In UO Extinction there are several mounts, they belong to three main categories:
Premium ones are usually obtainable through a donation or in rarer cases through special staff events. Can be included in special donation packages ..or stolen from your guild mates :)
The rare ones in the same way as premium ones can be obtainable through a donation or taming the mount around the world (as they rare their randomly spawning around with varying delays but usually long).
They belong to this category the classic mounts belonging to the world of Ultima Online. It will be enough to explore the world and be sufficiently trained in the taming ability.
They are therefore part of the custom tamables all the premium and rare mounts.