Pterodactylus compressirostris Owen, 1851

Rodrigues, Taissa & Kellner, Alexander Wilhelm Armin, 2013, Taxonomic review of the Ornithocheirus complex (Pterosauria) from the Cretaceous of England, ZooKeys 308, pp. 1-112 : 39-40

Pterodactylus compressirostris Owen, 1851 (nomen dubium) Fig. 14

Pterodactylus compressirostris Owen: Owen 1851b: p. 32, pl. V, figs 1-3. Owen 1851a: p. 95, pl. XXVIII, figs 8-10.

Ornithochirus [sic] compressirostris (Owen): Lydekker 1888: p. 11.

Ornithocheirus compressirostris (Owen): Arthaber 1922: p. 16, fig. 5.

Lonchodectes compressirostris (Owen): Hooley 1914: p. 535.

Ornthocheirus [sic] compressirostris (Owen): Kuhn 1967: p. 42.

Ornithocheirus compressirostris (Owen): Wellnhofer 1978: p. 56, fig. 4.

Lonchodectes compressirostris (Owen): Unwin 2001: p. 210, table 1.

Syntype.

NHMUK PV 39410, partial rostrum and mandible ( Fig. 14A-H ).

Type locality.

Burham, Kent, England.

Type horizon.

Chalk Formation (Cenomanian / Turonian).

Description.

The holotype of Pterodactylus compressirostris consists of the middle portion of the rostrum ( Fig. 14E-H ), without the anterior end of the rostrum, and by a mandibular fragment that is strongly compressed mediolaterally ( Fig. 14A-D ). The rostrum has been subject to some distortion. The symphyseal fragment has been considered part of the upper jaw since its original description ( Owen 1851b), until Kellner (1990: 100) demonstrated the presence of a medial groove and reidentified it as a lower jaw. Owen (1851a) referred both specimens to the same species, because they come "from the same pit, if not from the same block". It is unclear whether these specimens were found associated, and they could well represent different individuals (even if conspecific). It is noteworthy that at least two different pterosaur species from the Chalk Formation were found in the same pit ( Cimoliopterus cuvieri and Lonchodraco giganteus , according to Bowerbank 1852). Kellner (1990) suggested that these two fragments might belong to different individuals, so that (1) they should receive separate catalog numbers, and (2) one of them should be designated the lectotype. As the majority of species from the Ornithocheirus complex is based on jaw tips, we here designate the mandibular fragment as the lectotype, with the original catalogue number NHMUK PV 39410. The other specimen, comprising the middle part of the rostrum, should be renumbered.

The lectotype of Pterodactylus compressirostris does not have a mandibular crest or raised alveoli, excluding it from Lonchodraconidae . It is distinctly compressed, incomplete, and non-diagnostic. Regarding the the cranial portion, few comparisons to Lonchodraco(?) microdon are possible as the specimens are not directly comparable, but they differ in the depth of the palatal ridge, which is lower in Pterodactylus compressirostris . The cranial fragment has small and widely spaced alveoli, reminiscent of Lonchodraconidae , but it is not possible to evaluate whether this feature extended to the tips of the jaws, as in Lonchodraco giganteus , Lonchodraco machaerorhynchus , and Lonchodraco(?) microdon , or if the anteriormost alveoli showed size variation, as in Anhangueridae . The referred specimen shares with Anhangueridae small alveoli on raised alveolar margins in the posterior portion of the maxillae, with the spacing between them roughly equivalent to their diameters. It differs from Anhangueridae in the lack of a premaxillary crest. However, crucial information is lacking due to the absence of the anterior portion of the rostrum in this specimen, a portion very diagnostic for toothed pteranodontoids, and upon which the taxonomy of the group is largely based. Both specimens upon which the species is based are uninformative. Therefore, we here consider Pterodactylus compressirostris a nomen dubium.

Remarks.

Pterodactylus compressirostris was until recently involved in a taxonomic problem. Khozatskii and Yur’ev (1964) and Kuhn (1967) erroneously considered it the type species of Ornithocheirus . This proposal was adopted by latter researchers ( Wellnhofer 1978; Kellner and Tomida 2000; Veldmeijer et al. 2009). Unwin (2001), however, demonstrated that the type species of Ornithocheirus should be Ornithocheirus simus by monotypy.

To further complicate the taxonomy of this species, Kuhn (1967) also referred Pterodactylus compressirostris as the type species of Lonchodectes , and considered Lonchodectes synonymous with Ornithocheirus . Because we consider Pterodactylus compressirostris a nomen dubium, the genus Lonchodectes Hooley, 1914 and the family Lonchodectidae Unwin, 2001 should not be used.

Figures

Figure 14. Pterodactylus compressirostris, holotype NHMUK PV 39410 (Cenomanian / Turonian, Chalk Formation). A-D proposed lectotype, fragment of the mandibular symphysis A left lateral view B respective line drawing C dorsal view D respective line drawing. E-H referred specimen, portion of the rostrum E left lateral view F respective line drawing G ventral view H respective line drawing. Abbreviations: ch - choanae, d - dentary, m - maxillae, naof - nasoantorbital fenestra, pl - palatine, pm - premaxillae, prid - palatal ridge, sul - sulcus. Arrows indicate alveoli or teeth. Scale bar = 10 mm. Photos courtesy of The Natural History Museum.