FOSSIL FISHES OF THE EASTERN GULF LATE CRETACEOUS: WESTERN GULF AND ATLANTIC ASSEMBLAGES ADMIXED WITH A HINT OF GONDWANA

Fossil fishes are abundant and diverse in the eastern Gulf Coastal Plain (Georgia to eastern Mississippi) in early Santonian through late Maastrichtian deposits. Most known taxa also occur in the western Gulf assemblages, especially as known from Texas, and in central Atlantic assemblages best known from New Jersey and North Carolina. However, there are novel occurrences, including some with closest relations in Gondwana. Geographically, the eastern Gulf comprises the meeting of southern Atlantic pericontinental marine waters with the Interior Seaway, reflected in the detrital lithofacies in eastern Alabama and western Georgia and chalky carbonates in western Alabama and Mississippi. Chronologically, the rich fossil fish assemblages bridge the Santonian through mid-Maastrichtian interval, which is largely unrepresented as a continuous sequence elsewhere on the continent, revealing several anomalies and oddities

The known eastern Gulf assemblage includes 23 selachian taxa dominated by lamnoid sharks and sclerorhynchid sawfish, and 12 osteichthyan taxa with diverse morphologies and affinities. Several important taxa were first described or had first North American occurrences recognized in the eastern Gulf, including a Gondwanan shark, Squalicorax yangaensis and pycnodont, Phacodus punctosus; a miniscule sawfish, Borodinopristis schwimmeri; a giant coelacanth, Megalocoelacanthus dobiei; and a second species of large predatory teleost, Xiphactinus vetus.