A NOTE ON THE TRILOBITE GENUS DIXIPHOPYGE

Recovery of the first nearly complete thoracopygon of the trilobite ge nus Dixiphopyge Brezinski from the Chouteau Formation of central Misso uri aids in evaluating the paleoecology and taxonomic affinities of th is genus. Dixiphopyge is an isopygous trilobite, suboval in outline, a nd possessing nine thoracic segments. At the apex of each axial ring i s a hollow tubercle that may represent the base of a short spine. Dixi phopyge inhabited muddy biostrome environments. In an enrolled positio n Dixiphopyge is interpreted to have looked somewhat like a porcupine with its spines radiating outward, presumably to inhibit its consumpti on by predators. Previous subfamily assignment of Dixiphopyge in the O tarioninae with Cyphaspis and Namuropyge may have been incorrect, beca use the latter two genera possess broad preglabellar fields and are mi cropygous.