Mid-Cretaceous molluscan record from west-central New Mexico
William A. Cobban and Stephen C. Hook


Molluscan fossils are fairly abundant in most of the mid-Cretaceous rocks of west-central New Mexico The important guide fossils are reviewed and illustrated. The fossils are from the following rocks. from oldest to youngest: middle Cenomanian into lower part of upper Cenomanian, intenongued Dakota Sandstone and Mamas Shale: upper Cenomanian into lower or middle Turonian, Rio Salado Tongue of Mancos Shale; upper Cenomanian into upper Turanian or lower Coniacian, main body of Manors Shale; upper part of lower Turonian into lower part of middle Turonian. Atarque Sandstone; middle Turanian. Semilla Sandstone Member of Mancos Shale; middle Turonian into lower part of upper Turanian. Tres Hermanos Formation; upper Turonian. Juana Lopez Member of Mancos Shale, Pescado Tongue of Mancos Shale, D-Cross Tongue of Mancos  Shale, upper pan of Tres Hermanos Formation and locally part or all of Gallup Sandstone: lower Coniacian, upper part or locally all of Gallup Sandstone. Younger rocks of later Coniacian age. such as the Mulatto Tongue of the Mancos Shale. arc not treated.


  1. Cobban, William A.; Hook, Stephen C., 1989, Mid-Cretaceous molluscan record from west-central New Mexico, in: Southeastern Colorado Plateau, Anderson, Orin J.; Lucas, Spencer G.; Love, David W.; Cather, Steven M., New Mexico Geological Society, Guidebook, 40th Field Conference, pp. 247-264.

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