Carnotaurus

Charge. If the carnotaurus moves at least 20 feet straight toward a target and then hits it with a headbutt attack on the same turn, the target takes an extra 4 (1d8) bludgeoning damage. The carnotaurus can then make a bite attack against it as a bonus action.

Size Advantage. The carnotaurus has advantage on attack rolls with its bite against small or medium creatures. 

Sprinter. The carnotaurus can dash as a bonus action as long as it only moves in a straight line

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) piercing damage. 

Headbutt. Melee Weapon Attack: +5 to hit, reach 5ft., one target. Hit: 7 (1d8+3) bludgeoning damage. If the target is a creature, it must succeed on a DC 13 Dexterity saving throw or be knocked prone.