Acrocephalaspis vs Asaphellus

Acrocephalaspis is an extinct genus of Cambrian trilobites placed in the family Acrocephalitidae and generally treated within the order Ptychopariida. Its known material includes species from Cambrian rocks in Kazakhstan and the Avalonian cover of Cape Breton Island. The genus is distinguished by a raised or inflated median area on the preglabellar field, a curved anterior border, and a relatively...

Asaphellus is an extinct genus of asaphid trilobites from the Ordovician Period. Its fossils are widely reported from Gondwana and regions that were once situated near Gondwana, including parts of North Africa. Because the genus occurs in several geographically separated marine basins, its distribution has been used in comparisons of Ordovician faunas and in regional biostratigraphic correlation.