The Dinosaurs dominated the earth about 64 - 210 million years ago (mya) and then became extinct. Most of the animals that survived were omnivores or insectivores like Cimolestes. Around 63 mya the carnivorous group of animals, order Creodontia, appeared. Creodonts were slow, clumsy and inefficient. They became extinct in the early Pliocene which was about 4 million years ago (mya).

A pack of Creodonts brings to bay an Arsinotherium
(by far the best-known member of the extinct mammalian class Embrithopodama).

Creodonts were mostly replaced by the Carnivora who have differences in their shearing teeth, bones of the carpus and auditory bullae. Miacidae appeared about 60 mya and are the basal family of the order Carnivora. They are arboreal with long, lithe bodies, with long tails.

By 48 mya, the Miacids are divided into two groups: the Caniformia or miacines and the Feliformia. The Caniformia evolved into dogs, raccoons, bears, sea lions, seals, walruses and weasels. The Feliformia evolved into cats, hyaenas, civets, genets and mongooses.

HESPERON

Around 37 mya the canidae branch of the Caniformia branch began with the appearance of the Hesperocyon. It was the first canid genus and were small kit fox-sized animals with supple, muscular bodies, long tails, padded feet, and relatively short muzzles. They walked on their toes like modern canids and were good climbers. They had carnassials adapted for shearing and ossified auditory bullae.

About 30 mya, the Hesperocyon gave rise to the Borophaginae, the second radiation of the Canidae. Tomarctus evolved in this radiation which gave rise to Borophagus. Although Canis-like, based on skull and teeth features, the Tomarctus line doesn't appear to lead to the modern dogs, the canines

TOMARCTUS

About 16-23 mya the Caniformia group splits into other radiations which include the Ursidae (bears); Mustelidae (Weasels, mink, etc.); and Procyonidae (Raccoons).

By 9 - 19 mya, the Caninae, the third canid radiation of the Canidae began based on the small fox Leptocyon. The decline of the borophagines possibly opened the way for this radiation which began in North America with the appearance of the following lines: Vulpines - which include the foxes South American Canids - which include Lycalopex, Cerdocyon, Chrysocyon, and South American Bush Dog or Speothos (Ictycyon Venaticus). Eucyon which is now extinct. Canis - which includes the wolves, dogs, jackals, and coyotes Lycaon - the brown and yellow spotted hunting dogs of Africa

BOROPHAGUS

It is from the canine radiation based on Leptocyon that all living dogs are derived. That radiation began in the southwest United States, the birthplace of modern dogs. About 300,000 years ago, the gray wolf (Canis Lupus) was fully developed in northern Eurasia and spread all over Europe and northern Asia. Eventually, it crossed into North America via the Bering Strait land bridges. About 100,000 years ago, dire wolves appeared in North America. They had huge heads and tremendous teeth. Some were the largest members of the dog family ever to exist. The dire wolf became extinct about 8,000 years ago.

EURYON

Based on DNA research, the evolution of the wolf may suggest that there was a branching 1-2 million years ago from a common ancestor of gray wolves, the eastern North American wolves, and coyote. One of the branches migrated to Eurasia and there gave rise to the gray wolf. The other branch remained in North America and 150,000 - 300,000 years ago branched into the ancestor of the eastern North American wolves and the coyote.

Every breed of dog evolved from the Gray (Timber) Wolf. The domestication process began between 10,000 -15,000 years ago, by Hunter-Gatherer groups. Fossils found in some of man's early cave dwellings indicate the presence of dogs.

GRAY WOLF

DNA studies have shown that there is a .02% difference in the DNA of the dog and the wolf. However, wolves and dogs can still reproduce and produce breedable offspring.

In 1993, the Smithsonian Institution and the American Society of Mammalogists reclassified the dog from its separate species designation of Canis familiaris to Canis lupus familiaris. So, now, the Timber Wolf (Canis lupus nubilus), the Mackanzie or Tundra Wolf (Canis lupus occidentalis), the dog (Canis lupus familiaris), etc, fall under the genetic umbrella of the gray wolf: Canis lupus.

The dogs, which lived in a pack (hierarchy) soon recognized the human as the alpha dog, or leader. Actually the dog was man's first domestic animal. This relationship soon became a partnership, and early cave paintings show dogs helping men to trap wild game. It is conceivable that in those primitive times dogs also stood guard at their masters' caves, played with the young children and helped to haul loads.

One does not know exactly how man first domesticated the dog, but the most important clue to the answer lies in the nature of the dog itself. All dogs, even the wild breeds, are basically friendly, social animals that have the ability to develop a strong attachment to human beings.

It is believed that the wolves foraged for food around the camps of early humans, occasionally being eaten themselves. Perhaps a litter of wild cubs were probably taken into a cave dwelling as "pets" or as food, with an occasional youngster tamed and taken into the family group. It seems logical to assume that these exhibited submissive behaviors and were more amenable to a shared life; they, in turn, would produce offspring with other tamed wolves. Such propagation of behavioral characteristics is known to be paired with morphological and physical changes such as a shortened muzzle, shorter legs and perhaps changes in coat color.

It is also possible that many different groups of people domesticated different types or breeds of dogs, but no one is sure. It is a tribute to the intelligence and adaptability of the dog that it was able to take advantage of the relationship between man and the dog. The partnership proved to be fruitful.

The struggling human race, learning to live in a savage environment, found in the dog a loyal protector and devoted companion. Hunting became easier, the sounds of the night were less fearful - all because of a wild animal that chose to live with men.

Today there are over 400 recognized dog breeds throughout the world, varying from the diminutive Chihuahua to the stately and tall Irish Wolfhound. How did such a mind-boggling variety of shapes, sizes and "purposes" come to be? There is archaeological evidence of size variation dating to 9,000 years ago. The first recognized unique "breed" was probably a lanky and swift greyhound-type of dog, used for its speed in hunting. Paintings and pottery depict this as one of the most ancient of foundation breeds. Intense artificial selection pressures imposed by humans changed the appearance - and behavior - of dogs quickly so that, by the time of the Roman Empire, most general breed types were already identifiable.

In hunting alone, as its rules became more formalized, there were great differences in skill between the sight-hounds (such as the greyhound) and the scent-hounds (such as the beagle). Probably the closest our domestic dog can come to her wild-type ancestors is in the "Spitz" or northern group, which includes the Malamutes and Huskies. While this group continues to excel in the ancient skills of hunting, guarding and pulling, other breeds have strayed, as it were, far from their original purpose. Most striking in this regard are the toy breeds, developed simply as lap dogs and companions.

Present breeds exhibit distinctive and highly diverse characteristics. The causes for this evolution are to be found not only in the natural tendency to variation on the part of the dogs but also in the effects of prehistoric domestication, that is, in man's intervention. However, the dog's inclination toward fidelity and affection did not take long to develop. No other animal has accompanied and worked for the human race so willingly. No other animal will choose to fight at a man's side rather than seek its own freedom. No other animal will give of its affection so freely.

The duties of the dog have increased from the initial uses for hunting and herding. Despite technical progress he is still indispensable. Nothing can replace the dog which tracks the lost, leads the blind, finds the victims of avalanches. There is the gun dog; the guard dog; the drug finding dog; the sheep dog; the sled dog; and, in many other countless relationships man needs his four footed friend. The dog will certainly always keep his position as our best friend and most faithful companion.