The evolution and distribution of fishes / by John Muirhead Macfarlane.

  • John Muirhead Macfarlane
Date:
1923
Catalogue details

Licence: In copyright

Credit: The evolution and distribution of fishes / by John Muirhead Macfarlane. Source: Wellcome Collection.

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    3 to him for identification, or displayed others that he had gathered and on which he was then (1876-1882) pub- lishing. The impression was, therefore, almost unwillingly forced in on the writer’s mind, now fully forty years ago, that during the great Carboniferous epoch a practically continuous deposit of freshwater strata with typical plant and fish enclosures gave rise to the foundation beds or Calciferous Sandstone series of that system; that then an extensive though not deep submergence of land occurred under the sea, during which the Carboniferous Limestone was formed as a great marine deposit. Even then however occasional elevation for a longer or shorter time permitted the development of a nearby land flora and invasion again of teeming freshwater fishes in lakes or swamps of that per- iod. These however showed no trace of existence in marine strata. Finally, during deposit of the Coal Measures, freshwater fishes that were very different in type from those of the lower rocks, were met with in ironstone in shale, or in sandstone strata that alternated with and often shaded into coal beds. The mental picture thus gradually formed through a period of fully five years—namely from 1876 to 1881— seemed antagonistic to the tacit or openly expressed views of many palaeontologists and zoologists. Very slowly through succeeding decades a correct explanation began to dawn, and this was outlined recently in the volume that the present writer has entitled “The Causes and Course of Organic Evolution.” Shortly stated, and founding on facts presented in Chapters 11, 12, 14, and 18 of that work, he would claim that all organic life evolved in freshwater and even most primitively in thermal or subthermal areas akin to those of the Yellowstone, the New Zealand, the Austrian, the Icelandic and like regions of to-day. This also took place, he considers, in early proterozoic, protobiotic or archean time. Gradually new and ever more complex forms evolved which continued to inhabit freshwaters. But from such freshwater environment successive organ- ismal invasions of the sea first, and of the land at a later period, started the main groups of marine plants and ani-