Actually, that is true. The fossil record shows that whales, dolphins and other air-breathing mammals that live in the sea did actually evolve from land mammals.
Check any book on evolutionary Biology for details.
Answer:
True as said above. Evolutionarily speaking all mammals evolved from the same land dwelling proto-mammal. Later the cetaceans moved back into water to fill up a niche in the aquatic system where they have survived ever since (rather successfully I might add).definitely true.
they were not "invented" they evolved from other sea creatures to become dolphins
gametangia
Dolphins.
No dolphins had a different evolution from whales. Whales evolved from a footed creature similar to a hippo (no, seriously) and dolphins evolved from a footed creature a lot smaller.
No, dolphins did not evolve from men, no other species evolved from men. Dolphins are small whales. The closest land animal to the whale is the hippo. Or at least that is the current theory. So dolphins are more closely related to horses, cows, sheep, and deer than they are to people.
yes they evolved from the trilobites
They evolved from small rodents called "Casidinanerphalls".
by their homologous organ sturcture
Fossil records suggest that dolphins evolved around 10-15 million years ago during the Miocene epoch. They are believed to have evolved from land-dwelling mammals that returned to the sea.
The first animals to resemble modern dolphins evolved ca. 20 million years ago.
dolphins originally evolved from therasids. which is a reptile. so they question you are askin your self is how does a reptile evolve into a mammal. THATS WHAT IM ASKING YOU!!
Jovian planets are generally considered more evolved than terrestrial planets. They have larger sizes and more complex structures due to their higher gravity and gas composition. Terrestrial planets are usually simpler in structure and composition, as they are predominantly made of rock and metal.