td> 0.15 </Td> <Td> Birds </Td> </Tr> <Tr> <Td> 28 Dec </Td> <Td> 0.13 </Td> <Td> Flowers </Td> </Tr> <Tr> <Td> 30 Dec , 06 : 24 </Td> <Td> 0.065 </Td> <Td> Cretaceous -- Paleogene extinction event , Non-avian Dinosaurs Die Out </Td> </Tr> </Table>
if we compress the entire history of the universe into one year life on earth appeared
21 Sep