Dynamic Late Ordovician climate responses: The cascading effects of expanding continental ice?

The interplay between astronomical forcing, continental ice volume, and biotic immigration is well studied in the Cenozoic, and documentation of such connections in the Paleozoic is rapidly increasing. Herein, we present analyses from late Katian subtropical marine deposits, revealing a transition from obliquity- (∼33.8 ± 0.46 k.y.) and precession- (∼17−22 k.y.) dominated sedimentation to a regime dominated by obliquity and short eccentricity (∼93−125 k.y.). We term this shift the late Katian transition. Transition from precession- to short eccentricity−dominated sedimentary cycles suggests expansion of ice sheets over Gondwana. This shift precedes a major episode of faunal immigration in Laurentia, which may have been facilitated by this climatic transition.