Psephophorus Temporal range: Oligocene - Pliocene
Skull (LACM 162552) of P. sp. at the Natural History Museum of Los Angeles County
Scientific 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 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 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 [ edit ]

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 [ edit ]

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 [ edit ]

• 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 Kohler 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 [ edit ]

• List of organisms named after famous people (born 1900?1949)
• Archelon
• Gigantatypus
• Largest prehistoric animals

References [ edit ]

Further reading [ edit ]

• Callaway, Jack M.; Nicholls, Elizabeth L. Ancient Marine Reptiles .
• Nielsen, Eigil (1959). "Eocene Turtles from Denmark" (PDF) . Bulletin of the Geological Society of Denmark . 14 (2): 96?114.
• Wieland, G. R. (1900). "Some Observations on Certain Well-Marked Stages in the Evolution of the Testudinate Humerus" . American Journal of Science . Series 4. 9 (54): 413?424 [p. 421]. doi : 10.2475/ajs.s4-9.54.413 .
• Hay, O. P. (1898). "On Protostega, the Systematic Position of Dermochelys, and the Morphogeny of the Chelonian Carapace and Plastron" . The American Naturalist . 32 (384): 929?948. doi : 10.1086/277069 . S2CID   86769103 .

External links [ edit ]

• "geosites.dk" .
• "zipcodezoo.com" .
• "paleodb.org" .
• "www.taxonomy.nl" .
• "web.usal.es" . Archived from the original on 2007-06-23.
• "www.charleston.net" . Archived from the original on 2007-06-26.