Elpistostege

Elpistostege Temporal range: Frasnian PreꞒ Ꞓ O S D C P T J K Pg N
Elpistostege watsoni on display at the Miguasha National Park
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Sarcopterygii
Clade:	Tetrapodomorpha
Clade:	Stegocephali
Family:	†Elpistostegidae
Genus:	†Elpistostege Westoll, 1938
Species:	†E. watsoni
Binomial name
†Elpistostege watsoni Westoll, 1938

Elpistostege is an extinct genus of finned tetrapodomorphs that lived during the Frasnian age of the Late Devonian epoch. Its only known species, E. watsoni, was first described in 1938 by the British palaeontologist Thomas Stanley Westoll, based on a single partial skull roof discovered at the Escuminac Formation in Quebec, Canada.^[1]

In 2010, a complete specimen was found in the same formation, which was described by Richard Cloutier and colleagues in 2020. It reveals that the paired fins of Elpistostege contained bones homologous to the phalanges (digit bones) of modern tetrapods; it is the most basal tetrapodomorph known to possess these bones. At the same time, the fins were covered in scales and lepidotrichia (fin rays), which indicates that the origin of phalanges preceded the loss of fin rays, rather than the other way around.^[2][3]

Relationships

An analysis conducted by Swartz in 2012 found Elpistostege to be the sister taxon of Tiktaalik. Both were found to be primitive members of the group Elpistostegalia, along with other advanced stem-tetrapods.^[4]

The 2020 study by Cloutier et al. instead recovers Elpistostege as the sister taxon of all limbed vertebrates, crownward of Tiktaalik:^[2]

References

External links

• Elpistostege at Palaeos
• History of Elpistostege
• Recent Discovery of an entire well-preserved fossil of Elpistostege watsoni

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Tetrapodomorpha (Pan-Tetrapoda)

Kingdom: Animalia Phylum: Chordata Clade: Osteichthyes Clade: Sarcopterygii Clade: Rhipidistia
Gnathostomata see Gnathostomata Tetrapodomorpha see below↓

Tetrapodomorpha
Tetrapodomorpha †Bogdanovia †Chrysolepis †Geptolepis †Glyptopomus †Gogonasus †Greiserolepis †Gyroptychius †Harajicadectes †Kenichthys †Litoptychus †Lamprotolepis †Latvius †Medoevia †Megadonichthys †Muranjilepis †Osteolepis †Peregrina †Platyethmoidia †Shirolepis †Thaumatolepis †Thursius †Tungsenia †Viluichthys †Rhizodontida Archichthys Aztecia Barameda Gooloogongia Hongyu Letognathus Propycnoctenion Pycnoctenion Rhizodus Rossichthys Sauripterus Screbinodus Strepsodus Thysanolepis? Vorobjevaia? †Canowindridae Beelarongia Canowindra Koharalepis Marsdenichthys? Owensia? †Megalichthyidae Askerichthys Cladarosymblema Cryptolepis? Ectosteorhachis Lohsania? Mahalalepis Megalichthys Megapomus? Megistolepis? Palatinichthys Rhizodopsis Sengoerichthys Sterropterygion? Eotetrapodiformes †Palaeospondylus? †Tristichopteridae Bruehnopteron Cabonnichthys Callistipterus Canningius Devonosteus Edenopteron Eusthenodon Eusthenopteron Heddleichthys Hyneria Jarvikina Langlieria Litoptychus? Mandageria Marsdenichthys? Notorhizodon Platycephalichthys Spodichthys Tinirau Tristichopterus Elpistostegalia †Howittichthys? †Livoniana †Panderichthys †Parapanderichthys †Qikiqtania †Rubrognathus †Tiktaalik Stegocephali (Tetrapoda sensu lato) see below↓

Stegocephali (Tetrapoda sensu lato)
Stegocephali †Acanthostega †Brittagnathus †Densignathus †Elpistostege? †Hynerpeton †Ichthyostega †Jakubsonia †Metaxygnathus †Parmastega †Sinostega †Tulerpeton †Tutusius †Umzantsia †Ventastega †Ymeria †Elginerpetontidae Elginerpeton Obruchevichthys Webererpeton †Aistopoda Andersonerpeton Lethiscus Ophiderpeton Oestocephalidae Coloraderpeton Oestocephalus Phlegethontioidea Pseudophlegethontia Phlegethontiidae Phlegethontia Sillerpeton †Whatcheeriidae Ossinodus? Pederpes Whatcheeria †Colosteidae Colosteus Deltaherpeton Greererpeton Pholidogaster †Adelospondyli Acherontiscus Adelogyrinidae Adelogyrinus Adelospondylus Dolichopareias Palaeomolgophis †"Nectridea" see Nectridea †Baphetoidea Eucritta? Spathicephalus Baphetidae Baphetes Kyrinion Loxomma Megalocephalus †Other post- Devonian genera Antlerpeton Aytonerpeton Crassigyrinus Diploradus Doragnathus Ichthyerpeton Koilops Mesanerpeton Occidens Ossirarus Perittodus Sigournea Tantallognathus †Embolomeri Anthracosaurus Archeria Aversor Calligenethlon Carbonoherpeton "Cricotus" Diplovertebron Eobaphetes Eoherpeton? Leptophractus Neopteroplax Palaeoherpeton Papposaurus Pholiderpeton Proterogyrinus Pteroplax Seroherpeton Spondylerpeton †Gephyrostegidae Bruktererpeton Eusauropleura Gephyrostegus †Other "anthracosaurs" Caerorhachis Casineria? Eldeceeon Eoherpeton Silvanerpeton Termonerpeton Tetrapoda (crown group) Temnospondyli (Batrachomorpha?) see Temnospondyli likely includes Lissamphibia Reptiliomorpha (Pan-Amniota) see Reptiliomorpha includes Amniota

Related topics
Paraphyletic / Polyphyletic groups Stem tetrapoda Osteolepiformes Osteolepididae Megalichthyiformes? Tristichopteridae? Labyrinthodontia Rachitomi Ichthyostegalia Lepospondyli Holospondyli Phyllospondyli Anthracosauria Other topics Evolution of tetrapods Polydactyly in stem-tetrapods Romer's gap Timeline Zachelmie trackways

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