Crocodiles

Nile Crocodile

Crocodilia
Fossil range: Triassic - Recent
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Order: Crocodilia, Owen, 1842
Suborders: Eusuchia, Protosuchia †, Mesosuchia †, Sebecosuchia †, Thalattosuchia †

Crocodilia is an order of large reptiles that appeared about 220 million years ago. They are the closest living relatives of birds, as the two groups are the only survivors of the Archosauria.[1]

Spelling

The group is often spelled 'Crocodylia' for consistency with the genus Crocodylus Laurenti, 1768. However, Richard Owen used the -i- spelling when he published the name in 1842, so by the usual rules of scientific classification his name has priority. In any case, the -i- spelling is a more accurate Latinization of the Greek κροκόδειλος (krokodeilos, literally "pebble-worm", referring to the shape and texture of the animal).

Evolution

When their extinct species and stem group are examined, crocodylians prove to have been a very diverse and adaptive group of reptiles. Not only are an ancient group of animals, at least as old as the dinosaurs, they also evolved into a great variety of forms. The earliest forms, the Sphenosuchians, evolved during the Late Triassic, and were highly gracile terrestrial forms built like greyhounds. Several terrestrial species during the Cretaceous evolved herbivory, such as Simosuchus clarki and Chimaerasuchus paradoxus. During the Jurassic and the Cretaceous marine forms in the family Metriorhynchidae such as Metriorhynchus evolved forelimbs that were paddle-like and had a tail similar to modern fish. Dakosaurus andiniensis a closely related species to Metriorhynchus had a skull that was adapted to eat large marine reptiles.

Eusuchia, a modern clade which includes the crown group Crocodylia, first appeared in the Lower Cretaceous of Europe. The recently-described fossil, Isisfordia duncani, lived approximately 95 to 98 million years ago, during the Cenomanian epoch of the Upper Cretaceous. Isisfordia is the second oldest known eusuchian, and the earliest crocodylian yet found in Australia. Eusuchians underwent a mass radiation during the Late Cretaceous and the Paleogene, in which they evolved into numerous forms, such as semi-aquatic dinosaur-eating species (Deinosuchus); hooved, terrestrial carnivores (Pristichampus), and 'hatchet'-shaped skulled forms (Baru).

In popular Culture

• Several science fiction movies have giant crocodilians as their stars, such as Lake Placid, DinoCroc, and the crocodile series.

Extinct species

• Superorder Crocodylomorpha
  
  • (unranked) Sphenosuchia
    
    • Family Terrestrisuchidae
      Family Sphenosuchidae
  • (unranked) Crocodyliformes
    
    • Family Shartegosuchidae
    • (unranked) Protosuchia
      • Family Protosuchidae
    • (unranked) Mesoeucrocodylia
      
      • Family Hsisosuchidae
        Family Gobiosuchidae
      • Suborder Thalattosuchia
        
        • Family Teleosauridae
          Family Metriorhynchidae
      • Suborder Metasuchia
        
        • (unranked) Notosuchia
          
          • Family Notosuchidae
            Family Sebecosuchidae
            Family Baurusuchidae
        • (unranked) Neosuchia
          
          • Family Trematochampsidae
            Family Peirosauridae
            Family Atoposauridae
            Family Dyrosauridae
            Family Pholidosauridae
            Family Goniopholididae
          • Family Paralligatoridae
            • (unranked) Eusuchia (see below)

Modern species

• (unranked) Eusuchia
  
  • Genus Hylaeochampsa (extinct)
  • Genus Allodaposuchus (extinct)
    
    • Genus Borealosuchus (extinct)
      Genus Pristichampsus (extinct)
    • Superfamily Gavialoidea
      • Family Gavialidae
        
        • Genus Gavialis - Gharial/Gavial
          Genus Tomistoma - False Gharial/Gavial
    • Superfamily Crocodyloidea
      
      • Family Mekosuchidae (extinct)
      • Family Crocodylidae
        • Subfamily Crocodylinae - Crocodiles
    • Superfamily Alligatoroidea
      
      • Family Nettosuchidae (extinct)
      • Family Alligatoridae
        
        • Subfamily Alligatorinae - Alligators
        • Subfamily Caimaninae - Caimans

Links

• http://www.il-st-acad-sci.org/kingdom/rept007.html
• http://www.il-st-acad-sci.org/kingdom/rept007a.html
• Before Crocodiles, the Hairless Coyote
• Florida's Museum of Natural History's Crocodilians Natural History & Conservation site
• International Crocodile Rescue
• Mikko's Phylogeny Archive Crocodyliformes

This guide is licensed under the GNU Free Documentation License. It uses material from the Wikipedia.

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