TOTAL IMMERSION FACTOR IN WORKING HYPOTHESIS FORMULATION: G.A.COOPER'S CAREER AS AN EXAMPLE
G. Arthur Cooper, arguably the greatest student of brachiopods in the 20th Century, spent his entire career immersed in the study of brachiopods, fossil and living. Every classical mode of attack was applied in his research. Along the way, he developed the art of acid-etching of limestone for invertebrates and this method helped him in the detailed analysis of the complex internal structures of brachiopod shells. He became intimately familiar with the total morphology of these shells. Cooper studied every major articulate group and described more new genera of these shells than any other paleontologist.
In Cooper's presidential address to the Paleontological Society in 1958, he reflected on classification and genus-making in brachiopods. At that time, there were about 1700 valid genera in taxonomic use. He developed a spindle diagram to show the waxing and waning of brachiopod diversity through geologic time. And then hypothesized what the real diversity might have been by enlarging the spindle, based on his own knowledge , and asked the question, "How many brachiopod genera have there been?" His very conservative answer was about 4800.
Nearly 50 years later, and two detailed treatises on the phylum, we now are estimating that there may have been as many as 5000 genera of brachiopods in the past 600 million years. What aspects of Cooper's career led him to such an accurate appraisal? I will discuss several details of Cooper's life with the brachiopods that may shed some light on this question.