20Brogan

Try turning off the texture pack and if that doesn't fix it, it might be a bug like half-slabs in vanilla.

Building off this, use the middle mouse scroll to go up and down the list to select the different mobs you've killed.

1. The t-rex is probably a bug with the mod not the pack so complain to the developer about that one. 2. The t-rex breaks all blocks except iron blocks so start storing them in that