Delayed deepening: Bathymetric patterns of post-Paleozoic stalked crinoids in the Panthalassan realm

Stalked crinoids were widespread in shallow-marine ecosystems throughout much of the Paleozoic and Mesozoic but are confined to deep-sea environments today. In the Tethyan realm, this bathymetric restriction is inferred to have begun in the Cretaceous and was largely completed by the Eocene. This pattern started during the Mesozoic Marine Revolution when predators and predation became more prevalent. Whether this pattern was globally synchronous remains uncertain. We compiled Jurassic−Neogene occurrences of stalked crinoids from the Panthalassan realm to evaluate long-term bathymetric trends. Throughout the Jurassic, Cretaceous, and Paleogene, deep-water occurrences constitute a consistently minor component of the stalked crinoid record (3−13%), with the Cretaceous interval yielding the lowest relative proportion. An increase in the relative proportion of deep-water occurrences to 57% is observed only in the Neogene. These results indicate that the transition toward deep-sea restriction was temporally decoupled from ecological escalation in the late Mesozoic and was not globally synchronous. In the Panthalassan realm, shallow-marine persistence extended well beyond the interval of Tethyan depth restriction, underscoring the importance of basin-scale perspectives in interpreting the Meso-Cenozoic marine restructuring. Together, these findings challenge the assumption of a globally synchronized Mesozoic Marine Revolution−driven bathymetric shift and recast deep-sea restriction as a spatially asynchronous, long-term macroecological transition.