Cambrian United States

The Drumian is a stage of the Miaolingian Series of the Cambrian. It succeeds the Wuliuan and precedes the Guzhangian. The base is defined as the first appearance of the trilobite Ptychagnostus atavus around million years ago. The top is defined as the first appearance of another trilobite Lejopyge laevigata around million years ago.

Paradoxides is a genus of large to very large trilobite found throughout the world during the Middle Cambrian period. One record-breaking specimen of Paradoxides davidis, described by John William Salter in 1863, is . The cephalon was semicircular with free cheeks ending in long, narrow, recurved spines. Eyes were crescent shaped providing an almost 360° view, but only in the horizontal plane. Its elongate thorax was composed of 19–21 segments and adorned with longish, recurved pleural spines. Its pygidium was comparatively small. Paradoxides is a characteristic Middle-Cambrian trilobite of th

Lingulella is a genus of phosphatic-shelled brachiopod. It is known from the Middle Cambrian Burgess Shale (Canada) to the Upper Ordovician Bromide Formation (United States) in North America. 346 specimens of Lingulella are known from the Greater Phyllopod bed, where they comprise 0.66% of the community.

Plectronoceras is the earliest known shelled cephalopod, dating to the Late Cambrian. None of the fossils are complete, and none show the apex or aperture of the shell. Approximately half of its shell was filled with septa; 7 were recorded in a shell. Its shell contains transverse septa separated by about half a millimetre, with a siphuncle on its concave side. Its morphology matches closely to that hypothesised for the last common ancestor of all cephalopods.