The type specimen is UCLAVP 3686, a skull recovered from the Lower Permian Arroyo Formation (Texas, United States).

[1] UCLA VP 3686 was originally described by Olson (1985) as a larval "trematopsid" (now called 'trematopids').

This identification was challenged by Dilkes (1991), who noted that the construction of the naris was different from that of trematopids, implying convergence on this feature.

Schoch (2002) briefly noted that the specimen was "clearly an amphibamid ['amphibamiform' in the current framework].

[1] Schoch & Milner (2014) list six characters in their diagnosis of N. macrorhinus: (1) naris extending posterior to the septomaxilla, with the shape of a sideways '8'; (2) narrow interorbital distance; (3) large postfrontal; (4) frontal twice as wide anteriorly as it is posteriorly; (5) large denticle field extending onto the base of the cultriform process; (6) slender basipterygoid process of the pterygoid extending onto the basal plate of the parasphenoid.