Metamorphosis is absent in the Proteidae, leading to a number of paedomorphic features in adults. The premaxilla consists of separated, paired bones. Maxillary bones are absent. Bilaterally paired septomaxillary bones are absent. Lacrimal bone is absent.
Quadratojugal bone is absent.
Pterygoid bones are present. An internal carotid foramen is present in the parasphenoid bone. The angular bone is fused to the mandible. Ear bones include a detached columella but no operculum. Replacement of vomerine teeth proceeds laterally in parallel to the maxillary teeth.