““The way to peer into life’s past is to examine fossils and to determine when a branch was first created by assessing the age of rocks when a certain fossil was formed. The oldest known fossils are of bacteria that apparently lived in ponds or a shallow sea located in what is now western Australia. They are fossil mats of bacteria, called stromatolites, whose metabolism led them to excrete calcium carbonate, chalk, the stuff of seashells and limestone. The ancient ponds dried up for some climatological reason, and these bacterial mats turned to stone. They’re 3.5 billion years old. As””
![“Perhaps no order of mammals presents us with so extraordinary a series of gradations as this [step by step, from humans to apes to monkeys to lemurs] - leading us insensibly from the crown and summit of the animal creation down to creatures, from which there is but a step, as it seems, to the…” quote by Thomas Huxley](https://sms4smile.com/quotes/img-quotes/f0b/thomas-huxley-1183_animal_perhaps-no-order-of-mammals-presents-us_3051.jpg)
