Animal model Bone Heat Weighting Problem i've modeled a rat and i'm trying to get it parented to an armature through automatic weighting, since i dont have any experience with weight painting. The problem is anytime i try to parent them, with any type of armature, i get a warning with "bone heat weighting: failed to find solution for one or more bones" written on it. After searching through the internet, i've seen a lot of people answering ways to resolve this problem, but none of them work with my personal project. What might this specific problem be? The model can be downloaded here.

Thanks in advance.
I've done a quick test, maybe it's just because your model is too tiny. Scale up the model and the armature until they get similar to the default cube, then apply (Ctrl A) rotation and scale to the model in object mode. Do the same with the armature. 

This way Ctrl P with automatic weight should work.