A. fraternus et al., Appendix

1. Correlation between cranial diastema (6) and cranial muzzle length (5).
From the diastema lengths given by Hulbert it is possible to estimate the muzzle lengths using a regression calculated on extant E. caballus (Fig.A).

2. Correlation between mandibular diastema (3) and mandibular muzzle length (12).
From the diastema lengths given by Hulbert (1995) and Hay (1913) it is possible to estimate the muzzle lengths using a regression calculated on extant E. caballus (Fig.B).
It appears that the range of varaition for Equus sp. A is abnormally large as shown also by the diastema coefficient of variation (12.46 in Hulbert 1995, Table 2). The maximum is close to Equus sp. C.

3. Correlation between the cranial muzzle length (5) and the mandibular muzzle length (12).
There again, it is possible to estimate the cranial muzzle lengths using a regression calculated on extant E. caballus (Fig.C).
Not surprisingly the range of variation of Equus sp. A is abnormally large.