Combat damage can be assigned to other Dinosaurs you control as normal, but most of that damage will be prevented. For example, if a 3/3 Dinosaur you control blocks a 5/5 creature with trample, the attacking player may assign 2 of that creature's combat damage to the player or planeswalker it's attacking and Temple Altisaur will prevent 2 of the 3 damage assigned to the defending Dinosaur.