Paleorhinus

Paleorhinus
Temporal range: Late Triassic, Carnian
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Phytosauria
Genus: Paleorhinus
Williston, 1904
Type species
Paleorhinus bransoni
Williston, 1904
Species
  • P. angustifrons (Kuhn, 1936 [originally Francosuchus angustifrons])
  • P. bransoni Williston, 1904

Paleorhinus (Greek: "Old Nose") is an extinct genus of basal phytosaur known from the Late Triassic (late Carnian stage) of Texas and Wyoming, USA, Bavaria, Germany and possibly Poland. It contains two valid species, the type species: Paleorhinus bransoni and Paleorhinus angustifrons.[1][2] Paleorhinus had a length of about 2.5 meters (8.2 feet).

Species

P. bransoni

P. bransoni is the type species of Paleorhinus. It was first described and named by Samuel Wendell Williston in 1904 on the basis of the holotype FMNH UC 632, a complete but fragmentary skull that has been extensively reconstructed with plaster. It was collected at Squaw Creek of Fremont County, Wyoming, from the Carnian-aged Popo Agie Formation of the Chugwater Group. The holotype was thoroughly described by Lees (1907).[1][3] Hunt and Lucas (1991) referred PPM P217 to P. bransoni. It is an incomplete skull that was collected at Palo Duro Canyon, Randall County, west Texas, from the Carnian-aged Camp Springs Member of the Tecovas Formation.[4] Later, Long and Murry (1995) referred additional material, including isolated postcranial remains, to P. bransoni from the Carnian-aged Cooper Canyon Formation of the Dockum Group, Howard County, Texas. TMM 31025-172, a complete skull, was collected at Otis Chalk Quarry 1 (also known as SMU 122), TMM 31100-8, 101, 175, 418, 419, 453 were collected at Otis Chalk Quarry 3, and TMM 31185-11, 38 were collected at Otis Chalk Quarry 3A.[5]

P. angustifrons

P. angustifrons was first described and named by Oskar Kuhn in 1936 as a species of Francosuchus. P. angustifrons is known exclusively from the holotype BSPG 1931 X 502 a partial skull lacking the rostrum and mandibles. It was collected at Ebrach Quarry, bed number 9 of Bavaria, southern Germany, from the late Carnian-aged Blasensandstein Member of the Hassberge Formation.[6]

Hunt and Lucas (1991) mistakenly referred to F. angustifrons as Ebrachosuchus angustifrons, and considered it and the other two Francosuchus species, F. broilii and F. latus, to be synonyms of Paleorhinus neukami.[4] More recently, P. neukami was found to be more closely related to Phytosauridae than to Paleorhinus and thus the genus Ebrachosuchus was re-validated, while F. angustifrons was reassigned as P. angustifrons as it shares unique synapomorphies with P. bransoni and was found to be its sister taxon. The other two Francosuchus species, were not referred to P. angustifrons because they were found to be nomina dubia as their holotypes were destroyed during World War II.[2]

P. cf. arenaceus

Life restoration of Paleorhinus cf. arenaceus

Dzik & Sulej (2007) assigned several skulls, partial articulated postcranial skeletons, and numerous isolated phytosaur bones in various ontogenetic stages from Krasiejów, Poland to Paleorhinus cf. arenaceus. They found some similarities between the material and P. bransoni and also Ebrachosuchus neukami or F. angustifrons (mistakenly referred to as E. broili), as well as some apparent differences with Parasuchus. The shape of the external mandibular fenestra of the material resembled that of "Zanclodon" arenaceus but it is also shared with the proterochampsid Chanaresuchus bonapartei.[7] "Z." arenaceus was suggested to represent the oldest reliably dated phytosaur, and was reassigned to various phytosaur species over the years, including Belodon, Mystriosuchus and Phytosaurus. Although Hungerbühler (2001) redescribed "Z." arenaceus as not belonging to Phytosauria and referred it to Archosauria Incertae sedis,[8] Dzik & Sulej (2007) noted that its holotype "does not differ significantly from corresponding parts of the juvenile Krasiejów Paleorhinus, which is clearly a phytosaur". Furthermore, as the Feuerbacher Heide Schilfsandstein, from which "Z." arenaceus was collected, and Krasiejów share species of Metoposaurus, it might be possible that they also share the same species of phytosaur. Even though they agreed that due to the very fragmentary nature of "Z." arenaceus holotype the Krasiejów Paleorhinus can't be referred to it, they tentatively used the name Paleorhinus cf. arenaceus for the Krasiejów Paleorhinus.[7]

Other species

Model based on the Polish remains

Through the years, various species have been referred to as Paleorhinus. The species that are no longer considered to belong to Paleorhinus, are summarised in the list below:

References

  1. 1 2 Williston, S. W. (1904). Notice of some new reptiles from the Upper Trias of Wyoming. Journal of Geology 12:688-697.
  2. 1 2 3 4 5 6 7 8 9 10 11 Stocker, M. R.; Butler, R. J. (2013). "Phytosauria". Geological Society, London, Special Publications. doi:10.1144/SP379.5.
  3. 1 2 3 Michelle R. Stocker (2010). "A new taxon of phytosaur (Archosauria: Pseudosuchia) from the Late Triassic (Norian) Sonsela Member (Chinle Formation) in Arizona, and a critical reevaluation of Leptosuchus Case, 1922". Palaeontology 53 (5): 997–1022. doi:10.1111/j.1475-4983.2010.00983.x.
  4. 1 2 3 4 5 6 7 8 Hunt, A. P., and Lucas, S. G. (1991). The Paleorhinus biochron and the correlation of the non-marine Upper Triassic of Pangaea. Palaeontology 34(2):487-501.
  5. Long, R. A., and Murry, P. A. (1995). Late Triassic (Carnian and Norian) tetrapods from the southwestern United States. New Mexico Museum of Natural History and Science Bulletin 4:1-254.
  6. 1 2 Kuhn, O. (1936). Weitere Parasuchier und Labyrinthodonten aus dem Blasensandstein des mittleren Keuper von Ebrach. Palaeontographica, Abteilung A, 83:61-98.
  7. 1 2 Dzik, J. & Sulej, T. (2007). "A review of the early Late Triassic Krasiejów biotafrom Silesia, Poland" (PDF). Palaeontologia Polonica 64 (1): 3–27.
  8. Hungerbühler, A. (2001). "The status and phylogenetic relationships of "Zanclodon"arenaceus: The earliest known phytosaur?". Paläontologische Zeitschrift 75: 97–11. doi:10.1007/BF03022600.
  9. 1 2 Gregory, J. T. (1962). The relationships of the American phytosaur Rutiodon. American Museum Novitates 2095:1-22.
  10. Butler, R. J. (2013). "'Francosuchus' trauthi is not Paleorhinus: Implications for Late Triassic vertebrate biostratigraphy". Journal of Vertebrate Paleontology 33 (4): 858–864. doi:10.1080/02724634.2013.740542.
  11. 1 2 3 4 Stocker, M. R. (2013). "A new taxonomic arrangement for Paleorhinus scurriensis". Earth and Environmental Science Transactions of the Royal Society of Edinburgh 103 (3–4): 1. doi:10.1017/S1755691013000340.
  12. Sankar Chatterjee (1978). "A primitive parasuchid (phytosaur) reptile from the Upper Triassic Maleri Formation of India" (PDF). Palaeontology 21 (1): 83–127.
  13. (Case 3165) (2003). "Parasuchus Hislopi Lydekker, 1885 (Reptilia, Archosauria): Lectotype Replaced By A Neotype" (PDF). Bulletin of Zoological Nomenclature 60: 174–175.
  14. Case, E. C. (1922). New reptiles and stegocephalians from the Upper Triassic of western Texas. Carnegie Institution of Washington Publication 321:1-84.
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