Life in a Middle Devonian Lake

Male and female Microbrachius

Lake Orcadie is one of the best examples in the world of a Middle Devonian lacustrine environment with a high potential for preservation of its different faunal components. During the Middle Devonian (Middle Old Red Sandstone period) this area with one or probably more interconnected lakes was situated south of the equator. The fossil fish of Orkney will be highlighted here.

The rocks found in the Orkney Islands are part of the Orcadian Lake basin which extended at this time from Greenland through Shetland as far as the Moray Firth area (see literature, list of papers, books).

Many different species of fish were living in the lake or in the rivers which were flowing into the lake from the north and the west. It is also possible the lakes also drained south-eastwards to the sea.

Due to shifts in the climate, the lake could change from a relatively deep extended lake to several smaller interconnected lakes and eventually to a completely dried out lake basin. The sediments on Orkney show these (cyclic) climate changes clearly. Well laminated sediments indicate a deep lake facies while sediments showing mud cracks and current ripples are found in shallower marginal to dry lake conditions.

Plants were only able to grow near the lake border or along the rivers. This was because seeds had not developed yet and propagation by spores required an aquatic habitat.

In periods when the lake was deep, the bottom water could be hyper saline and often anoxic. These conditions were very favorable for dead fish in the lake or dead fish washed in from the rivers to be perfectly preserved as articulated specimens.

Gyroptychius milleri, an example of a well preserved articulated fish

When the lake started to dry up, the environment for fish became very hostile and fish who did not manage to escape through the river system died. Because of the aerobic conditions most of the fish carcasses fell apart and are now found as disarticulated remains.

The sediments from the deep lake stage are now found as finely laminated (laminites) carbonate rich mudstones and siltstones. The sediments from the shallow to dry lake stage are found as less well laminated (or not laminated at all) mudstones, coarse flagstones or sandstone deposits. Fish in these sediments are disarticulated.

Gyroptychius milleri, disarticulated plates of the head half with half without cosmine.

The stratigraphy of the sediments in the Orcadian Basin in the Middle Devonian (Middle old Red) can be shown in a stratigraphic table with a rough indication of the thickness. For all the groups of fishes living in the lake and or in the rivers their place in the stratigraphy will be shown.

Such a table in which the fish stratigraphy is indicated is called a biostratigraphic table. For each group of fish specific literature references will be given. Also the morphology and histology of the scales and dermal plates of each group will be presented on the general group pages (Acanthodians, Crossopterygians, Placoderms, Dipnoans).

Most of the fish living in the Orcadian Lake and its rivers have played a crucial role in the evolution of all recent fish and especially in the establishment of the first vertebrate life on land.

The fossil fishes and other faunal components are illustrated on this website with pictures of specimens from Orkney and other parts of Scotland. Since the fishes are so important in the history of palaeontology drawings of specimens and drawings of reconstructions from historically important literature have been added, together with more modern drawings of reconstructions. Each group of fishes will be dealt with on a general group page.

Links can be found at the bottom of the page with a selection of the most important books and papers dealing with the subject in general. For every group of fishes specific reference will be given at the end of the group page. The group webpage will have links to the different species found on Orkney.

Recent research has resulted in several paper where fossil Devonian fish from other countries, especially the Baltic states (Estonia, Latvia, Lithuania and Belarus) are compared. Several species from Scotland are also recorded from these states, indicating that the Orcadian Lake was sometimes connected by rivers.

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General literature on Scottish Devonian fishes:
  • Agassiz, L. 1833-43. Recherches sur les Poissons Fossiles. Imprimerie de Petitpierre et Prince, Neuchâtel.
  • Agassiz, L. 1844-45. Monographie de Poissons Fossiles des Vieux Grès Rouges ou Système Dévonien (Old Red Sandstone) des Îles Britanniques et de Russie. Imprimerie de Petitpierre et Prince, Neuchâtel.
  • Andrews, S.M. 1982. The Discovery of Fossil Fishes in Scotland up to 1845 with Checklists of Agassiz’s Figured Specimens. Royal Scottish Museum, Edinburgh.
  • Astin, T.R. 1990. The Devonian lacustrine sediments of Orkney, Scotland; implications for climatic cyclicity, basin structure and maturation history. Journal of the Geological Society of London, 147:141–151.
  • Berg LS. 1940. Classification of fishes, both recent and fossil. Trudy Zoologicheskogo Instituta Akademiya Nauk SSSR 5:1–517.
  • Brazeau, M.D. 2009. The braincase and jaws of a Devonian ‘acanthodian’ and modern gnathostome origins. Nature, 457(7227):305–308.
  • Crampton CB, Carruthers RG. 1914. The geology of Caithness. Glasgow: HM Stationery Office.
  • Davidson, R.G. and Trewin, N.H. 2005. Unusual preservation of the internal organs of acanthodian and actinopterygian fish in the Middle Devonian of Scotland. Scottish Journal of Geology, 41:129–134.
  • Davis, S.P., Finarelli, J.A., and Coates, M.I. 2012. Acanthodes and shark-like conditions in the last common ancestor of modern gnathostomes. Nature, 486(7402):247–250.
  • Dean, B. 1895. Fishes, living and fossil. MacMillan and Co. New York. 300 pp.
  • Dineley, D.L. and Metcalf, S.J. (editors) 1999. Fossil Fishes of Great Britain. Geological Conservation Review, 16. Joint Nature Conservation Committee Peterborough, UK.
  • Donovan RN, Foster RJ, Westoll TS. 1974. A stratigraphical revision of the Old Red Sandstone of north-eastern Caithness. Transactions of the Royal Society of Edinburgh 69: 167–201.
    Egerton, P. de M.G. 1860. Palichthyologic notes, n. 12, remarks on the nomenclature of Devonian fishes. Quarterly Journal of the Geological Society, 16:119–136.
  • Egerton, P. de M.G. 1861. British fossils, 51–75. In Huxley, T.H. (ed.), Preliminary Essay Upon the Systematic Arrangement of the Fishes of the Devonian Epoch, Figures and Descriptions Illustrative of British Organic Remains. Memoirs of the Geological Survey, U.K, (Decade 10).
  • Eichwald, E. 1860. Lethaea Rossica ou paléontologie de la Russié, 1, seconde sectione de l’ancienne période, p.681-1657. Libraire et Imprimerie de E. Schweizerbart, Stuttgart.
  • Flett, J. F. 1898. The Old Red Sandstone of the Orkneys. Transactions of the Royal Society of Edinburgh, 39:383-424.
  • Foster-Cooper, C. 1937. The Middle Devonian fish fauna of Achanarras. Transactions of the Royal Society of Edinburgh, 59, 223-239.
  • Frickhinger, K.A. 1991. Fossilien-Atlas Fische. Mergus Verlag, Melle.
  • Friedman M, Sallan LC. 2012. Five hundred million years of extinction and recovery: a Phanerozoic survey of large scale diversity patterns in fishes. Palaeontology 55: 707–742.
  • Glinskiy, V.N. and Pinakhina, D.V. 2018. New data on psammosteid heterostracans (Pteraspidomorpha) and acanthodians (Acanthodii) from the Pärnu Regional Stage (Lower Eifelian, Middle Devonian) of Estonia. Estonian Journal of Earth Sciences, 67(1):76–87.
  • Gross, W. 1940. Acanthodier und Placodermen aus den Heterostius-Schichten Estlands und Lettlands. Annals societatis rebus naturae investigandis in Universitate Tartuensiconstitutae, 46:12–99.
  • Gross, W. 1942. Die Fischfaunen des baltischen Devons und ihre biostratigraphische Bedeutung. Korrespondenzblatt des Naturforscher-Vereins zu Riga, 64:373–436.
  • Gross, W. 1971. Downtonische und Dittonische Acanthodier-Reste des Ostseegebietes. Palaeontographica A, 136:1–82.
  • Gross, W. 1973. Kleinschuppen, Flossenstacheln und Zähne von Fischen aus europäischen und nordamerikanischen Bonebeds des Devons. Palaeontographica A, 142:51–155.
  • Hanke, G.F. and Wilson, M.V.H. 2004. New teleostome fishes and acanthodian systematics, p. 189–216. In Arratia, G., Wilson, M.V.H. and Cloutier, R. (eds.), Recent Advances in the Origin and Early Radiation of Vertebrates. Verlag Dr. Friedrich Pfeil, Munich.
  • Hamilton, R.F.M., and Trewin, N.H. 1988. Environmental controls on fish faunas of the Middle Devonian Orcadian Basin, p. 589–600. In McMillan, N.J., Embry, A.F., and Glass, D.J. (eds.), Devonian of the World, Vol. III. Canadian Society of Petroleum Geologists Memoirs 14.
  • Huxley TH. 1861. Preliminary essay upon the systematic arrangement of the fishes of the Devonian epoch. London: Longman, Green, Longman, and Roberts.
  • Long, J.A. 1995. The Rise of Fishes. University of New South Wales Press, Sydney.
  • Michie, U.M., Newman, M.J. & den Blaauwen, J.L. 2015. The vertebrate biostratigraphy of the Rousay sequence in the Middle Devonian of Orkney, Scotland. Scottish Journal of Geology, 51:149-156.
  • M’Coy, F. 1848. On some new Ichthyolites from the Scotch Old Red Sandstone. The Annals and Magazine of Natural History, Second Series 11:297–312.
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  • Miller, H. 1841. Old Red Sandstone or new walks in an old field (first edition). John Johnstone, Edinburgh.
  • Miller, H. 1849. Foot-prints of the creator or the Asterolepis of Stromness. Johnstone and Hunter, Edinburgh. 313 pp.
  • Miller, H. 1858b. Cruise of the Betsey/ Rambles of a Geologist. Thomas Constable and Co., Edinburgh. 486 pp.
  • Moy-Thomas, J.A., and Miles, R.S. 1971. Palaeozoic Fishes. Chapman and Hall, London.
  • Mykura, W. 1976. British Regional Geology. Orkney and Shetland. HMSO, Edinburgh.
  • Newman, M.J. and Dean, M.T. 2005. A biostratigraphical framework for geological correlation of the Middle Devonian strata in the Moray-Ness Basin Project area. British Geological Survey Internal Report IR/05/160.
  • Newman, M. J. 2010 Middle Devonian fish from the Orcadian Basin of Scotland. International Palaeontological Congress, London, Pre-conference field trip guide, 90pp. [Field guide]
  • Newman, M.J., Mark-Kurik, E., Blaauwen, J.L. den and Zupiņš, I. 2015. Scottish Middle Devonian fishes in Estonia. Scottish Journal of Geology, 51(2):141–147.
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  • Schultze H-P, Cloutier R, eds. Devonian fishes and plants of Miguasha, Quebec, Canada. Munic: Verlag Dr. Friedrich Pfeil, 198–226.
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  • Watson, D. M. S. and DAY, H. 1916. Notes on Palaeozoic fishes. Memoirs and Proceedings of the Manchester Literary and Philosophical Society, 2, 1-52.
  • Watson, D. M. S. 1932. On three new species of fish from the Old Red Sandstone of Orkney and Shetland. Summary of Progress of the Geological Survey, U.K. for 1931, 2, 157-166.
  • Watson, D.M.S. 1935. Fossil fishes of the Orcadian Old Red Sandstone, p. 157–169. In Wilson, G.V., Knox, J., Jones, R.C.B. and Stephens, J.V. The Geology of the Orkneys. His Majesty’s Stationery Office, Edinburgh.
  • Woodward, A. S. 1891. Catalogue of fossil fishes in the British Museum (Natural History. Part 2. British Museum (Natural History), London. 567 pp.
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