Crocodylia (Including Crocodiles and Alligators)


The order Crocodylia contains the sole reptilian survivors of the Archosauria, which also included the dinosaurs. Understanding the biology, natural history and evolution of the living crocodylians is critical to appreciate fully their place in nature.

Keywords: alligator; caiman; crocodile; gharial; evolution

Figure 1.

American alligator (Alligator mississippiensis). Photo courtesy of L. D. Densmore.

Figure 2.

Broad‐snouted caiman (Caiman latirostris). Photo courtesy of L. D. Densmore.

Figure 3.

Two interpretations of relationships among the eight genera of living Crocodylia. (a) Phylogenetic tree based on morphological analyses with Gavialis distinct and basal to all other crocodylians. (b) Phylogenetic tree based on molecular analyses with Tomistoma and Gavialis as sister taxa.


Further Reading

Brazaitis P (1973) The identification of living crocodilians. Zoologica 58: 59–101.

Brochu CA (1997) Morphology, fossils, divergence timing, and the phylogenetic relationships of Gavialis. Systematic Biology 46: 479–521.

Buffetaut E (1979) The evolution of the crocodilians. Scientific American 1979(Oct): 130–139.

Densmore LD (1983) Biochemical and immunological systematics of the order Crocodilia. Evolutionary Biology 16: 397–465.

Hecht MK and Malone B (1972) On the early history of the gavialid crocodilians. Herpetologica 28: 281–284.

McIlhenney EA (1935) The Alligator's Life History. Boston, MA: The Christopher Publishing House.

Neill WT (1971) The Last of the Ruling Reptiles. New York: Columbia University Press.

Poe S (1996) Data set incongruence and phylogeny of crocodilians. Systematic Biology 45: 393–414.

Ross CA (ed.) (1989) Crocodiles and Alligators. New York: Facts on File.

Ross JP (ed.) (1998) Crocodile – Status Survey and Conservation Action Plan, 2nd edn. Cambridge, UK: IUCN/SSC Publications.

Steel R (1973) Crocodylia. In: Kuhn O (ed.) Handbuch der Palaeoherpetologie 16: 1–116. Portland, OR: Fischer‐Verlag.

Tarsitano SF, Frey E and Reiss J (1989) The evolution of the Crocodilia: A conflict between morphological and biochemical data. American Zoologist 29: 843–856.

Thorbjarnarson JB (1996) The reproductive characteristics of the order Crocodylia. Herpetologica 52: 8–24.

Vliet K (1989) Social displays of the American alligator (Alligator mississippiensis). American Zoologist 29: 1019–1031.

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How to Cite close
Densmore, Llewellyn D(May 2001) Crocodylia (Including Crocodiles and Alligators). In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0001544]