Does a cat dolphins and bat share a common ancestor?

A dolphin's flipper, a bird's wing, a cat's leg, and a human arm are considered homologous structures. ... Bats, whales, and many other animals have very similar homologous structures, demonstrating that these creatures all had a common ancestor

Just don't worry about the human part

hope this helps

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.

it's     c       this is a cell (b) with a nucleus (c) containing dna (a). the dna is organized into chromosomes (d). a section of the chromosome that codes for a trait is called a gene (e).