| Nicorhynchus | |
|---|---|
 | |
| Holotype jaw fragment ofN. capito in multiple views | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | †Pterosauria |
| Suborder: | †Pterodactyloidea |
| Clade: | †Anhangueria |
| Family: | †Anhangueridae |
| Subfamily: | †Coloborhynchinae |
| Genus: | †Nicorhynchus Holgado & Pêgas, 2020 |
| Type species | |
| †Ornithocheirus capito Seeley, 1870 | |
| Species | |
| Synonyms | |
Synonyms ofN. capito
Synonyms ofN. fluviferox
| |
Nicorhynchus (meaning "knucker snout", in reference to its likely ecology) is a genus ofanhangueridpterosaur from theCretaceous period. It contains two species, thetype species,N. capito, from theCambridge Greensand of England, andN. fluviferox from theKem Kem Group of Morocco. These species were previously assigned toColoborhynchus.[1]
The genusColoborhynchus has had a convoluted history, with many species having been assigned to the genus. In 2013, Rodrigues and Kellner consideredColoborhynchus to bemonotypic, containing onlyC. clavirostris, and placed most other species in other genera, or declared themnomina dubia. One of these species wasColoborhynchus capito, which was originally named byHarry Seeley in 1870 as a species ofOrnithocheirus. Itsholotype is CAMSM B 54625, a snout. In 2001, this species was moved toColoborhynchus byDavid Unwin, who also synonymizedOrnithocheirus reedi (known from a lost specimen) with it. Rodrigues and Kellner recognized that the species was distinct fromColoborhynchus, but did not give it a new name pending the discovery of more complete material.[2]
In 2018, Jacobset al. named a new species ofColoborhynchus,C. fluviferox from theIfezouane Formation of theKem Kem Group ofMorocco based on a partial snout, and also tentatively referred another specimen from the same locality to a different, unnamed species.[3] A 2020 review of a subfamily calledColoborhynchinae by Borja Holgado and Rodrigo Pêgas moved bothC. capito andC. fluviferox to a new genus,Nicorhynchus, and also associated the unnamed Ifezouane Formation coloborhynchine toN. fluviferox. The nameNicorhynchus is derived from the Old Englishnicor (knucker, a kind of water dragon) and the Ancient Greekrhynchos ("snout"), in reference to its likely ecology as a fish-eating, flying reptile found in river and marine deposits.[1]
However, a review of Kem Kem pterosaurs found the traits that distinguishNicorhynchus fromColoborhynchus to be subtle enough to justify their synonymy, stating that the material was damaged and fragmentary enough to support this.[4]
The speciesN. capito represents the second largest knownanhanguerid (after aTropeognathus specimen),[5] and indeed the second largest toothed pterosaur known afterTropeognathus. A referred specimen from theCambridge Greensand ofEngland described in 2011 consists of a very large upper jaw tip which displays the tooth characteristics that distinguishN. capito from other species. The jaw tip is nearly 10 cm (3.9 in) tall and 5.6 cm (2.2 in) wide, with teeth up to 1.3 cm (0.51 in) in base diameter. If the proportions of this specimen were consistent with species ofColoborhynchus, the total skull length could have been up to 75 cm (30 in), leading to an estimated wingspan of 7 m (23 ft).[6]
As ananhanguerid pterosaur,Nicorhynchus would've been a large flying animal with a long snout filled with many long protruding teeth. The end of the snout formed a "rosette", a region wider than the rest of the jaw, and would have borne a prominent crest running along its top. As a member ofColoborhynchinae, this rosette would have a boxy shape, and the front of the snout (called the deltoid process) consisted of a flat surface derived from thepalate, oriented at a perpendicular angle relative to the roof of the mouth. The first set of teeth, rooted in large oval sockets, projected directly forwards from the deltoid process. Second and third pairs of teeth were also enlarged, with a more ordinary orientation, and subsequent teeth would be smaller in size.[1]
Compared to other coloborhynchines,Nicorhynchus is distinguished by the high shape of its deltoid process, taller than wide, a pair of ridges on either side of the deltoid process, adepressions on the bone surface between its first and second pairs of teeth, as well as an additional depression behind its second teeth absent in other taxa. It differs fromColoborhynchus in having its teeth (after the forward-oriented first position) pointing downwards, rather than somewhat flared to the side, and the front edge of the crest having a small groove running down its center. Both of these traits are shared withUktenadactylus, butNicorhynchus differs from it in lacking the distinctive protrusion at the tip of the jaw inUktenadactylus, placed between the second apir of teeth. Each genus also differs in the pattern of depressions on the front of the snout;Coloborhynchus has a single oval depression immediately below the first pair of teeth, andUktenadactylus has a round one above the first pair, whereasNicorhynchus possesses depressions both above the first pair of teeth and below them, the latter in a lower position than inColoborhynchus.[1][3]
The recognized species ofNicorhynchus are distinguished by subtle traits of the front of the snout. On the top of the snout, the front of the crest is distinctly concave inN. capito, whereas that ofN. fluviferox rises at a straight sixty degree angle and has arugose texture. The ridges along the side of the deltoid process ofN. capito are similarly rugose, convering to form a shallow central groove that transitions into the base of the crest. Both species possess a groove running along the center of the crest's front edge. Depressions on the surface of the deltoid process differ in the two species.N. capito possesses a single centralrhomboid-shaped depression above the first pair of teeth, and the depression above the second pair possesses a sharp angular top edge. Contrastingly,N. fluviferox has two adjacent and nearly circular depressions above the first pair of teeth and lacks the angular edge of the depression and instead has a circular shape. The first set of teeth themselves differ in position between the two species; inN. capito the pair is placed fully above the second pair of teeth, whereas inN. fluviferox the first pair is lower and the center of the sockets is level with the top of the second pair of sockets. An additional potential morphology is seen in NHMUK PV R481, a specimen tentatively considered to belong toN. capito. The concave shape of the crest and overall shape of the deltoid process resembles that of otherN. capito specimens, identifying it as a potential member of the species. However, the deltoid process as a whole is much taller than in otherNicorhynchus specimens, rising well over twice the height of the first pair of the teeth, which are unusually small. While it possible this indicates the existence of an additional species, it was noted as possible that erosion of the specimen exposed theroots of the tooth rather than the surface of the socket, altering its apparent shape and position and artificially giving the appearance of distinct anatomy.[1][3]
The describers of the genus, Holgado and Pêgas, had recoveredNicorhynchus within the subfamily Coloborhynchinae, which in turn was within the family Anhangueridae, sister taxon toUktenadactylus. Their cladogram is shown below.[1]
