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Embolomeres Temporal range: Mississippian - Wuchiapingian PreꞒ Ꞓ O S D C P T J K Pg N
Restoration of Archeria from the Lower Permian of Texas.
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Sarcopterygii
Clade:	Tetrapodomorpha
Clade:	Elpistostegalia
Clade:	Stegocephali
Order:	†Embolomeri Cope, 1885
Genera
See text.

Embolomeri is an order of tetrapods or stem-tetrapods, possibly members of Reptiliomorpha. Embolomeres first evolved in the Early Carboniferous (Mississippian) Period and were the largest and most successful predatory tetrapods of the Late Carboniferous (Pennsylvanian) Period. They were specialized semiaquatic predators with long bodies for eel-like undulatory swimming. Embolomeres are characterized by their vertebral centra, which are formed by two cylindrical segments, the pleurocentrum at the rear and intercentrum at the front. These segments are equal in size. Most other tetrapods have pleurocentra and intercentra which are drastically different in size and shape.

Embolomeres were among the earliest large carnivorous tetrapods, with members such as the crocodilian-like Proterogyrinus appearing in the Visean stage of the Carboniferous. They declined in diversity during the Permian period, though at least one representative (Archeria) was common in the Early Permian. Embolomeres went extinct shortly before the end of the Permian.

Classification

The order Embolomeri was first named by Edward Drinker Cope in 1884 during his revision of "batrachian" (amphibian) evolution. Embolomeri was differentiated from several other newly named amphibian orders, such as "Rachitomi", by the presence of intercentra and pleurocentra of the same size and shape, that being large cylinders. At the time, embolomere fossils were uncommon, so Cope could only identify "cricotids" such as Cricotus as possessing embolomerous vertebrae. The genus name "Cricotus" is dubious, as it has been used by Cope to refer to embolomere fossils spanning anywhere between mid-Pennsylvanian deposits of Illinois and the Permian red beds of Texas. Most paleontologists now refer the red bed "Cricotus" specimens to the genus Archeria.

Michel Laurin (1998) formally defined Embolomeri as "the last common ancestor of Proterogyrinus and Archeria and all of its descendants." This definition excludes Eoherpeton, which is almost always considered a close ally of the group. Some authors place Silvanerpeton or chroniosuchians as close relatives as well, though they are generally agreed to lie outside Embolomeri proper.

The poorly-defined group Anthracosauria is sometimes considered synonymous with Embolomeri, and the group's namesake, Anthracosaurus, is an embolomere. However, other authors use the term "Anthracosauria" in reference to a broader group which includes embolomeres in combination with various other reptile-like amphibians (reptiliomorphs). Reptiliomorphs are all tetrapods more closely related to living reptiles and synapsids (mammals and their ancestors), rather than living amphibians. Despite this, reptiliomorphs likely had amphibian-like biological traits, such as water-based reproduction.

Many studies conducted since the 1990s have also placed the group Lepospondyli as closer to amniotes than embolomeres were. Lepospondyls are a particularly unusual group of tetrapods, with some members (i.e. brachystelechids) very similar to lissamphibians and others (i.e. tuditanids) very similar to amniotes. If lepospondyls are both close relatives of amniotes and the ancestors of modern amphibians, then that means that crown-Tetrapoda (descendants of the common ancestor to all living tetrapods) is a much more restricted group than previously assumed. In this situation, various traditional orders of Tetrapoda such as Embolomeri and Temnospondyli actually would qualify as stem-tetrapods due to having evolved prior to the split between modern amphibians and amniotes.

However, most authors consider temnospondyls to be the ancestors of modern amphibians. This would suggest that embolomeres are likely reptiliomorphs (closer to reptiles) and within the clade Tetrapoda. However, even this classification is not stable, as some analyses have found embolomeres to be more basal than temnospondyls.

Below is a cladogram from Ruta et al. (2003):

Genera

List of genera
Name	Year	Age	Location	Notes	Images
Anthracosaurus	1863	Pennsylvanian (Westphalian A-B)	United Kingdom ( Scotland)	The namesake of Anthracosauria, possessed a small number of large fangs compared to other embolomeres
Archeria	1918	Early Permian	United States ( Texas)	A common, late-surviving member of the group, sometimes considered a species of Cricotus
Aversor	1985	Early Permian (Ufimian)	Russia	Supposedly the latest surviving eogyrinid, but very poorly known
Calligenethlon	1934	Pennsylvanian (Bashkirian)	Canada ( Nova Scotia)	The largest named tetrapod preserved inside lycopod tree stumps in the Joggins Fossil Cliffs
Cricotus	1875	Pennsylvanian	United States ( Illinois)	Responsible for the identification of Embolomeri as a unique order of tetrapods, although its history is convoluted and its taxonomic validity is questionable
Carbonoherpeton	1985	Pennsylvanian (Westphalian D)	Canada ( Nova Scotia)	A lightly built member of the group with characteristics of both archeriids and eogyrinids
Diplovertebron	1879	Pennsylvanian (Moscovian)	Czech Republic	A small member of the group sometimes confused with Gephyrostegus
Eobaphetes	1916	Pennsylvanian	United States ( Kansas)	A possible relative of Anthracosaurus, originally named "Erpetosuchus" until it was determined that the name was preoccupied by a Triassic reptile.
Eogyrinus	1926	Pennsylvanian (Westphalian B)	United Kingdom ( England)	One of the largest and most well-known of the eogyrinids, although sometimes synonymized with Pholiderpeton
Eoherpeton	1975	Mississippian-Pennsylvanian (Visean-Bashkirian)	United Kingdom ( Scotland)	One of the oldest and most basal members of the group (if it even counts as part of it), without vertebrae that were not fully embolomerous
Leptophractus	1873	Pennsylvanian (Westphalian D)	United States ( Ohio)	Known from a skull found at the Linton Diamond Mine
Neopteroplax	1963	Pennsylvanian	United States ( Ohio)	One of the largest Carboniferous limbed vertebrates known from North America
Palaeoherpeton	1970	Pennsylvanian (Westphalian A-B)	United Kingdom ( Scotland)	An eogyrinid known as Palaeogyrinus from 1926 to 1970, until it was determined that this name was occupied by a genus of beetles
Papposaurus	1914	Mississippian-Pennsylvanian (Namurian)	United Kingdom ( Scotland)	Known from a femur, may have been a relative of Proterogyrinus
Pholiderpeton	1869	Pennsylvanian (Westphalian A-B)	United Kingdom ( England,  Scotland)	An eogyrinid similar to Eogyrinus which would take priority if the two were synonymized
Proterogyrinus	1970	Mississippian (Serpukhovian)	United States ( West Virginia),  United Kingdom ( Scotland)	An early member of the group possessing robust limbs but lacking certain adaptations of later members of the group
Pteroplax	1868	Pennsylvanian (Westphalian B)	United Kingdom ( England)	Poorly known despite being among the first embolomeres to be described
Seroherpeton	2020	Late Permian (Wuchiapingian)	China	The youngest known embolomere
Spondylerpeton	1912	Pennsylvanian	United States ( Illinois)	A close relative of Cricotus known from vertebrae found at the Mazon Creek fossil beds

References

1. Panchen, A. L. (10 February 1972). "The skull and skeleton of Eogyrinus attheyi Watson (Amphibia: Labyrinthodontia)". Phil. Trans. R. Soc. Lond. B. 263 (851): 279–326. Bibcode:1972RSPTB.263..279P. doi:10.1098/rstb.1972.0002. ISSN 0080-4622.
2. ^ Romer, Alfred Sherwood (11 January 1957). "The Appendicular Skeleton of the Permian Embolomerous Amphibian Archeria" (PDF). Contributions from the Museum of Paleontology. 13 (5): 105–159.
3. Chen, Jianye; Liu, Jun (2020-12-01). "The youngest occurrence of embolomeres (Tetrapoda: Anthracosauria) from the Sunjiagou Formation (Lopingian, Permian) of North China". Fossil Record. 23 (2): 205–213. doi:10.5194/fr-23-205-2020. ISSN 2193-0066.
4. Cope, E.D. (January 1884). "The Batrachia of the Permian Period of North America". The American Naturalist. 18: 26–39. doi:10.1086/273563. S2CID 84133633.
5. Laurin, Michel (1998). "The importance of global parsimony and historical bias in understanding tetrapod evolution. Part I. Systematics, middle ear evolution and jaw suspension". Annales des Sciences Naturelles - Zoologie et Biologie Animale. 19 (1): 1–42. doi:10.1016/S0003-4339(98)80132-9.
6. Chen, Jianye; Liu, Jun (2020-12-01). "The youngest occurrence of embolomeres (Tetrapoda: Anthracosauria) from the Sunjiagou Formation (Lopingian, Permian) of North China". Fossil Record. 23 (2): 205–213. doi:10.5194/fr-23-205-2020. ISSN 2193-0066.
7. Klembara, Jozef; Clack, Jennifer A.; Čerňanský, Andrej (2010-09-16). "The anatomy of palate of Chroniosaurus dongusensis (Chroniosuchia, Chroniosuchidae) from the Upper Permian of Russia". Palaeontology. 53 (5): 1147–1153. doi:10.1111/j.1475-4983.2010.00999.x. ISSN 0031-0239.
8. Carroll, Robert L. (2012-10-18). "The Importance of Recognizing Our Limited Knowledge of the Fossil Record in the Analysis of Phylogenetic Relationships among Early Tetrapods". Fieldiana Life and Earth Sciences. 5: 5–16. doi:10.3158/2158-5520-5.1.5. ISSN 2158-5520. S2CID 85114894.
9. Sookias, Roland B.; Böhmer, Christine; Clack, Jennifer A. (2014-10-07). "Redescription and Phylogenetic Analysis of the Mandible of an Enigmatic Pennsylvanian (Late Carboniferous) Tetrapod from Nova Scotia, and the Lability of Meckelian Jaw Ossification". PLOS ONE. 9 (10): e109717. Bibcode:2014PLoSO...9j9717S. doi:10.1371/journal.pone.0109717. ISSN 1932-6203. PMC 4188710. PMID 25290449.
10. Laurin, M.; Reisz, R.R. (1999). "A new study of Solenodonsaurus janenschi, and a reconsideration of amniote origins and stegocephalian evolution". Canadian Journal of Earth Sciences. 36 (8): 1239–1255. doi:10.1139/e99-036.
11. ^ Marcello Ruta, Michael I. Coates and Donald L. J. Quicke (2003). "Early tetrapod relationships revisited" (PDF). Biological Reviews. 78 (2): 251–345. doi:10.1017/S1464793102006103. PMID 12803423. S2CID 31298396. Archived from the original (PDF) on 2008-05-22. Retrieved 2012-05-26.
12. Clack, J. A. (July 2002). "An early tetrapod from 'Romer's Gap'". Nature. 418 (6893): 72–76. doi:10.1038/nature00824. ISSN 0028-0836. PMID 12097908. S2CID 741732.

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

• Embolomeres
• Mississippian first appearances
• Permian extinctions
• Taxa named by Edward Drinker Cope
• Tetrapodomorph orders