Paleorhinus

Paleorhinus
Temporal range: Late Triassic, 221.5–205.6 Ma
Skull of the P. angustifrons holotype with CT scan
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Clade: Archosauriformes
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 widespread basal phytosaur known from the Late Triassic (late Carnian stage). The genus was named in 1904 based on the type species Paleorhinus bransoni, which is known from Wyoming and Texas in the United States. Another valid species, Paleorhinus angustifrons from Bavaria, Germany, is also commonly referred to the genus.[1][2] Paleorhinus had a length of about 2.5 meters (8.2 feet).

Paleorhinus has had a complicated taxonomic history involving frequent synonymy between diagnostic and undiagnostic material. This is mainly due to the fact that it is a quintessential basal phytosaur, mostly distinguished by a lack of specializations rather than unique traits. Historically, it was common practice to lump all basal phytosaurs into only one or two genera, rendering those genera paraphyletic evolutionary grades ancestral to later phytosaurs. More recently, these grades have been broken up into multiple genera.[2] Arganarhinus magnoculus (from Morocco) and Wannia scurriensis (from Texas)[3] were two phytosaur genera originally considered species of Paleorhinus. "Paleorhinus" sawini (from Texas) and "Paleorhinus" parvus (from Wyoming) are two more phytosaur species informally referred to Paleorhinus, though likely closer to more advanced phytosaurs.[2][4]

P. angustifrons was originally considered a species of Francosuchus (a dubious phytosaur genus from the same area), and has also been compared to Ebrachosuchus neukami, another Paleorhinus-like Bavarian phytosaur. "Paleorhinus" cf. arenaceus (formerly "Zanclodon" arenaceus), fragmentary phytosaur remains from Poland, may represent Paleorhinus fossils.

Parasuchus hislopi, a basal phytosaur species named in 1885 from fossils discovered in India, was often lumped into Paleorhinus or considered a dubious chimera of phytosaur and rhynchosaur fossils. More complete neotype fossils for Parasuchus hislopi have helped to re-establish it as a valid genus and species.[5] Some phylogenetic analyses suggest that Parasuchus hislopi forms a clade with Paleorhinus bransoni and angustifrons. If this is the case, the valid species of Paleorhinus may instead be considered species of Parasuchus, since that genus name has priority over Paleorhinus.[6][4]

  1. ^ Williston, S. W. (1904). "Notice of some new reptiles from the Upper Trias of Wyoming". Journal of Geology. 12 (8): 688–697. Bibcode:1904JG.....12..688W. doi:10.1086/621190. S2CID 140167568.
  2. ^ a b c Stocker, M. R.; Butler, R. J. (2013). "Phytosauria". Geological Society, London, Special Publications. 379 (1): 91–117. Bibcode:2013GSLSP.379...91S. doi:10.1144/SP379.5. S2CID 219192243.
  3. ^ Cite error: The named reference Wannia was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference :1 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference ICZN was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference :0 was invoked but never defined (see the help page).