Unlike character, quadruped has no official skeleton. Assets in UE marketplace are using different skeletons. In my opinion, the situation is chaotic. For example, the authors of horse have to make their own custom skeleton. And the users of those assets usually have big trouble in using them together because of different skeletons. The animations, unlike character, can’t be retargeted or shared.
This is a job that can only be done by Epic team to publish a standard or suggested skeleton for quadruped.Hope you can pay an attention to this request.
To specify a default for a quadruped isn’t that simple though. If you would use the same skeleton for a rat / ferret / rabbit / tiger animations would look pretty broken without some tweaking. Or that skeleton for a frog model. It’s possible though to some point. Even on the humanoid skeleton you would fo project specific tweaks. I wish we could automatically generate those skeletons and properly automate the tweaking with pose estimation. If we get a proper plugin for maybe DeepLabCut this could be done.
I have a post about it here with some relevant documents:
The EPIC human skeleton is used pretty much as a standard on the marketplace but because it is not project specific you end up implementing and removing your bones when you start developing with it. Same goes for any standard on this engine because the engine itself targets such a broad group of users. If you are working on a low poly project, think minecraft or a 1996 game then you’re not going to end up with 100 bones a model, eye bones or facial movements. If you simulate something accurately like robotics or well maybe for medical uses then you need something anatomically correct. Marketplace animation creators are likely none of both. If EPIC will provide such standard it needs to target specific fields perhaps.