A standard take on a classic archetype.
Card Choices with my initial thoughts
Ramp:
Druid of the Cowl - being a creature makes this fragile, and it dies to all 3 damage removal, but I think this is a necessary choice, would like feedback if you think you have a replacement.
Thunderheard Migratation - In the spoiler post the math was calculated that with 10 dinosaurs you have an 80% chance of hitting on turn 2. That's good enough for me, and with the inclusion of Commune with Dinosaurs it bumps this 80% up. Seems like a key addition to make this deck viable.
Gift of Paradise - The clear choice over New Horizons, as we may not always have a creature on board. The 3 life may be relevant?
Hour of Promise - Can often come out on turn 4 to send you into 7 or 8 mana on turn 5. With the inclusion of 12 deserts the Zombies are a given. Can really help to stabilize. Unless I'm casting a threat on turn 4, this is what I want to be doing. ramping and surviving.
Threats:
Carnage Tyrant - What's not to like? Dependable and a strong ramp target. Maybe this is the deck that will justify this cards price?
Walking Ballista - Can come down with 4 mana and be effective, or can be a late game mana sink.Waker of the Wilds - Not sold on this choice, but provides another mana sink. Worried that its too fragile to be effective.
Sandwurm Convergence - Getting to 8 mana is still difficult even in a ramp deck. However its a turn late game engine that will win you the game. Dodges common removal.
Ghalta, Primal Hunger - This doesn't seem like the ramp target we want, but man it would be sweet to cast. It doesn't effect the board when cast, can get stuck in your hand, but I'm seeing this coming down around turn 6-7 in most cases, which can't be that bad. Plus its a dinosaur?
Ripjaw Raptor - A curve consideration. With 8x 2 mana ramp options having a 4 cost threat seems necessary, and this was the best I could find. As good a blocker as they come, no one wants to feed you cards.