Zoology - Evolution Question with Solution | TestHub

In the solar system of the milky way galaxy, earth was supposed to have been formed about 4.5 billion years back. The first non-cellular forms of life could have originated 3 billion years back. About 2000 million years ago (mya) or 2 billion years ago, the first cellular forms of life appeared on earth. By the time of 500 mya, invertebrates were formed and active. Jawless fish probably evolved around 350 mya. Sea weeds and few plants existed probably around 320 mya. About 65 mya, the dinosaurs suddenly disappeared from the earth. We do not know the true reason. Some say climatic changes killed them. Some say most of them evolved into birds. The truth may live in between.