Psephophorus
Encyclopedia
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
. It was first named by Hermann von Meyer in 1847, and contains seven species, P. polygonus, P. calvertensis, P. eocaenus, P. oregonesis, P. californiensis, P. rupeliensis, P. scaldii, and a recently discovered species, P. terrypratchetti.
Psephophorus is the only Miocene
dermochelyid turtle found in Europe. One species of Psephophorus could measure up to ten feet in length.
, which contained seventy bone
s.
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 Armadillo
es." 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.
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. The platelet comprises an external compact layer and an internal zone of cancellous bone.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of sea turtle
Sea turtle
Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...
that lived from the Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
to the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
. Its remains have been found in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
. It was first named by Hermann von Meyer in 1847, and contains seven species, P. polygonus, P. calvertensis, P. eocaenus, P. oregonesis, P. californiensis, P. rupeliensis, P. scaldii, and a recently discovered species, P. terrypratchetti.
Psephophorus is the only Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
dermochelyid turtle found in Europe. One species of Psephophorus could measure up to ten feet in length.
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 carapaceCarapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
, which contained seventy bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
s.
In 1879, Professor H.G. Seeley
Harry Seeley
Harry Govier Seeley was a British paleontologist.-Career:Seeley was born in London, the son of Richard Hovill Seeley, goldsmith, and his second wife Mary Govier. He attended classes at the Royal School of Mines, Kensington before becoming an assistant to Adam Sedgwick at the Woodwardian Museum,...
was asked to study the Psephophorus specimen by Franz Ritter von Hauer
Franz Ritter von Hauer
Franz Ritter von Hauer, or Franz von Hauer , was an Austrian geologist.-Biography:Hauer was born in Vienna, the son of Joseph von Hauer , who was equally distinguished as a high Austrian official and authority on finance and as a palaeontologist.He was educated in Vienna, afterwards studied...
, 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 Armadillo
Armadillo
Armadillos are New World placental mammals, known for having a leathery armor shell. Dasypodidae is the only surviving family in the order Cingulata, part of the superorder Xenarthra along with the anteaters and sloths. The word armadillo is Spanish for "little armored one"...
es." 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
Chelonian
Chelonian has multiple, interrelated meanings:*Green turtle*Chelonia, the superorder uniting turtles, tortoises and terrapins with the "proto-turtle" Australochelys*Chelonians, monsters from Doctor Who...
order.
Relation to modern Leatherback sea turtles
For a long time, modern Leatherback sea turtles (Dermochelys) were believed to be descended directly from Psephophorus, specifically the species P. polygonus. However, a 1996 analysis by Wood et al. proved that most of the taxa in the two generaGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
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
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
and size. The platelet comprises an external compact layer and an internal zone of cancellous bone.
Species
- Psephophorus polygonus is the type speciesSpeciesIn biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, 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. It was so named for being found in the Calvert Formation. P. calvertensis is a rarely found specimen.
- Psephophorus eocaenus was first named by Andrews in 1901.
- Psephophorus californiensis was first named by Gilmore in 1937.
- In 1995, Robert Kohler found a specimen of the Psephophorus genus in New ZealandNew ZealandNew Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, which proved to be different from the species which had been found in EuropeEuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, EgyptEgyptEgypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
, and the United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
. It was then declared a new species altogether, and because Kohler was a fan of Terry PratchettTerry PratchettSir Terence David John "Terry" Pratchett, OBE is an English novelist, known for his frequently comical work in the fantasy genre. He is best known for his popular and long-running Discworld series of comic fantasy novels...
, he named the species Psephophorus terrypratchettiPsephophorus terrypratchettiPsephophorus terrypratchetti is a species of Eocene turtle identified from the fossil record. It is named after the author Terry Pratchett who wrote a series of fantasy books set on a world carried on the back of a giant turtle....
after him. Pratchett considered it an honor.
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.