This would also explain their somewhat 'random' distribution in areas of the body which would not have been that easy to display had they been applied as a form of status marker.

It can be as a marker member of Late Cretaceous for its broad distribution in geography, but short duration in geologic period and well used for strata classification and correlation.

This paper gives a review of the current status of the research on epidermal stem cell including biological features, surface marker, distribution features, and changes in wound repair, etc.