Power Mosfet Information Mismatch: On Region Characteristics vs Total Charge Graphs
I believe the Fig 8 Vds , Ids values only represent 1 point on the conduction curve which is not constant during the plateau charge region.

This device which adds a dual Y axis Vds curve for fig 8 at the fixed 50A limit gives more information and may anwser your query.  

It assumes you understand the Id current is limited to the value stated in the graph and also by Vds/Ron controlled by Vgs during the total dynamic  charge range.   Generally Q increases as RdsOn decreases. 

Since Q=CV also consider Ic=C *dV/dt + V * dC/dt how this affects conduction noise during switching.