Kayentachelys aprix (Gaffney et al. 1987, Hutchinson et al. 1987; Early Jurassic, 190mya, 0.6m, (2 ft) in length) was originally considered a primitive (the earliest known) cryptodire turtle, which would have made it a sister and basal to Terrapene and Chelonia. The large reptile tree and Anquetin 2012 nested it more primitively closer to Proganochelys. This specimens includes two lateral fenestrae. Skull sutures and bone identification differ from original drawings and more closely match those of sister taxa, like Baena.

Baena arenosa (Leidy 1871; Eocene) this turtle appears to have a tiny upper temporal fenestra surrounded by the squamosal and another between the jugal and quadratojugal. The nasals are backset from the lower premaxillary.

Glyptops plicatulus (Marsh 1890; AMNH 336; Late Jurassic), an associated skull, shell, and partial skeleton. Gaffney (1979) reported, "The poor preservation of the skulls precludes a detailed study of the skull roof." That may be true. The bones may be largely lost. On the other hand, perhaps Glyptops had large skull openings as shown above.

Anquetin JRM 2012. Reassessment of the phylogenetic interrelationships of basal turtles (Testudinata). Journal of Systematic Palaeontology. 10: 3. doi:10.1080/14772019.2011.558928

Gaffney ES 1972. The systematics of the North American family Baenidae (Reptilia, Cryptodira). Bulletin of the American Museum of Natural History 1478(5): 241–320.

Gaffney ES 1979. The Jurassic Turtles of North America. Bulletin of the American Museum of Natural History 162(3):91-136.

Gaffney ES, Hutchison JH, Jenkins FA and Meeker LJ 1987. Modern turtle origins: the
oldest known cryptodire. Science 237: 289–291.

Khosatzky LI 1997. Big turtle of the Late Cretaceous of Mongolia. Russian Journal of Herpetology 4(2):148-154.

Leidy J 1871. Report on the vertebrate fossils of the Tertiary formations of the West. US Geological Survey of Wyoming and portions of contiguous territories, 2nd (4th) annual report: 340–370.

wiki/Kayentachelys
wiki/Glyptops