The Micropalaeontological Society

Spring Meeting 2011 – Report

Skye Group Photo
Meeting group photograph, Geology Department, University of Leicester

Leicester, 4th June, 2011

The meeting was organised and hosted by David Siveter and Mark Williams in the Department of Geology, University of Leicester. Our thanks go to David and Mark for this and to the university for allowing us to use its facilities. With over twenty people and ten talks this meeting, following on from the well-attended meeting in October 2010, marks a sustained resurgence in activity. Matt Wakefield (BG Group) has kindly provided a concise summary of the talks:

Alan Lord  & Maria Cabral (University of Lisbon) presented “Ostracod evidence and the Neolithic environment of Rio Sizandro, western Portugal”. The work was based on borehole material from around Benfica that penetrated river valley deposits, dated at c. 6500-6100yrs BP, which cut into Upper Jurassic strata. The area was originally flooded with sea-water but following a sea-level fall (6-7ky BP) the valley began to fill with sediment, some of which may have been agriculturally mediated. Brackish water ostracods were present in the base of the succession including Cyprideis torosa (un-noded) and Leptocythere porcellanea with occasional Callistocythere murrayi. Rare, poorly preserved freshwater ostracods (Ilyocypris bradyi, Ilyocypris inermis – a first record in Portugal, Limnocythere inopinata and Darwinula stevensoni) were also present.

Dinah Smith (University of Leicester) discussed some of her doctoral work in the English fens; “Once upon a time…there was a roddon”. So, what is a roddon?  You may indeed ask. Basically it is the dried raised bed of a river or tidal-creek. They can be seen from aerial photographs or better still, from IFSAR satellite images and are visible due to seventeenth century draining leading to the peats drying, shrinking and compacting thus allowing the sands/silts/gravels of channels to appear in bas-relief. To date Dinah has been working on describing the sedimentology of the roddon at the Mist Farm site that was exposed during quarrying. She has recovered fossil material of foraminifera, ostracods, fish scales and teeth but hasn?t described them yet. The work is part of a multi-disciplinary approach with much attention focused on the archaeology with eel-traps having been found along with woven nettle material and pots containing food.

Ray Bate (Global Exploration Services) discussed his Oil Industry related ostracod work: “Early Cretaceous Pre-Salt basins of the South Atlantic” Ray described the current two-phase opening of the South Atlantic and how this is reflected in the stratigraphy of the basins along the West African and South American margins. The first phase is early Neocomian while the Barremian Atlantic-Hinge second phase of rifting is of particular interest as it broke up the large-scale non-marine lacustrine systems that were contiguous between the now separate continents. The salinity of there lakes was not controlled by any marine connection. Ray described the basic ostracod biozonation from the Kwanza Basin and how it reflects sequence stratigraphy and/or climate forcing. The ostracod fauna was generally of low diversity but contained high specimen numbers.

Ian Boomer & Chris Nash (University of Birmingham) talked about Chris’ final year undergraduate project entitled “An early post-glacial multiproxy record from lowland NE England and a new post-Hoxnian record for the UK” . (Good look with your ‘finals’ Chris!). This work looked at sediments inland from Bamburgh Castle, the peaty upper portion of which have previously been investigated palynologically. Ostracods were recovered from the lowermost laminated clays and silts dated at 15-20ky that overlay glacial sediments. Candona candida dominates the fauna along with the cool-water Cytherissa lacustris and Limnocythere sussenbornensis. Application of the MOTR method indicates January & July temperatures of -8 to +3oC and 12 to 23oC respectively.

David Siveter (University of Leicester) talked about “Exceptionally preserved myodocope ostracods from the Herefordshire (Silurian) Lagerstatte: implications for the systematic affinity of palaeocopes’ and illustrated with computer 3-D animations the latest two ostracods to be discovered: Nasunaris flata and an as yet unpublished species, informally called ‘wingy’ due to its posterero-dorsal ?alae that make it look like a 1950’s Cadillac. These are both Cylindroleberid myodocopes with preserved softparts including eyes, gill structures and well developed second antennae suggesting a nektobenthic life mode. Both are huge ostracods 10-12mm in length. What is of particular interest is that the hard-part morphology indicates that these species ought to be palaeocopes but the soft-parts clearly show this not be the case, suggesting our understanding of Palaeozoic ostracod taxonomy may be erroneous. For further information on Cylindroleberid ostracods you should check out Anna Syme’s 2007 Ph.D. thesis “A systematic revision of the Cylindroleberididae (Crustacea: Ostracoda: Myodocopa)”, which can be downloaded here

Robin Whatley (Aberystwyth University), following on from David Siveter’s theme of the hard parts can’t always be trusted taxonomically, discussed in his inimitable fashion “An unusual ostracod from down under”. The Australian ostracod in question has many features that are taxonomically confusing. It was originally thought to be a lancellate shaped Trachyleberid without an eye tubercle. However, its lateral flattening and large well-defined marginal areas with numerous normal pores are also at odds with this. In addition it has a pectodont rather than an amphidont hinge suggesting it may be an indo-pacific Pectocytherid. Eventually Robin decided that the presence of five adductor muscle scars was the defining taxonomic character i.e. the species is a Bythocytherid, a fact that was agreed upon by many in the audience. However, work to solve this taxonomic conundrum is set to continue as Bythocytherids are not known to possess sieve pores. It was particularly nice to see Robin back in harness after his long illness and recuperation.

Mike Ayress (Ichron Ltd), using data from Statoil Well 35/a-F-1H defined “A new record of Aratrocypris from the Early Cretaceous of the North Sea: a range extension for the genus”. This strange looking genus has a ‘plough-like’ extension to its anterior margin that is considered to have been used when feeding across the sediment. It occurs at two horizons within the well succession; firstly as part of a reworked Maastrictian assemblage within the Lower Palaeocene and secondly within the Valhall Formation. The range can now be extended back from the Coniacian into the Lower Barremian/Hauterivian.

Mohib Khan (University of Leicester) described his doctoral work that asked the question “Do ostracods define patterns of Ordovician climate change”. The end-Ordovician extinction accounted for 5-10% of all species known at that time, although ostracods appear not to have been affected. Mohib was able to show that the late Orovician to early Silurian ostracods from Iran were similar to those from the US, i.e. ostracods from Gondwana, Laurentia and Baltica were similar. Recent isotopic data suggests that for much of Ordovician times the earth experienced a ‘greenhouse’ climate, although a glaciation is known from the end of that period. Chitinozoan data suggest movement of an oceanic ‘polar front’ from 60oS to 40oS during this late Ordovician interval. Using ordination analysis of ostracod data, Mohib separated out two ostracod biotopes within data from six Laurentian localities of Carodocian age. These are believed to represent tropical and subtropical settings.

Dave Horne (Queen Mary University of London) talked about his recent sabbatical in Gatineau and Ottawa, Canada, where he worked on “The Delorme Collection and database of Canadian non-marine ostracods”. Denis Delorme’s collection amounts to some 30,000 ostracod records from 5,000 separate locations. The database records locations, species identifications and highly detailed environmental information both chemical and physical. The sampling was often based on a systematic grid (selecting the nearest water body to the grid point) or along major highways. Dave is trying to harmonise North American and European non-marine ostracod taxonomy. He suggested that Candona acutula Delorme 1967 may be synonymous with Fabaeformiscandona levanderi (Hirschman 1912) although further work is required. Dave has also chased down the actual location of all the type-material and this will be documented in a forthcoming publication. Finally, Dave showed us some images that suggested his sojourn in Canada was not all work-oriented, including a striking photograph of him wearing a hat we had not seen before.

Ian Boomer, Sarah Hawkes & Phil Copestake talked about “Early Jurassic Microfossils and the Toarcian Oceanic Anoxic Event (TOAE) in SW England”. A new section at Hurcott, near Ilminster in Somerset has become available that has alternating muds, silts and friable limestones of latest Pleinsbachian through Toarcian age. The ostracods recovered by Sarah in her final year undergraduate project from this shallow-water succession can easily fit into the existing ostracod zonation for this time period. The foraminiferal fauna recovered was more diverse than the ostracod fauna, though the former were all long- ranging so could not help refine the age dating. C isotopic work on the Hurcott section and that at Mochras reveal the position of the OAE but the former is shelfal, not basinal. Further work is planned in Gloucestershire, at Thorncome in Dorset and from the Kerr-McGee 97/12-1 well in Lyme Bay to understand the development of the TOAE in shelfal settings.

And later … John Whittaker (NHM) writes: After the scientific meeting most of the party stayed on into the Saturday evening and, accompanied in many cases by our wives, proceeded to the “White Horse”, Leire, quite near to the Siveters’ country residence.  Like the famous Monsieur Rick of the film Casablanca, the proprietor, also called Rik, did us proud.  It was hoped, with a well-known and successful entrepreneur in our presence, that the wine might be sponsored, but even though this was not to be, a most pleasant dinner was enjoyed by all. David and Pauline Siveter are also to be gratefully thanked for their personal hospitality to several members of the group.