Mid-Cretaceous molluscan record from west-central New Mexico

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.