At the present time many archaeologists group both phases under the name _Developmental Pueblo_.[110] This term, which is used in this book, seems apt, for this was a period of transition which led to the classic Pueblo era. In many ways the culture was still a generalized one, as was the one which preceded it, but specialization, which was to become so marked later, was already beginning. Sites belonging to this phase are found throughout the Plateau area. [Illustration: Fig. 19—Developmental-Pueblo diorama in the Museum at Mesa Verde National Park. (Courtesy of Mesa Verde National Park.)] Assigning dates to this period is rather complicated. It might be thought that in dealing with somewhat more recent sites, where tree-ring dates are more commonly available, it would be easy to say that a specific period began at a definite time and ended at another. Actually, such is not the case, for development was far from uniform in all places. In some sections the period which we define as Developmental Pueblo began toward the end of the seventh century; in other areas the earliest date which can be given is in the middle of the ninth century. Terminal dates are equally variable. In some regions this period had ended and the next phase of development had begun by the middle of the tenth century, and in others this change did not take place until the twelfth century. In general, the dates 700 to 1100 A. D. may be assigned to the Developmental Pueblo phase, but this represents a simplification of a very complex situation. For many years it had been thought that the people of Basketmaker and those of Pueblo times were of entirely different physical types. The Basketmakers were considered dolichocephalic, or long-headed, and the Pueblos were believed to be brachycephalic, or broad-headed. The first appearance of the latter was thought to mark the advent of an entirely different racial group which became dominant and caused the disappearance of the earlier inhabitants of the region. It was not believed that the Basketmakers were entirely exterminated, but rather that many were assimilated and absorbed by the new group while some were killed and others driven into peripheral areas. Some archaeologists and anthropologists still hold this theory.