Ossinodus pueri (Warren and Turner 2004, Warren 2007; Viséan, Lower Carboniferous) was orignally considered close to Whatcheeria. Here it nests between Trimerorhachis and Acanthostega. The presence of an intertemporal appears likely.
Distinct from sister taxa, the maxilla is deep and houses twin canine fangs. A third fang arises from the palatine. Distinct from Acanthostega, the skull is flatter, the naris is larger. The tabular is not hook-shaped. These are traits shared with Tiktaalik.