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February 28, 2012
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Palaeontology Department Seminar

 

 

Chert on the beach

 

Dr. Lil Stevens,

Department of Palaeontology, NHM

 

Thursday 1st March
Neil Chalmers Seminar Room, DC2,

16:00 - 17:00

 

 

 

In 2004 an amateur collector found a dull brown cobble on the beach at Sandsend, part of the Yorkshire Jurassic coast. Hammer at the ready, he broke the cobble into eleven pieces and looked into its interior. It was probably raining, which would have helped him to see small pieces of fossilised plants preserved within the chert, including what looked like reproductive structures. The cobble made its way to Birmingham University and after many months of sectioning and polishing, there began to emerge the most beautifully preserved Palaeozoic plant and crustacean remains I have ever seen.

Contained in the cobble were vegetative and reproductive fragments of an arborescent lycopsid with cellular preservation. The cone fragments were described as Flemingites arcuatus sp. nov. and analyses confirmed a provisional assignment to Paralycopodites stem genus. Associated with the plant remains were many small univalve crustaceans described as Ebullitiocaris elatus sp. nov., the same genus as those found in the Devonian Rhynie chert from Scotland. Extremely rarely for this age of fossil, both internal organs and appendages are visible and show a long morphological stasis and even some features still retained by modern Cladocera.

The cobble has preserved organisms of mid to late Carboniferous age and is therefore ex-situ. Chert content analysis and the level and mode of preservation of the fossils suggests not necessarily a hot spring environment, but a swamp certainly influenced by some sort of hydrothermal volcanic activity that caused rapid solidification. Comparison with other cherts has not helped to narrow down the original locality and it is thought that although the cobble was probably transported south east by glacial activity, it is also possible that it was dumped as ballast on the busy shipping routes around north east Britain, and so could have originated from almost anywhere in the world.

 

 

 

For additional details on attending this or other seminars see http://www.nhm.ac.uk/research-curation/seminars-events/index.html

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Zoology Seminar


TUESDAY
28th February, 12 noon

Neil Chalmers Science Seminar Room  (DC.LG16)

 

Contact: Ronald Jenner, Zoology



The Mysterious World of Vampire Amoebae and  Plasmodiophorid Plant Parasites

Sigrid NEUHAUSER & Cédric  BERNEY
Department of Zoology, NHM

Vampire amoebae  (Vampyrellida) and plasmodiophorid plant parasites (Phytomyxea) have been known  since the second half of the XIXth century, yet have been given very little  attention up to now in spite of their fascinating biology. The taxonomic  position of both groups has been much debated for over a century, but recent  molecular work showed them to be sister lineages within the eukaryotic  supergroup Rhizaria. From their common ancestor, the Vampyrellida evolved to  become super-predators of algae, fungi and other microorganisms in all marine  and terrestrial microbial ecosystems, with some species adopting a peculiar mode  of feeding that earned them the name of vampire amoebae. In contrast, the  Phytomyxea evolved to become obligate, endobiotic parasites of higher plants,  diatoms, brown algae and oomycetes. Members of this group can cause devastating  and significant plant diseases (e.g. Plasmodiophora brassicae causing  clubroot disease), while others will spend their life hidden inside their hosts  without causing any visible symptoms. As part of our research group’s focus on  the biodiversity, evolution, and ecological importance of poorly known members  of the Rhizaria, we will present some of our results and illustrate the  enigmatic nature and contrasting lifestyles of vampire amoebae and  plasmodiophorid plant parasites.