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Since the late Cenozoic, the Mediterranean area underwent intricate paleogeographical and climatic evolution that caused remarkable shifts in the marine ecosystems and their life. Several benthic groups, including echinoids, are known to have undergone several crises involving the loss of many taxa at the genus and species levels. Though in the last two decades significant developments have been achieved in the knowledge of the Mediterranean fossil and Recent echinoids, no relevant progress has been achieved on the knowledge of their late Cenozoic diversity, with particular regard to the shallow-water shelf assemblages.
In our study, we combined stratigraphical and (paleo)ecological data to describe the diversity changes of the Mediterranean echinoid assemblages over the last 6 Ma. A detailed biostratigraphic scheme based on some Italian key sites was integrated with bathymetric, climatic and biogeographical data mostly available in OBIS. The OBIS database was therefore used as an efficient source for the reconstruction of (paleo)ecological requirements and biogeography of many of the discussed taxa.
This actualistic approach, based on paleontological and present-day data from literature and OBIS database, allowed the detection of four main steps that led to a progressive diversity decrease of the Mediterranean echinoids during the Late Pliocene-Early Pleistocene time. Dramatic events were recorded in the Late Pliocene (about 3.5–3.0 Ma), when about 40% of the tropical Pliocene genus-level assemblage disappeared due to the onset of the Northern Hemisphere glaciation, which triggered a remarkable climatic deterioration. The 3.0 Ma event was correlated with the disappearance of several warm mollusks from the Mediterranean sea domain. The very late Miocene salinity crisis, known to have caused deep paleogeographic changes in the Mediterranean area, was not as drastic as for other marine groups. 92% of the pre-evaporitic genera repopulated the basin at the beginning of the Pliocene, with the re-establishment of the normal marine conditions. The extant Mediterranean echinoid fauna, with 21 genera, partly derives from the Late Miocene fauna, with which it shares 15 genera.
Full publication available at:
Borghi E. & Garilli V. 2022. Climate-driven diversity changes of Mediterranean echinoids over the last 6 Ma. Acta Palaeontologica Polonica 67 (4): 781–805. https://www.app.pan.pl/article/item/app009932022.html