This model of an adult Ostrich (*Struthio camelus*) shows the 3D orientations and magnitudes of the different jaw muscles. In the background is a ternary plot that shows these orientations in 2 dimensions. Notice how the pink muscle (mPSTs) is such a dominating temporal muscle in Ostrich (and other paleognathe birds). This differs from other birds that use other temporal muscles more signifantly whereas mPSTs is just a small slip of muscle under the orbit. Featured in Cost et al 2022, JEB). doi: 10.1242/jeb.243216.