Get a dino with around 1000 hp and 1k melee and you should defeat these easily. I find fire wyverns are best but you can also use thylas, rexes and alot of other stuff. Sometimes you can spot them as they spawn in so keep an eye out while going across the desert and you should find some pretty fast. Got 15 horns after 30 minutes on my fire wyvern (2000 hp and around 1.4k melee)
Ragnarock - Go into ice cave and kill the weak deathworms there. Use a good shield to block their attacks and melee them with a sword, easy quick kills because they have so little health and they drop the same loot as a regular deathworm. Make sure to wear warm cloths.