Carpet Bomb Boss: Lion (IVORY), Skull (SILVER)
Armoured Shotgunner (where you pick up the Wes-44 from a pit, not a Kickback boss): Lion (SILVER), Skull Bead (SILVER)
Lieutenant Draza: Lion (GOLD), Yamantaka Head (SILVER)
Carpet Bomb Boss: Ottoman Bracelet (GOLD) (WolfiePL), Spanish Chalice (GOLD)
M-32 Hammer Boss: Pattern Ring (SILVER) (anidais) (see glitches section), Ottoman Bracelet (GOLD), Jeweled Cross (GOLD)
Carpet Bomb Boss:* (Hard, Normal and Easy) Yama On Buffalo (LAPIS-LAZULI), Spanish Goblet (GOLD) (VlCiOuS-V)
Cluster Bomb Boss:* (Crushing Only) Yama on Buffalo (LAPIS-LAZULI) (Bendtner92), Spanish Goblet (GOLD)
M-32 Hammer Boss: Skull Bead (HEMATITE), Spanish Goblet (SILVER)
*These two are the same boss, but have different Kickbacks on different difficulties.
Cluster Bomb Boss: Wrathful Deity Head (GOLD)**, Wrathful Deity Head (SILVER)**, Wrathful Mask (SILVER), Thogchag Ghau Amulet (HEMATITE)
Carpet Bomb Boss: Wrathful Deity Head (SILVER), Shive Amulet (BRONZE), Shive Amulet (SILVER)
Brute: Wrathful Deity Head (GOLD), Shive Amulet (SILVER), Shive Amulet (BRONZE), Wrathful Mask (SILVER)**
**After the 1.04 Patch, these treasures cannot be gotten from these bosses anymore.
Eddy: Antique Watch (SILVER), Sanxingdui Stickeye Head (GOLD)
Flynn: Ottoman Ring (GOLD), Wrathful Mask (GOLD)
Lazarevic: Antique Pipe (IVORY), Sanxingdui Flattop Head (GOLD)
And here^ if you don't want to click thë link.
Thë formatting is better if you click the link though, since it is a copy and paste and I am on my iPhone
If you are farming for Skeleton skins, here's some info to help:
Sir Frances Drake (London Underground) is one of the easier ones to get. Ghegis (Borneo), Skelzor (Syria) and Marco Polo (Airport) are all about the same in difficulty on a farm. By far, the toughest farm is the Skull Bead for Doughnut Drake at the end of Monastery.
I farmed EVERYTHING on Hard, altho some treasures were picked up on Crushing play throughs for the Star. Either way, if you are patient and farm on Hard, it's doable. Farming on Crushing is very tough and may not be worth the time or effort.
Be prepared to play each map about 2-3 times in a row, or more. You must become a farming machine.
If you farm on Hard, two players can do this and give you more lives and more opportunities to get drops. You must suffer through blank and duplicate drops to find the rare ones. Your farms might be more successful if you play with someone who already has the skin.