[Question_Assumptions]

Very. Unless they generally died by hitting their heads on low-hanging branches, or were very susceptible to strokes (fossil brain tumors have already been found in at least one dino), it appears to reinforce the view that there was a single, basically global cause for their disappearance.

Consider the rise of a new disease or parasite to which the dinosaurs were particularly vulnerable. There are plenty of disease and parasite related ways to damage a brain, that might even explain why the damage was all so similar.

[SunkenCiv]

I’ll go with the model for which there is a preponderance of evidence (mass extinction due to impact).