The domestic dog (Canis lupus familiaris or Canis familiaris) is a member of genus Canis (canines) that forms part of the wolf-like canids, and is the most widely abundant carnivore. The dog and the extant gray wolf are sister taxa, with modern wolves not closely related to the wolves that were first domesticated. The dog was the first domesticated species and has been selectively bred over millennia for various behaviors, sensory capabilities, and physical attributes.
The domestic cat (Latin: Felis catus) is a small, typically furry, carnivorous mammal. They are often called house cats when kept as indoor pets or simply cats when there is no need to distinguish them from other felids and felines. Cats are often valued by humans for companionship and for their ability to hunt vermin. There are more than 70 cat breeds, though different associations proclaim different numbers according to their standards.
Birds (Aves), a subgroup of reptiles, are the last living examples of dinosaurs. They are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. Birds live worldwide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich. They rank as the class of tetrapods with the most living species, at approximately ten thousand, with more than half of these being passerines, sometimes known as perching birds. Birds are the closest living relatives of crocodilians.