Domestic dogs have been selectively bred for millennia for various behaviour, sensory capabilities, and physical attributes.Modern dog breeds show more variation in size, appearance, and behaviour than any other domestic animal. Nevertheless, their morphology is based on that of their wild wolf ancestors.Dogs are predators and scavengers, and like many other predatory mammals, the dog has powerful
muscles, fused wrist bones, a cardiovascular system that supports both sprinting and endurance, and teeth for catching and tearing. The smallest known adult dog was a Yorkshire Terrier, that stood only 6.3 cm (2.5 in) at the shoulder, 9.5 cm (3.7 in) in length along the head-and-body, and weighed only 113 grams (4.0 oz). The largest known dog was an English Mastiff which weighed 155.6 kg (343 lb) and was 250 cm (98 in) from the snout to the tail.The tallest dog is a Great Dane that stands 106.7 cm (42.0 in) at the shoulder.
