I disagree a bit, I feel that you should drop the Rampant Growth for sure, but I would keep the Birds of Paradise in the deck.
I would also lose the Sunflare Shaman , maybe for two Groundbreaker
Also I would lose Vigor and Blaze , the reasoning is because this deck obviously wants to be a speed deck, and those are both rather slow cards. You should be maximizing on speed.
Also, although it is not an elemental Bloodbraid Elf would rock in this deck.
I'm not sure about groundbreaker. I mean, can his mana base support RRR from ball ligthning AND GGG.
A cool card to include would be raging ravine. It's an elemental too and it fixes your mana.
You could drop black if it's only for spike cannibal. A better splash would be blue. You get cytoshape wich you can use as removal by turning creatures into 0/0. You can also pump your own creature turning them into eldrazis with +1/+1 counters on them. It can't kill Emrakul thought.
Don't forget skeleton ship. It's a skeleton and a ship so it's on theme, and it has a nice ability.
Edit: my favorite skeleton is Augur of Skulls. It's a two for one and it regenerates.
I'm not sure about groundbreaker. I mean, can his mana base support RRR from ball ligthning AND GGG.
A cool card to include would be raging ravine. It's an elemental too and it fixes your mana.
You can also look at the more recent artifacts:
Etherium Sculptor, Master of etherium,
Inkwell Leviathan or Darksteel Colossus with copper gnomes or tinker for exemple.
Lifeline is also a nice artifact.
Blue can improve heartstone into training grounds.
You could remplace spike cannibal with Cytoplast Root-Kin.
There are also nice lands you could add like Llanowar Reborn and Oran-Rief, the Vastwood.
If you want ramp that bad try Smokebraider and fertilid instead.
http://forums.mtgsalvation.com/showthread.php?t=262237
Sound the Call isn't bad.
Edit: my favorite skeleton is Augur of Skulls. It's a two for one and it regenerates.