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Borghi, Enrico, Garilli, Vittorio, and Bonomo, Sergio. 2014 ABSTRACTPalaeontological evidences of autochthonous deep-water echinoids are so rare that the well-preserved assemblage herein described from the Plio-Pleistocene of Capo Milazzo (NE Sicily) provide an important opportunity to investigate the biodiversity of the bathyal echinoids in the Mediterranean late Cenozoic. The low diversity fauna studied is dominated by Cidaris margaritifera, Histocidaris sicula and Stirechinus scillae, which are species closely related to Recent echinoids today confined to the western Atlantic deep bottoms. The echinoid assemblages of Capo Milazzo and of the Plio-Pleistocene Argille Azzurre Formation (Italy) share a number of species, most of which are known also from shallow water Plio-Pleistocene deposits and the presentday Mediterranean; C. margaritifera is the only strictly bathyal echinoid that occurs in both formations. The palaeoecological study of these echinoids indicates an epibenthic way of life on muddy bottoms, in deep waters with psychrospheric conditions. The following species from the Argille Azzurre are interpreted as strictly bathyal: Histocidaris rosaria, Schizaster braidensis and Schizaster ovatus (transferred into the genus Holanthus). The modern Mediterranean (impoverished) deep-water echinoid assemblage has north-eastern Atlantic affinities and, with the exception of Holanthus expergitus, all the Mediterranean species found at bathyal depth are eurybathic, as they live also in shelf settings. In contrast, the bathyal echinoids of Capo Milazzo show strongest affinities with strictly deep-water western Atlantic species, particularly those of the Caribbean area. They vanished from the Mediterranean during the Quaternary due to the loss of psychrospheric conditions. Based on the Punta Mazza section, dated by nannofossils and data from literature, their stratigraphic range at Capo Milazzo is late Piacenzian-Calabrian.

<p>The Messinian Salinity Crisis (MSC) was the greatest paleoenvironmental perturbation the Mediterranean has ever seen. The literature is abundant in hypotheses on the repercussions of the MSC on organisms. However, all these are based on incomplete and still uncertain scenarios about the MSC evolution, as well as on the assumption that such a paleoenvironmental perturbation must have completely reset marine biota. Having prevailed for many decades now, this assumption has leaked from paleontology and geosciences to biological sciences, with numerous studies taking this scenario for granted instead of using it as a starting hypothesis to be tested. Here, we review and revise the marine fossil record across the Mediterranean from the Tortonian until the Zanclean to follow the current rules of nomenclature, correct misidentifications, and control for stratigraphic misplacements. We examine the composition of marine faunas, both taxonomically and considering the function of each group in the marine ecosystem and the transfer of energy through the marine food web. Specifically, we investigate the following functional groups: 1) primary producers, 2) secondary producers, 3) primary consumers, 4) secondary consumers, and 5) top predators. Our study includes sea grasses, phytoplankton, corals, benthic and planktonic foraminifera, bivalves, gastropods, brachiopods, echinoids, bryozoans, fishes, ostracods, and marine mammals. We calculate biodiversity indexes to provide independent evidence quantifying to what degree the marine fauna underwent:</p><ol><li>A drop of overall regional biodiversity of the Mediterranean due to environmental stress during the Messinian.</li> <li>A taxonomic and functional change between the Tortonian, Messinian, and the Zanclean, that is before and after the MSC, as well as during the precursor events to that actual crisis taking place after the Tortonian/Messinian boundary.</li> <li>The onset of the present-day west-to-east decreasing gradient in species richness, which has been related to the sea temperature and productivity gradients and the distance from the Gibraltar connection to the Atlantic.</li> </ol>

New material from the Miocene of Italy allows revision of the spatangoid genus Mariania Airaghi, 1901 and proposal of an emended diagnosis. Particularly characteristic, previously overlooked features of the genus include the presence of well-developed phyllodes made up from short, almost equidimensional plates in oral ambulacra II, III and IV. Unlike in other Spatangoidea, where the adoral plates rapidly become elongated towards the margin, they stay short in Mariania and are not constricted halfway between the peristome and the margin. In addition, most species of Mariania possess a characteristic domal profile with steep sides and lack a raised keel in aboral interambulacrum 5. Their petals are wide, open distally and extend almost to the margin. The plastron is not indented behind the episternal plates and the labral plate extends to the second ambulacral plates. Fascioles are missing in all specimens examined. The combination of these morphological features enable the separation of Mariania from the genera Macropneustes, Hypsopatagus and Spatangus, to which members of the genus have been assigned by previous authors. Cladistic analysis carried out to unravel the uncertain systematic position of Mariania failed to find well-supported relationships, but firmly places Mariania within the Brissidina. Most previous family attributions could be, however, ruled out. Based on the available data a placement within Spatangoidea seems most likely, where it takes up an intermediate position between maretiids, loveniids and spatangids. Three different species are identified within the studied sample: Mariania marmorae, the type species of the genus; M. stefaninii sp. nov. from the late Burdigalian-early Langhian of northern Italy; M. comaschicariae sp. nov. from the Burdigalian of Sardinia. These new species are distinguished from M. marmorae by their lower tests, shorter labral plates and shorter petals. Mariania comaschicariae sp. nov. differs from M. stefaninii sp. nov. by its lower test, more anterior apical disc and less numerous plates in the oral anterior paired ambulacra. Test morphology and parent rock sedimentology suggest that Mariania was an epifaunal echinoid, which lived in inner shelf environments, characterized by soft bottoms and a tropical climate. •

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