i have my collection and it states that during saurons bid for power about the time during the 2 book/movie a attack started by the forces of rhun came a great worm one who did not use wings or breath of flame but tooth and claw and it's destruction was overwhelming to the dwarves who fell to this powerful beasts but it was told that about the time of the siege of gondor the dwarves gathered and slew this beast and broke the attack of rhun with the help of elves from mirkwood who's bows were powerful against the beast and after this no tale tells of these evil creatures during the third age