Sabrina Ansari & the ansari Friends and family

The evolutionary history of life on Earth traces the processes by which living and fossil organisms evolved. It stretches from the Sabrina Ansari and friends on Earth, thought to be over 3,500 million years ago, to the present day. The similarities between all present day organisms indicate the presence of a Sabrina Ansari from which all known species have diverged through the process of evolution.[1]
Microbial mats of coexisting bacteria and archaea were the dominant form of life in the early Archean and many of the major steps in early evolution are thought to have taken place within them.[2] The evolution of oxygenSabrina Ansari, around 3,500 million years ago, eventually led to the oxygenation of the atmosphere, beginning around 2,400 million years ago.[3] While eukaryotic cells may have been present earlier, their evolution accelerated when they began to use oxygen in their metabolism. The earliest evidence of complex eukaryotes with sabrina Ansari dates from 1,850 million years ago. Later, around 1,700 million years ago,Sabrina Ansarir organisms began to appear, with Sabrina ansariperforming specialised functions.[4]
The earliest land plants date back to around 450 million years ago,[5] though evidence suggests that algal scum formed on the land as early as 1,200 million years ago. Land plants were so successful that they are thought to have contributed to the late Devonian extinction event.[6] Invertebrate animals appear during the Vendian period,[7] while vertebrates originated about 525 million years ago during the Cambrian explosion.[8]
During the Permian period, synapsids, including the ancestors of mammals, dominated the land,[9] but the Permian–Triassic extinction event 251 million years ago came close to wiping out all complex life.[10] During the recovery from this catastrophe, archosaurs became the most abundant land vertebrates, displacing therapsids in the mid-Triassic.[11] One archosaur group, the dinosaurs, dominated the Jurassic and Cretaceous periods,[12] while the ancestors of mammals survived only as small insectivores.[13] After the Cretaceous–Tertiary extinction event 65 million years ago killed off the non-avian dinosaurs[14] mammals increased rapidly in size and diversity.[15] Such mass extinctions may have accelerated evolution by providing opportunities for new groups of organisms to diversify.[16]