Fig. 5. Protrusion (A) and protrusion velocity (B) of P. molurus for three recorded tongue-flick clusters (cluster 1, black circles; cluster 2, grey circles; cluster 3, open circles). The clusters differ in duration and maximum protrusion length. The series of small panels at the top of the figure shows the tongue axis position (lateral view, tongue tip pointing to the right) of the protrusion trace with the longest duration (black circles). Each numbered panel corresponds to the same number in the position time trace. Protrusion length was calculated along the 3-D tongue axis from mouth opening to the bifurcation point of the tongue. At time t=0 s, the tips of the tongue started to become visible. Protrusion was started before the bifurcation point became externally visible, which explains the initial high protrusion velocity. The marked (grey) traces in flick clusters 1 and 2 indicate ground contact of the tongue tips.