Plesiochelyidae

Plesiochelyidae Temporal range: Late Jurassic, Oxfordian–Tithonian PreꞒ Ꞓ O S D C P T J K Pg N
Holotype carapace and plastron of Plesiochelys etalloni (previously Emy etalloni). Mount is situated upside-down.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Pantestudines
Clade:	Testudinata
Clade:	†Thalassochelydia
Family:	†Plesiochelyidae Baur, 1888
Genera[2]
†Craspedochelys †Globochelus †Plesiochelys †Portlandemys †Tropidemys †Hylaeochelys[1]

The Plesiochelyidae are an extinct family of turtles in the clade Thalassochelydia originally classified within the Cryptodira suborder, mostly belonging from the Jurassic period.^[2] An alternate study placed the clade Thalassochelydia in the Angolachelonia and outside the Testudines.^[3]

Palaeoecology

Phosphatic δ¹⁸O values indicate that plesiochelyids were inhabitants of coastal marine environments.^[4]

References

1. Milner, A.R. (2004). "The turtles of the Purbeck Limestone Group of Dorset, southern England" (PDF). Palaeontology. 47 (6): 1441–1467. Bibcode:2004Palgy..47.1441M. doi:10.1111/j.0031-0239.2004.00418.x.
2. Anquetin, J.; Püntener, C.; Joyce, W.G. (2017). "A Review of the Fossil Record of Turtles of the Clade Thalassochelydia" (PDF). Bulletin of the Peabody Museum of Natural History. 58 (2): 317–369. doi:10.3374/014.058.0205. S2CID 31091127.
3. Evers, S. W., & Benson, R. B. (2019). A new phylogenetic hypothesis of turtles with implications for the timing and number of evolutionary transitions to marine lifestyles in the group. Palaeontology, 62(1), 93-134.
4. Billon-Bruyat, Jean-Paul; Lécuyer, Christophe; Martineau, François; Mazin, Jean-Michel (1 February 2005). "Oxygen isotope compositions of Late Jurassic vertebrate remains from lithographic limestones of western Europe: implications for the ecology of fish, turtles, and crocodilians". Palaeogeography, Palaeoclimatology, Palaeoecology. 216 (3–4): 359–375. doi:10.1016/j.palaeo.2004.11.011. Retrieved 23 August 2025 – via Elsevier Science Direct.