Metriorhynchus, VON MEYER, 1832

Young, Mark T., Brignon, Arnaud, Sachs, Sven, Hornung, Jahn J., Foffa, Davide, Kitson, James J. N., Johnson, Michela M. & Steel, Lorna, 2021, Cutting the Gordian knot: a historical and taxonomic revision of the Jurassic crocodylomorph Metriorhynchus, Zoological Journal of the Linnean Society 192 (2), pp. 510-553 : 531

METRIORHYNCHUS VON MEYER, 1832

( FIGS 1–3 )

Type specimen: MHNG V-2232 , partial cranial rostrum .

Eugène Eudes-Deslongchamps (1867 – 69: 118) attempted to rectify the taxonomic issues associated with Metriorhynchus , and designated a new type species for the genus (Me. superciliosus ). However, the ICZN did not exist during that time, and under Article 68.3 of the Code, M. geoffroyii is the type species by monotypy. As stated above, von Meyer (1832) never designated a type specimen for Me. geoffroyii . The first time MHNG V-2232 was considered to the lectotype was by Vignaud (1995) in his unpublished PhD thesis, which Young et al. (2010) followed. However, as noted above, Young et al. (2010) merely stated that MHNG V-2232 was the lectotype, they did not designate it so. Thus, until this publication, no-one has ever designated a type specimen for Metriorhynchus geoffroyii that fulfils Article 74.7.3 of the ICZN Code. As herein, we formally designate MHNG V-2232 to be the lectotype; it ensures that the cranial rostrum description of von Meyer (1832), which was the basis for the generic name, is reflected in the type specimen and ensures taxonomic stability. With the ‘Havre snout’ (MHNG V-2232) being the lectotype of both Me. geoffroyii and Ga. jurinii it renders them both junior objective synonyms of Steneosaurus brevirostris Holl, 1829 .

Type species: Metriorhynchus geoffroyii von Meyer, 1832 , a junior objective synonym of Steneosaurus brevirostris Holl, 1829 (following Recommendation 67B of the ICZN Code).

Note: We cannot use Article 23.9 to preserve Me. geoffroyii as it does not fulfil Article 23.9.1.2. A Google Scholar online search for ‘ Metriorhynchus geoffroyii ’ from 1970–2020 gave 13 results: all are from 2001 onwards and most of the first authors mentioning the species are co-authors on this contribution. We recognize that Google Scholar is not an ideal literature search, especially for historical names, but it does give a general overview of how widespread the usage of a name is.

Etymology: Latinized from Greek µέτριο, moderate, and ρύγχος, snout.

Diagnosis: Same as the only species herein regarded to be validly assigned to the genus Metriorhynchus (see below).

Figures

Figure 1. Metriorhynchus brevirostris holotype MHNG V-2232. A, dorsal view; B, palatal view. See text for anatomical abbreviations.

Figure 2. Metriorhynchus brevirostris holotype MHNG V-2232. A, left lateral view; B, right lateral view. See text for anatomical abbreviations.

Figure 3. Metriorhynchus brevirostris holotype MHNG V-2232. A, anterior view; B, posterior view. See text for anatomical abbreviations.