In Table 1 are the original data (5 sheets) provided by John Howe ; in Table 2, they are ordered by accession numbers. Most measurements were not taken in my way. For comparisons with E. hemionus onager I used scatter diagrams of the three measurements close to mine : maximal length (1), minimal breadth of diaphysis (3), and maximal distal breadth (7).

Fig.1 shows one extremely large specimen (64588). Moreover, a group of Natural Trap calcanea has strikingly wider breadths. The rest is mostly larger than the extant E. hemionus onager but with a small overlap. The large 64558 is close to A. occidentalis.

Fig.2 shows the same very large specimen, again close to A. occidentalis, plus three specimens with a wider distal end. The previous group with very wide diaphyses, however, is lost among the rest of the calcanea. The three specimens plotting apart on this scatter diagram are also lost among the main group in the previous diagram. I have no explanation for these strange proportions but they are found neither in A. leoni nor in Caballines.
The main group is larger than E. hemionus onager with a small overlap.