Eryosuchus

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Eryosuchus
Temporal range: Middle Triassic
E. tverdochlebovi skull
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Order: †Temnospondyli
Suborder: †Stereospondyli
Clade: †Capitosauria
Family: †Mastodonsauridae
Genus: †Eryosuchus
Otschev, 1966
Species
  • †E. tverdochlebovi Otschev, 1966 (type)
  • †E. garjainovi Otschev, 1966
Restoration

Eryosuchus is an extinct genus of capitosauroid temnospondyl from the Middle Triassic of northern Russia. It was a very large predator: the largest specimen known could reach up to 3.5 m (11.5 ft) in length, with a skull over 1 m long.[1]

History of study

Eryosuchus was named by Ochev (1966) based on the type species, E. tverdochlebovi from exposures of the Donguz Formation in Orenburgskaya Oblast.[2] In the same publication, Ochev also named E. garjainovi and E. antiquus, both from the same formation and oblast as E. tverdochlebovi. Several other species previously placed in other genera have sometimes been placed in Eryosuchus, such as "Stanocephalosaurus" pronus from Tanzania and "Stanocephalosaurus" rajareddyi from India,[3] but this is largely disputed, as is the validity of E. antiquus, which is only based on a lower jaw fragment.[1][4][5][6][7] These species, as well as more confidently assigned species of Eryosuchus, were sometimes placed in the expansive genera Parotosaurus/Parotosuchus, which underscores the complexities of capitosaur taxonomy and the role of biogeography in formalizing such taxonomy. In the most restrictive concept of Eryosuchus (that of Schoch & Milner, 2000, and most other authors), Eryosuchus is exclusively a Russian taxon. Morales (1988) mentioned a possible new species of Eryosuchus that would represent the largest known, with an uncatalogued skull exceeding 1 m in length that would be one of the largest known temnospondyls;[8] Schoch & Milner (2000) reiterated this and suggested that a description by Morales was forthcoming, but this specimen has never been described and could represent a different genus. If this specimen is not considered, the largest known specimen of Eryosuchus is only slightly more than 50 cm.[1]

Anatomy

Competing concepts of Eryosuchus produce different summaries of diagnostic features. Schoch & Milner's concept, that of an exclusively Russian clade and that is adopted by most other workers, listed only two synapomorphies of the genus: intermediately sized orbits (larger than most capitosauroids other than mastodonsaurids) and an elongate post-glenoid area (PGA) that is shallowly concave and with a medial ridge aligned sagittally. Damiani's (2001) more expansive concept listed only laterally directed tabular horns with an antero-distal 'lappet' as apomorphic for this genus. Eryosuchus tverdochlebovi and E. garjainovi are represented by many skulls and postcranial remains, which secures their validity in contrast to E. antiquus, represented by one lower jaw fragment. The two definitive species are differentiated by their relative orbit size and the length of their basicranial suture. This is one of the few capitosaurs from which fully ossified intercentra are known.[9]

Phylogeny

Below is the phylogeny from Fortuny et al. (2011); E. garjainovi is typically used as the representative of this genus:[10]

Biostratigraphy

The Russian framework for Triassic biostratigraphy is larged based on temnospondyls,[11][12][13] in contrast to the South African Assemblage Zones, which are largely based on amniotes.[14] Eryosuchus is among the taxa used to make regional correlations given its relatively common occurrence in Russia. It is thought that the Eryosuchus Fauna is at least partially correlative with the Cynognathus Assemblage Zone in South Africa.[15] [11]

References

  1. ^ a b c Schoch, Rainer R.; Milner, Andrew R. (2000). Handbuch der Paläoherpetologie Part 3B. Stereospondyli. Stuttgart: Verlag Dr. Friedrich Pfeil. pp. 1–220. ISBN 978-3-931516-26-0. OCLC 580976.
  2. ^ Ochev, Vitalii G. (1966). Systematics and phylogeny of capitosaurid labyrinthodonts. Saratov: Saratov State University Press.
  3. ^ Damiani, Ross J. (2001). "A systematic revision and phylogenetic analysis of Triassic mastodonsauroids (Temnospondyli: Stereospondyli)". Zoological Journal of the Linnean Society. 133 (4): 379–482. doi:10.1111/j.1096-3642.2001.tb00635.x.
  4. ^ Morales, Michael; Shishkin, Michael A. (2002-03-14). "A re-assessment ofParotosuchus africanus(Broom), a capitosauroid temnospondyl amphibian from the Triassic of South Africa". Journal of Vertebrate Paleontology. 22 (1): 1–11. doi:10.1671/0272-4634(2002)022[0001:araopa]2.0.co;2. ISSN 0272-4634. S2CID 86254209.
  5. ^ Sengupta, Dhurjati Prasad (2003). "Triassic temnospondyls of the Pranhita–Godavari basin, India". Journal of Asian Earth Sciences. 21 (6): 655–662. doi:10.1016/S1367-9120(02)00114-1.
  6. ^ Schoch, Rainer R. (2008-12-30). "The Capitosauria (Amphibia): characters, phylogeny, and stratigraphy" (PDF). Palaeodiversity. 1: 189–226.
  7. ^ Dahoumane, Anissa; Nedjari, Ahmed; Aït-Ouali, Rachid; Taquet, Philippe; Vacant, Renaud; Steyer, Jean-Sébastien (2016). "A new Mastodonsauroid Temnospondyl from the Triassic of Algeria: Implications for the biostratigraphy and palaeoenvironments of the Zarzaïtine Series, northern Sahara". Comptes Rendus Palevol. 15 (8): 918–926. doi:10.1016/j.crpv.2015.09.005.
  8. ^ Morales, Michael (1988). "New metoposaurid and capitosaurid labyrinthodonts from the Triassic of Germany and the Soviet Union". Journal of Vertebrate Paleontology. 8 (Abstracts): 23A.
  9. ^ Warren, Anne; Snell, Nicola (1991). "The postcranial skeleton of Mesozoic temnospondyl amphibians: a review". Alcheringa: An Australasian Journal of Palaeontology. 15 (1): 43–64. doi:10.1080/03115519108619009. ISSN 0311-5518.
  10. ^ Fortuny, Josep; Galobart, Àngel; Santisteban, Carles De (2011). "A New Capitosaur from the Middle Triassic of Spain and the Relationships within the Capitosauria". Acta Palaeontologica Polonica. 56 (3): 553–566. doi:10.4202/app.2010.0025. ISSN 0567-7920. S2CID 55068128.
  11. ^ a b Ochev, V. G.; Shishkin, M. A. (1988). "Global Correlation of the Continental Triassic on the Basis of Tetrapods". International Geology Review. 30 (2): 163–176. doi:10.1080/00206818809465998. ISSN 0020-6814.
  12. ^ Sennikov, A.G. (1996). "Evolution of the Permian and Triassic tetrapod communities of Eastern Europe". Palaeogeography, Palaeoclimatology, Palaeoecology. 120 (3–4): 331–351. doi:10.1016/0031-0182(95)00041-0. ISSN 0031-0182.
  13. ^ Lucas, Spencer G. (2010). "The Triassic timescale based on nonmarine tetrapod biostratigraphy and biochronology". Geological Society, London, Special Publications. 334 (1): 447–500. doi:10.1144/sp334.15. ISSN 0305-8719. S2CID 128911449.
  14. ^ Smith, R.M.H.; Rubidge, B.S.; Day, M.O.; Botha, J. (2020-06-01). "Introduction to the tetrapod biozonation of the Karoo Supergroup". South African Journal of Geology. 123 (2): 131–140. doi:10.25131/sajg.123.0009. ISSN 1996-8590. S2CID 225829714.
  15. ^ "多重解析--DOI注册管理系统--中国知网". doi.cnki.net. doi:10.19615/j.cnki.1000-3118.170808. Retrieved 2022-03-16.
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