Let's be honest, this world is dead. Eerily dead. It's a great foundation but it needs more. I have a detailed list of suggested AI to help.
Hook Clawed Eagles: The eagles would be large predatory bird like creatures that ambush from the Redwood trees to capture prey. They prefer hunting hatchies swooping in and grabbing them to be carried back to their nests to feed on. This would allow more use of the hatchlings' struggle mechanic and make life as a hatchling more immersive. The eagles would be large and slow with little armor, easy to take down if you're an adult or juvi. If no prey were present in the redwoods for a while these eagles would venture out into the grasslands to find other sources of food, sometimes even eating the carcasses of dead creatures.
Spiked Pronghorns: Weak but fast, pronghorns would stay in large groups and constantly travel across land in fear of the apex predators they are surrounded by. Their males would be more armored and covered in thick bone that pierces through their skin, so biting such creatures would inflict damage upon attacker as well. Their running speed would match that of an adult shadowscale's flight. They would rather run than fight, but if a male is isolated from it's herd, it would fight till it's last breath.
They would be grazers like the IronHide, but would avoid being near them.
Crystal Bears: These crystalline bears live in caves and only come out at night to bask in the moon's glow. Their strong claws dig through the rocky ground of the caves to find small mineral deposits to munch on. They get their energy from the crystals that decorate large caves and are very territorial. They would have heavy armor and would hit hard, but are very heavy and slow. A few good full charge SS shots could shatter their armor and kill them. They sleep in positions that camouflage their appearance to look like another glowing crystal cluster so dragons would do well to be on high alert when venturing these caves.