life first arose earth ref name brasiermcloughlinetal freshlook ref analyses carbon isotope ratios may help identify climate changes even explain major transitions permian triassic extinction event ref name twitchett ref relatively recent discipline molecular phylogenetics compares dna rna modern organisms construct family trees evolutionary ancestors also used estimate dates important evolutionary developments although approach controversial doubts reliability molecular clock ref name petersonetal ref techniques engineering used analyse bodies ancient organisms might worked
Natural science Earth science Paleontology