Originally the suture must have terminated on the posterior border of the parietal bone, not far from the lambda.
"A Bilateral Division of the Parietal Bone in a Chimpanzee; with a Special Reference to the Oblique Sutures in the Parietal Bulletin of the AMNH, Vol. XIII, Article XXI, pp. 281-295, Dec. 31, 1900"
Ales Hrdlicka
Kulindon: Kappa, upsilon, lambda, iota, nu, delta, omega, nu.
"Sagittulae, Random Verses"
E. W. Bowling