One key anthropometric trait is the facial index. It is measured by the length of the face from the root of the nose to the bottom of the chin, expressed as a percentage of the greatest breadth across the cheek-bones. High facial indices indicate a long face while low facial indices indicate a broad face.
Interestingly, individuals of mixed ancestry often show a higher facial index than the original types. Men often show slightly higher values. Also, nutrition can alter the facial index, e.g. coarse-fibered nutrition during childhood stimulates growth of the masticatory muscles and leads to broader faces.
Thus the importance of the facial index as an anthropological criterion is only modest. Still, several types can be characterised by relatively broad faces compared to other types.
For those reasons, on this site only a distinction between broad and narrow face is mentioned in some type descriptions. More precisely, the facial index can be grouped into leptoprosop (narrow-faced), mesoprosop (medium- to wide-faced) and euryprosop (wide-faced).