Natural Trap, Femora, Data
In Table 1 are the original data (2 sheets) provided by John Howe. One specimen was measured twice ; two seem to be the left and right of the same animal. In Table 2 are the data I used (diaphysis and proximal depths were not used because they are difficult to measure and bring little information) ; later on I discarded also the diameter of caput femoris because of its too large variation.
Scatter diagrams (Fig.1-2) show three very large and robust specimens ; a large variation exists even among the other femora. Most Natural Trap femora are bigger than in extant E. hemionus onager.
Robust Femora (Fig.3)
The largest one is similar to the average Amerhippus leoni.
Two smaller may belong to a Caballine.
Gracile and very gracile Femora (Fig.4)
I am unable to propose any attribution for these specimens.