Temporal range: Maastrichtian-Late Eocene
~70–34 Ma
Euclastes sp.jpg
Euclastes sp. skeleton
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Clade: Pancheloniidae
Genus: Euclastes
Cope, 1867
  • E. acutirostris Jalil et al., 2009
  • E. platyops Cope, 1867
  • E. wielandi (Hay, 1908)

Euclastes is an extinct genus of sea turtles that survived the Cretaceous–Paleogene mass extinction. The genus was first named by Edward Drinker Cope in 1867, and contains three species. E. hutchisoni, was named in 2003 but has since been reassigned to the genus Pacifichelys,[3] while E. coahuilaensis named in 2009 was reassigned as Mexichelys coahuilaensis in 2010.[4][5]


E. platyops skull
E. platyops skull

Unlike the sea turtles Toxochelys and Eochelone, Euclastes has a secondary palate. However, the secondary palate of Euclastes is not as extensive as it is in Ctenochelys and Angolachelys.[6] The genus can be distinguished by later sea turtles based on its broad, low skull; broad, flat palate; wide, flat dentary bone with an elongated symphysis; and low tomial ridge on the beak. The widened palate and dentaries give Eochelone wide, flat jaws suitable for crushing hard-shelled organisms.[3]




Cladogram based on Lynch and Parham (2003)[3] and Parham and Pyenson (2010):[7]

Cheloniidae sensu lato 










Cheloniidae sensu stricto


Fossils of Euclastes have been found in:[8]



  1. ^ Parham, James F.; Pyenson, Nicholas D. (March 2010). "New sea turtle from the Miocene of Peru and the iterative evolution of feeding ecomorphologies since the Cretaceous". Journal of Paleontology. 84 (2): 231–247. doi:10.1666/09-077R.1. ISSN 0022-3360. S2CID 62811400.
  2. ^ Ullmann, S. G.; Carr, E. (2021). "Catapleura Cope, 1870 is Euclastes Cope, 1867 (Testudines: Pan-Cheloniidae): synonymy revealed by a new specimen from New Jersey". Journal of Systematic Palaeontology. 19 (7): 491–517. doi:10.1080/14772019.2021.1928306. S2CID 236504236.
  3. ^ a b c Lynch, S.C.; Parham, J.F. (2003). "The first report of hard-shelled sea turtles (Cheloniidae sensu lato) from the Miocene of California, including a new species (Euclastes hutchisoni) with unusually plesiomorphic characters" (PDF). PaleoBios. 23 (3): 21–35.[permanent dead link]
  4. ^ Euclastes coahuilaensis from the Paleobiology Database
  5. ^ Exibidos fósseis de tartarugas com 72 mi de anos
  6. ^ Mateus, Octávio; Jacobs, Louis; Polcyn, Michael; Schulp, Anne S.; Vineyard, Diana; Buta Neto, André; Telles Antunes, Miguel (December 2009). "The Oldest African Eucryptodiran Turtle from the Cretaceous of Angola". Acta Palaeontologica Polonica. 54 (4): 581–588. doi:10.4202/app.2008.0063.
  7. ^ James F. Parham; Nicholas D. Pyenson (2010). "New Sea Turtle from the Miocene of Peru and the Iterative Evolution of Feeding Ecomorphologies since the Cretaceous". Journal of Paleontology. 84 (2): 231–247. doi:10.1666/09-077R.1. S2CID 62811400.
  8. ^ Euclastes at
  9. ^ Mateus, O., M. J. Polcyn, L. L. Jacobs, R. Arujo, A. S. Schulp, J. Marinheiro, B. Pereira and D. Vineyard. 2012. Cretaceous amniotes from Angola: dinosaurs, pterosaurs, mosasaurs, plesiosaurs, turtles. Actas de V Jornadas Internacionales sobre Paleontologia de Dinosaurios y su Entorno, Salas de los Infantes, Burgos 71-105