Plesiosaurus (Greek: plesios, near to + sauros, lizard) was a large (about 3 to 5 meters long), marine Sauropterygian reptile that lived during the early part of the Jurassic period, and is known by nearly complete skeletons from the Lias of England and Germany. It was distinguished by its small head, long and slender neck, broad turtle like body, a short tail, and two pairs of large, elongated paddles. It lends its name to a larger group of reptiles as a whole Plesiosauria, of which it is an early but fairly typical member. Groups ?Placodontia Pachypleurosauridae Nothosauridae    Plesiosauria Sauropterygia (lizard flippers) is a group of very successful aquatic reptiles that flourished during the Age of the Dinosaurs before they became extinct. ... Orders See text. ... The Jurassic period is a major unit of the geologic timescale that extends from about 200 Ma (million years ago) at the end of the Triassic to 146 Ma at the beginning of the Cretaceous. ... Lias may refer to: Lias, the lower Jurassic period which saw much deposition of clay followed by limestone. ... Families Cryptoclididae Elasmosauridae Plesiosauridae Pliosauridae Plesiosaurs (PLEE-see-oh-SORES) were large, carnivorous aquatic reptiles. ...

Discovery

Plesiosaurus was one of the first of the "antediluvian reptiles" to be discovered (by Mary Anning), and excited great interest in Victorian England. It was so-named ("more lizard") by William Conybeare, to indicate that it was more like a normal reptile than Ichthyosaurus, which had been found in the same rock strata just a few years previously. Mary Anning. ... Queen Victoria (shown here on the morning of her Accession to the Throne, June 20, 1837) gave her name to the historic era. ... William Daniel Conybeare (June 7, 1787 - August 12, 1857), dean of Llandaff, one of the most distinguished of English geologists, who was born in London, was a grandson of John Conybeare, bishop of Bristol (1602-1785), a notable preacher and divine, and son of Dr William Conybeare, rector of Bishopsgate. ... Groups Cymbospondylus Mixosauridae Merriamosauria Shastasauridae/Shastasauria Euichthyosauria Parvipelvia Leptonectidae Thunnosauria Stenopterygidae Ichthyosauridae Ichthyosaurs (Greek for fish lizards) were giant marine reptiles that resemble a dolphin with teeth (see convergent evolution). ...

Description

The snout is short, but the mouth was able to open very wide, and the jaws are provided with a series of conical teeth in sockets, much like those of the living gavial. The neck is long and slender, but seems to have been rather stiff, because the vertebrae are nearly flat-ended, which indicates that it could not have been bent in the swan-fashion represented in many old restorations. The other vertebrae are similarly almost flat-ended and firmly united, and there is no sacrum. The ribs are single-headed, and in the middle of the trunk, between the supports of the paired limbs, they meet a dense plastron of abdominal ribs. The short tail is straight and rapidly tapering, Binomial name Gavialis gangeticus (Gmelin, 1789) Taxonomy The Gharial (Gavialis gangeticus) is the only surviving member of the family Gavialidae, a long-established group of crocodile-like reptiles with long, narrow jaws. ... Image of pelvis. ...

The pectoral and pelvic girdles which support the paired limbs are greatly expanded, the pectoral arch being similar to the corresponding bones of turtles.

The limbs are elongated paddles, with five complete digits, although each consists of a very large number of phalanges. Some traces of skin discovered suggest that it was smooth, not scaly. The phalanges in a human hand The name Phalanges is commonly given to the bones that form fingers and toes. ...

Lifestyle

Plesiosaurus was exclusively marine, feeding on belemnites, fishes and other prey. It propelled itself by the paddles, the tail being too short to be of much use. Extinct Orders Aulacocerida Phragmoteuthida Belemnitida Diplobelida Belemnoteuthina Belemnites (or belemnoids) are an extinct group of marine cephalopod, very similar in many ways to the modern squid and closely related to the modern cuttlefish. ...

Species

At one time, Plesiosaurus was a wastebin taxon used to describe any Mesozoic plesiosaur of generally similar appearance. More recently there has been a number of revisions in sauropterygian taxonomy, and many species previously included here have been moved to other genera and families. Only two species are unambiguiously recognised. A term used in taxonomic circles that refers to a taxon that has the sole purpose of holding on to things that dont fit anywhere else. ... Families Plesiosaurs (IPA ) (Greek: plesios, near to + sauros, lizard) were large, carnivorous aquatic reptiles. ... In biology, a genus (plural genera) is a taxonomic grouping. ... In biological classification, family (Latin: familia, plural familiae) is 1) a rank or 2) a taxon in that rank. ...

Plesiosaurus dolichodeirus is the type species, known from the Lower Lias (Sinemurian) of Lyme Regis, which was about three metres long. Other plesiosauria from the same formation seem to have measured five to six metres in length. Type specimens When a new species is discovered, more important than creating a new and unique name for the species is developing a reasonably detailed description. ... The Sinemurian is a stage of the Early Jurassic Epoch. ... Location within the British Isles The Cobb, with boats grounded in the harbour at low tide. ... Families Cryptoclididae Elasmosauridae Plesiosauridae Pliosauridae Plesiosaurs (PLEE-see-oh-SORES) were large, carnivorous aquatic reptiles. ...

Plesiosaurus guilelmiimperatoris is known from a large almost complete skeleton from the Upper Lias (Toarcian) of Wurttemberg. There seems to be the impression of a rhomboidal flap of skin in a vertical plane; if so, many plesiosaurs may have been equipped in this way. The Toarcian Stage was the last faunal stage of the Early Jurassic period. ... Württemberg (often spelled Wurttemberg in English) refers to an area and a former state in Swabia, a region in south-western Germany. ...

Reference

• Richard Owen, Fossil Reptili of the Liassic Formations, pt iii. (Monogr. Palaeont. Soc., 1865)

Sir Richard Owen and Dinornis bird skeleton Sir Richard Owen (July 20, 1804 - December 18, 1892) was an English biologist, comparative anatomist and palaeontologist. ...

External links

• Plesiosauroidea - Palaeos
• Plesiosauria – Mikko's Phylogeny Archive

This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain. Encyclopædia Britannica, the 11th edition The Encyclopædia Britannica Eleventh Edition (1910–1911) is perhaps the most famous edition of the Encyclopædia Britannica. ... The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ...