Two neat things are happening here:
First, Parker is lifting his head up! Normally Tyler has the great head control but today Tyler was a bit tired (probably from his upper GI drama) and brother held his head up for a really long time. Just amazing to see!
Second, brothers are staring at each other! They usually don't acknowledge each other and barely look if you put them in front of each other. As they played and had "tummy time", brothers actually checked each other out for a little while!