Here is the full list of all 18 DAMNOSAUR achievements.
Reached 1,000,000 points in a single run
Survive for 30 minutes in a single run
Survived an encounter with a B-Rex
Survived an encounter with an Armoured Triceratops
Survived an encounter with a Scary Lizard
Used the Revive 4 times in a single Co-Op run
Defeat 250 Raptors
Defeat 100 Triceratopses
Defeat 100 Pterodactyls
Defeat 80 Lizards
Survived an encounter with an Exploding Pterodactyl
Survived for 3 minutes without changing from the Pistol
Unlocked the Meteor Gun!