Quick Identification Gallery

Alligator mississippiensis (Daudin, 1801)

(collection of Robert Sheridan)

Taxonomic Index

Kingdom Animalia

Phylum Chordata

Subphylum Vertebrata

Class Reptilia

Subclass Diapsida

(Crocodiles, Crocodylians, Alligators, and Alligatoroids)

• Order Choristodera (Semiaquatic Reptiles)
  • Family Champsosauridae
    • Champsosaurus laramiensis Brown (Montana) 
• Infraclass Archosauromorpha
  • Superorder Crocodylomorpha
    • Order Crocodyliformes
      • Suborder Mesoeucrocodylia
        • Infraorder Eusuchia
          • Group Crocodylia
            • Group Alligatoroidea
              • Deinosuchus rugosus (Emmons)  (Mexico) 
              • Leidyosuchus Lambe sp. (Montana) 

• Classification scheme is based on:  Schwimmer, D. R.  2002.  King of the Crocodylians.  The Paleobiology of Deinosuchus.  Bloomington & Indianapolis:  Indiana University Press, 220 pp (see p. 138).
• The modern concept of the Cretaceous Crocodyliformes is intriguing.  Like dinosaurs, the classification of this ancient group has outgrown the usefulness of the Linnéan classification system.  We've tried to accommodate this in the index.
• Schwimmer points out that groupings below infraorders are not assigned labels (p. 138), so we've listed them simply as "group ...".
• Both Leidyosuchus and Deinosuchus are commonly referred to as crocodiles.  However, as Schwimmer explains in his book, Deinosuchus (applies to Leidyosuchus as well) is not closely related to modern crocodiles or alligators, and is more properly referred to as a "basal crocodylian", inclusive of early gavialoids, crocodyloids, and alligatoroids.