A redescription of Glyptochelone suyckerbuykii (Ubaghs, 1879), an enigmatic fossil sea turtle (Chelonioidea) from the Maastrichtian of the Netherlands and Belgium, sheds new light on fossil sea turtle shell variation and neural bone homology.

We here provide a redescription the Late Cretaceous (Campanian-Maastrichtian) fossil marine turtle Glyptochelone suyckerbuykii to document its anatomy and intraspecific variation. This redescription highlights the complete absence of a nuchal pedestal, presence of a radiating shell surface texture pattern easily differentiated from that of coeval marine turtles, and the presence of interneural elements, a characteristic unique among Late Cretaceous turtles. A phylogenetic analysis suggests that Glyptochelone suyckerbuykii is located at the base of Dermochelyidae, a dubious result likely resulting from missing data. To allow constructing phylogenetic characters based on the presence of supernumerary neural elements, we suggest a revised classification for the midline column of the carapace of turtles based on novel homology criteria as consisting of neurals, which are outgrowths of the neural arches, as opposed to preneurals, interneurals, and postneurals, which are independent bones that form in front, within, and posterior to the neural column, respectively. We suggest use of this novel classification in future phylogenetic analysis. Supplementary Information: The online version contains supplementary material available at 10.1186/s13358-025-00389-y.