This paper explores the relationship between an author's position in the bylines of an article and the research contributions they have made to analyze the validity of five bibliometric counting methods (arithmetic, fractional, geometric, harmonic, and harmonic parabolic author credit allocation) in the field of Chemical Biology. By classifying the tasks found in the author contribution statements of articles published in Nature Chemical Biology according to a three-tiered scheme, it was possible to divide the authors into three types: core-layer authors, middle-layer authors, and outer-layer authors. When ordering the authorships according to the position in the bylines, there is a distinct u-shaped distribution for the share of authors involved in writing the paper or designing the research (i.e., core authors) and for the average number of tasks performed by each author. The harmonic parabolic model best distributes author credit according to the observed empirical data. It also outperforms the other models in predicting which authors are core authors and which are not. The harmonic parabolic model should be the preferred choice for bibliometric exercises in chemical biology and fields with similar practices regarding authorship order.