You can get a change through time, from Time 1 to
Time 2, in which size only is changing. You could take
the anterior dotted line on the top sort of as a central
sulcus. You could look at the bottom one as perhaps a
lunate sulcus, which separates primary visual striate
cortex. You simply enlarge it and nothing really is happening.
They are scaling exactly isometrically. In the
case of reorganization, however, you can change the
growth patterns as to what is developing through the
ontogenetic time. Here we see that the size is the same
thing, but look what has happened to what I would
call the lunate sulcus here: It is moving posteriorly
and you're getting a reduction in primary visual striate
cortex (area 17) and what might be an increase in the
parietal lobe or extra-striatal parts (areas 18 and 19).
That's just one example of reorganization. You
could get reorganization if you change the hierarchy
or maturation rates so that you would get different
fiber distributions in here, which might not change
the size at all. But you are never going to be able to
discover those from endocasts. Those are lost in the
prehistory.