Question

Question 8. Another aspect of biology that must deal with enormous scales is in the history of life of our planet. The oldest unequivocal fossil evidence of life is that of bacterial fossils that are about 3.5 billion years old (3,500,000,000 yrs). Animals are at least 500 million years old, and perhaps as old as 1 billion years (500,000,000 to 1,000,000,000). And the final extinction of the dinosaurs (end-Cretaceous extinction), followed closely by the explosive diversification of the mammals, occurred about 66 million years ago. If we let 100 years represent a human lifespan (rather genęrous but it keeps the numbers simple), how many times longer than a human lifespan are we removed from the extinction of the dinosaurs (never mind the oldest bacterial fossils)? If we represent the hundred years of a human lifespan by 1 millimeter, what is the length needed to represent the time back to the end- Cretaceous extinction? Find some familiar structure that is that high, or familiar places that are that far apart.

Answer 1

One of the most imporatant aspect of biology is the history of life on earth. It is belived that earth is formed around 4.54 billions years ago.But the earliest evidence of life on earth is belived to be around 3.5 billions years ago.It was initiated with small microscopic organism and gradually give rise to multicellular organisms.

Life may be oriiginated inside the depth of the sea ans such oldest unequivocal fossil evidence are abour 3.5 billion years ago in old rocks. The oldest bacterial fossil was found to be of Cyanobacteria. Bacterial fossil had also found in amber fossilised tree resin.

Evidence of animal fossil are considered to about 1billion years ago. earliest fossil records had been studied through trace fossils. The first multicellular organism are developed around 900 million years ago.single celled organism goes through series of periods and give rise to multicellular organisms. Early multicellular organism divides into sponges called eumetazoa. It then break into   placozoa. Around 100 millions ago Creataceous dinosaurs reach their peak in size. Giant sauropod was believed to be the largest animal in the earth history. But by the end of the jurrasic some of the giant sauropod extinct but titanosaurs flourished.

But around 65.5 millions ago all vertebrates and probably many tropical invertebrates become extinct in some geological and biological events called as K-Pg extinction events also called creataceous tertiary events. But during this phase smaller mammals like lizards, birds were able to be survive

Human ancestors evolved around 10 millions years after the extiction of dinosaurs .