During the last few decades, research on climate change and threats to biodiversity have drawn public attention to present-day modifications of the world environment. Thus the public is now receptive to the concept of a changing Earth, a vision familiar to paleontologists for roughly two centuries, as investigations into fossilized life-forms began a few decades before the nineteenth century. A method for establishing the chronological distribution of the fossil record was rapidly developed and continuously improved, thereby providing access to Earth history for the first time. From a very restricted number of research centers, convergent information resulted in a completely new view of the Earth that outlines progressive changes in geography, and reconstructs environmental and faunal modifications through time. Also, up through the first half of the twentieth century, improving our description of the fossil record was an essential activity. It was the golden age of great paleontological monographs, in which the compositions of fossil faunas were compared in minute detail.

In the middle part of the twentieth century new physical methods were developed that led to innovative uses of fossils, many of which were based on study of the chemical record preserved in biogenic calcium carbonate of shells, reflecting environments in which the fossilized organisms lived. The first application of such a new method is precisely known: the reconstruction of annual variations in water temperature in Jurassic seas (about 150 million years before present), as a result of the study of variations in oxygen isotope ratios.