This is a view to Lower Triassic Union Wash Formation strata at Union Wash; the noted Neopopanoceras ammonoid zone occurs in the vicinity of this area. Note fossil seeker, for scale, at lower right.

Ammonoid species described from the Neopopanoceras zone include Neopopanoceras haugi, Keyserlingites pacificus, Goricanites noblei, Pseudacrochordiceras inyoense, Eodanubites (Dumitricaceras) judae, Courtilloticeras stevensi, Inyoceras bittneri, Courtilloticeras stevensi, Hungarites vatesi, Paranannites oviformis, Trilolites pacifica, Keyserlingites (sp.), Acrochorduceras inyoense, Xenodiscus bittneri and Xenodiscus multicamaratus. In addition to the ammonoids, a few other fossil varieties have also been described from the Neopopanoceras horizon. These include an orthocone nautiloid cephalopod related to Orthoceras sp., pelecypods, and several species of conodonts--minute tooth-like structures, unrelated to modern jaws, that served as a feeding apparatus in an extinct lamprey eel-like organim (seen only in the insoluble residues of Union Wash limestones treated with dilute acetic acid).