Article · Wikipedia archive · Last revised Jun 23, 2026

Sinemydidae

Sinemydidae is an extinct family of turtles from the Jurassic and Cretaceous of East Asia. Their exact position is engimatic, they have alternatively been considered stem-group cryptodires, but also "crownward stem-turtles" alongside Macrobaenidae, Paracryptodira, Xinjiangchelyidae, Thalassochelydia and Sandownidae outside of crown Testudines.

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Jun 23, 2026
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Sinemydidae
Temporal range:
Jeholochelys
Ordosemys
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Pantestudines
Clade: Testudinata
Clade: Perichelydia
Family: †Sinemydidae
Yeh, 1963
Genera

See text

Sinemydidae is an extinct family of turtles from the Jurassic and Cretaceous of East Asia.1 Their exact position is engimatic, they have alternatively been considered stem-group cryptodires, but also "crownward stem-turtles" alongside Macrobaenidae, Paracryptodira, Xinjiangchelyidae, Thalassochelydia and Sandownidae outside of crown Testudines.

Genera

  • Dracochelys2 Lianmugin Formation, China, Early Cretaceous (Aptian-Albian)
  • Hongkongochelys2 Upper Shaximiao Formation, China, Middle-Late Jurassic
  • Jeholochelys2 Jiufotang Formation, China, Early Cretaceous (Aptian)
  • Liaochelys12 Jiufotang Formation, China, Early Cretaceous (Aptian)
  • Manchurochelys2 Yixian Formation, China, Early Cretaceous (Aptian)
  • Ordosemys2
    • O. leios Luohandong Formation, China, Early Cretaceous
    • O. liaoxiensis Chengzihe Formation, China, Early Cretaceous (Aptian)
    • O. brinkmania Lianmugin Formation, China, Early Cretaceous (Aptian-Albian)
    • O. perforata Khulsangol Formation, Mongolia, Early Cretaceous (Albian)
    • O. donghai Chengzihe Formation, China, Early Cretaceous (Aptian-Albian)
  • Sinemys2
  • Wuguia2
    • †Wuguia efremovi Khozatsky 1996 Hutubei Formation, China, Hauterivian/Barremian Lianmuxin Formation, China, Early Cretaceous (Aptian-Albian)
    • †Wuguia hutubeiensis Matzke et al. 2004 Hutubei Formation, China, Hauterivian/Barremian
  • Xiaochelys12 Lianmugin Formation, China, Early Cretaceous (Aptian-Albian)
  • Yumenemys2 Hui-Hui-P'u, China, Late Cretaceous

Material from the Paleocene of California previously attributed to c.f. Sinemyididae is now attributed to macrobaenids.3

Phylogeny

Cladogram of Perichelydia after Miller et al. 2023, showing the two proposed positions of Sinemydidae.4

Perichelydia

†Mongolochelys

†Meiolaniformes (Meiolania)

†Paracryptodira

†Sinemydidae+†Xinjiangchelyidae?

Pleurodira (side-necked turtles)

Pan‑Cryptodira

†Sinemydidae+†Xinjiangchelyidae?

Cryptodira (hidden-neck turtles)

Pan-Trionychia (soft-shelled and pig-nosed turtles)

Pan-Testudinoidea (tortoises, pond turtles/terrapins, etc)

Pan-Chelonioidea (sea turtles, possibly including †Protostegidae)

Pan-Kinosternoidea (musk turtles, hickatee, etc)

Chelydridae (snapping turtles)

References

References

  1. C.-F. Zhou; M. Rabi (2015). "A sinemydid turtle from the Jehol Biota provides insights into the basal divergence of crown turtles". Scientific Reports. 5 16299. Bibcode:2015NatSR...516299Z. doi:10.1038/srep16299. PMC 4639786. PMID 26553740.
  2. "Sinemydidae". Fossilworks. Retrieved 17 December 2021.
  3. Gentry, Andrew D.; Kiernan, Caitlín R.; Parham, James F. (June 2023). "A large non-marine turtle from the Upper Cretaceous of Alabama and a review of North American "Macrobaenids"". The Anatomical Record. 306 (6): 1411–1430. doi:10.1002/ar.25054. ISSN 1932-8486. PMID 37158131.
  4. Miller, Eve; Lee, Hiu Wai; Abzhanov, Arkhat; Evers, Serjoscha W. (August 2024). "The topological organization of the turtle cranium is constrained and conserved over long evolutionary timescales". The Anatomical Record. 307 (8): 2713–2748. doi:10.1002/ar.25356. ISSN 1932-8486.
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