Micropaleontology of the Gulfian of the Davis Mountain front

Rocks of Gulfian age composed principally of marl and impure limestone crop out along the northern and eastern front of the Davis Mountains. Evidence obtained through a study of the Foraminifera and Ostracoda indicates that units, equivalent to the Eagle Ford, Austin, and Taylor Groups of northern and central Texas, are present. No paleontological indication of a Navarro equivalent was found.

A foraminiferal fauna consisting of 16 families, 36 genera, and 81 species was found. The Order Ostracoda is represented by 2 sub-orders, 3 families, 6 genera, and 17 species. Four new species of Foraminifera and two new species of Ostracoda are described. The foraminiferal fauna is characterized by a large number of individuals, particularly pelagic forms, but a small number of species. Many of the planktonic and nektonic forms exhibit a comparatively long stratigraphic range.

Names are proposed for the lithic and paleontologic divisions of the series.

The types of sediments and the contained fossils indicate that deposition and accumulation took place nearshore in the warm shallow water of a normal marine sea. A notable exception is the "Pena Negra" Formation where the evidence indicates restricted environment.