Calibrations without raw data - a response to "Seasonal calibration of the end-cretaceous Chicxulub impact event"

Abstract

In a recent paper by DePalma et al., the End-Cretaceous mass extinction was calibrated to spring/summer on the basis of stable isotopic analyses and other data. An independent study, which was concurrently in review and known to DePalma et al,. reached the same conclusion using osteohistology and stable isotope analysis. Notwithstanding this agreement, there are a number of concerning anomalies regarding the isotope analysis presented by DePalma et al. Primary data are not provided, the lab where the analyses were performed is not specified, and the methods are insufficiently described. Furthermore, isotopic graphs for carbon and oxygen contain anomalies (missing data points, double-data points, identical-length error bars for both elements despite different scales) that are inconsistent with genuine machine outputs. Some graphs supposedly derived from different fossil specimens match perfectly when overlaid on each other, while others do so when one is stretched to 150% or compressed to 70% of original length. Since these observations are uncharacteristic for genuine biological data, we are compelled to ask whether the data may be fabricated, created to fit an already known conclusion.