Pliosauroidea

Pliosauroidea is an extinct group of ancient sea reptiles called plesiosaurs. They lived from the latest Triassic to the early Late Cretaceous.

A special subgroup called Thalassophonea had short necks, big heads, and strong jaws with sharp teeth. They were great hunters in the ocean.

Unlike other plesiosaurs with long necks, pliosauroids had short necks and long heads. They had larger back flippers than front ones. They were carnivorous, meaning they ate meat. They could grow from 4 to over 10 meters long. They likely hunted fish, sharks, ichthyosaurs, and even other plesiosaurs.

Some of the biggest pliosauroids included Kronosaurus, Sachicasaurus, Monquirasaurus, and Pliosaurus. Other well-known types were Rhomaleosaurus, Peloneustes, Liopleurodon, and Macroplata. Fossils of these animals have been found in Africa, Australia, China, Europe, North America, and South America.

Name

Pliosauroidea was named by Welles in 1943. The name comes from the genus Pliosaurus, which means "more lizard" in Greek. The word Pliosaurus was created in 1841 by Richard Owen. He thought it looked like crocodilians because of their teeth.

Classification

The classification shown here is based on a study from 2011 by scientists Hilary F. Ketchum and Roger B. J. Benson.

• Suborder Pliosauroidea
  • Eurysaurus?
  • Sinopliosaurus?
  • Family Rhomaleosauridae
    • Archaeonectrus
    • Bishanopliosaurus?
    • Borealonectes
    • Eurycleidus
    • Macroplata
    • Maresaurus
    • Meyerasaurus
    • Rhomaleosaurus
    • Sthenarosaurus
    • Yuzhoupliosaurus?
  • Family Pliosauridae
    • Anguanax
    • Attenborosaurus
    • Eardasaurus
    • Gallardosaurus
    • Hauffiosaurus
    • Liopleurodon
    • Marmornectes
    • Megalneusaurus
    • Pachycostasaurus
    • Peloneustes
    • Pliosaurus
    • Rhaeticosaurus
    • Simolestes
    • Thalassiodracon
    • Subfamily Brachaucheninae
      • Brachauchenius
      • Kronosaurus
      • Luskhan
      • Makhaira
      • Megacephalosaurus
      • Monquirasaurus
      • Polyptychodon
      • Sachicasaurus
      • Stenorhynchosaurus

Pliosauroidea is a group that includes all animals more closely related to Pliosaurus brachydeirus than to Plesiosaurus dolichodeirus. Both Pliosauridae and Rhomaleosauridae are also defined in similar ways. The family tree shown here comes from the 2011 study by Ketchum and Benson.

Large pliosauroids

Some pliosauroids, all in Pliosauridae, grew very big—over 10 meters long. This made them the largest of all plesiosaurs, though some elasmosaurs were longer because of their long necks.

In 2002, a very large pliosaur was found in Mexico and called the "Monster of Aramberri". Its remains included part of a backbone and teeth. In 2006, scientists from the University of Oslo found a giant pliosaur in Svalbard, near the North Pole. This was shown on a History TV show called Predator X. In 2009, an even bigger pliosaur was found near Weymouth, in Dorset, on Britain’s Jurassic Coast. In 2023, another very complete pliosaur skull was found on the Dorset coast and was featured in a PBS documentary with David Attenborough.