Journal of Vertebrate Paleontology

The anatomy of Stratesaurus (Reptilia, Plesiosauria) from the lowermost Jurassic of Somerset, United Kingdom

ROGER B. J. BENSON1*, MARK EVANS2,3 and MICHAEL A. TAYLOR 4,5

1Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, United Kingdom, [email protected]; 2New Walk Museum and Art Gallery, 53 New Walk, Leicester LE1 7EA, United Kingdom, [email protected]; 3Department of Geology, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom; 4Department of Natural Sciences, National Museums Scotland, Chambers St, Edinburgh EH1 1JF, United Kingdom; 5School of Museum Studies, University of Leicester, Museum Studies Building, 19 University Road, Leicester LE1 7RF, United Kingdom, [email protected]

*Corresponding author

APPENDIX S1 Preparation and authenticity of the type specimen, and additional specimen provenance data

Preparation of the type specimen OUMNH J.10337 is well preserved, though the skull especially is somewhat dorsoventrally crushed. The specimen was originally collected as a set of laminated limestone blocks, with some loss of bone as shown by the presence of incomplete bones at the edges of some blocks. The matrix layers varied from almost pure limestone, a light cream probably because of deep subsurface weathering, to a greyish relatively clayey marlstone. The blocks were originally prepared mechanically, inverted so as to expose the lower surface as the specimen originally lay (the lower side usually being better preserved and less disturbed, as in this instance). The blocks were then embedded in a cement-like compound in a wooden frame, and the cement and matrix overpainted in the usual Victorian style (Fig. S1). The original mechanical preparation was very good for the time, and might have been carried out by Thomas Hawkins himself. Nevertheless this preparation, and/or initial collection, inevitably caused some damage, and some parts were detached and stuck back onto the main part. The originally exposed parts of the bone and teeth can mostly be recognised by the bleaching of their original mid-brown colour to a pale cream during display from 1874 to 1979, at least for those elements not covered in cement. MAT chemically prepared OUMNH J.10337 in 1979–1983 using the then standard techniques, after a sample of matrix was removed and record photographs were taken (Rixon, 1976). The matrix was removed by cycles of immersion in acetic acid. The acid was glacial acetic acid diluted initially with water to give a 10% per volume stock. This stock was further diluted as necessary to prevent effervescence caused by any excessively vigorous reaction with the carbonate-rich limestone, which might damage or displace elements. Each period of acid immersion lasted for about four to six hours, dissolving no more than about 2 mm depth of matrix at a time. Acid immersion was followed by rinsing to eliminate soluble salts by being placed in a bath of clean water for at least two nights and a day; the water was gently renewed during the day by a small stream of water into the corner of the bath. The acid and rinse waters were sieved to catch any loose teeth and other small elements. The specimen was air- dried overnight at room temperature. Any remaining residue of softened matrix was removed with a hand-held needle under a binocular microscope, and newly exposed bone and tooth surface was consolidated with Vinalak 5911, a then available commercial preparation of polybutylmethacrylate, diluted with butan-1-one, in the routine technique used at the time (Rixon, 1976). The consolidant was then allowed to dry overnight and the specimen was put into the acid cycle again the next morning. A silicone rubber/GRP jacket was used to cover and support the front of the block containing the skull, to control acid attack on the bone side until the rear of the block was substantially reduced (Rixon, 1976). A similar approach was taken during preparation of CAMSM J.46986, another Hawkins plesiosaur specimen from Street (Storrs and Taylor, 1996). OUMNH J.10337 generally responded superbly to this technique, revealing many fine details, but it is now fragile, and clearly acid preparation of Street fossils should only be done with great care to avoid damage to irreplaceable specimens. X-ray microtomography provides an alternative to specimen preparation for visualising anatomy, and RBJB has attempted this with two specimens from Street: CAMSM J.46986 and GSM 26035. In both cases the X-ray contrast between matrix and bone was low, so results were poor (Benson et al., 2011a).

Figure S1. OUMNH J.10337 prior to preparation. (A) Archival photograph (copyright and courtesy of Oxford University Museum of Natural History); (B) interpretive line drawing with numbered blocks.

Authenticity of the type specimen of Stratesaurus taylori OUMNH J.10337 was preserved as a number of blocks of bones, teeth and matrix; as each element was exposed during preparation, it was numbered in the form x-y where x was the block number and y was the individual specimen number within the block (some elements bear more than one number because they were originally exposed in more than one place, or were assembled from pieces from more than one block). The head, anterior neck and some elements lay on blocks 5, 6 and 7 which fitted together continuously (Fig. S1). The remaining elements lay mostly jumbled together on several other blocks without demonstrable fits to the others (except that blocks 2 and 3 fitted together). This raised the question of whether extraneous elements from other individuals had been used to bulk out an incomplete specimen, especially one that had passed through Thomas Hawkins’s hands. Hawkins was by no means the only 19th century collector to indulge in this practice, but he is, with some justice, notorious for it (McGowan, 1990, 2002; Taylor, 2003, 2005; Lomax and Massare, 2012). Worryingly, another ‘specimen’ in his 1874 donation to OUMNH was known to be a composite of no fewer than three partial individual ichthyosaurs (collectively OUMNH J.10305, OUMNH records of dismounting by MAT in 1981). OUMNH J.10337 was accordingly viewed with suspicion right from the start of our work. However, its blocks do appear to be from the same individual, because of the absolute similarity of the scattered bones and teeth and their preservation, and the similarity of the laminated matrix in the blocks. In particular, the axial intercentrum, which closely articulates with other elements of the atlas-axis complex, was found on a block separate from those carrying the main head-neck area.

Additional provenance data for referred specimens of S. taylori BGS GSM 26035 was obtained at Street by Thomas Clark junior (1792-1864) of Bridgwater, Somerset. He was a member of the Clark family of Street and later partner in the notable shoemaking firm of C. and J. Clark which became the largest employer in the village (Anon., 1950; Bowen, 1854; Torrens, 1980; Palmer, 2013). The specimen was apparently sent to the Geological Society of London in 1823 via Robert Anstice (1757- 1845), the Bridgwater merchant, civil engineer and geologist who collaborated with William Buckland (Anon., 1824, p. 428; Torrens, 1982; Greenfield, 2002). It was prepared clear of excess matrix by the famous sculptor Francis Leggatt Chantrey (1781- 1841) (Bowen, 1854; Buckland, 1835, p. 228; Taylor, 1997). The Society’s museum passed later to BGS (Torrens, 1982; Evans, 2010). AGT 11 is one of two significant plesiosaur specimens in the AGT, the other being a postcranial skeleton referred to Avalonnectes arturi (Benson et al., 2012: AGT large specimen 19). Both specimens are presumed to have been collected by Alfred Gillett (1814-1904), who was related to Cyrus and James Clark, the founders of the firm of C. and J. Clark (Sutton 1979, foldout between pp. 204-5). He was a keen amateur collector who originally lived in Langport, Somerset, but moved to Street on retirement (Woodward, 1904; McGarvie, 1987, pp. 15, 16, 18). Gillett established the Street Museum in the new Crispin Hall, the village’s community centre, in 1887 and provided most (but not all) of the marine reptiles and other fossils therein. When the museum was closed in the mid-20th century, the local fossils were retained in AGT (Anon., 1887a, 1887b; Palmer, 2013, pp. 90, 92; MAT pers. obs.). AGT 11 is labelled ‘Lower Lias, Street’ in a label which almost certainly dates from a 1930s re-curation (Anon., 1948). It is assumed that Gillett collected AGT 11 at Street, where his parents lived and where he collected even before he moved there (e.g., Anon., 1863, p. 29). However, it remains possible that the specimen came not from Street itself but the Langport-Somerton area some 8km to the south of Street, where the same beds outcrop. LITERATURE CITED Anon. 1824. A list of donations to the Library, to the Collection of maps, plans, sections and models; and to the Cabinet of Minerals belonging to the Geological Society; from the close of the Fourteenth Session in June, 1821, to the close of the Sixteenth Session in June, 1823, together with the dates at which they were respectively made and the names of the donors. Transactions of the Geological Society of London, series two 1:427–439. Anon. 1863. Local Museum. Proceedings of the Somerset Archaeological and Natural History Society 11(1):29-30. Anon. 1887a. Opening of the Geological Museum. Western Chronicle, 29 April 1887. Anon. 1887b. Opening of the Geological Museum at Street. Dr. Woodward on the study of geology. Central Somerset Gazette, 30 April 1887. Anon., 1948. Street Museum: temporary storage and closure. Museums Journal, 48:39. Anon. 1950 [believed to be Barber L. H.]. Clarks of Street, 1825-1950. C. & J. Clark, Street. Benson, R. B. J., K. T. Bates, M. R. Johnson, and P. J. Withers. 2011. Cranial anatomy of Thalassiodracon hawkinsii (Reptilia, Plesiosauria) from the Early Jurassic of Somerset, United Kingdom. Journal of Vertebrate Paleontology 31:562–574. Benson, R. B. J., M. Evans, and P. S. Druckenmiller. 2012. High diversity, low disparity and small body size in plesiosaurs from the Triassic–Jurassic boundary. PLOS One 7(3): e31838. Bowen, J. 1854. A brief memoir of the life and character of William Baker, F. G. S., Secretary to the Somersetshire Archaeological and Natural History Society; and Vice-President of the Bridgwater Literary and Scientific Institution, prepared principally from his diary and correspondence by John Bowen. May, Taunton, iii + 128pp. Buckland, W. 1835. On the discovery of coprolites, or fossil fæces, in the Lias at Lyme Regis, and in other formations. Transactions of the Geological Society of London, series two 3:223–236. Evans, M. 2010 . The roles played by museums, collections and collectors in the early history of reptile palaeontology. Pp. 5-29 in Moody, R. T. J., Buffetaut, E., Naish, D. & Martill, D. M. (eds) Dinosaurs and Other Extinct Saurians: A Historical Perspective. Geological Society, London, Special Publications 343. Greenfield, D. 2002. Anstice, Robert (1757-1845) … Pp. 17-18 in Skempton, A. W. (ed.) A biographical dictionary of civil engineers. Volume 1 – 1500 to 1830. Thomas Telford, London. Lomax, D. R., and J. A. Massare. 2012. The first reported Leptonectes (Reptilia: Ichthyosauria) with associated embryos, from Somerset, England. Paludicola 8:263–276. McGarvie, M. 1987. The book of Street. A history from the earliest times to 1925, Barracuda, Buckingham, 164pp. McGowan, C. 1990. Problematic ichthyosaurs from southwest England: a question of authenticity. Journal of Vertebrate Paleontology 10:72–79. McGowan, C. 2002. The dragon seekers. How an extraordinary circle of fossilists discovered the dinosaurs and paved the way for Darwin. Little, Brown, London, xvii + 270pp. Palmer, M. 2013. Clarks. Made to last. The story of Britain’s best-known shoe firm. Profile Books, London, 398pp. Rixon, A. E. 1976. Fossil animal remains: their preparation and conservation. Athlone, London, vii + 304pp. Storrs, G. W., and M. A. Taylor. 1996. Cranial anatomy of a new plesiosaur genus from the lowermost Lias (Rhaetian/Hettangian) of Street, Somerset, England. Journal of Vertebrate Paleontology 16:403–420. Sutton, G. B. 1979. C. and J. Clark 1833-1903, a history of shoe making in Street, Somerset. Sessions, York, viii + 208pp. Taylor, M. A. 1997. Before the dinosaur: the historical significance of the fossil marine reptiles. Pp. xix-xlvi in J.M. Callaway and E.L. Nicholls (eds.) Ancient marine reptiles. Academic Press. Taylor, M. A. 2003. Joseph Clark III’s reminiscences about the Somerset fossil reptile collector Thomas Hawkins (1810-1889); ‘very near the borderline between eccentricity and criminal insanity’: Proceedings of the Somerset Archaeological and Natural History Society 146:1-10 and frontispiece. Taylor, M. A. 2005. Hawkins, Thomas (1810–1889). Oxford Dictionary of National Biography, Oxford University Press, 2004; online edn, revised [http://www.oxforddnb.com/view/article/12682, accessed 3 June 2012]. Torrens, H. S. 1980. Collections and collectors of note. 28. Colonel Birch (c. 1768-1829). The Geological Curator 2:561–562. Torrens, H. S. 1982. The Reynolds-Anstice Shropshire geological collection, 1776-1981. Archives of Natural History 10:429–441. Woodward, H., 1904. [Alfred Gillett], Geological Magazine, decade five, 1:96.