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Psephophorus

Psephophorus is an extinct genus of sea turtle that lived from the Oligocene to the Pliocene. Its remains have been found in Europe, Africa, North America, and New Zealand.[1] It was first named by Hermann von Meyer in 1847, and contains seven species, P. polygonus, P. calvertensis, P. eocaenus, P. oregonesis,[2] P. californiensis,[3] P. rupeliensis,[4] P. scaldii,[4] and a species discovered in 1995,[1][5] P. terrypratchetti.

Psephophorus
Temporal range: Oligocene-Pliocene
Skull (LACM 162552) of P. sp. at the Natural History Museum of Los Angeles County
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Superfamily: Chelonioidea
Family: Dermochelyidae
Genus: †Psephophorus
von Meyer, 1847
Type species
†P. polygonus
Species
  • †P. polygonus
  • †P. calvertensis
  • †P. eocaenus
  • †P. oregonesis
  • †P. californiensis
  • †P. terrypratchetti
  • †P. rupeliensis
  • †P. scaldii

Psephophorus is the only Miocene dermochelyid turtle found in Europe.[6] One species of Psephophorus could measure up to ten feet in length.[7]

Discovery and identification

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Shell

Von Meyer originally named Psephophorus in 1846.[8] At first he was unable to identify the creature beyond its dermal plates, but when he later received a drawing he was able to describe the specimen, which was then in Pressburg, as a fragment of a carapace, which contained seventy bones.[8]

In 1879, H. G. Seeley was asked to study the Psephophorus specimen by Franz Ritter von Hauer, the Director of the Austro-Hungarian Imperial and Royal Geological Survey.[8] Up until then, the specimen's identity had been undeterminable, with even Seeley describing it at first to seem like "the dermal covering of an Edentate closely allied to the Armadilloes."[8] Seeley examined some bone fragments and concluded the specimen was that of a reptilian creature,[8] furthermore a chelonid. It also proved to be more closely related to Sphargis than any other type in the Chelonian order.[8]

Relation to modern Leatherback sea turtles

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For a long time, modern Leatherback sea turtles (Dermochelys) were believed to be descended directly from Psephophorus,[9] specifically the species P. polygonus.[10] However, a 1996 analysis by Wood et al. proved that most of the taxa in the two genera were not connected, meaning Psephophorus could not be a direct ancestor of the modern leatherbacks.[9] The platelets on Psephophorus are quite similar to those on Dermochelys, despite differences in outer morphology and size.[11] The platelet comprises an external compact layer and an internal zone of cancellous bone.[11]

Species

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restoration of Psephophorus californiensis based on morphological descriptions
 
Hypothetical reconstruction of Psephophorus terrypratchetti
  • Psephophorus polygonus is the type species, and was discovered by von Meyer in 1846.[8] Fossils of the species have shown bony, carapacial ridges, adjacent, small and polygonal bony ossicles which measure about 22 × 25 mm.[10] When the ossicles extend further along the longitudinal axis, their size increases up to an average of 33 × 41 mm.[10]
  • Psephophorus calvertensis was first named by Palmer in 1909.[12] It was so named for being found in the Calvert Formation.[13] P. calvertensis is a rarely found specimen.[13]
  • Psephophorus eocaenus was first named by Andrews in 1901.[14]
  • Psephophorus californiensis was first named by Gilmore in 1937.[3]
  • Psephophorus terrypratchetti was discovered in the 1990s by Richard Köhler in New Zealand and named in 1995 after the author Terry Pratchett, who wrote a series of fantasy books set on a world carried on the back of a giant turtle.[1] This species reached 2.3–2.5 m (7.5–8.2 ft) in body length which is more than 80% bigger than P. eocaenus.[1]

See also

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References

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  1. ^ a b c d Kohler, R. (September 1995). "A new species of the fossil turtle Psephophorus (Order Testudines) from the Eocene of the South Island, New Zealand". Journal of the Royal Society of New Zealand. 25 (3): 371–384. doi:10.1080/03014223.1995.9517495. Archived from the original on 4 October 2021.
  2. ^ "The Oregon Fossil Guy". www.mailtribune.com. 2008-04-27. Retrieved 2008-06-28.
  3. ^ a b "Sharktooth Hill Fauna, circa 2003". Shark Tooth Hill.com (optionally viewed as a Microsoft Word document). 2003. Archived from the original on 2012-12-09. Retrieved 2008-06-28.
  4. ^ a b Proceedings; page 8. By the Zoological Society of London; published 1891. Retrieved on June 28th, 2008.
  5. ^ "New Zealand species of Psephophorus". Everything2.com (partially derived from an interview with Terry Pratchett on The Discworld Companion). 2001-11-01. Retrieved 2008-06-27.
  6. ^ "New Remains of Psephophorus polygonus (Chelonii: Dermochelyidae) from the Miocene of Southern Italy" (PDF). digilander.libero.it. 2004. Retrieved 2008-06-27.
  7. ^ Henry Alleyne Nicholson; Richard Lydekker (1889). A Manual of Palaeontology. p. 1091.{{cite book}}: CS1 maint: multiple names: authors list (link)
  8. ^ a b c d e f g Seeley, H. G. (1880). "Note on Psephophorus polygonus, v. Meyer, a new Type of Chelonian Reptile allied to the Leathery Turtle". Quarterly Journal of the Geological Society. 36 (406–413): 406–413. doi:10.1144/GSL.JGS.1880.036.01-04.32. S2CID 131226091.
  9. ^ a b "Turtles of the World". nlbif.eti.uva.nl. Archived from the original on 2011-06-08. Retrieved 2008-06-27.
  10. ^ a b c "Fossil sea turtles (Chelonii, Dermochelyidae and Cheloniidae) from the Miocene of Pietra Leccese (late Burdigalian-early Messinian), Southern Italy" (PDF). 2007. Archived from the original (PDF) on 2009-04-19. Retrieved 2008-06-27.
  11. ^ a b "Bone histological results of Testudinata" (PDF). hss.ulb.uni-bonn.de. Retrieved 2008-06-27. [dead link‍]
  12. ^ "Psephophorus calvertensis at the Paleobiology Database". paleodb.org. Retrieved 2008-06-27.
  13. ^ a b Weems, Robert E. (1974). "Middle Miocene sea turtles (Syllomus, Procolpochelys, Psephophorus) from the Calvert Formation". Journal of Paleontology. 48 (2): 279–303.
  14. ^ "Psephophorus eocaenus at the Paleobiology Database". paleodb.org. Retrieved 2008-06-27.

Further reading

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