The earliest fossils of
Acronichthys are known from late Turonian-aged deposits in the
Kaiparowits Plateau of Utah, US. They are also known from the
Santonian-aged
Iron Springs Formation of Utah & the
Milk River Formation of Alberta, Canada, the
Campanian-aged
Belly River Group of Alberta & the
Aguja Formation of Texas, US, and the
Maastrichtian-aged
Hell Creek Formation of Montana, the
Lance Formation of Wyoming, and the
Scollard Formation of Alberta. Aside from the Scollard Formation specimens (which represent articulated skeletons), all other records of
Acronichthys are of isolated vertebra. Some vertebra of
Acronichthys appear different from those of the species
A. maccagnoi, suggesting that other species also existed. == References ==