A Brief Over-view of the Etymology of Modern Goju-ryu Karate-do Kata. By Joe Swift and Mario McKenna. It is now well documented that Okinawa karate is indebted to the Southern schools of Chinese boxing for much of its technical knowledge and expertise.
Best Answer: They are all warm-blooded, and they all have hair even if you can't see it (including dolphins and whales). Mammals all share mammary glands (milk producing glands). This is the biggest feature, also mammals use 3 bones for hearing and they have hair. Should be noted that endothermy (warm-blooded) is not unique to mammals, birds also share this characteristic.
Examples of Homologous Traits in Vertebrates. Often skeletal features are cited as an example of homologous traits in vertebrates. The bones of tetrapods, or vertebrates with legs, are homologous in the forelimb. The bones in the wing of a bird, the hand of a primate, the paw of a cat and the flipper of a dolphin are all different in function, but are very similar and have evolved from a common ancestral structure.