Investigating Fossils. Wilson J. Wall. Читать онлайн. Newlib. NEWLIB.NET

Автор: Wilson J. Wall
Издательство: John Wiley & Sons Limited
Серия:
Жанр произведения: Биология
Год издания: 0
isbn: 9781119698487
Скачать книгу
as pointers to the past became undeniable. That we now had a series of items which indicated that species had come and gone, that life had a history and was not brought into being fully formed, made it possible to think of species as being rather more plastic than the ideas of immutability would have had us believe. With that knowledge, species, both fossil and extant, could take their central place in describing evolution.

      1  Allentoft, M.E., Collins, M., Harker, D. et al. (2012). The half‐life of DNA in bone: measuring decay kinetics in 158 dated fossils. Proceedings of the Royal Society. B 279 (1748): 4724–4733.

      2 Charriere, H. (1970). Papillon. Rupert Hart‐Davis Ltd.

      3 Chrichton, M. (1990). Jurassic Park. USA: Alfred A. Knopf.

      4 CITES (2016). 17th Conference Report Johannesburg (South Africa) 24th September – 5th October 2016. Identification of Elephant and Mammoth Ivory in Trade.

      5 CITES (2019). 18th Conference Report Colombo (Sri Lanka) 23May – 3rd June 2019. Consideration of Proposals for Amendment of Appendices I and II.

      6 Da Vinci, L. (1880). Notebooks of Leonardo Da Vinci (ed. J.P. Richter). Volume 2 section XVII Topographical Notes (1880). Reprinted 1888 edition pages 223‐270 Dover Publications 1970, New York, USA.

      7 Daily Mail (2013). Preserved Wooly Mammoth from Siberia. Daily Mail (9 July 2013).

      8 Greenwood, P.H. (1988). A Living Fossil Fish. The Coelocanth. London: British Museum (Natural History).

      9 Hooke, R. (1668). Discourse on Earthquakes. St Pauls, London: Richard Waller.

      10 Lyell, C. (1832). Principles of Geology. London: John Murray.

      11 Mace, G. (1998). Getting the measure of extinction. People & the Planet 7 (4): 9.

      12 Moyal, A. (2004). Platypus. Baltimore, USA: The John Hopkins University Press.

      13 Oskam, C.L., Haile, J., McLay, E. et al. (2010). Fossil avian eggshell preserves ancient DNA. Proceedings of the Royal Society. B 277 (1690): 1991–2000.

      14 Plot, R. (1705). The Natural History of Oxford‐Shire: Being An Essay Towards the Natural History of England, 2e. London: C. Brome.

      15 Thomson, K. (2005). Fossils: A Very Short Introduction. Oxford University Press.

      16 Vaux, F., Morgan‐Richards, M., Daly, E.E., and Trewick, S.A. (2019). Tuatara and a new morphometric dataset for Rhynchocephalia: comments on Herrera‐Flores et al. Palaeontology 62 (2): 321–334.

      Part of the complex relationship which society has had over the centuries with fossils is at least in part associated with the conceptual problem of exactly how fossils are formed. It was not always assumed that these structures were plant or animal in origin, for a very good reason. From the earliest years of a monotheistic culture, the mortal remains were seen as disposable, epitomised by the Book of Common Prayer of 1662 where the funeral oratory includes the well‐known ‘earth to earth, ashes to ashes, dust to dust’ indicating almost by redundant usage that mortal remains will not survive in any shape or form. So it was naturally assumed that with this authority, everything would disappear, and if nothing remained, those stone‐like inclusions within rocks could not possibly be animal or plant in origin.

      Although inadvertently, the Book of Common Prayer reflects something which should be obvious; that fossils are rare. Looking at this from the other direction, it implies that the process of fossilisation is a rare event, and consequently the chances of a specific plant or animal being fossilised are vanishingly small. It took a long time before we understood enough about chemistry that we could have a reasonable idea of how fossilisation takes place.

      Fossilisation is a result of a set of conditions which have to be just right to work. It does not necessarily work perfectly every time, and the final product will not always be made of the same material. As we will see later in this chapter, the processes which create fossils vary considerably in detail, which is why fossils also vary so much in their structure and appearance.

      Before the advent of geochemistry, first described by Christian Schönbein in 1838 (Kragh 2008), and for many years afterwards, there was little by way of a clear idea of changes that can take place in the chemistry of rocks and fossils. It was for many years a simple study of chemical composition of rocks, rather than changes in composition of rocks. This lack of clarity of what might be taking place in the fossilisation process meant that any attempt to describe the process was really a descriptive process of observed events. This was the situation when Charles Lyell (1832) was writing Principles of Geology. In grappling with the questions of fossil formation, Lyell expends considerable effort in explaining how various phenomena can result in biological material of all sorts and can become frozen in time. The explanations all stop at the point of ‘inhumation’, but have an interesting historical context, with descriptions of many examples. These range from inundations by rivers and landslips, such as the draining of a lake in Vermont, USA, in 1810, and the burying of villages when the mountain of Piz in Italy fell in 1772, through to blown sand in Africa. The examples cover many different natural causes of burial, by way of explaining how plant and animal material could move in to the geological strata. At the same time, there is no attempt to describe a mechanism by which this buried material could be changed from biological material, essentially organic, to stone, essentially inorganic, while still retaining some structure of the original organism.

      There are exceptions to the normal process of fossilisation, which may not at first even appear to be fossilisation in the popular imagination. These are pickling, freezing, amber and tar pits.