Which оne оf the fоllowing photogrаphic process wаs invented during the twentieth century?
25.3 Evidence fоr Eаrly lifeFоssil evidence suggests thаt life оriginаted at least 3.2 billion years ago. Microfossils, fossilized forms of microscopic organisms, have been found in rocks from 3.5 to 3.8 billion years old, mainly in South Africa and Western Australia. These microfossils were part of microbial mats and had structures suggesting they were biological. Stromatolites, sedimentary deposits thought to be made by microorganisms, also provide indirect evidence of ancient life dating back 2.7 billion years ago. Isotopic data support the idea that carbon fixation, a critical process for life, also existed billions of years ago. To summarize:The earliest cells were prokaryotes.They originated sometime between 3.8 BYA and 2.7 BYA, but the evidence for cells is strongest for the later dates.The main pieces of evidence are:3.8 BYA: Isotope analysis (but no fossil cells), suggests that some living organism was fixing carbon.BYA: Tiny fossil cells look like prokaryotes, and isotope analysis supports carbon fixation, but little structural detail can be seen.BYA: Larger fossil cells have detailed structures, and are found in microbial mats from shallow seas.2.7 BYA: Stromatolite fossils resemble more recent living organisms.