1 Abstract 11 Background Molecular clocks have become powerful tools given increasing sequencing and 12 fossil resources. However, outcome of calibration analyses depend on choosing priors. Here we 13 revisit a seminal dating study of the genus Carabus by Andujar et al. proposing that their prior 14 choices need re-evaluation with the hypothesis that reflecting fossil evidence and the 15 Gondwanan split properly rewinds the molecular clock significantly. We used the similar dataset 16 including five mitochondrial and four nuclear DNA fragments with 7888 nt total length. We set 17 the root age based on the fossil evidence of Harpalinae ground beetles in the Upper Cretaceous 18 and introduce the Paleogene divergence of the outgroup taxa Ceroglossus (endemic to South-19 America) and Pamborus + Maoripamborus (Australia, New Zealand) as a new prior based on 20 current paleontological and geological literature. 21 Results The ultrametric time-calibrated tree of the extended nd5 dataset resulted in a median 22 TMRCA Carabus age of 59.72 Ma (HPD95% 49.92-70.38), roughly 35 Ma older than in the 23 Andujar study. The splits between C. rugosus and C. morbillosus (A), between C. riffensis from 24 the European Mesocarabus (B), and between Eurycarabus and Nesaeocarabus (C) were dated 25 to 19.19 (13.16-25.64), 25.95 (18.68-33.97), and 23.99 (17.75-31.67) Ma and were thus 26 decidedly older than previously reported (7.48, 10.93, and 9.51 Ma). Constraining the Carabidae 27 time tree root with the Burmese Oodini amber fossil at ~99 Ma resulted in the largest increase, 28 while including the Canary Hotspot and Gondwana split calibrations stabilized the overall dating, 29 mediating between the root and remaining calibration points. Utilizing our clades A-C results, 30 TMRCA of Carabus was dated to 53.56 (41.25-67.05) Ma in the complete MIT-NUC data set 31 compared to 25.16 (18.41-33.04). 32 Conclusion Taking into account the Gondwanan split as a new prior, together with the fossil 33 evidence of the outgroup taxon Harpalini in the Late Cretaceous, our new approach supports an 34 origin of the genus Carabus in the Paleocene-Early Eocene. Our results are preliminary due to 35the heavy reliance on the nd5 gene and thus will have to be tested with sufficient set of nuclear 36markers. Such subsequent analyses will likely extend the dating even further back in time. 37