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]
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).
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).
This guide is licensed under the GNU Free Documentation License. It uses material from the Wikipedia.
Need an webmaster? Click HERE
English
Română
Comments