Ichthyosaurs of the British Middle and Upper Jurassic. Part Two. Brachypterygius, Nannopterygius, Macropterygius, and taxa invalida

Nov 2018 Monographs of the Palaeontographical Society

Moon, B. C. & Kirton, A. M. 2018 Ichthyosaurs of the British Middle and Upper Jurassic. Part Two. Brachypterygius, Nannopterygius, Macropterygius, and taxa invalida . Monographs of the Palaeontographical Society 172(650): 85–176 doi:10.1080/02693445.2018.1468139

While part one of this monograph covered one taxon, Ophthalmosaurus, part two includes three different ichthyosaur taxa, and a few others that aren’t considered valid. Brachypterygius and Nannopterygius are the two better-known ichthyosaurs, both from the Late Jurassic of the UK, and both funky and unusual in their own ways. Additionally there is the potential taxon Macropterygius that is known from particularly poor remains, but seems to represent a different taxon.

Brachypterygius in Bristol Museum
Brachypterygius in Bristol Museum and Art Gallery.

Surprisingly there are relatively few complete and articulated ichthyosaur specimens from the Late Jurassic. Of those only Nannopterygius was known historically from a single specimen, of which Ophthalmosaurus has been put together from multiple specimens (Andrews 1915). More recent collections by Steve Etches has led to a whole new museum full of excellently-preserved ichthyosaurs.

Nannopterygius in the Natural History Museum, London
Perhaps my best view of Nannopterygius in the Natural History Museum , London. Tall as I am I just couldn’t reach it.

And at the end I also compared the material to an American taxon, Baptanodon/Ophthalmosaurus with some re-drawings that I’m quite proud of, even if they are relatively simple.

Outlines of the skull of Baptanodon/Ophthalmosaurus
Redrawn outlines of the skull of Baptanodon/Ophthalmosaurus natans (after Gilmore 1905; from Moon & Krton 2018).

While I, in this monograph, described the available British material, both Brachypterygius and Nannopterygius have undergone further revision based on worldwide finds, particularly from Russia (Zverkov et al. 2015; Zverkov and Jacobs 2020). A few of my interpretations have been changed, such as the limb moprhology in Nannopterygius, and I may not fully agree with including the Bristol Museum specimen in Grendelius rather than Brachypterygius, however, much of my observations have been corroborated. In certain cases more extensive and complete material is required to make extensive comparisons.

References

Andrews, C.W. 1915. Note on a mounted skeleton of Ophthalmosaurus icenicus, Seeley. Geological Magazine 2 (4): 145–146.

Gilmore, C.W. 1905. Osteology of Baptanodon (Marsh). Memoirs of the Carnegie Museum 2 (2): 77–129.

Moon, B.C. and Kirton, A.M. 2018. Ichthyosaurs of the British Middle and Upper Jurassic. Part 2, Brachypterygius, Nannopterygius, Macropterygius, and Taxa Invalida. Monograph of the Palaeontographical Society 172 (650): 85–176.

Zverkov, N.G., Arkhangelsky, M.S. and Stenshin, I.M. 2015. A review of Russian Upper Jurassic ichthyosaurs with an intermedium/humeral contact. Reassessing Grendelius McGowan, 1976. Proceedings of the Zoological Institute RAS 319 (4): 558–588.

Zverkov, N.G. and Jacobs, M.L. 2020. Revision of Nannopterygius (Ichthyosauria: Ophthalmosauridae): reappraisal of the ‘inaccessible’ holotype resolves a taxonomic tangle and reveals an obscure ophthalmosaurid lineage with a wide distribution. Zoological Journal of the Linnean Society.

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