The only oral anticoagulant available was
warfarin
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).
The answer is the muscular system
Insulin receptors regulate glucose level in blood. without that, glucose level would be uncontrolled/not normal (high/low) and it would be impossible to maintain homeostasis (stability) :P hope it will help.. :))
