titanichthys

from The Century Dictionary.

• noun An extinct genus of arthrodiran fishes, of the family Coccosteidæ. with very large cranial shield and much reduced edentulous, probably hornsheathed jaw-elements. The dorsomedian plate is without an inferior longitudinal keel and is deeply emarginate in front. The antero- and postero-dorsolaterals are fused, articulated to the cranial shield by a long hinge, and overlapped by the large claviculars. The genus is found in the Cleveland shale (Upper Devonian) of Ohio.