Monodactyl Equids from Konso, Discussion

Discussion

Gen Suwa et al., 2003 distinguish an earlier fauna, with endemic bovids, prior to 1.7 Ma, followed by “an influx of external elements…most likely related to a general East African trend of climatic drying†, resulting in “the post-1.5 Ma characterized by newly occurring taxa and locally continued lineages†.

I have found evidence for two forms of during Interval 1 : one reminding of Wild Asses ; the other with wider and flatter diaphyses and deep distal keels.

The following observations can be made by pooling the data for the post-1.5 Ma equids.
1. The only evidence for the apparition of a new form is provided by the metatarsals of Konso 5, KGA 12. The only three MT inside the whole Konso sample to be entire were collected at KGA 12 (Fig. 26).
Moreover, all the MT of KGA 12 have similar proportions. One fragment from KGA 7 seems to belong to the same form. Metatarsals and Ph1 resemble fossils from Olduvai Bed II.
2. Apart from Interval 5, KGA 12, there is always evidence for two forms : one more or less Ass-like and one, much more frequent, apparently more robust.

Relation between Cranium and MC dimensions
Figure 27 shows the relation between basilar lengths and supra-articular MC widths in extant Equus, and how the basilar length of the cranium from Konso relates to the supra-articular widths of the MC.
It shows that almost all MC from Konso, whatever the Intervals, are compatible by their size with the cranium KGA 8-374.