Crocodylia
Earliest known fossil crocodilians _ middle Triassic (~210-220 mya).
- Earliest forms were relatively small and terrestrial.
3 extant ‘families’ and 22 extant species.
- Subtropical and tropical areas around the world.
- Few species (e.g., Alligator mississipiensis) inhabits warm temperate regions.
Primarily occur in freshwater habitats.
- Some species enter brackish and marine environments.