A new otarionine trilobite from the henryhouse formation (Silurian, ludlow) of Oklahoma

Abstract

Cyphaspis wessmani new species is a morphologically aberrant taxon from the Ludlow Henryhouse Formation of south-central Oklahoma. Its long, scoop- shaped cephalic border is without close comparison in the family Aulacopleuridae, but its possession of eleven thoracic segments with an axial spine on the sixth, an inflated glabella with tiny L1 and dorsal tuberculate sculpture, a prominently expressed bilobate eye socle, and a micropygous pygidium all support assignment to Cyphaspis. The genus is common in Silurian rocks from most parts of the world, but C. wessmani is the first published record from southern Laurentia.