The long slog toward resolving more than a decade of legal conflicts over snowmobiles in Yellowstone National Park took another procedural step forward Wednesday, as the National Park Service issued a formal record of decision that marks the end of the planning process that will govern over-snow travel in the park. “I think we have a fighting chance,” Yellowstone Superintendent Dan Wenk said Thursday of the plan’s prospects for avoiding or withstanding courtroom entanglements.