These are called the Sutures, and in infancy they are not joined.
"The Wonder Island Boys: Exploring the Island"
Roger Thompson Finlay
The opinion of modern authorities on this subject is that those who say that the closure of the Sutures of the skull determines brain growth would or should also say that the cart pulls the horse, for, if the Sutures of the Native skull close at a somewhat earlier date in the average Native than in the average European then it simply means that the Native reaches maturity slightly earlier than the average white man.
"The Black Man's Place in South Africa"
Peter Nielsen
One cavern at Lauang, however, is famous over the whole country on account of the gigantic, flat, compressed skulls, without Sutures, which have been found in it.
"The Former Philippines thru Foreign Eyes"
Tomás de Comyn Fedor Jagor Rudolf Ludwig Carl Virchow Charles Wilkes