- Were you looking for the Venomhide Ravasaur mob, or the [Venomhide Ravasaur] mount?
This achievement is gained by acquiring a [Venomhide Ravasaur] mount, and is limited to Horde faction members. There is a corresponding Winterspring Frostsaber (achievement) achievement available to the Alliance.
This can be done by completing the quest chain ending in  They Grow Up So Fast. Acquiring items for it requires, among other things, completing daily quests over 20 days.