The Palaeontographical Society

Research reports

Reports from past Richard Owen Fund recipients

 

 

2011 Research Grant Reports

1. British Devonian Crinoidea: Fresh results from the field

Fiona E. Fearnhead

Natural History Museum, London


Whittaker & Leveridge (2011) recently noted that the Valley of Rocks, Lynton Formation, contains “a variety of fossil forms amongst which bivalve, brachiopods, bryozoans and crinoid debris are relatively common together with bands rich in Modiomorphia”. This proposal was for support to collect this crinoid material for description and inclusion in a forthcoming Monograph of the Palaeontographical Society, ‘British Devonian Crinoidea’ (Donovan & Fearnhead, research in progress).

                  The Valley of Rocks GCR site, Lynton Formation, and its fossils played a key role in the definition of the Devonian System and in the stratigraphic correlation of the marine Devonian stratigraphy of southwest England with the Old Red Sandstone.  Originally designated as Cambrian or Silurian age by Sedgwick and Murchison, the sequences contributed significantly to the scientific debate with De la Beche and Greenough (Rudwick, 1985).

                  The principal aim of this fieldwork was to collect crinoid material (both articulated, if available, and disarticulated columnals and pluricolumnals) from the Valley of Rocks. This field research was undertaken in late July 2012, resulting in a large collection filling four large shoe-boxes with natural moulds of fossil crinoids. Material includes crinoid columnals, with at least two new, as yet undescribed morphogenera. Associated trace fossils and brachiopods were also collected.

                  Identification and description of this new crinoid material is ongoing. The columnals collected at the Valley of Rocks show that there was a wider diversity of crinoids from this site than first thought. There are at least five distinct morphospecies awaiting description. Unexpectedly, none of the more distinctive columnal morphologies commonly associated with Devonian strata, such as Cupressocrinites Goldfuss, Hexacrinites Phillips or Floricolumnus (col.) Stukalina, are present in this collection. A manuscript is being prepared for publication (Fearnhead & Donovan, research in progress), the results of which will contribute to Part 2 of ‘British Devonian Crinoidea’.

                  In addition to the objectives stated above, I visited Combe Martin and identified a thin, crinoid-rich horizon containing small disarticulated ossicles. My reconnaissance also extended to David’s Hole and Sandy Cove, but with less success. I also noted and reported to Mr. J.S.H. Collins (the Natural History Museum, London) on the presence of the Recent pedunculate barnacle Lepas fascicularis (Ellis & Solander), a small clump of five specimens linked together by their float. Useful contacts were made with the local museum.

                  I thank the Palaeontographical Society for the financial support of this grant which made this short field season possible.

 

References

 

Rudwick, M.J.S. 1985. The Great Devonian Controversy. University of Chicago Press, Chicago, 494 pp.

Whittaker, A. & Leveridge, B.R. 2011. The North Devon Basin: a Devonian passive margin shelf succession. Proceedings of the Geologist Association, 122, 718-744.

 

2. The British Middle and Late Jurassic ichthyosaur Ophthalmosaurus

Benjamin Moon

School of Earth Sciences, University of Bristol

The Middle and Upper Jurassic strata of Great Britain are dominated by two great clay formations, the Oxford and Kimmeridge clays. The fine-grained nature of the matrix, and the hypoxic/anoxic seafloor conditions, has led to the exceptional preservation of many different animal groups. Much of the vertebrate material was collected by Mr Charles Leeds and his son Alfred between 1867 and 1917 (Leeds, 1956). This was sold in two collections, the first entirely to the British Museum (Natural History) (now Natural History Museum), London (BMNH), in 1890–1893 and the second to several museums, including the BMNH and the New Walk Museum, Leicester (LNWM).

                  Among the collections was a significant amount of ichthyosaur material. The distinct morphology of this, compared to the better know Liassic material, led Seeley (1874) to erect the new genus and species, Ophthalmosaurus icenicus. Importantly, Ophthalmosaurus was only the second ichthyosaur genus to be named, after Ichthyosaurus (König, 1818). The preservation of the material is largely three-dimensional, unlike the more familiar Liassic type specimens, which are commonly preserved flattened on slabs. This is compromised by the material mostly being disarticulated to a lesser or greater extent (e.g., Martill, 1987).

                  The purpose of the present study was to examine and re-describe the British material of O. icenicus. Much of this is derived from the Callovian (Upper Jurassic) Peterborough Member of the Oxford Clay Formation (Andrews, 1910; Hudson & Martill, 1994). A certain amount of material has been collected from the more recent Kimmeridge Clay, particularly from the Jurassic Coast of Dorset, and Wiltshire and Cambridgeshire. Complete descriptions of this taxon are few (Andrews, 1910; Kirton, 1983), and there are a few more partial descriptions (Seeley, 1874; Appleby, 1956).

                  The material held in the BMNH includes the type specimens of O. icenicus (BMNH UK R2133 and R2134), along with several others. The designation of holotype in the original publication is unclear and will be rectified following consultation with the International Code of Zoological Nomenclature. The LNWM contains many more specimens from the Leeds collections, including the type of Ophthalmosaurus monocharactus Appleby, 1956. These two species were diagnosed on solely on the number of notches present on the coracoids; O. icenicus possesses two notches – anterior and posterior – and O. monocharactus has a single anterior notch. Examination of the material confirms the diseased nature of part the type specimen (BMNH UK R2133) and the significant amount of intraspecific variation present. This condition corroborates previous hypotheses on the synonymy of these taxa. There have also been questions on the generic separation of O. icenicus and the American species “Ophthalmosaurus” (Baptanodon) natans (Marsh, 1879). Comparisons between descriptions (Gilmore, 1905; Appleby, 1956; Kirton, 1983) suggest that there is no material referable to “O.” (B.) natans from the British Middle and Upper Jurassic.

                  To quantify this variation, landmark morphometric techniques will be used. These will focus upon the humerus and scapula of several specimens. These elements were chosen because of the number of well-preserved, uncrushed specimens available and for the ease of landmark recognition, and were photographed comprehensively for this purpose. In particular, there is a noticeable difference in the relative sizes of the distal humeral facets, for articulation with the ulna, radius and a preaxial accessory element. The ratios between these have been used as diagnostic characters, as for Acamptonectes densus Fischer et al., 2012. Morphometric analysis will aim to show the total variation of the material assigned to O. icenicus; however, it is expected that the sample size will be too small for certain hypotheses to be drawn on, for example, sexual dimorphism.

                  This study is part of a larger project on the taxonomy of British Middle and Upper Jurassic ichthyosaurs. Completion of a manuscript is expected in October 2013.

                  I and gratefully acknowledge the Society’s support in completion of this study. I thank Dr Mark Evans (LNWM) and Ms Sandra Chapman (BMNH) for allowing access to the relevant collections, and for their help during this research. My thanks go to Dr Angela Kirton, whose materials form the basis of this project, and Professor Mike Benton as my supervisor.

 

References

 

Andrews, C.W. 1910. A Descriptive Catalogue of the Marine Reptiles of the Oxford Clay. Part I. British Museum (Natural History), London, xxiv+205 pp.

Appleby, R.M. 1956. The osteology and taxonomy of the fossil reptile Ophthalmosaurus. Proceedings of the Zoological Society of London, 126, 403–448.

Fischer, V., Maisch, M.W., Naish, D., Kosma, R., Liston, J.J., Joger, U., Krüger, F.J., Pérez, J.P., Tainsh, J. & Appleby, R.M. 2012. New ophthalmosaurid ichthyosaurs from the European Lower Cretaceous demonstrate extensive ichthyosaur survival across the Jurassic–Cretaceous boundary. PLOS ONE, 7, e29234.

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

Hudson, J.D. & Martill, D.M. 1994. The Peterborough Member (Callovian, Middle Jurassic) of the Oxford Clay Formation at Peterborough, UK. Journal of the Geological Society, London, 151, 113–124.

Kirton, A. M. 1983. A review of British Upper Jurassic ichthyosaurs. Unpublished Ph.D. thesis, University of Newcastle-upon-Tyne, 239 pp.

König, C.D.E. 1818. Synopsis of the contents of the British Museum. British Museum (Natural History), London.

Leeds, E.T. (Swinton, W.E., ed.). 1956. The Leeds Collection of Fossil Reptiles from the Oxford Clay of Peterborough. Blackwell Publishing, Oxford, 104 pp.

Marsh, O.C. 1879. A new order of extinct reptiles (Sauranodonta) from the Jurassic Formation of the Rocky Mountains. Annals and Magazine of Natural History, 3, 175–176.

Martill, D.M. 1987. A taphonomic and diagenetic case study of a partially articulated ichthyosaur. Palaeontology, 30, 543-555.

Seeley, H.G. 1874. On the pectoral arch and fore limb of Ophthalmosaurus, a new ichthyosaurian genus from the Oxford Clay. Quarterly Journal of the Geological Society, 30, 696–707.

 

3. Pterosaurs of the British Jurassic

Michael O'Sullivan

School of Earth and Environmental Sciences, University of Portsmouth

During the Mesozoic, pterosaurs were the dominant volant vertebrates. Arising in the Middle-Late Triassic, they were spread globally by the Lower Jurassic, occurring from Europe to Antarctica. They appear to have undergone a speciation event in the Late Jurassic, leading to a boom in diversity throughout the Early Cretaceous (Butler et al., 2009). They became less numerous in the Late Cretaceous, reduced to only two groups in the Maastrichtian (Witton & Naish, 2008).

                  Within the United Kingdom, pterosaur fossils are limited to Lower and Middle Jurassic strata. Only two families with three taxa are known: the Dimorphodontidae (Dimorphodon macronyx Owen, 1859); and the Rhamphorhynchinae (Parapsicephalus purdoni Arthaber, 1921, Rhamphocephalus Seeley, 1880). Dimorphodon from the Blue Lias Formation (Sinemurian) of Lyme Regis is one of the earliest pterosaurs to have had a formal description (Buckland, 1829). It possesses a highly distinctive, extremely deep skull and robust forelimbs. Parapsicephalus from the Alum Shale Formation (Toarcian) of Whitby was described on a single, near complete skull (BGS GSM 3166), missing only the anterior portion of the rostrum. BGS GSM 3166 is preserved in 3-D and, after preparation, was shown to possess an endocast (Newton, 1888), one of the few pterosaur brain casts on record (Unwin, 1996). Rhamphocephalus from the Taynton Limestone Formation (Bathonian) of Oxfordshire was erected for a skull table preserved in dorsal view. The name was later applied to hundreds of partial Middle Jurassic pterosaurs collected from what is colloquially called the Stonesfield Slate.

                  Over four hundred pterosaur fossils are known from the Stonesfield Slate, with collection dating to the mid-18th century (Anon, 1757), making them the first pterosaur fossils to be mentioned in the formal literature, even if the pterosaurian nature of these remains would not be formally recognised for many years (Buckland, 1836). Over the next century, hundreds of isolated pterosaur remains were collected. These consisted almost entirely of isolated appendicular elements, with only a handful of cranial and axial fossils. Wingspan estimates suggest some of these pterosaurs reached ~2 m, large for Jurassic pterosaurs, which rarely exceed 1.6 m (Hazelhurst & Rayner, 1992). Despite the huge number of fossils (well over 400), only one genus has been erected, Rhamphocephalus, which has three species: R. prestwichi, the type species; and R. bucklandi and R. depressirostris, both erected for isolated mandibles. Rhamphocephalus bucklandi was first described as Pterodactylus bucklandi Meyer, 1832. Huxley (1859) re-appraised the taxon, diagnosing it as Rhamphorrhynchus bucklandi and erected a second species, R. depressirostris. Seeley (1880) erected R. prestwichi, identifying it as a pterosaur (based on the thin bone wall) with an overall crocodilian arrangement of the bones. Lydekker (1888) placed Pt. bucklandi and Rh. depressirostris in Rhamphocephalus, and advocated that all pterosaur material from so-called Stonesfield Slate lithologies be placed in either one of the existing species or Rhamphocephalus sp. Several authors (Unwin, 1996; Buffetaut & Jeffrey, 2012) have expressed doubt over the pterosaurian nature of R. prestwichi. As part of a large, monographic review of the pterosaurs of the Lower and Middle Jurassic of England, the type specimen is currently being re-evaluated. Early results suggest the arrangement of the bones visible across the dorsal aspect of the skull does not correspond to that of any known pterosaur. Similarities have been found with several marine reptiles, including sauropterygians and thallatosuchians. The specimen remains in review. Regardless of the nature of the type material, given the lack of any analogous or comparative material in any Stonesfield collections, the genus Rhamphocephalus cannot be assigned to any other fossil. Therefore, a major re-evaluation of the isolated appendicular material has been undertaken. Preliminary results suggest more than one pterosaur family is present, although how diagnostic the material is remains to be seen.

                  While this project is a review of established collections, it has included a newly discovered fossil (BMNH PV R36634) from the Alum Shale consisting of an associated humerus and scapulocoracoid. The humerus is 100 mm long and, as such, is one of the largest known for any Jurassic pterosaur. Analysis suggests it is a large (~2 m or more) rhamphorhynchine. While there is no comparable material with the BGS GSM 3166, bivariate morphometric analyses suggest the humerus is approximately the size of one predicted for a rhamphorhynchine as with a skull the size of that specimen. Intriguingly, the humerus has a paedomorphic morphology. Pterosaur humeri become more robust relative to their length as they grow, yet the humerus of PV R36634 is highly elongate. This condition is only present in ontogentically immature rhamphorhynchines and has never been seen previously in a humerus of this size. A manuscript is currently in preparation.

                  Hundreds of specimens remain to be examined in greater depth, most critically the holotypes of the various species of Rhamphocephalus. A re-appraisal of Parapsicephalus purdoni is also in its early stages.  Preliminary data suggests that pterosaurs from the Lower and Middle Jurassic were larger than previously believed, and may have possessed unique morphologies.

 

References

 

Anon. 1757. [Further accounts of fossils.] Gentleman’s Magazine, 27, 122–123.

Arthaber, G. v. 1921. Studien ueber Flugsaurier auf Grund der Bearbeitung des Wiener Exemplares von Dorygnathus banthensis Theod. Sp. Denkschriften der königlichen Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Klasse 97, 391-464.

Buckland, W. 1829. On the discovery of a new species of Pterodactyle in the Lias at Lyme Regis. Transactions of the Geological Society (series 2), 3, 217-222.  

Buckland, W. 1836. Geology and Mineralogy Considered with Reference to Natural Theology. The Bridgewater Treatises on the Power, Wisdom and Goodness of God as Manifested in Creation, Treatise VI (2 vols). William Pickering, London.

Buffetaut, E. & Jeffery, P. 2012. A ctenochasmatid pterosaur from the Stonesfield Slate (Bathonian, Middle Jurassic) of Oxfordshire, England. Geological Magazine, 149, 552-556.

Butler, R.J., Barrett, P.M., Nowbath, S. & Upchurch, P. 2009. Estimating the effects of sampling biases on pterosaur diversity patterns: implications for hypotheses of bird/pterosaur competitive replacement. Paleobiology, 35, 432446.

Hazelhurst, G.A. & Rayner, J.M.V. 1992. Flight characteristics of Triassic and Jurassic Pterosauria: an appraisal based on wing shape. Paleobiology, 18, 447–463.

Huxley, T.H. 1859. On Rhamphorhynchus bucklandi a new pterosaurian from the Stonesfield Slate. Quarterly Journal of the Geological Society, 15, 658-670.

Lydekker, R. 1888, Catalogue of the fossil Reptilia and Amphibia in the British Museum (Natural History). Part I. London, pp. 2–42.

Meyer, H.V. 1832. Palaeologica zur Geschichte der Erde und ihrer Geschöpfe, Verlag von Siegmund Schmerber, Frankfurt am Main, 560 pp..

Newton, E.T. 1888. On the skull, brain and auditory organ of a new species of pterosaurian (Scaphognathus purdoni) from the Upper Lias near Whitby, Yorkshire. Proceedings of the Royal Society, 23, 436-440.

Owen, R. 1859. On a new genus (Dimorphodon) of pterodactyle, with remarks on the geological distribution of flying reptiles. Report on the Twenty-Eight Meeting of the British Association for the Advancement of Science, 97-98.

Seeley, H.G. 1880. On Rhamphocephalus Prestwichi Seeley, an Ornithosaurian from the Stonesfield of Kineton. Quarterly Journal of the Geological Society, 36, 27-30.

Unwin, D.M. 1996. The fossil record of Middle Jurassic pterosaurs. In: Morales, M. (ed.), The Continental Jurassic. Museum of Northern Arizona Bulletin, 60, 291-304.

Witton, M.P. & Naish, D. 2008. A reappraisal of azhdarchid pterosaur functional morphology and paleoecology. PLoS ONE, 3 (5), e2271. doi:10.1371/journal.pone.0002271.

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