Mammal species with the greatest diversity

In terms of variety in size and shape, the species of mammal with the greatest diversity are dogs (Canis lupus familaris). As of May 2006, national canine associations worldwide acknowledged up to 800 varieties, with the UK Kennel Club and American Kennel Club recognising 203 and 253 breeds of dog, respectively. The smallest breed, chihuahuas, typically measure 15-23 cm (6-9 in) to the shoulder, the largest breeds of Irish wolfhounds and great Danes, typically stand at 90 cm (36 in) to the shoulder. In addition to pure-bred dogs, numerous mongrel, mixed-breed and cross-breeds also exist, examples of the latter are: 'labradoodles' and 'goldendoodles' (labradors or golden retrievers crossed with poodles), 'puggles' are a cross between pugs and beagles, whilst a bulldog / boxer cross is often referred to as a 'bulloxer'!