User blog comment:Mckrongs/July 14 2010 - New Famitsu MHP3 Scans!/@comment-75.110.120.100-20100714165259

It's probably worth mentioning this basically confirms Lagiacrus, and almost certainly the rest of the aquatic Leviathans, are not going to get on in this-- the original Long Sword art for MHTri featured a Thunderclap with Lagiacrus Armor, whereas this features entirely new art of the starting armor and a Long Sword I can't identify.

Everything else with new art has a reasos too-- the new art for Bowguns because there was no initial distinction between Bowguns in Tri, so there was no art specifically for a Light and a Heavy Bowgun, and the rest of the weapons weren't in Tri, so they needed new art anyway.