Elizabeth Osmon, age 12, of Sarasota, Florida, for her question:
How did dogs get started in the world?
Scientists have tried hard to trace back the family tree of the dog. They have found and studied the fossil remains of dog like mammals through 40 million years. But this detective work is very difficult. Naturally the family has changed a lot through all of these generations. What's more, it branched out in different directions and several branches died out, leaving no descendants.
Snoopy and Lassie can trace their ancestors back some 40.million years which is more than we humans can do. However, our dogs would not recognize their original ancestor, and neither would we. Scientists named him Miacis. We all know that our modern dogs tend to produce a variety of offspring a litter of pups may be very different from their parents. This trait seems to date back to the beginning for the offspring of miacis branched out in many surprising directions. Ages later, one branch gave birth to the bear family and another branch to the very different cat family.
Miacis lived soon after the dinosaurs departed, at the tfme when the Age of Mammals began. All the early mammals were small, furry animals, and miacis was no exception. He was about the size and shape of a long bodied, short legged weasel. He had a long nose, fine teeth and sharp retractile claws for climbing trees. His fossil remains were found in the forested regions. So most likely he hunted birds and other small animals among the boughs.
Through millions of years, as his offspring branched out, certain species became more dog like. They grew bigger and left the trees to live on the ground.
About 30 million years ago, the ancestor of the dog had a long, mink sized body and long, strong running legs plus a long bushy tail. His neck also was long and his pointed face was topped with a pair of roundish ears. The scientists who studied his fossil remains named him Cynodictus and Cynodictus is the true great grand daddy of the entire modern dog family. He lived when the frisky little ancestors of our stately horse ran on toes instead of hoofs and herds of small, humpless camel roamed in North America.
Some 15 million years later, we would recognize the descendant of Cynodictus as a dog type animal. He was the size of the average modern dog with powerful muscles built for strength and endurance. Scientists named him Tomarctus. He succeeded because his character included the splendid qualities inherited by the modern dog family. He was born smart and he enjoyed community life. And he used these wonderful talents to hunt for food and to protect the members of his family. With a group of relatives, he went on hunting parties, tracking and catching often larger and faster animals. The future of the dog family was secure because this ancestor of 15 million years ago learned to co operate and share life with his kinfolk on a give and take basis.
Various branches of the dog family lived throughout the world, wherever hunting . was good. The Borophagus branch of North American dogs had huge heads and massive hyena like jaws. These dogs did not survive. The wolves, foxes and our other well known wild dogs descended from Tomarctus while certain round eared hunting dogs of Africa descended from a slightly different branch of the family tree.