| Gnathorhizidae | |
|---|---|
 | |
| Gnathorhiza | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Sarcopterygii |
| Class: | Dipnoi |
| Order: | Ceratodontiformes |
| Family: | †Gnathorhizidae Miles, 1977 |
| Genera | |
TheGnathorhizidae are an extinct family oflungfish that lived from the lateCarboniferous until the middleTriassic. Gnathorhizidfossils have been found inNorth America,Madagascar,Australia, and possiblyEastern Europe andSouth Africa. They are characterized by high-ridged toothplates that form cutting blades and a reduction in cranial bones.
Previously, based on morphological evidence, it was assumed that Gnathorhizidae was thesister group to theextant familiesLepidosirenidae andProtopteridae, which still live inSouth America andAfrica.[1] However, phylogenetic evidence indicates that Gnathorhizidae is abasal group of freshwater lungfish with no close extant relatives, and African and South American lungfish are most closely related toAustralian lungfish inNeoceratodontidae.[2]
Gnathorhizids are found in North America, Eastern Europe, Australia, and Africa. Gnathorhizids from North America range from theGzhelian through theRoadian. In Africa, gnathorhizids are found inOlenekian of Madagascar and possibly South Africa. Lungfishteeth attributed to gnathorhizids have been reported from theLopingian to the Olenekian in Poland and Western Russia. It is likely, then, that gnathorhizids had aPangean distribution throughout the latePaleozoic and earlyMesozoic.
Gnathorhizids are found primarily inpaleosols representingephemeralwetlands. Additionally, gnathorhizids, unlike most groups of fossil lungfish, are often found in association with regularburrow structures, suggesting this group of lungfish may haveestivated during the dry season, much like modernAfrican andSouth American lungfish.
Unlike most fossil lungfish, but again, like modern South American and African lungfish, gnathorhizids have bladelike toothplates. This suggests gnathorhizids were active predators unlike most lungfish, which feed primarily onbenthicinvertebrates.
