Editorial preface to special issue: The Mediterranean tropical legacy: perspectives from Upper Miocene marine environments

The Mediterranean Sea is a vast, semi-enclosed basin characterised by high biodiversity and a unique mix of Atlantic, endemic, and non-indigenous tropical species. This complexity also stems from its ongoing “retropicalisation” driven by climate change alongside human-altered connections to the Red Sea and accidental introductions. Interestingly, these modern shifts represent an inverted parallel to the Late Miocene. Back then, climate cooling and restriction of oceanic connections degraded the Mediterranean's tropical environment, paving the way for the establishment of temperate conditions during the Pliocene. Rather than a direct analogue the Late Miocene record provide a critical benchmark for understanding how marine ecosystems react to forced biotic reorganisation in a semi-enclosed basin. Across the Western, Central, and Eastern Mediterranean, this special issue compiles case studies that reconstruct the environmental evolution of the basin during this major transition. The resulting picture is not one of sudden collapse, but rather a prolonged, spatially heterogeneous, ecological reorganisation. Tropical ecosystems progressively adapted and displayed remarkable resilience before ultimately, though not at the same time, succumbing to the dramatic shifts of the Messinian Salinity Crisis. This new evidence provides an unprecedentedly detailed baseline for understanding tropical ecosystem collapse driven by coupled climatic change and altered basin connectivity.