Page:Popular Science Monthly Volume 76.djvu/586

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582
THE POPULAR SCIENCE MONTHLY

speakers making their approach from different fields of interest. The conference was an effort to define and emphasize the common platform on which the paleontologists must stand together; even more than this, it was a purpose to declare at the outset that the organization, though the patron of detailed researches and patient endeavor, recognizes that the sole impulse which can guarantee its usefulness and maintain its integrity is its devotion to a standard which touches close on human interests.

 


ADEQUACY OF THE PALEONTOLOGIC RECORD
By Professor SAMUEL CALVIN

UNIVERSITY OF IOWA

WHEN or how life began on our planet no one may be able to tell us; but that life has been present and has been an important factor in the world's geological development since before the beginning of the Cambrian is known to the most callow of embryo geologists taking his first course at the village high school. So far as relates to the skeleton-bearing, marine invertebrates which have lived on floors of epicontinental seas, there are remarkably complete records of this long history of living things, the order of their succession, their migrations, their geographic distribution during any given portion of geologic time, as well as of the progressive and orderly modifications which resulted in the extermination of decadent or unfit types, on the one hand, or resulted, on the other hand, in the advancement of certain types and their adaptation to the conditions prevailing in the living world to-day.

The zoologist, confining attention to living forms, gets a view of the animal creation as it exists, after ages of development and modification, during a fraction of a single faunal stage. The paleontologist, while unable to see the beginnings of life, gets the broader view which comes from a study of the organic world as it has appeared during numberless successive stages. He may trace the origin of forms and note the trend and tendency of variations in ways denied the zoologist. Neither the depth of the water nor the distance from the shore at the points where the objects of his study lived interferes with the thoroughness of his explorations. He is not limited to what he may learn by taking samples of the old sea bottom, here and there, with a dredge; he traces his life zones with practical continuity over areas of continental extent.

The faithfulness with which the paleontological record has been kept since the beginning of the Cambrian is a matter of constant surprise. No organism was too small for preservation, if only its soft