CHONDRICHTHYANS AND OSTEICHTHYANS FROM A TURONIAN–CONIACIAN LAG DEPOSIT BETWEEN THE GALLUP SANDSTONE–MULATTO TONGUE (MANCOS SHALE), SANDOVAL COUNTY, NEW MEXICO, USA WITH COMMENTS ON COEVAL LAGS IN THE WESTERN INTERIOR SEAWAY

A lag deposit between the Gallup Sandstone and Mulatto Tongue of the Upper Cretaceous Mancos Shale in Sandoval County, New Mexico, USA, contains an assemblage of Turonian–Coniacian chondrichthyans and osteichthyans. This assemblage consists primarily of isolated teeth that derive from at least 17 taxa including: Hybodus sp.; Ptychodus mortoni; Scapanorhyncus raphiodon; Protolamna sp.; Cretodus semiplicatus; Cretodus crassidens; Cretalamna appendiculata; Dallasiella sp.; Squalicorax falcatus; Ischyrhiza mira; Ptychotrygon triangularis; Pseudohypolophus mcnultyi; Rhinobatos sp.; Chondrichthyes indet.; Pycnodontiformes indet.; Protosphyraena sp.; Enchodus cf. E. petrosus; Pachyrhizodus sp.; and Osteichthyes indet. The Gallup Sandstone–Mulatto Tongue lag was deposited along a series of outer shoreface sandbars in the southeastern corner of the San Juan Basin during eustatic sea-level fluctuation in the late Turonian–early Coniacian. This sea-level event and the concentration of chondrichthyans and osteichthyans into lag deposits are also recorded at several other localities within the Western Interior Seaway. These stratigraphic properties have correlative potential across basins, regions, and seaways that provide a framework by which intra- and inter-basin eustatic sea-level events can be interpreted. Differences in coeval faunas found within these Turonian–Coniacian lags are bathymetrically controlled, related to the degree of taphonomic reworking, and the proximity of the ancestral shoreline.