Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Polyraptor

Enrage — Whenever this creature is dealt damage, create a token that's a copy of this creature.

Palani's Hatcher

Other Dinosaurs you control have haste.
When this creature enters, create two 0/1 green Dinosaur Egg creature tokens.
At the beginning of combat on your turn, if you control one or more Eggs, sacrifice an Egg, then create a 3/3 green Dinosaur creature token.

Marauding Raptor

Creature spells you cast cost {1} less to cast.
Whenever another creature you control enters, this creature deals 2 damage to it. If a Dinosaur is dealt damage this way, this creature gets +2/+0 until end of turn.