For how to spawn the mob look at Console Commands
The Dactyl Hatchling is an unfinished neutral mob that the player can spawn, it is a neutral mob that runs around the area but deals damage if the player touches it. Currently it can only be spawned using console commands as it does not spawn in the wild.
According to Fishlicka on Discord, he is considering making the enemy hatch out of an egg and/or make the enemy spawn in some sort of prehistoric area. The Dactyl Hatchling is currently work in progress.
The Dactyl Hatchling is an entity and NPC that has appeared in a pre-release 0.1.11 youtube video posted by Ian gussey. But it was using console commands.
It is unknown when this will be implemented, but Fishlicka has mentioned many times he plans on adding it in a future update.
Description[]
The Dactyl Hatchling is a tall yellow monster with bipedal, spindly legs of dark brown/purple. It has two stubby limbs that are in the shape of a wing, along with a long tail on the back. The head of it has a long nose, two goblin-like ears, an open mouth, and two realistic, human-like eyes, which are both unlike the cartoony features of the rest of the model. It is about as tall as the regular size of a Stroll Fiend.
It is neutral and does not attack, it instead walks quickly in a irregular line that it is facing, often changing direction for seemingly no reason. It may clear trees that is in it's way. It has trouble climbing up steep hills.
Currently there are no "Adult" variants of the Dactyl, and there is currently no information on what they will look like when implemented.