Article · Wikipedia archive · Last revised Jun 19, 2026

Hadrianus (turtle)

Hadrianus is an extinct genus of tortoise belonging to the Testudinidae found in the United States, the Yolomécatl Formation of Mexico, the Alai Beds of Kyrgyzstan and Spain and believed to be the oldest true tortoise known. The genus is thought to be closely related to the genus Manouria. The genus may have evolved in the subtropics of Asia and subsequently migrated to North America and Europe. Evangelos Vlachos (2018) reassessed the North American species attributed to the genus, and determined only two as accepted namely H. corsoni & H. majusculus. The remaining species were identified as either junior synonyms, moved to other genera or considered nomen dubium due to incomplete fossils.

Last revised
Jun 19, 2026
Read time
≈ 1 min
Length
342 w
Citations
9
Source
Wikipedia ↗
Hadrianus
Temporal range: Eocene1
"Hadrianus majusculus"
Hadrianus majusculus
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Clade: Pantestudinoidea
Superfamily: Testudinoidea
(unranked): †Pantestudinidae
Genus: †Hadrianus
Cope, 187221
Species
  • H. corsoni
  • H. majusculus

Hadrianus is an extinct genus of tortoise belonging to the Testudinidae1 found in the United States, the Yolomécatl Formation of Mexico, the Alai Beds of Kyrgyzstan and Spain and believed to be the oldest true tortoise known.3 The genus is thought to be closely related to the genus Manouria.3 The genus may have evolved in the subtropics of Asia and subsequently migrated to North America and Europe.3 Evangelos Vlachos (2018) reassessed the North American species attributed to the genus, and determined only two as accepted namely H. corsoni & H. majusculus. The remaining species were identified as either junior synonyms, moved to other genera or considered nomen dubium due to incomplete fossils.4

Taxonomy

The species 'Testudo' sharanensis is hypothesized to actually be a species of Hadrianus.5

  • Hadrianus corsoni (Leidy, 1871)
    • Synonyms Emys carteri Leidy, 1871; Testudo hadriana Cope, 1871; Hadrianus quadratus Cope, 1871; Hadrianus octonaria Cope, 1871; Hadrianus tumidus Hay 1908; Hadrianus robustus Gilmore, 1915; Hadrianus utahensis Gilmore, 1915; Geochelone gilmorei Auffenberg, 1974
  • Hadrianus majusculus Hay, 1904

Nomen dubium

  • "Hadrianus allabiatus" Cope, 1871

Moved species

  • "Hadrianus schucherti" Hay, 1899 moved to Cymatholcus schucherti (Hay, 1899)
References

References

  1. "Fossilworks: Hadrianus". fossilworks.org. Retrieved 17 December 2021.
  2. E. D. Cope. 1872. Second account of new Vertebrata from the Bridger Eocene. Proceedings of the American Philosophical Society (separate) 1-3
  3. Ehret, Dana Joseph 2004 "Skeletochronology as a method of aging Oligocene Gopherus laticuneus and Stylemys nebrascensis, using Gopherus polyphemus as a modern analog" Thesis, University of Florida.
  4. Vlachos, E (2018). "A Review of the Fossil Record of North American Turtles of the Clade Pan-Testudinoidea". Bulletin of the Peabody Museum of Natural History. 59 (1): 3. doi:10.3374/014.059.0101. hdl:11336/117896. ISSN 0079-032X. S2CID 214641639.
  5. Chroust, Milan; Szczygielski, Tomasz; Luján, Àngel H. (2025-10-03). "Manouria morla sp. nov., the Ancient One: an Early Miocene large tortoise from the Swamps of Ahníkov, Czechia". Swiss Journal of Palaeontology. 144 (1): 63. doi:10.1186/s13358-025-00400-6. ISSN 1664-2384.