Certain Fossils Are Very Indicative of the Geological Period in Which

question 19

Short Answer

Certain fossils are very indicative of the geological period in which they occurred.These are referred to as index or _______________ fossils.

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Definitions:

Lungs

Paired respiratory organs in the chest of vertebrates with structures facilitating gas exchange between blood and the atmosphere, primarily for oxygen uptake and carbon dioxide excretion.

Blood Returning

Refers to the process of blood flowing back to the heart after having circulated through the body's organs and tissues.

Left Atrium

The upper left chamber of the heart that receives oxygen-rich blood from the lungs and pumps it into the left ventricle.

Electrocardiogram

A test that records the electrical activity of the heart over a period of time, used to detect heart abnormalities.