Nest Building Animals
Currently nine animals build nests in the wild: Compy, Dilo, Dimorphodon, Parasaurs, Microraptor, Morellatops, Terrorbird, Vulture and Ichthyornis. Nests can be found around the spawn locations of these animals.
Be careful when approaching nests! Nearby dinos will try to defend the eggs in the nest. If the nest is empty it may be easily demolished.
Nest Mechanics
Nests have a lifetime matching the time the baby dinos need to hatch, after that time is up the nest is demolishable.
The fertilised egg in the nest hatches like regular fertilised eggs and the baby can be claimed by players.
While the nest is intact it provides insulation against the elements effectively incubating the egg. Players staying near the nest can claim a baby dino rather easily this way, but getting it back to your base and safety is a whole other issue. Nearby dinos, including the parents, may try to kill the newly claimed babies.