Sauropterygia

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Sauropterygia

Sauropterygia ("lizard

Lizard

Lizards are a large and widespread group of squamate reptiles, with nearly 5,000 species, ranging across all continents except Antarctica as well as most oceanic island chains....
flipper

Flipper

Flipper may refer to:In entertainment:*Film and television series featuring the intelligent bottlenose dolphin named Flipper:**Flipper , directed by James B....
s") is a group of very successful aquatic reptile

Reptile

Reptiles, or members of the class Reptilia, are air-breathing, cold-blooded vertebrates that have skin covered in scale as opposed to hair or feathers....
s that flourished during the Age of the Dinosaurs

Mesozoic

The Mesozoic Era is one of three Geologic time scale of the Phanerozoic eon . The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the 'Mesozoic' was 'Secondary' ....
before they became extinct. They are united by a radical adaptation of their shoulder

Shoulder

In human anatomy, the shoulder joint comprises the part of the body where the humerus attaches to the scapula. The shoulder refers to the group of structures in the region of the joint....
, designed to support powerful flipper strokes. Some later sauropterygians like the pliosaur

Pliosaur

Pelvis

The pelvis or pelvic girdle is the irregular bone structure located at the base of the spine . In the adult human, it is formed by the sacrum and the coccyx, the caudal part of the axial skeleton, and a pair of hip bones, part of the appendicular skeleton or human leg....
.

earliest sauropterygians appeared about 245 million years ago (Ma), at the start of the Triassic

Triassic

The Triassic is a geologic period that extends from about 251 to 199 annum . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic....
period.

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Encyclopedia

Sauropterygia ("lizard

Lizard

Lizards are a large and widespread group of squamate reptiles, with nearly 5,000 species, ranging across all continents except Antarctica as well as most oceanic island chains....
flipper

Flipper

Reptile

Mesozoic

Shoulder

Pliosaur

Pelvis

Origins and evolution

The earliest sauropterygians appeared about 245 million years ago (Ma), at the start of the Triassic

Triassic

The Triassic is a geologic period that extends from about 251 to 199 annum . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic....
period. Early examples were small (around 60 cm), semi-aquatic lizard-like animals with long limbs (pachypleurosaur

Pachypleurosaur

Pachypleurosaurs were primitive sauropterygian reptiles that vaguely resembled aquatic lizards, and were limited to the Triassic period. They were elongate animals, ranging in size from 20 cm to about a meter in length, with small heads, long necks, paddle-like limbs, and long deep tails....
s), but they quickly grew to be several meters long and spread into shallow waters (nothosaur

Nothosaur

Nothosaurs were Triassic marine sauropterygian reptiles that may have lived like pinniped of today, catching food in water but coming ashore on rocks and beaches....
s). The Triassic-Jurassic extinction event

Triassic-Jurassic extinction event

The Triassic?Jurassic extinction event marks the boundary between the Triassic and Jurassic periods, , and is one of the major extinction events of the Phanerozoic eon, profoundly affecting life on land and in the oceans....
wiped them all out except for the plesiosaur

Plesiosaur

Plesiosaurs were carnivore aquatic reptiles. After their discovery, they were somewhat fancifully said to have resembled , although they had no shell....
s. During the Early Jurassic

Early Jurassic

The Early Jurassic epoch is the earliest of three epochs of the Jurassic period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event and ends at the start of the Middle Jurassic ....
these diversified quickly into both long-necked small-headed plesiosaurs proper, and short-necked large-headed pliosaur

Pliosaur

The Pliosaurs were Marine reptiles from the Jurassic and Cretaceous Period . They originally included members of the family Pliosauridae, of the Order Plesiosauria, but several other genera and families are now also included; the number and details of which vary according to the classification used....
s. Originally it was thought that Plesiosaurs and Pliosaurs were two distinct superfamilies that followed separate evolutionary paths. It now seems that these were simply morphotypes in that both types evolved a number of times, with some pliosaurs evolving from plesiosaur ancestors, and vice-versa.

Size and ecology

Each morphotype filled a specific ecological role. The large pliosaurs, like the Jurassic

Jurassic

The Jurassic is a geologic period that extends from about annum to Ma, that is, from the end of the Triassic to the beginning of the Cretaceous....
Rhomaleosaurus
Rhomaleosaurus

Rhomaleosaurus is an extinct genus of sauropterygian reptile belonging to the pliosaur superfamily. It was about long and lived in the Early Jurassic Period....
, Liopleurodon
Liopleurodon

'Liopleurodon' is a genus of large, Carnivore marine reptile belonging to the Pliosauroidea, a clade of short-necked plesiosaurs. Two species of Liopleurodon lived during the Callovian stage of the Middle Jurassic Period , while the third, L....
and Pliosaurus
Pliosaurus

Pliosaurus is a genus of extinct marine reptiles, from the Mesozoic era. It is included in the family Pliosauridae. It was a large predatory reptile and its diet would have included fishes, squids and other marine reptiles....
, and the Cretaceous

Cretaceous

The Cretaceous , usually abbreviated K for its German translation Kreide, is a geologic period from circa to million years ago . In the geologic timescale, the Cretaceous follows on the Jurassic period and is followed by the Paleogene period....
Kronosaurus
Kronosaurus

Kronosaurus is an extinct genus of short-necked pliosaur. It was among the largest pliosaurs, and is appropriately named after the leader of the Titan , Cronus....
and Brachauchenius
Brachauchenius

Brachauchenius is an extinct genus of pliosaur that lived in America during the Cretaceous.The type species, Brachauchenius lucasi, lived in the Western Inland Sea of North America around 93.5-89.3 million years ago, during the Turonian stage of the Cretaceous....
, were the superpredators of the Mesozoic seas, around 7 to 12 meters in length, and filled a similar ecological role to that of killer whales today. The long-necked plesiosaurs, meanwhile, included both those with medium-long necks, like the 3 to 5 meter-long Plesiosauridae and the Cryptoclididae

Cryptoclididae

Cryptoclididae is a family of medium size plesiosaurs from the Middle Jurassic to the Late Cretaceous....
, and the Jurassic and Cretaceous Elasmosauridae

Elasmosauridae

Elasmosauridae was the family of plesiosaurs. They had the longest necks of the plesiosaurs and survived from the Early Jurassic to the end of the Cretaceous....
, which evolved progressively longer and more flexible necks, so that by the middle and late Cretaceous the entire animal was over 13 meters in length (e.g. Elasmosaurus
Elasmosaurus

Elasmosaurus Greek language e?as???/elasmos = thin plate + sa????/sauros = lizard) is a genus of plesiosaur with an extremely long neck that lived in the Late Cretaceous....
), although as most of this was the neck, the actual body size was much smaller than that of the larger pliosaurs. These long-necked forms undoubtedly fed on fish, which they probably snared in their tooth-lined jaws with rapid lunges of the neck and head.

Extinction

The sauropterygians thrived throughout the Mesozoic

Mesozoic

The Mesozoic Era is one of three Geologic time scale of the Phanerozoic eon . The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the 'Mesozoic' was 'Secondary' ....
. However, despite their success they became extinct along with the non-avian dinosaurs

Dinosaur

Dinosaurs were the dominant vertebrate animals of Landform ecosystems for over 160 million years, from the late Triassic Period until the end of the Cretaceous Period , when most of them became extinct in the Cretaceous?Tertiary extinction event....
, pterosaurs

Pterosaur

Pterosaurs were flying reptiles of the clade or Order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight....
and mosasaurs

Mosasaur

Mosasaurs were serpentine marine reptiles. The first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1778. These ferocious marine predators are now considered to be the closest relatives of snakes, due to cladistic analysis of symptomatic similarities in jaw and skull anatomies....
during the end Cretaceous mass extinction.

Taxonomy

Classification

Scientific classification

Biological classification or scientific classification in biology, is a method by which biologists group and categorize species of organisms....
is difficult because the demands of the aquatic environment caused the same characteristics to evolve multiple times, illustrating convergent evolution

Convergent evolution

Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action....
. While sauropterygians are considered diapsid

Diapsid

Diapsids are a group of reptiles that developed two holes in each side of their skulls, about 300 million years ago during the late Carboniferous period....
s, they are also sometimes classified with turtle

Turtle

Turtles are reptiles of the Order Testudines , most of whose body is shielded by a special bone or cartilage animal shell developed from their ribs....
s. The bulky-bodied, mollusc-eating placodont

Placodont

Placodonts were a group of marine reptiles that lived during the Triassic period, becoming extinct at the end of the period. It is believed that they were related to the Sauropterygia, the group that includes Plesiosaurs....
s may also be sauropterygians. In addition to the modifications of the shoulder, the group is also united by several modifications in their skull

Skull

The skull is a bone structure found in the head of many animals. The skull supports the structures of the face and protects the head against injury....
s.

Class Reptilia (alternatively Sauropsida
Sauropsida

Sauropsida is a group of amniotes that includes reptiles, dinosaurs, and birds. Among amniotes, sauropsida is distinguished from theropsida , also called synapsids....
)

Infraclass Lepidosauromorpha
Lepidosauromorpha

Lepidosauromorpha is a group of reptiles comprising all diapsids closer to lizards than to archosaurs . The only living sub-group is the Lepidosauria: extant lizards, snakes, and tuatara....
(lizard
Lizard

Lizards are a large and widespread group of squamate reptiles, with nearly 5,000 species, ranging across all continents except Antarctica as well as most oceanic island chains....
s and relatives)

SUPERORDER SAUROPTERYGIA

Order Thalattosauriformes

Suborder Thalattosauria

Order Placodontia
Placodont

Placodonts were a group of marine reptiles that lived during the Triassic period, becoming extinct at the end of the period. It is believed that they were related to the Sauropterygia, the group that includes Plesiosaurs....
(unranked) Eusauropterygia

Order Nothosauroidea
Nothosaur

Nothosaurs were Triassic marine sauropterygian reptiles that may have lived like pinniped of today, catching food in water but coming ashore on rocks and beaches....

Suborder Pachypleurosauria
Pachypleurosaur

Pachypleurosaurs were primitive sauropterygian reptiles that vaguely resembled aquatic lizards, and were limited to the Triassic period. They were elongate animals, ranging in size from 20 cm to about a meter in length, with small heads, long necks, paddle-like limbs, and long deep tails....
Suborder Nothosauria
Nothosaur

Nothosaurs were Triassic marine sauropterygian reptiles that may have lived like pinniped of today, catching food in water but coming ashore on rocks and beaches....

(unranked) Pistosauroidea

Corosaurus
Chinchenia
Chinchenia

is an extinct genus of plesiosaur.See also* List of plesiosaursReferences...
Kwangsisaurus
Cymatosaurus
Cymatosaurus

is an extinct genus of plesiosaur.See also* List of plesiosaursReferences...
Family Pistosauridae
Order Plesiosauria
Plesiosauria

Plesiosauria are an Order of Mesozoic marine reptiles. They first appeared in the middle Triassic Period and became especially common during the Jurassic Period, thriving until the Cretaceous-Tertiary extinction event at the end of the Cretaceous Period....

Suborder Plesiosauroidea
Plesiosaur

Plesiosaurs were carnivore aquatic reptiles. After their discovery, they were somewhat fancifully said to have resembled , although they had no shell....
(long-necked plesiosaurs)
Suborder Pliosauroidea
Pliosaur

The Pliosaurs were Marine reptiles from the Jurassic and Cretaceous Period . They originally included members of the family Pliosauridae, of the Order Plesiosauria, but several other genera and families are now also included; the number and details of which vary according to the classification used....
(short-necked plesiosaurs)

External links

. Palaeos. July 15, 2003. Retrieved January 19, 2004.
. Adam Stuart Smith. The Plesiosaur Directory. Retrieved April 17, 2006.
- lists every species and synonyms. Retrieved February 26, 2006