Afossil species is found in the same rock layer with fossil 3 and fossil 4. when could these species have existed? a) 500-245 mya b) 500-500 mya c) 540-245 mya d) 540-505 mya

option a and d is the correct answer

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they deliver oxygen to the blood

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.