Nicorhynchus cf. capito ( Seeley, 1870 ), 2020

Holgado, Borja & Pêgas, Rodrigo V., 2020, A taxonomic and phylogenetic review of the anhanguerid pterosaur group Coloborhynchinae and the new clade Tropeognathinae, Acta Palaeontologica Polonica 65 (4), pp. 743-761 : 748-750

Nicorhynchus cf. capito ( Seeley, 1870)

Material.— NHMUK PV R481, a highly worn portion of the rostrum displaying the alveoli of, presumably, the 1st and 2nd pairs of teeth ( SOM: fig. S2), from Albian fossils in Cenomanian Cambridge Greensand, Cambridgeshire, UK.

Remarks.— NHMUK PV R481 was originally referred to the species “ Coloborhynchus” capito based on the purported presence of a markedly concave anterior margin of the premaxillary crest ( Unwin 2001; Martill and Unwin 2012), which is a diagnostic feature of the species ( Unwin 2001; Rodrigues and Kellner 2008, 2013). Subsequently, such assignment of NHMUK PV R481 to “ Coloborhynchus ” capito was questioned for the first time by Kellner et al. (2013), who mentioned that a markedly concave anterior margin of the premaxillary crest cannot be confidently seen in NHMUK PV R481. In any case, a markedly concave anterior margin of the premaxillary crest is not exclusive of Nicorhynchus capito , being also present in FSACK­KK 5024 and Uktenadactylus wadleighi . Apart from that, we further note that NHMUK PV R481 displays a remarkably high deltoid facet, which extends dorsally more than twice the level of the first pair of alveoli. This feature cannot be seen in any other coloborhynchine, but is close to Nicorhynchus fluviferox , both specimens ( Jacobs et al. 2019, 2020), in which the height of the deltoid facet is roughly twice the level of the first pair of alveoli (but not over as in Nichorhynchus cf. capito ). However, such relationship could indicate a continuous variation rather than a discrete character. Considering that the anhanguerid premaxillary crest grows ontogenetically ( Pinheiro and Rodrigues 2017), and that NHMUK PV R481 is a much larger specimen than the other coloborhynchines, then this feature could be linked to the ontogenetic growth of the premaxillary crest. In addition, as the rostral surface is highly worn off, it is possible that what is preserved of the presumable first tooth in NHMUK PV R481 would actually be a root cross section. In that case, the root would taper posteriorly and it would be posterodorsally directed. This could be a plausible explanation for its comparatively higher position, as well as its distinctively small first tooth. On the other hand, Jacobs et al. (2019, 2020) have presented a phylogenetic analysis in which NHMUK PV R481 was coded separately from the holotype specimen of “ Coloborhynchus ” capito , and a sister­group relationship between NHMUK PV R481 and “ C ”. fluviferox was recovered by their analysis. In any case, they did not present a discussion about this relationship, as a review of the genus Coloborhynchus was beyond their scope ( Jacobs et al. 2019). Taking all of the above into account, there is not enough evidence to establish NHMUK PV R481 as a new taxon different from Nicorhynchus capito due to its poor preservation, and consequently we assign it to Nicorhynchus cf. capito .

Nicorhynchus fluviferox ( Jacobs, Martill, Ibrahim, and Longrich, 2019) comb. nov.

Holotype: FSAC­KK 10701, an anterior portion of the rostrum displaying the alveoli from the 1st to the 3rd pair of teeth ( Fig. 3 ).

Type locality: South­eastern Morocco, possibly Aferdou N’Chaft, Hassi El Begaa, Er Rachidia Province (see Ibrahim et al. 2010; Martill et al. 2018; Jacobs et al. 2019).

Type horizon:?Albian–Lower Cenomanian Kem Kem Group, Ifezouane Formation.

Material.—FSAC­KK 5024/SMNK PAL 45833 (cast of a private specimen) from the type locality and horizon.

Diagnosis.—Coloborhynchine distinguished by the following autapomorphies: deltoid facet defining a high isosceles triangle with concave dorsolateral margins in anterior view; deltoid facet with two shallow, sub­circular depressions located dorsal to first upper tooth pair; deltoid facet dorsal region with a shallow sagittal groove defined by low ridges that transitions into a broad rugose anterodorsal margin of the premaxilla; and central point of first upper alveoli level with dorsal border of second tooth pair (modified from Jacobs et al. 2019).

Remarks.—The FSAC­KK 5024 was originally described as a potential second coloborhynchine species from the Kem Kem Group ( Jacobs et al. 2020). This specimen shares with the holotype of N. fluviferox the following features: high deltoid facet, over twice the level of the first tooth pair; anteroventral depression below first tooth pair (also shared with N. capito ); ridges on the lateral margin (in anterior) extending dorsally onto the crest base (also shared with N. capito ); first tooth alveolus ventral border slightly ventral to dorsal border of the second tooth alveolus (unique of N. fluviferox among coloborhynchines); and paired depression dorsal to firth tooth pair (unique of N. fluviferox ).

Jacobs et al. (2019) reported on a paired depression for N. fluviferox dorsal to the first tooth pair; and a ventrally bifurcated, single depression for FSAC­KK 5024 ( Jacobs et al. 2020). However, in both specimens, the deltoid facet surface is abraded ( Jacobs et al. 2019, 2020). The division between left and right depressions in the holotype of N. fluviferox is very discrete and low, and thus may have been lost to abrasion in FSAC­KK 5024. The well­preserved ventral outline of the depression in FSAC­KK 5024 is strongly bifurcated and matches well the condition seen in the holotype of N. fluviferox , in both shape and position. This suggests that the holotype of N. fluviferox and FSAC­KK 5024 bore the same feature.

According to Jacobs et al. (2020), FSACK­KK 5024 differed from the holotype of N. fluviferox based on the following features: the slight medial depression on the premaxillary crest dorsal surface (thought of as unique to the specimen) and the lateral margins in anterior view slightly convex, with no narrowing into the premaxillary crest; while the holotype specimen of N. fluviferox exhibits a prominent narrowing and concave margins. The slight medial depression on the dorsal surface of the premaxillary crest (which forms a groove similar to the ones seen in N. capito and Uktenadactylus wadleighi ) cannot be assessed in the holotype of N. fluviferox due to incompleteness. The prominent narrowing and concave margins (in anterior view) in the holotype of N. fluviferox are the anterior margins of the premaxillary crest, located dorsal to the deltoid facet. Therefore, the shape of the lateral margins in anterior view (dorsal to the deltoid facet) are intrinsically related to the development of the premaxillary crest, and the reported variation can thus be easily explained by ontogenetic development and/ or sexual dimorphism. In fact, if premaxillary crests are unconsidered, then the anterior outline of the holotype of N. fluviferox becomes a match for FSACK­KK 5024, with slightly convex lateral margins without a dorsal narrowing. This feature therefore does not exclude FSACK­KK 5024 from N. fluviferox and we regard the two as most likely conspecific, due to the above mentioned features that they share. The referred specimen adds to the known morphology of N. fluviferox by showing the presence of a groove on the anterodorsal margin of the premaxillary crest, similar to that seen in N. capito and U. wadleighi .

Stratigraphic and geographic range.— Type locality and horizon only.

Genus Uktenadactylus Rodrigues and Kellner, 2008

Type species: Uktenadactylus wadleighi ( Lee, 1994) ; Albian, Texas, USA.

Included species: Uktenadactylus wadleighi ( Lee, 1994) and Uktenadactylus rodriguesae sp. nov.

Diagnosis.—Coloborhynchines with a roughly subcircular single depression on the deltoid facet above the first pair of upper teeth; and a palatal bulbous projection between the second pair of upper teeth.

Remarks.—In the present work, we regard the genus Uktenadactylus to contain two species: U. wadleighi and U. rodriguesae sp. nov., based on IWCMS 2014.82, originally described by Martill (2015) and attributed to Coloborhynchus sp. based on the first pair of upper teeth being of anteriorly directed, and a 90° upturn of the palate. These features are herein regarded as general for the Coloborhynchinae (see Discussion). Martill (2015) mentioned the existence of a palatal bulbous projection between the second pair of upper teeth in IWCMS 2014.82, but did not comment on it further. We note here that it is a shared trait with Uktenadactylus wadleighi . We further note that these two taxa share a round depression on the deltoid facet, located above the first pair of upper teeth; which was already reported as present in U. wadleighi ( Lee 1994; Rodrigues and Kellner 2008). The surface of the dorsal region of the deltoid facet is flat in Coloborhynchus clavirostris , whereas it bears a pair of lateral ridges in Nicorhynchus .

Jacobs et al. (2019) considered that Nicorhynchus fluviferox shared with Uktenadactylus wadleighi the following feature: a palatal depression posterior to the second pair of upper teeth. However, upon first­hand analysis of the holotype of U. wadleighi , we report here that the condition present in U. wadleighi is not the same that was described for Nicorhynchus fluviferox . In Nicorhynchus fluviferox , a true depression excavates the palatal surface posterior to the second pair of upper teeth, as reported by Jacobs et al. (2019). However, in Uktenadactylus wadleighi , this feature is not present. The palatal surface posterior to the second pair of upper alveoli is not level with the surface between the second pair of upper alveoli, indeed; but this does not happen due to a depression posterior to the second pair of upper alveoli. Instead, it happens due to a bulbous projection between the second pair of upper alveoli, protruding beyond the palatal plane. This feature can only be seen in U. wadleighi and IWCMS 2014.82.

Stratigraphic and geographic range.—Barremian–Albian; Wessex Formation, England; Paw Paw Formation, USA.

Figures

Fig. 3. Anhanguerid pterosaur Nicorhynchus fluviferox comb. nov., FSAC­KK 10701, Hassi El Begaa, Er Rachidia Province, Morocco,?Albian–lower Cenomanian.In anterior (A1), posterior (A2), left (A3) and right (A4) lateral, palatal (A5), and dorsal (A6) views. Photographs courtesy of Megan L.Jacobs.