Tree Eldering is a technique used to elder dinosaurs in a undisturbed way. To Tree Elder, there are two methods...
Method #1 - Flyers
Create a pack and use a juvenile or older flying creature to fly to the top of a tall tree, next place a nest on the top of the tree, then spawn in as the Dino you wish to elder, then just sit there until your stats run low. When they do run low just jump down, eat/drink then goto menu then come back.
Method #2 - Glitch
Get any dinosaur and goto a large tree, get as close to the trunk as possible and then goto menu, after you get into the menu, spawn in and you should be on top of the tree. To stay up there without having to do the same method above every time, just create a nest up there.
Places To Tree Elder
On the current default map, there is an island, this island is located near the rocky mountains, this place is great for Tree Eldering because it is semi-remote and hardly anyone goes there.
Outside the middle on the current map is two trees, they are located on the outside of the hill where the large cave is, this is a good place for Tree Eldering because the hills hide you from being seen.