Bromide Formation

is an extinct genus of large asaphid trilobites from the Middle and Late Ordovician Period, fairly common in the northeastern United States into eastern Canada. Isotelus is the state fossil of Ohio, and through multiple specimens from the 1800s into the modern day has held the title of largest trilobite fossil in the world, reaching over long. Isotelus was carnivorous and a burrower which lived in warm shallow seas, feeding on worms and other soft-bodied animals on and below the substrate. As larvae, Isotelus was planktonic, drifting in the water column with a morphology very different from 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.

Ceraurus is a genus of cheirurid trilobite of the middle and, much more rarely, the upper Ordovician. They are commonly found in strata of the lower Great Lakes region. These trilobites have eleven thoracic segments, a very small pygidium and long genal and pygidial spines.

thumb|upright|Bumastus barriensis, from the [[Silurian Wenlock series, found at Dudley, Worcestershire.]]

Illaenus is a genus of trilobites from Russia and Morocco, from the middle Ordovician.