Here is the full list of all 14 Carnivore Land achievements.
Kill 5 Enemies
Kill 10 Enemies with the Pirate Gun
Kill 50 Enemies with the Stools of Death
Kill 50 Enemies with the Double Pistols
Visit The Trainyard
Complete the main campaign
Die 10 times
Kill 100 Enemies
Kill 10 Players in Multiplayer
Visit the 2 unique areas
Kill 500 Enemies
Kill 10 Players with Melee Weapons in Multiplayer
Survive 40 Minutes in Free Roam Hard
Kill 1000 Enemies