Article: Two new cornutes from the lower Ordovician of Shropshire and southern France

Two new cornutes, Chauvelicystis vizcainoi sp. nov., and Prochauvelicystis semispinosa gen. et sp. nov. are described. C. vizcainoi, from the lower Ordovician (Lower Arenig) of the South of France, has previously been synonymized with Chauvelicystis spinosa Ubaghs, 1969, and is shown to be the sister taxon of C. ubaghsi (Chauvel, 1966). Prochauvelicystis semispinosa is found in the Tremadoc stage (lowest Ordovician) of Shropshire, England, It is the smallest known cornute, and has spines along the right marginals of the head and fixed extensions of the marginal plates forming horizontal appendages on the left side of the head. The spines and appendages are for support on a soft substrate and prevention of movement in an unwanted direction during locomotion. It is the most primitive member of the new subfamily Chauvelicystinae.