glsl – How to write a matrix array in a vertex attribute in openGL?

I have an animated model with up to 60 bones. This means that I have an array of 60 matrices when I want to render the model. Previously, I just wanted to create a fixed size uniform (mat4[60]), but now I want to render the model via an instantiated rendering, which means that I have to write 60 matrices per instance in the model's VAO.

This would mean that I have to create 240 vertex attributes, each containing 4 floats, because this is the maximum number of floats an attribute can have. This is obviously a ridiculous solution, besides the fact that I think it exceeds the maximum number of attributes that a VAO can have.

So, how can I render animated models via instance rendering?