Explanation:
Birds belong to phylum vertebrates; but so do mammals.
Birds are vertebrates with feathers, lay eggs with hard shells, homeothermic, forelimbs become wings, and have a beak
Mammals on the other hand are vertebrates with hair, homeothermic, heart has four chambers, young feed on milk from mammary glands, and have different types of teeth (incisors, canines...)
Phylum vertebrates include: Fish, amphibians, reptiles, birds and mammals.
other than that, there's a phylum called arthropods which have an exoskeleton and no backbone and include:Crustaceans, Arachnids, insects and myriapods
Hope I answered your question.