Lower Mississippian dendroid graptolites of Missouri.
Understanding the paleoclimate of the Rheic Ocean at the beginning
of the Mississippian Period, throughout the Kinderhookian, will help
determine the spatial and temporal limits of the dendroid Graptolite Dictyonema within Missouri. The paleoclimate is understood through the
interpretation of the lithology of the Kinderhookian, specifically the
Chouteau group limestones and shales. Current geologic map data from the
DNR and previous literature on the Chouteau and Graptolites in Missouri
forms the foundation from which the author built the structure of this
research. Hundreds of hours of field work tracked down Dictyonema blairi
Gurley (flabelliform morphology) and D. shelbini Lewis n. sp.
(infundibuliform morphology) throughout the upper Chouteau group of late
Kinderhookian. Dictyo-nema seems to have lived throughout the Upper
Chouteau and was deposited in the following Fm(s) after death in atleast
the Northview of Southwestern Missouri, the Sedalia of Central Missouri,
the Chouteau undifferentiated and possibly the McCraney Ls of
Northeastern Missouri. Random sampling of the above formations indicated
that certain zones within them were more likely to contain Dictyonema.
The silty limey mudstones or limestones of the Undifferentiated
Chouteau/ McCraney seem to contain more whole Graptolites, which may
represent the environment from which the Graptolites lived. According to
the data collected, Graptolites lived intermittently within the shallow
benthos of the epeiric sea of North America.
* Lewis, D. Independent Amateur Paleontologist.