RECENT ADVANCES IN UNDERSTANDING THE LATE TRIASSIC VERTEBRATE FAUNA OF THE DEEP RIVER BASIN (NEWARK SUPERGROUP: CHATHAM GROUP), NORTH CAROLINA

Vertebrate fossils obtained from artificial outcrops (quarries) and screenwashing have substantially increased the known diversity of fossil assemblages from the Deep River basin in North Carolina of late Carnian-early Norian age. Rich assemblages are now known from the Pekin and Cumnock formations in the Sanford sub-basin, with microvertebrates also adding to the known diversity of “Lithofacies Association II.” The richest Pekin Formation locality yields semionotids, coelacanthids, temnospondyls, a rhynchosaur, phytosaurs, a rauisuchian, two new aetosaurs, a new crocodylomorph, dicynodonts, and the traversodont cynodont Boreogomphodon. A diverse microvertebrate assemblage from the overlying Cumnock Formation yields redfieldiids, semionotids, Arganodus (a lungfish), temnospondyls, Colognathus, lepidosaurs, phytosaurs, a rauisuchian, the venomous archosauriform Uatchitodon schneideri, Revueltosaurus olseni, Boreogomphodon, and the dromatheriid Microconodon. Fragmentary fossils from the Cumnock Formation in the Wadesboro sub-basin include redfieldiids, the lungfish Arganodus, metoposaurid temnospondyls, and phytosaur skulls with associated postcrania. The Sanford Formation yields few taxa, principally osteichthyans, temnospondyls, phytosaurs, and traversodontids. The stratigraphically enigmatic “Lithofacies Association II” (Durham sub-basin) yields the paleonisciform Turseodus, redfieldiids, additional Arganodus-grade lungfish and an exceedingly rare record (for the Newark Supergroup) hybodont shark (aff. Lissodus), in addition to the poposaur Postosuchus, the sphenosuchian Dromicosuchus, the traversodont Boreogomphodon (=Plinthogomphodon) and an aetosaur. Although some taxa are endemic, many of Deep River vertebrates are closely related to taxa known from western North America, Africa, and Europe, and some are only found as extremely small fossils that may represent dwarfed species. Aetosaurs, Postosuchus, sphenosuchians, and revueltosaurs are all fully terrestrial animals that are comparatively rare in other Newark Supergroup basins. Developing microvertebrate assemblages has greatly increased the known diversity, providing the first records of lungfish, hybodonts, Revueltosaurus, Uatchitodon, and Colognathus from the Deep River basin.