Chitinozoans in the Subsurface Lower Paleozoic of West Texas

Studies based on both comprehensive sample analysis and electric logs substantially facilitate dating, subdivision, and environmental interpretation of the subsurface pre-Woodford section in West Texas. Acid-insoluble chitinozoans are shown to occur in sufficient quality and quantity to aid in subdividing well sections where the rarely occurring corals, brachiopods, and ostracodes are lacking. About half of the composite cutting samples processed yielded chitinozoans.

Angochitina was found only in the Devonian. Ancyrochitina, a long-ranging (Ordovician through Devonian) genus, has distinctive species that can be utilized. A long-necked form seems prevalent at one level in the Silurian and has a widespread though rare occurrence. Conochitina and Rhabdochitina are restricted to the Middle and Upper Ordovician in West Texas. Lagenochitina and Sphaerochitina are long-ranging forms needing additional study before species are of much value in correlation. Associated acid-insoluble microfossils are graptolite siculae, scolecodonts, and acritarchs (“hystichospharid’s”).