Jean,

Do you know what sort of numbers, where and were they all in one location or were they scattered over large area(s) etc?

You'd know a lot more about it than I would, but like you, I'd have thought if a disease killed wildebeest, it would also kill other species.

If it was a lot of wildebeest in one area, perhaps it was a herd of rampaging giraffe had rounded up an entire herd and had a feast.......

Ah maybe not, if it were that, the skulls would all be up in the trees!