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Parioxys

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Parioxys
Temporal range: Early Permian
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Order: †Temnospondyli
Family: †Parioxyidae
Moustafa, 1955
Genus: †Parioxys
Cope, 1878
Species

Parioxys is an extinct genus of temnospondyl amphibian from the Early Permian of Texas.

History of study

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The type species, Parioxys ferricolus, was named in 1878 by American paleontologist Edward Drinker Cope based on two badly preserved skulls were collected from the early Permian Texas red beds.[1] Both skulls were collected in the same year from Mount Barry, a site in the Petrolia Formation[2] (formerly "Belle Plains Formation") of Wichita County, Texas. They are now stored in the American Museum of Natural History (AMNH). One of the P. ferricolus skulls, AMNH 4309, has frequently been conflated with AMNH 4310, a slightly larger Eryops skull ("Eryops anatinus") collected from Wichita County in 1880. The other P. ferricolus skull is designated AMNH 2445.[3]

Over the course of several papers in 1952 and 1955, Egyptian paleontologist Youssef S. Moustafa redescribed Cope's skulls along with new material from additional localities in Texas.[3][4][5][6] AMNH 4309 was designated as the holotype of P. ferricolus.[3] One of the new specimens, MCZ 1162, was collected from Baylor County in 1934. MCZ 1162 consists of a large block containing fossils from at least eight individuals, including four skulls and numerous postcranial bones.[4][5]

Further preparation of P. ferricolus skull material allowed a redescription by Schoch & Sues (2022).[2] Moustafa described a second species, P. romeri, on the basis of an isolated humerus, but this was regarded as being indeterminate.[2] Another proposed species, Parioxys bolli, was named and described by Canadian paleontologist Robert Carroll in 1964.[7] This species is only known from postcranial fragments from the Archer City Formation of Archer County.[2] Some sources have suggested that P. bolli is an unrelated species of temnospondyl, possibly a trematopid close to Ecolsonia cutlerensis.[8]

Relationships

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Parioxys was historically considered to be closely related to eryopoids, more specifically the well-known Eryops megalocephalus. Eryops fossils have been collected from the same locality as the type material of P. ferricolus. Subsequent to his original description, Cope listed P. ferricolus as a species of Eryops,[9][10] possibly because he considered it to be a juvenile specimen of Eryops.[11]

In 1911, Parioxys was revived as a distinct genus[11][12] with a suggestion that the original specimens described by Cope might have been inadvertently described as other taxa by later authors.[13] Its affinities continued to be debated, with some suggestions that it might instead belong to the Trematopidae.[14][15] Moustafa (1955) placed Parioxys in its own family and suggested that it was related to the Dissorophidae.[5] Schoch & Milner (2014) placed Parioxys within Dissorophidae based on personal observations of further preparation of historic material, although at the time this suggestion was not tested via a phylogenetic analysis, due to the poor quality of much of the material.[16]

The revision by Schoch & Sues (2022) finally tested the position of P. ferricolus in a dissorophoid-oriented phylogenetic matrix. They recovered it as a eucacopine dissorophid, most closely related to Kamacops from the Middle Permian of Russia. They list the following features as features shared between this species and Kamacops and not with Cacops: (1) smaller interpterygoid vacuities, resulting from the medial expansion of palatine and pterygoid (condition more extreme in K. acervalis); (2) the enlarged vomer with the posteriorly elongated, slit-like choana; and (3) the absence of an internarial fenestra.

References

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  1. ^ Cope, E. D. (1878). "Descriptions of Extinct Batrachia and Reptilia from the Permian Formation of Texas". Proceedings of the American Philosophical Society. 17 (101): 505–530. ISSN 0003-049X. JSTOR 982652.
  2. ^ a b c d Schoch, Rainer R.; Sues, Hans-Dieter (2022-03-31). "The dissorophoid temnospondyl Parioxys ferricolus from the early Permian (Cisuralian) of Texas". Journal of Paleontology. 96 (4): 950–960. Bibcode:2022JPal...96..950S. doi:10.1017/jpa.2022.10. ISSN 0022-3360. S2CID 247920021.
  3. ^ a b c Moustafa, Y.S. (1952). "The type of Parioxys ferricolus, Cope". Bulletin de l'Institute d'Égypte. 33: 295–300.
  4. ^ a b Moustafa, Y.S. (1952). "Amphibian mass death in the Permian". Bulletin de l'Institute d'Égypte. 33: 301–304.
  5. ^ a b c Moustafa, Y.S. (1955). "The skeletal structure of Parioxys ferricolus, Cope". Bulletin de l'Institut d'Égypte. 1: 41–76.
  6. ^ Moustafa, Y.S. (1955). "The affinities of Parioxys ferricolus and the phylogeny of the 'eryopsoid' amphibians". Bulletin de l'Institut d'Égypte. 36: 77–104.
  7. ^ Carroll, Robert L. (21 February 1964). "The relationships of the rhachitomous amphibian Parioxys". American Museum Novitates (2167).
  8. ^ Gee, Bryan M. (2021-11-08). "Returning to the roots: resolution, reproducibility, and robusticity in the phylogenetic inference of Dissorophidae (Amphibia: Temnospondyli)". PeerJ. 9: e12423. doi:10.7717/peerj.12423. ISSN 2167-8359. PMC 8582317. PMID 34820181.
  9. ^ Cope, E. D. (1882). "Synopsis of the Vertebrata of the Puerco Eocene epoch". Proceedings of the American Philosophical Society. 20 (112): 461–471. ISSN 0003-049X. JSTOR 982693.
  10. ^ Cope, E. D. (1888). "Systematic Catalogue of the Species of Vertebrata Found in the Beds of the Permian Epoch in North America with Notes and Descriptions". Transactions of the American Philosophical Society. 16 (2): 285–297. doi:10.2307/1005392. ISSN 0065-9746. JSTOR 1005392.
  11. ^ a b Case, E.C. (1911). Revision of the Amphibia and Pisces of the Permian of North America. Vol. 146. Carnegie Institution of Washington.
  12. ^ Mehl, M. G. (1912-09-27). "A Revision of the Amphibia and Pisces of the Permian of North America". Science. 36 (926): 408–409. doi:10.1126/science.36.926.408. ISSN 0036-8075.
  13. ^ Watson, D. M. S. (1920-01-01). "The Structure, Evolution and Origin of the Amphibia. The "Orders' Rachitomi and Stereospondyli". Philosophical Transactions of the Royal Society B: Biological Sciences. 209 (360–371): 1–73. Bibcode:1920RSPTB.209....1W. doi:10.1098/rstb.1920.0001. ISSN 0962-8436.
  14. ^ Romer, Alfred S. (1936). "Studies on American Permo-Carboniferous tetrapods". Problems of Paleontology, USSR. 1: 85–93.
  15. ^ Romer, Alfred Sherwood (1947). Review of the labyrinthodontia. OCLC 253748351.
  16. ^ Schoch, Rainer R.; Milner, Andrew R. (2014). Sues, Hans-Dieter (ed.). Temnospondyli I - Handbook of Paleoherpetology Part 3A2. Stuttgart: Verlag Dr. Friedrich Pfeil. ISBN 9783899371703.
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