A consistent chronostratigraphic framework is required to understand the effect of major paleoclimate perturbations on both marine and terrestrial ecosystems. Transient global warming events in the early Eocene, at 56-54g Ma, show the impact of large-scale carbon input into the ocean-atmosphere system. Here we provide the first timescale synchronization of continental and marine deposits spanning the Paleocene-Eocene Thermal Maximum (PETM) and the interval just prior to the Eocene Thermal Maximum 2 (ETM-2). Cyclic variations in geochemical data come from continental drill cores of the Bighorn Basin Coring Project (BBCP, Wyoming, USA) and from marine deep-sea drilling deposits retrieved by the Ocean Drilling Program (ODP). Both are dominated by eccentricity-modulated precession cycles used to construct a common cyclostratigraphic framework. Integration of age models results in a revised astrochronology for the PETM in deep-sea records that is now generally consistent with independent 3He age models. The duration of the PETM is estimated at ĝ1/4 200g kyr for the carbon isotope excursion and ĝ1/4 120g kyr for the associated pelagic clay layer. A common terrestrial and marine age model shows a concurrent major change in marine and terrestrial biota ĝ1/4 200g kyr before ETM-2. In the Bighorn Basin, the change is referred to as Biohorizon B and represents a period of significant mammalian turnover and immigration, separating the upper Haplomylus-Ectocion Range Zone from the Bunophorus Interval Zone and approximating the Wa-4-Wa-5 land mammal zone boundary. In sediments from ODP Site 1262 (Walvis Ridge), major changes in the biota at this time are documented by the radiation of a "second generation" of apical spine-bearing sphenolith species (e.g., S. radians and S. editus), the emergence of T. orthostylus, and the marked decline of D. multiradiatus.
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Acknowledgements. We thank Editor Yves Godderis and the two anonymous reviewers for their effort and critical comments improving the paper. This research used samples and data provided by the International Ocean Discovery Program (IODP). IODP is sponsored by the US National Science Foundation (NSF) and participating countries. Financial support for this research was provided by the Deutsche Forschungsgemeinschaft (DFG) and the National Science Foundation (EAR0958821, EAR0958583, EAR1261312).
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