Americhelydia is a clade of turtles that consists of sea turtles, snapping turtles, the Central American river turtle and mud turtles, supported by several lines of molecular work.[4][5][6] Prior to these studies some morphological and developmental work have considered sea turtles to be basal members of Cryptodira and kinosternids related to the trionychians in the clade Trionychoidea.[7][8] Americhelydia and Testudinoidea, both clades within Durocryptodira (hardshell turtles), split a part during the early Cretaceous.[9][10]
^Joyce, W. G., Parham, J. F., Lyson, T. R., Warnock, R. C., & Donoghue, P. C. (2013). A divergence dating analysis of turtles using fossil calibrations: an example of best practices. Journal of Paleontology, 87(04), 612-634.
^"Protostegidae". The Paleobiology Database. Retrieved 27 July 2013.
^Chandler, C. H., & Janzen, F. J. (2009). The phylogenetic position of the snapping turtles (Chelydridae) based on nucleotide sequence data. Copeia, 2009(2), 209-213.
^Barley, A. J., Spinks, P. Q., Thomson, R. C., & Shaffer, H. B. (2010). Fourteen nuclear genes provide phylogenetic resolution for difficult nodes in the turtle tree of life. Molecular Phylogenetics and Evolution, 55(3), 1189-1194.
^Crawford, N. G., Parham, J. F., Sellas, A. B., Faircloth, B. C., Glenn, T. C., Papenfuss, T. J., ... & Simison, W. B. (2015). A phylogenomic analysis of turtles. Molecular Phylogenetics and Evolution, 83, 250-257.
^Joyce, W. G. (2007). Phylogenetic relationships of Mesozoic turtles. Bulletin of the Peabody Museum of Natural History, 48(1), 3-102.
^Werneburg, I., & Sánchez-Villagra, M. R. (2009). Timing of organogenesis support basal position of turtles in the amniote tree of life. BMC Evolutionary Biology, 9(1), 82.
