A kind of horse-like creature was used by the Sycorax to mount
Biology
The sycorax horses had, like the Sycorax, both an endo- and exoskeleton, but instead of just cover they heads, covered the mostly body, with bony tails and bone-like spikes over they hips.
History
When a second Sycorax invasion was tried by the widows of the Christmas Invasion on 2008, a few sycorax riders mounted then to patrol the coasts of Shadow Cay. Later the Doctor stolen one of them to escape of his persecuters. All the creatures were presumably killed when Shadow Cay exploted (The Widow's Curse (comic story)).