Psephophorus

Taxobox
name = "Psephophorus"
fossil_range=Oligocene-Pliocene


image_width =
regnum = Animalia
phylum = Chordata
classis = Sauropsida
ordo = Testudines
suborkhuido = Cryptodira
familia = Dermochelyidae
genus = "Psephophorus"
genus_authority = von Meyer, 1847
type_species = †"P. polygonus"cite web |url=http://jgslegacy.lyellcollection.org/cgi/content/abstract/36/1-4/406 |title=Note on Psephophorus polygonus, v. Meyer, a new Type of Chelonian Reptile allied to the Leathery Turtle |publisher=Journal of the Geological Society, London, Legacy |date=1880 |accessdate=2008-06-27]
subdivision_ranks=Species
subdivision=
* †"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.cite web |url=http://www.rsnz.org/publish/jrsnz/1995/44.php |title=Köhler - A new species of Psephophorus |publisher=R. Köhler; "Journal of The Royal Society of New Zealand" |date=1995-09 |accessdate=2008-06-27] It was first named by Hermann von Meyer in 1847, and contains seven species, "P. polygonus", "P. calvertensis", "P. eocaenus", "P. oregonesis", [cite web |url=http://www.mailtribune.com/apps/pbcs.dll/article?AID=/20080427/LIFE/804270308/-1/LIFE01 |title=The Oregon Fossil Guy |publisher=www.mailtribune.com |date=2008-04-27 |accessdate=2008-06-28] "P. californiensis",cite web |url=http://209.85.173.104/search?q=cache:65arLJPxsl8J:www.sharktoothhill.com/sharktooth_hill_fauna.doc+Psephophorus&hl=en&ct=clnk&cd=48&gl=ca&lr=lang_en |title=Sharktooth Hill Fauna, circa 2003 |publisher=Shark Tooth Hill.com (optionally viewed as a Microsoft Word document) |date=2003 |accessdate=2008-06-28] "P. rupeliensis","Proceedings"; page 8. By the Zoological Society of London; published 1891. Retrieved on June 28th, 2008.] "P. scaldii", and a recently discovered species,cite web |url=http://everything2.com/e2node/Psephophorus%2520terrypratchetti |title=New Zealand species of "Psephophorus" |publisher=Everything2.com (partially derived from an interview with Terry Pratchett on "The Discoworld Companion") |date=2001-11-01 |accessdate=2008-06-27] "P. terrypratchetti".

"Psephophorus" is the only Miocene dermochelyid turtle found in Europe.cite web |url=http://digilander.libero.it/tulse/32ndICG2004.pdf |title=New Remains of "Psephophorus polygonus" (Chelonii: Dermochelyidae) from the Miocene of Southern Italy |publisher=digilander.libero.it |date=2004 |accessdate=2008-06-27] One species of "Psephophorus" could measure up to ten feet in length. ["A Manual of Palaeontology"; page 1091. By Henry Alleyne Nicholson and Richard Lydekker; published 1889, Blackwood. Retrieved on June 28th, 2008.]

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.

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. 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." Seeley examined some bone fragments and concluded the specimen was that of a reptillian creature, furthermore a chelonid. It also proved to be more closely-related to "Sphargis" than any other type in the Chelonian order.

Relation to modern Leatherback sea turtles

For a long time, modern Leatherback sea turtles ("Dermochelys") were believed to be descended directly from "Psephophorus",cite web |url=http://nlbif.eti.uva.nl/bis/turtles.php?selected=beschrijving&menuentry=groepen&id=36 |title=Turtles of the World |publisher=nlbif.eti.uva.nl |accessdate=2008-06-27] specifically the species "P. polygonus".cite web |url=http://www.mnhn.fr/museum/front/medias/publication/10539_g07n2a5.pdf |title=Fossil sea turtles (Chelonii, Dermochelyidae and Cheloniidae) from the Miocene of Pietra Leccese (late Burdigalian-early Messinian), Southern Italy |date=2007 |accessdate=2008-06-27] 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. The platelets on "Psephophorus" are quite similar to those on "Dermochelys", despite differences in outer morphology and size.cite web |url=http://hss.ulb.uni-bonn.de/diss_online/math_nat_fak/2007/scheyer_torsten/teil5.pdf |title=Bone histological results of Testudinata |publisher=hss.ulb.uni-bonn.de |accessdate=2008-06-27] The platelet comprises an external compact layer and an internal zone of cancellous bone.

pecies

*"Psephophorus polygonus" is the type species, and was discovered by von Meyer in 1846. Fossils of the species have shown bony, carapacial ridges, adjacent, small and polygonal bony ossicles which measure about 22 x 25 mm. When the ossicles extend further along the longitudinal axis, their size increases up to an average of 33 x 41 mm.
*"Psephophorus calvertensis" was first named by Palmer in 1909. [cite web |url=http://paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=83314 |title="Psephophorus calvertensis" at the Paleobiology Database. |publisher=paleodb.org |accessdate=2008-06-27] It was so named for being found in the Calvert Formation."Journal of Paleontology"; page 279. The Society of Economic Paleontologists and Mineralogists; published March 1974. Retrieved on June 27th, 2008.] "P. calvertensis" is a rarely-found specimen.
*"Psephophorus eocaenus" was first named by Andrews in 1901. [cite web |url=http://paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=86268&is_real_user=0 |title="Psephophorus eocaenus" at the Paleobiology Database. |publisher=paleodb.org |accessdate=2008-06-27]
*"Psephophorus californiensis" was first named by Gilmore in 1937.
*In 1995, Robert Kohler 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. It was then declared a new species altogether, and because Kohler was a fan of Terry Pratchett,Verify credibility|date=June 2008 he named the species "Psephophorus terrypratchettii" after him. Pratchett considered it an honor.Verify credibility|date=June 2008

References

External links

* [http://geosites.dk/themes/macro_vertebrate/mv_gram_lergrav/index.html geosites.dk]
* [http://zipcodezoo.com/Key/Psephophorus_Genus.asp zipcodezoo.com]
* [http://paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=36369&is_real_user=0 paleodb.org]
* [http://www.taxonomy.nl/taxonomicon/TaxonTree.aspx?id=48464 www.taxonomy.nl]
* [http://web.usal.es/~geologia/Studia/30.html web.usal.es]
* [http://www.charleston.net/news/2007/jun/15/scientists_dig_rare_fossil/?print www.charleston.net]

Further reading

*Jack M. Callaway and Elizabeth L. Nicholls, "Ancient Marine Reptiles".
*"Bulletin of the Geological Society of Denmark" p. 99 - 108. Published 1958 Geological Society of Denmark.
*"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.