Allosaurus rework by SoapingLance

Pounce: If the allosaurus moves at least 30 feet straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 13 Strength saving throw or be knocked prone. If the target is prone, the allosaurus can make one bite attack against it as a bonus action.

Bloodlust: Whenever the Allosaurus strikes a creatre with its bite attack, it must make a dc16 con save or take 4(1d8) bleed damage at the start of its turn if it is not stopped by magically healing the victim or other methods of healing.

Multiattack: The alllosaurus can make either one bite attack or two claw attacks as its action.

Bite: Melee weapon attack: +6 to hit, 23 (3d12+4) piercing damage

Claw: Melee weapon attack: +6 to hit, 11 (2d6+4) slashing damage.