Ceratodus (lungfish) (seh-RAT-o-dus)
Lungfishes are freshwater fish with lungs that allow them to breathe air. This supplements the oxygen they get from the water, through their gills. Lungfish are part of an ancient fish lineage that is more closely related to humans and other land-living vertebrates than to most other types of fishes. We know they were abundant and widely distributed during the Cretaceous because because their fossils are common and have been found on all continents except Antarctica. Today, only a few species remain in Africa, South America, and northeastern Australia. The Early Cretaceous lungfish fossils from Maryland, along with similar examples from the western United States, represent some of the last lungfish species to have survived in North America. Scientists don't know yet why their range contracted so dramatically.