Protopterus dolloi (Boulenger 1900, Criswell 2015) is the spotted or slender lungfish from the Congo River in Africa. This obligate air-breather has an eel-like body with slender fins. Crushing teeth are present in the pterygoid and prearticular. The premaxilla, maxillla and circumorbital bones, if present (based on the adult Neoceratodus) are restored here in the small Digimorph.org image. Juveniles have dentaries, but adults do not.

Neceratodus forsteri (Kreft = Krefft 1870; 150cm) is the extant Australian lungfish. Here the smaller skull includes no premaxilla, maxilla, quadrate and circumorbital bones. This informs the situation in Protopterus (above).

Dipnorhynchus sussmilchi (originally Ganorhynchus sussmilchi, Etheridge 1906; Early to Late Devonian; up to 90cm in length) is a primitive lungfish with tooth plates on the palate and mandible. The skull bones were subdivided on this derived taxon.

Uranolophus wyomingensis (Denison 1968; FMNJ PF 3805, 3792; Early to Late Devonian) is a flat-head lungfish with large pterygoid micro-tooth plates. The premaxilla was transverse. See below for a museum mount with a pronounced overbite.

Janusiscus schultzei (Giles et al. 2015; Early Devonian, 415 mya) was considered a possible ancestor to Chondrichthyes (sharks, etc.) or Osteichthyes (bony fish, etc.) or both. Here tiny Janusiscus nests is compared to the coeval flathead lungfish, Uranolophus. Is it a juvenile form? Or a primitive form? Too little is known to answer either question.

Dipterus valenciennesi (Sedgwick & Murchison, 1828; Middle Devonian; 35cm long) was similar in most respects to Howipterus with shorter, stouter lateral fins and a smaller second dorsal fin. The tetrapod homologs of the skull bones are labeled differently here than in Uranolophus (above). Not sure which is correct. Here the intertemporal and supratemporal are larger as they anchor powerful crushing jaw muscles, whereas the parietals would house the small brain.

Thompson, Sutton and Thomas 2003 attempted to show Palaeospondylus was a larval Dipterus needing a bit of metamorphosis. In the LRT Palaeospondylus nested with the torpedo ray, Torpedo (= Tetronarce).

Howidipterus donnae (Long 1992; NMV P181884; Middle Devonian) is a primitive lungfish with large medial fins. The pectoral and pelvic fins are not known. Howidipterus nests with Polypterus in the LRT. Note the many subdivided bones of the skull, typical of lungfish. The lateral teeth are absent. The pterygoid developed a tooth plate. The dentary is not visible laterally, where the splenial, angular and surangular overlap it. The squamosal is tiny.