- Kingdom containing multicellular organisms having cells bound by a plasma membrane and organized into tissue and specialized tissue systems that permit them to either move about in search of food or to draw food toward themselves. Unable to make their own food within themselves, as photosynthetic plants do, they rely on consuming preformed food. They possess a nervous system with sensory and motor nerves, enabling them to receive environmental stimuli and to respond with specialized movements.
- The class of vertebrate animals that are typically bipedal and warm-blooded, lay large-yolked hardshelled eggs, often arboreal, and possessing feathers, hollow bones, forelimbs adapted for flight (although some have lost the ability to fly) and hindlimbs for perching and locomotion, a four-chambered heart, keen vision, a horny beak without teeth, and a large muscular stomach. Birds arose from theropod dinosaurs, which were an order of carnivorous dinosaurs.