Hearthpwn

Because you want to beat Skelesaurus as quickly as possible to minimise the impact of the free cards they draw, you want a good aggressive deck, such as the new Overload Aggro Shaman you see around the ladder. 

One reason to choose Shaman over Face Hunter or Aggro Druid is that it can be much more explosive, even if potentially less consistent. When you're dealing with PvE, being less consistent fine. Skelesaurus is also not as well versed with the ladder metagame and how to correctly play against Overload Shaman, and will probably consider attacking you directly instead, which makes Shaman's explosiveness even more pronounced.