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, known from Wyoming and Texas in the United States. Another valid species, Paleorhinus angustifrons from Bavaria, Germany, is also commonly known in the genus. Paleorhinus had a length of about 2.5 meters (8.2 ft).
Paleorhinus has had a complicated taxonomic history involving frequent synonymy between diagnostic and non-diagnostic material. This is mainly due to the fact that it is a quintessential basal phytosaur, distinguished primarily by a lack of specializations rather than unique traits. Historically, it was common practice to group all basal phytosaurs into just one or two genera, converting those genera into ancestral paraphyletic evolutionary grades of later phytosaurs. More recently, these grades have been divided into several genres. Arganarhinus magnoculus (from Morocco) and Wannia scurriensis (from Texas) were two genera of phytosaurs originally considered species of Paleorhinus. "Paleorhinus" sawini (from Texas) and "Paleorhinus" parvus (from Wyoming) are two more species of phytosaurs informally called Paleorhinus, although probably closer to more advanced phytosaurs.
P. angustifrons was originally considered a species of Francosuchus (a dubious genus of phytosaurs from the same area), and has also been compared with Ebrachosuchus neukami, another Bavarian phytosaur resembling Paleorhinus. "Paleorhino" cf. arenaceus (formerly "Zanclodon" arenaceus), fragmentary remains of phytosaurs from Poland, may represent fossils of Paleorhinus.
Parasuchus hislopi, a species of basal phytosaur named in 1885 from fossils discovered in India, was often grouped within Paleorhinus or considered a dubious chimera of phytosaur and rhynchosaur fossils. More complete neotype fossils of Parasuchus hislopi have helped reestablish it as a valid genus and species. Some phylogenetic analyzes suggest that Parasuchus hislopi forms a clade with Paleorhinus bransoni and angustifrons. If this is the case, the valid species of Paleorhinus can be considered a species of Parasuchus, since that genus name takes precedence over Paleorhinus.
Species[]
P. bransoni[]
P. bransoni is the type species of Paleorhinus. It was first described and named by Samuel Wendell Williston in 1904 based on holotype FMNH UC 632, a complete but fragmentary skull that has been extensively reconstructed in plaster. It was collected in Squaw Creek of Fremont County, Wyoming, from the Carnian-aged Popo Agie Formation of the Chugwater Group. The holotype was described in detail by Lees (1907). Hunt and Lucas (1991) referred PPM P217 to P. bransoni. It is an incomplete skull that was collected in Palo Duro Canyon, Randall County, west Texas, from the Camp Springs member of the Carnian-age Tecovas Formation. 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.
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 holotype BSPG 1931 X 502, a partial skull missing a face and jaws. It was collected in the Ebrach quarry, bed number 9 of Bavaria, southern Germany, from the Blasensandstein member of the Hassberge Formation of late Carnian age.
Hunt and Lucas (1991) mistakenly referred to F. angustifrons as Ebrachosuchus angustifrons, and considered it along with the other two Francosuchus species, F. broilii and F. latus, synonyms of Paleorhinus neukami. More recently, P. neukami was found to be more closely related to Mystriosuchinae than Paleorhinus and thus the genus Ebrachosuchus was revalidated, 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.
P. cf. arenaceus[]

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

Skull and skeleton from Poland

Model based on the Polish remains
Over the years, several species have been referred to as Paleorhinus. Species no longer considered to belong to Paleorhinus are summarized in the following list:
- Ebrachosuchus neukami Kuhn, 1936 - Hunt and Lucas (1991) reassigned the species as Paleorhinus neukami. Subsequent research accepted this reference. More recently, a phylogenetic analysis found that E. neukami is more closely related to Phytosauridae than to Paleorhinus and, therefore, the genus Ebrachosuchus was revalidated.
- Francosuchus broilii and F. latus Kuhn, 1933 - Gregory (1962)[13] and Wastphal (1976) referred these species, as well as E. neukami and P. angustifrons, to the subgenus Francosuchus of Paleorhinus, while Chatterjee (1978) placed the four species of Francosuchus in a different subfamily. Hunt and Lucas (1991) considered these species to be synonymous with Paleorhinus neukami. More recently, F. broilii and F. latus were considered nomina dubia.
- "Francosuchus" trauthi Huene, 1939 - "F." trauthi was synonymized with Paleorhinus, but a redescription of the species by Butler (2013) found no evidence supporting synonymy, or even a phytosaurian identification. Although based solely on a tribune fragment, "F." trauthi possesses a unique combination of characters that distinguish it from all other Triassic tetrapods. It was therefore reassigned to a new genus, Dolerosaurus, now belonging to Tetrapoda incertae sedis.
- Paleorhinus magnoculus Dutuit, 1977b - Long and Murry (1995) reassigned this species to a new genus Arganarhinus. Although several studies reassigned it to Paleorhinus, more recent studies disagree with this derivation. Kammerer et al. (2016) considered P. magnoculus as a species of Parasuchus, along with P. hislopi, P. bransoni and P. angustifrons.
- "Paleorhinus" parvus Mehl, 1928 - Hunt and Lucas (1991) considered that this species was synonymous with P. bransoni, while Stocker and Butler (2013) suggested that "P." a small puede no ser attributable to Paleorhinus.
- "Paleorhinus" sawini Long and Murry, 1995: some studies considered this species to be synonymous with P. bransoni, although recent phylogenetic analyzes of phytosaurs at the species level suggest that this species is more closely related to Phytosauridae than to P. bransoni and, therefore, reference to Paleorhinus may not be made.
- "Paleorhinus" scurriensis Langston, 1949 - Hunt and Lucas (1991) considered this species to be synonymous with P. bransoni, although recent phylogenetic analyzes at the phytosaur species level suggest that this species is basal to the clade formed by P. bransoni and Phytosauridae , so it cannot be referred to Paleorhinus. This species was reassigned to its own genus, Wannia by Stocker (2013), and represents the most basal phytosaur known.
- Parasuchus hislopi Lydekker, 1885 – P. hislopi was based on a chimeric syntype material: a rhynchosaur basicranium mixed with partial snout, scutes, and some phytosaur teeth. Friedrich von Huene (1940) identified the basicranium as belonging to Paradapedon huxleyi (now known as Hyperodapedon huxleyi), so he assigned the phytosaur material to a species newly named "aff". Brachysuchus maleriensis. Later, Edwin Harris Colbert (1958) designated all Indian parasuchian material as Phytosaurus maleriensis. Gregory (1962) accepted this proposal. Sankar Chatterjee (1978), who described many complete remains of the Indian parasuchian, showed that it is assignable neither to Brachysuchus (which is closely related or synonymous with Angistorhinus), nor to Phytosaurus (a dubious name, probably the primary synonym of Nicrosaurus). . He noted that since rhynchosaurus basicranium is neither the holotype of P. hislopi nor the lectotype of Paradapedon huxleyi, deletion of P. hislopi should be avoided. However, Hunt and Lucas (1991) considered the species to be a nomen dubium and provisionally created the combination Paleorhinus hislopi for diagnosable phytosaur specimens from the Lower Maleri Formation, stating that the Indian species can be distinguished from other Paleorhinus species. To avoid further confusion, the non-diagnostic holotype of P. hislopi was replaced by a neotype with the approval of the ICZN (Opinion 2045) following the request of Chatterjee (2001). As a result, most subsequent studies referred all Paleorhinus species to Parasuchus according to ICZN rules, while others continued to refer P. hislopi to Paleorhinus. In light of the complex taxonomic history of Paleorhinus, the 2013 studies considered synonymy between the genera premature. However, later studies argued that Paleorhinus bransoni and Paleorhinus angustifrons formed a strong clade with Parasuchus hislopi. This clade would be named Parasuchus according to ICZN rules, formally synonymizing the two genera in this more restricted sense.
- Promystriosuchus ehlersi case, 1922 - Gregory (1962) and Hunt and Lucas (1991) referred this taxon to Paleorhinus at the genus level, and considered it a nomen dubium at the species level, due to the poor conservation of its holotype and the only known specimen. . Stocker and Butler (2013) suggested that P. ehlersi may not be attributable to Paleorhinus and referred it to Phytosauria incertae sedis.
Phylogeny[]
Parasuchidae |
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