Sauropterygia 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 an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...

. However, despite their success they became extinct along with the non-avian dinosaurs

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

, pterosaur

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...

s and mosasaur

Mosasaur

Mosasaurs are large extinct marine lizards. The first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764...

s during the end Cretaceous mass extinction.

Taxonomy

Classification 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. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...

. 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. Living diapsids are extremely diverse, and include all crocodiles, lizards, snakes, and tuatara...

s, they are also sometimes classified with turtle

Turtle

Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...

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 part of 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 bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...

s.

• Class Reptilia (alternatively Sauropsida
  Sauropsida
  Sauropsida is a group of amniotes that includes all existing reptiles and birds and their fossil ancestors, including the dinosaurs, the immediate ancestors of birds...
  
  )
  • 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 widespread group of squamate reptiles, with nearly 3800 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 part of Sauropterygia, the group that includes Plesiosaurs...
        
        
      • (unranked) Eusauropterygia
        • Order Nothosauroidea
          Nothosaur
          Nothosaurs were Triassic marine sauropterygian reptiles that may have lived like seals of today, catching food in water but coming ashore on rocks and beaches. They averaged about in length, with a long body and tail. The feet were paddle-like, and are known to have been webbed in life, to help...
          
          
          • 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. The...
            
            
          • Suborder Nothosauria
            Nothosaur
            Nothosaurs were Triassic marine sauropterygian reptiles that may have lived like seals of today, catching food in water but coming ashore on rocks and beaches. They averaged about in length, with a long body and tail. The feet were paddle-like, and are known to have been webbed in life, to help...
            
            
        • (unranked) Pistosauroidea
          • Chinchenia
            Chinchenia
            Chinchenia is an extinct genus of pistosauroid....
            
            
          • Corosaurus
            Corosaurus
            Corosaurus is an extinct genus of pistosauroid known from Wyoming of the USA.-Description:Corosaurus is known from the holotype UW 5485, a partial skeleton which includes the skull...
            
            
          • Cymatosaurus
            Cymatosaurus
            Cymatosaurus is an extinct genus of pistosauroid sauropterygian. It is known from Early Triassic to the Middle Triassic period of Germany....
            
            
          • Kwangsisaurus
          • Family Pistosauridae
          • Order Plesiosauria
            Plesiosauria
            Plesiosauria is an order of Mesozoic marine reptiles. Plesiosaurs first appeared in the Early Jurassic Period and became especially common during the Jurassic Period, thriving until the K-T extinction at the end of the Cretaceous Period.The name "plesiosaur" is used to refer to the order...
            
            
            • Suborder Plesiosauroidea
              Plesiosaur
              Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
              
               (long-necked plesiosaurs)
            • Suborder Pliosauroidea
              Pliosaur
              Pliosauroidea is an extinct clade of marine reptiles. Pliosauroids, also commonly known as pliosaurs, are known from the Jurassic and Cretaceous Periods. The pliosauroids were short-necked plesiosaurs with large heads and massive toothed jaws. These swimming reptiles were not dinosaurs but distant...
              
              (short-necked plesiosaurs)

External links

• Unit 220: 100: Lepidosauromorpha. Palaeos. July 15, 2003. Retrieved January 19, 2004.
• A review of the Sauropterygia. Adam Stuart Smith. The Plesiosaur Directory. Retrieved April 17, 2006.
• Paleofile taxalist - lists every species and synonyms. Retrieved February 26, 2006