Low diversity Selachian assemblage from the Upper Cretaceous Greenhorn Limestone, Socorro County, New Mexico
— Spencer G. Lucas and Justin A. Spielmann

We document a selachian assemblage from the Bridge Creek Member of the Greenhorn Limestone near the town of Carthage in Socorro County, New Mexico (sec. 8, T5S, R2E). This fossil assemblage occurs within the Sciponoceras gracile ammonite zone of late Cenomanian age. Specimens of Ptychodus dominate the assemblage, with a single blade-shaped tooth that can be identified as Squalicorax sp. Ptychodus specimens belong to P. occidentalis and P. anonymous and further confirm their presence in upper Cenomanian strata. The low diversity and Ptychodus domination of the Carthage selachian assemblage may reflect a relatively deep water, offshore paleoenvironment, though the allochthonous nature of the assemblage hinders definitive paleoenvironmental interpretation.