Geological Evidence for Late Cretaceous Solar System Chaos and Its Imprint on Climate and Biodiversity

Chaotic interactions among planets reshape Earth’s climate and biosphere, yet the lack of constraints between 66 and 76 Ma has left a critical gap for resolving astronomical solutions and tracing the Solar System’s history. Here, we integrate astrochronology, sedimentology, and sedimentary noise modelling to extract orbital signals from Cretaceous marine and terrestrial records. High-resolution sea-level reconstructions pinpoint the timing of major fluctuations and reveal chaotic Earth–Mars orbital dynamics, expressed as shifts in obliquity modulation periodicities (~1.1, 0.8, and 1.2 Myr) and long-term eccentricity modulations (~2.3, 1.6, and 2.4 Myr). These orbital variations paced global sea-level changes that covaried with soil water δ18O, temperature, and atmospheric CO2, but were out of phase with cool-water calcareous nannofossil diversity. Higher obliquity modulation values coincided with sea-level rise, warmer climate, elevated CO2, and reduced calcareous nannofossil abundance, and vice versa. This study bridges orbital reconstructions across the Mesozoic–Cenozoic transition and provides direct geological evidence that chaotic Earth–Mars interactions drove coupled responses in climate, sea level, and biodiversity.