Just wanted to point out another way how to assign fields of classes / structs in the constructor. Ben called the parameters of the constructor aTime, aPos, aRot. Instead you can use the this reference so you do not need to have them have a different name than your fields:
public struct MyKeyFrame {
public float frameTime;
public Vector3 position;
public Quaternion rotation;
public MyKeyFrame(float frameTime, Vector3 position, Quaternion rotation)
{
this.frameTime = frameTime;
this.position = position;
this.rotation = rotation;
}
}