Giving you exactly what you need to get the job done.
Quake was the first popular engine that had true 3D polygonal characters. To animate the characters, Quake uses a single base model that is manipulated at the vertex level to create animation.
Today skeletal animation is used. An internal skeleton is added to the character, to which all vertices are attached. By transforming the bones in the skeleton, the vertices attached to them are transformed as well. Each bone can now be animated separately. This means you gain a lot of flexibility when modeling characters.
Quake 1 Mesh & Animation (.mdl)