What structures of the embryonic and adult anatomy of manatees and elephants establish the evolutionary relationship between these two animals?

manatees evolved from elephants..or elephants evolved from manatees

http://www.thewildones.org/Animals/manatee.html

To establish the evolutionary relationship between manatees and elephants, we need to examine their embryonic and adult anatomical structures. Manatees and elephants belong to the order Sirenia, which also includes dugongs and sea cows.

1. Limbs: Both manatees and elephants possess similar limb structures. They have adapted from the original five-fingered tetrapod limb to modified structures with fewer digits. Manatees have forelimbs that are paddle-like flippers, similar to elephant limbs but modified for swimming.

2. Skull: The skull features of manatees and elephants demonstrate evolutionary similarities. Both have elongated skulls with no external nose and nostrils positioned on the top of the snout. The position of the nostrils allows both animals to remain partially submerged in water while still being able to breathe through their noses.

3. Teeth: Both manatees and elephants have a unique dental structure with continuously growing teeth throughout their lives. Their molars possess a similar pattern of ridges and cusps, adapted for their herbivorous diet.

4. Mammary Glands: Manatees and elephants are both mammals and possess mammary glands for lactation. The structure and function of these glands are essential for nourishing their young.

By comparing embryonic and adult anatomical structures, studying genetic evidence, and examining the fossil record, scientists have determined that manatees and elephants share a common ancestor in their evolutionary history. They both evolved from a common ancestor and diversified into separate species over time. Manatees adapted to a marine environment, while elephants became terrestrial animals.