Ambystoma hibbardi was named by Tihen (1955) [A transformed species of Ambystoma closely related to extant A. tigrinum in size, proportions, and general features; estimated snout-vent length 100 mm; agrees with A. tigrinum in absence of diastema in vomerine tooth series at level of choana, in possession of nearly straightsided parasphenoid, and in similarity of form and proportions of vertebrae. Differs from A. tigrinum in having a narrower premaxillary spine, in (apparently) usual failure of columellar footplate to fuse with otic capsule, and in probable weak ossification of orbitosphenoids, quadrates, and ischia.]. Its type specimen is UMMP 31440, a partial skull (Posterolateral portion of a left vomer), and it is a 3D body fossil.