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Caerorhachis Temporal range: Early Carboniferous 340 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Life restoration of Caerorhachis bairdi
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Sarcopterygii
Clade:	Tetrapodomorpha
Clade:	Stegocephali
Genus:	†Caerorhachis Holmes and Carroll, 1977
Species
†C. bairdi Holmes and Carroll, 1977 (type)

Caerorhachis (meaning "suitable spine" in Greek) is an extinct genus of early tetrapod from the Early Carboniferous of Scotland, probably from the Serpukhovian stage. Its placement within Tetrapoda is uncertain, but it is generally regarded as a primitive member of the group. The type species C. bairdi was named in 1977.

Classification

Caerorhachis has usually been placed as a basal anthracosaur or a close relative of anthracosaurs. In this classification, Caerorhachis is a close ancestor of amniotes, or tetrapods that lay eggs on land. Caerorhachis has also been classified as the sister taxon of temnospondyls, a large group of extinct amphibians, based on the presence of several primitive traits. In fact, when it was named in 1977, Caerorhachis was thought to be a dendrerpetontid temnospondyl.

The vertebrae of Caerorhachis are more similar to anthracosaurs, however. As in all early tetrapods, the centrum, or central part of the vertebra, is composed of two parts: the intercentrum and the pleurocentrum. While temnospondyls have large intercentra and small pleurocentra, Caerorhachis and anthracosaurs have larger pleurocentra than intercentra. A 2003 phylogenetic analysis of early tetrapods placed Caerorhachis outside the clade that included temnospondyls and anthracosaurs in an ancestral position to both groups.

Paleobiology

Caerorhachis is thought to have had a primarily terrestrial lifestyle. It lacks the lateral lines across the skull that served as an adaptation for earlier aquatic tetrapods and their ancestors. The large, well developed limbs suggest it was able to move on land better than other early tetrapods like colosteids and baphetids. Robert Holmes and Robert L. Carroll, the first to describe Caerorhachis, interpreted it as " animal spending much of its life in the damp mud on the margins of ponds or streams, feeding on stranded fish, or occasionally venturing into the water to catch aquatic larvae of other amphibians."

References

1. Ruta, M.; Coates M.I.; Quicke D.L.J. (2003). "Early tetrapod relationships revisited" (PDF). Biological Reviews. 78 (2). Cambridge Philosophical Society: 262. doi:10.1017/s1464793102006103. PMID 12803423. Archived from the original (PDF) on 22 May 2008. Retrieved 3 December 2012.
2. ^ Holmes, R.; Carroll, R. (1977). "A temnospondyl amphibian from the Mississippian of Scotland". Bulletin of the Museum of Comparative Zoology. 147: 489–511.
3. Ruta, M.; Milner, A.R.; Coates, M.I. (2001). "The tetrapod Caerorhachis bairdi Holmes and Carroll from the Lower Carboniferous of Scotland" (PDF). Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 92 (3): 229–261. doi:10.1017/S0263593300000249.
4. Clack, J.A. (2002). Gaining ground: the origin and evolution of tetrapods. Indiana University Press. p. 369. ISBN 978-0-253-34054-2.
5. Ruta, M.; Jeffery, J. E.; Coates, M. I. (2003). "A supertree of early tetrapods". Proceedings of the Royal Society B. 270 (1532): 2507–16. doi:10.1098/rspb.2003.2524. PMC 1691537. PMID 14667343.

v t e 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) Devonian taxa †Acanthostega †Brittagnathus †Densignathus †Elpistostege? †Hynerpeton †Ichthyostega †Jakubsonia †Metaxygnathus †Parmastega †Sinostega †Tiktaalik? †Tulerpeton †Tutusius †Umzantsia †Ventastega †Ymeria †Elginerpetontidae Elginerpeton Obruchevichthys Webererpeton Post-Devonian taxa †Antlerpeton †Aytonerpeton †Crassigyrinus †Diploradus †Doragnathus †Gaiasia †Ichthyerpeton †Koilops †Mesanerpeton †Occidens †Ossirarus †Perittodus †Sigournea †Tantallognathus †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 †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 Crown group Tetrapoda Temnospondyli (Batrachomorpha see Temnospondyli 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
Category

v t e Reptiliomorpha (Pan‑Amniota)
Kingdom: Animalia Phylum: Chordata Clade: Osteichthyes Clade: Sarcopterygii Clade: Tetrapoda Tetrapodomorpha see Tetrapodomorpha Reptiliomorpha see below↓ Reptiliomorpha / Pan-Amniota
Reptiliomorpha †Caerorhachis? †Casineria? †Eldeceeon? †Romeriscus †Silvanerpeton? †Solenodonsaurus? †Termonerpeton? †Westlothiana? †Embolomeri? †Gephyrostegidae? †Chroniosuchia? Laosuchus Bystrowianidae Axitectum Bystrowiana Bystrowiella Dromotectum Hassiacoscutum Jiyuanitectum Synesuchus Yumenerpeton Chroniosuchidae Chroniosaurus Chroniosuchus Ingentidens Jarilinus Madygenerpeton Phratochronis Suchonica Uralerpeton †Seymouriamorpha? Ariekanerpeton Biarmica Discosauriscus Enosuchus? Karpinskiosaurus Kotlassia Leptoropha Makowskia Microphon Nyctiboetus Seymouria Spinarerpeton Utegenia Volgerpeton Waggoneria "Microsauria"? see Microsauria possibly includes Lissamphibia Amniota †Diadectomorpha? Limnoscelis? Tseajaia Diadectidae Alveusdectes Ambedus Desmatodon Diadectes Diasparactus Kuwavaatakdectes Orobates Phanerosaurus Stephanospondylus †"Protorothyrididae" Anthracodromeus Brouffia Cephalerpeton Coelostegus Hylonomus Paleothyris Protorothyris Thuringothyris †Araeoscelidia Aphelosaurus Araeoscelis Dictybolos? Halgaitosaurus Kadaliosaurus Petrolacosaurus Spinoaequalis? Zarcasaurus †Captorhinidae Acrodenta Baeotherates Captorhinoides Captorhinus Euconcordia? Labidosauriscus Labidosaurus Opisthodontosaurus? Protocaptorhinus Puercosaurus? Reiszorhinus Rhiodenticulatus Rhodotheratus Riabininus? Romeria Saurorictus Moradisaurinae Balearosaurus Captorhinikos Gansurhinus Gecatogomphius Indosauriscus Kahneria Labidosaurikos Moradisaurus Rothianiscus Sumidadectes Tramuntanasaurus Amniota (crown group) Synapsida (Pan‑Mammalia) see Synapsida includes mammals Sauropsida (Pan‑Reptilia) see Sauropsida includes reptiles and birds
See also: Labyrinthodontia Lepospondyli Anthracosauria Batrachosauria Cotylosauria Eureptilia

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