Psephophorus

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Psephophorus
Temporal range: Oligocene-Pliocene
250px
Shell
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Sauropsida
Order:
Testudines
Suborder:
Cryptodira
Family:
Dermochelyidae
Genus:
†Psephophorus

von Meyer, 1847
Type species
†P. polygonus[1]
Species
  • †P. polygonus
  • †P. calvertensis
  • †P. eocaenus
  • †P. oregonesis
  • †P. californiensis
  • †P. terrypratchetti
  • †P. rupeliensis
  • †P. scaldii

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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.[2] It was first named by Hermann von Meyer in 1847, and contains seven species, P. polygonus, P. calvertensis, P. eocaenus, P. oregonesis,[3] P. californiensis,[4] P. rupeliensis,[5] P. scaldii,[5] and a species discovered in 1995,[2][6] P. terrypratchetti.

Psephophorus is the only Miocene dermochelyid turtle found in Europe.[7] One species of Psephophorus could measure up to ten feet in length.[8]

Discovery and identification

Von Meyer originally called Psephophorus "Jahrbuch" in 1846. 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.[1]

In 1879, Professor 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.[1] 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."[1] Seeley examined some bone fragments and concluded the specimen was that of a reptilian creature,[1] furthermore a chelonid. It also proved to be more closely related to Sphargis than any other type in the Chelonian order.[1]

Relation to modern Leatherback sea turtles

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

  • Psephophorus polygonus is the type species, and was discovered by von Meyer in 1846.[1] Fossils of the species have shown bony, carapacial ridges, adjacent, small and polygonal bony ossicles which measure about 22 x 25 mm.[10] When the ossicles extend further along the longitudinal axis, their size increases up to an average of 33 x 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.[4]
  • In 1995, Richard Köhler found a specimen of the Psephophorus genus in New Zealand, which proved to be different from the species which had been found in Europe, Egypt, and the United States.[2] It was then declared a new species altogether, and Köhler named the species Psephophorus terrypratchetti after the author Terry Pratchett, who wrote a series of fantasy books set on a world carried on the back of a giant turtle.[6][unreliable source?][15]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.0 2.1 2.2 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 Proceedings; page 8. By the Zoological Society of London; published 1891. Retrieved on June 28th, 2008.
  6. ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ A Manual of Palaeontology; page 1091. By Henry Alleyne Nicholson and Richard Lydekker; published 1889, Blackwood. Retrieved on June 28th, 2008.
  9. ↑ 9.0 9.1 Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ 10.0 10.1 10.2 Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ 11.0 11.1 Lua error in package.lua at line 80: module 'strict' not found.[dead link]
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ 13.0 13.1 Journal of Paleontology; page 279. The Society of Economic Paleontologists and Mineralogists; published March 1974. Retrieved on June 27th, 2008.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Curiosities of Biological Nomenclature

External links

Further reading

  • Jack M. Callaway and Elizabeth L. Nicholls, Ancient Marine Reptiles.
  • Nielsen, Eigil (1959) Eocene Turtles from Denmark. Bulletin of the Geological Society of Denmark 14 (2): 96-114.
  • American Journal of Science; page 421. Edited by Benjamin Silliman; published Published 1900, Converse.
  • The American Naturalist; page 933. By the American Society of Naturalists; published 1898.
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