From a Q & A at the publisher's website:
Q: Why study the fossil history of dogs?Read the complete Q & A.
Xiaoming Wang: The fossil records of the canids (dogs) present a unique opportunity to study this important family of predators. The richness and diversity of the fossil canids are unparalleled among modern families of Carnivora (mammalian predators). Such fantastic records, assembled over more than 100 years of careful collecting by vertebrate paleontologists, permit us to piece together a detailed evolutionary history of the family and enable us to ask many questions that cannot be easily answered by studying other groups of carnivorans.
Q: Why are the fossil records for canids so rich and abundant?
XW: Canids were among the first carnivorans to evolve, dating back to more than 40 million years ago. This long history gave canids an early head start in diversifying before other carnivoran groups had an opportunity to compete. In addition, there are rich fossil records for canids because they evolved adaptations to a more cursorial locomotion (capable of running fast and for long distances), which is ideal for living in open grassland. The global climate became cooler and drier during the late Cenozoic, conditions that favor grassland over trees. Canids thrive in such an environment and the great number of fossils of members of this family testifies to their success.
--Marshal Zeringue