Cheirolepis trailli (Agassiz 1835; Middle Devonian, 390 mya; 30-55?cm in length) is considered one of the earliest actinopterygian (ray-finned) fish with 'standard' dermal skull bones. Those bones are homologous with those of sarcopterygian fish, like Eusthenopteron and Osteolepis (above right) and tetrapods, like Ichthyostega. The series of small rostral bones will fuse to become the nasal in tetrapods. The maxilla will become much shallower, the rostrum will lengthen.
In Cheirolepis, now the basal taxon in this study, the orbit is far forward. The jaws opened at right angles to form a large gape. The pineal opening pierces the interfrontal. Bony gill covers are present. The pectoral fins are lobed and muscular, but the hind fins are not. The pelvis and dorsal fins are large and broad-based. The tail is heterocercal, like a shark's tail. The body is deep and broad anteriorly, narrower posteriorly.
The homology of the tabular and postparietal are questionable here, so two solutions are shown.