How do scientists know that mega mammals live during the Cenozoic era

scientists can determine when any animal of plant lived simply based on it's structure, or by examining their bones. They can then determine what they ate, and how they lived. There was this study with two birds, on with a long beak, and the other with a shorter one. They were extinct but they could tell how and what they ate based on their beaks. The longer beak was for long flowers, and the shorted for smaller ones. The long-beaked bird needed a longer beak to reach the pollen that lay deep within the flower.

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