Article: Osteology of the Palaeocene teleost Esox tiemani
The Palaeocene pike Esox tiemani combines many typically esocid features such as an elongate body depressible and canine teeth, elongate snout and jaws, almost straight preopercle, small second and third hypurals separated by a gap, large ethmoid process on the ectopterygoid, and anteriorly lobed scales with other features in which it is intermediate between Recent umbrids and esocids. Branchiostegal rays are almost equally divided between the ceratohyal and epihyal, while in Recent umbrids they are more numerous on the ceratohya and in Recent esocids they are more numerous on the epihyal. The opercle of E. tiemani has a prominent dorsolateral flange that probably covered part of the insertion of the levator operculi muscle. The flange is largei in umbrids and virtually absent in Recent esocids, in which much of the insertion for the levator operculi is on the dorsolateral surface of the opercle.