In 1963, paleontologist John Wells proposed that fine growth ridges on the epitheca of fossilized Devonian rugose corals represented daily accretionary cycles, allowing an empirical estimation of the number of days per year in the Middle Devonian period. While Wells’ initial calculations of approximately 400 days per year aligned remarkably well with astronomical models of tidal friction and planetary deceleration, subsequent microstructural analyses revealed significant complications. Critics noted that secondary calcification frequently obscures fine growth lines, and environmental perturbations���such as fluctuations in water temperature and sediment deposition—can cause systemic omissions in daily ridge formation. To salvage the core paleorotational thesis without relying on contentious daily counts, recent investigators have focused instead on monthly lunar rhythms preserved in broader annulations. By shifting analytical emphasis from diurnal increments to synodic monthly bands, these researchers aim to bypass the noise of daily accretionary anomalies. Consequently, while the absolute length of the Devonian day remains subject to calibrated refinement, the utility of coral epithecal analysis in geochronology has been substantially rehabilitated.
Based on the passage, which of the following best describes the rhetorical function of the highlighted sentence?
- It outlines a methodological shift adopted by researchers to overcome the empirical vulnerabilities of an earlier approach.Answer
- BIt presents empirical evidence that directly refutes the theoretical assumption that Earth's rotation was faster during the Devonian period.
- CIt summarizes the primary biological mechanism responsible for secondary calcification in Devonian marine organisms.
- DIt asserts that fine accretionary ridges provide a far more precise geochronological record than synodic monthly bands.
- EIt demonstrates that astronomical models of tidal friction are fundamentally flawed and require comprehensive revision.