Certain aspects
of certain turtle skulls have been traditionally misinterpreted, as reported earlier.

Figure 1. The skull of the Cretaceous sea turtle, Desmatochelys, is relabeled here with the addition of color.
A not so recent paper on the sea turtle, Desmatochelys
(Fig. 1), by Cadena and Parham 2015 misidentified several skull bones, here corrected.
References
Cadena EA and Parham. JF 2015. Oldest Known Marine Turtle? A New protostegid from the Lower Cretaceous of Colombia. PaleoBios. 32(1).