According to modern classification I will say that Jake is correct. With the use of tracing back and DNA technology then we can say that this is the digital way which is used nowadays to classify animals.
Sophie says through her observation that the characteristics of the animal classification used.
The answer to the question is PCR
The fossils that provide information on the formation of an oxygen-rich atmosphere are the stromatilites from the Precambrian era. These are layered and columnar fossils consisting mainly of cyanobacteria which were the original life form back then. These bacteria took in carbon dioxide and produced oxygen by photosynthesis as early as 2.5 billion years ago (the earth is about 4.5 billion yrs old).
