New Middle Pliocene ichthyofauna (2.4-2.2 Ma) from central-eastern Italy (Samoggia Torrent, Bolog... more New Middle Pliocene ichthyofauna (2.4-2.2 Ma) from central-eastern Italy (Samoggia Torrent, Bologna) are described. These ichthyolites were found in a rather thin laminated layer that was deposited after the 2.4 Ma climatic crisis. The origin of this deposit, in which 31 taxa have been classified, is to be related to anoxic events on a regional and, probably, supraregional scale. This ichthyofaunistic association, which consists of living genera, is characterized by a clearcut predominance of mesopelagic species. The palaeoclimatic characters of these ichthyofauna indicate subtropical-type waters, while from a palaeobiogeographic point of view there is a close relationship with the present-day Atlantic-Mediterranean bioprovince. The Samoggia deposit has yielded six taxa that are absent or only occasionally present in the Mediterranean: one of these, Spratelloides gracilis, is exclusive of the Indo-Pacific bioprovince.
The early Pliocene sediments of the Súa Member (Onzole Formation) are spectacularly exposed along... more The early Pliocene sediments of the Súa Member (Onzole Formation) are spectacularly exposed along coastal cliffs in the surroundings of Súa (northwestern Ecuador). The shellbed at the base of these strata contains rich mollusk and fish assemblages and provides a rare opportunity to document the virtually unknown Pliocene shallow-water faunas of Ecuador. Stratigraphic context, faunal composition (both mollusks and fishes), biofabric trend, ichnological signatures, and taphonomic features presented here, all indicate that the shellbed is a stratigraphically condensed (hiatal) skeletal concentration generated primarily by low rates of net background sedimentation. Shellbeds of this type, immediately overlying a Glossifungites-demarcated ravinement surface, are regarded as onlap shellbeds and record landward stratal convergence and attenuation during the earliest phases of marine transgression. Although composed of largely autochthonous-parautochthonous specimens, the fossil assemblage contains mollusk species from a range of water depths and both soft-and hard-bottom habitats, implying in situ time averaging and admixture of different assemblages as transgression proceeded on a sediment-starved shoreline. The mollusk assemblage is composed of 54 taxa (26 bivalves, 26 gastropods, 2 scaphopods), and the fish assemblage of 31 taxa belonging to 16 families. Both are indicative of a welloxygenated marine biotope swept by currents and waves, and devoid of a benthic macrophyte cover. With the exception of a few fish species and a single gastropod, the largest number of the mollusk and fish taxa are presently distributed throughout the Tropical Eastern Pacific Biogeographic Region.
New Middle Pliocene ichthyofauna (2.4-2.2 Ma) from central-eastern Italy (Samoggia Torrent, Bolog... more New Middle Pliocene ichthyofauna (2.4-2.2 Ma) from central-eastern Italy (Samoggia Torrent, Bologna) are described. These ichthyolites were found in a rather thin laminated layer that was deposited after the 2.4 Ma climatic crisis. The origin of this deposit, in which 31 taxa have been classified, is to be related to anoxic events on a regional and, probably, supraregional scale. This ichthyofaunistic association, which consists of living genera, is characterized by a clearcut predominance of mesopelagic species. The palaeoclimatic characters of these ichthyofauna indicate subtropical-type waters, while from a palaeobiogeographic point of view there is a close relationship with the present-day Atlantic-Mediterranean bioprovince. The Samoggia deposit has yielded six taxa that are absent or only occasionally present in the Mediterranean: one of these, Spratelloides gracilis, is exclusive of the Indo-Pacific bioprovince.
The early Pliocene sediments of the Súa Member (Onzole Formation) are spectacularly exposed along... more The early Pliocene sediments of the Súa Member (Onzole Formation) are spectacularly exposed along coastal cliffs in the surroundings of Súa (northwestern Ecuador). The shellbed at the base of these strata contains rich mollusk and fish assemblages and provides a rare opportunity to document the virtually unknown Pliocene shallow-water faunas of Ecuador. Stratigraphic context, faunal composition (both mollusks and fishes), biofabric trend, ichnological signatures, and taphonomic features presented here, all indicate that the shellbed is a stratigraphically condensed (hiatal) skeletal concentration generated primarily by low rates of net background sedimentation. Shellbeds of this type, immediately overlying a Glossifungites-demarcated ravinement surface, are regarded as onlap shellbeds and record landward stratal convergence and attenuation during the earliest phases of marine transgression. Although composed of largely autochthonous-parautochthonous specimens, the fossil assemblage contains mollusk species from a range of water depths and both soft-and hard-bottom habitats, implying in situ time averaging and admixture of different assemblages as transgression proceeded on a sediment-starved shoreline. The mollusk assemblage is composed of 54 taxa (26 bivalves, 26 gastropods, 2 scaphopods), and the fish assemblage of 31 taxa belonging to 16 families. Both are indicative of a welloxygenated marine biotope swept by currents and waves, and devoid of a benthic macrophyte cover. With the exception of a few fish species and a single gastropod, the largest number of the mollusk and fish taxa are presently distributed throughout the Tropical Eastern Pacific Biogeographic Region.
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