Archaeonassa fossulata Fenton et Fenton, 1937

Description. Straight to sinuous traces having a median groove flanked by rounded ridges. The flanking ridges are very well developed, and locally display an undulating morphology. In cross-sectional view the median groove commonly displays a V-shaped morphology. Trace width is 6.2-11.6 mm. Maximum length observed is 91.2 mm. Preserved as positive epirelief in fine- to very fine-grained sandstone.
Remarks. The ichnotaxonomic status of Archaeonassa is still uncertain (see discussion in Buckman, 1994; Yochelson and Fedonkin, 1997). A single ichnospecies, Archaeonassa fossulata , is known. It is interpreted as a grazing trace (pascichnion) produced by a wide variety of invertebrates, including arthropods and mollusks (Buckman, 1994; Yochelson and Fedonkin, 1997).