Italo Di Geronimo

Enhanced biodiversity in the deep: Early Pleistocene coral communities from southern Italy

The Early Pleistocene fault plane of Furnari, that outcrops in northeastern Sicily (southern Italy), provided a primary hard substrate for the settling and growth of large coral colonies. Even though the corals did not form frameworks, they influenced the composition and distribution of the benthic communities. Corals and associated fauna produced organogenic debris, which was deposited along the fault scarp, within its fractures or at its base.

PLEISTOCENE BATHYAL MOLLUSCAN ASSEMBLAGES FROM SOUTHERN ITALY

Four Pleistocene bathyal molluscan assemblages from southern Italy (Calabria and Messina area) were studied. One hundred and thirty-six species were recorded. Twenty-four were classified and described in detail and thirty-five were illustrated. The following new combinations are pro posed: Solariella marginulata (Philippi, 1844), Iphitus tenuisculptus (Seguenza, 1876), Benthomangelia tenuicostata (Seguenza, 1879), Chrysallida microscalaria (Seguenza, 1876), Ennucula corbuloides (Seguenza, 1877), Ennucula rotundata (Seguenza, 1877), Thestyleda cuspidata (Philippi, 1844), Katadesmia confusa (Seguenza, 1877), Austrotindaria pusio (Philippi, 1844), Austrotindaria salicensis (Seguenza, 1877). Comments concerning the taxonomy of Fissurisepta Seguenza, 1862, Solariella Wood, 1842, Ennucula Iredale, 1931, Thestyleda Iredale, 1929, Ledella Verrill & Bush, 1897, Yoldiella Verrill & Bush, 1897, Bathyspinula Filatova, 1958, Katadesmia Dall, 1908, Austrotindaria Fleming, 1948 and Cadulus Philippi, 1844 are included. The assemblages are dominated by nuculoids and fit the general compositional pattern of the deep-sea molluscan communities. A paleodepth of 500-600 m is inferred for two assemblages, whereas a greater depth, pro bably not exceeding 1,000 m, is suggested for the other two. Taxonomic affinities with northeast Atlantic and more generally with World Ocean deep-sea molluscan faunas are remarkable. The Plio-Quaternary evolution of the deep Mediterranean benthos is discussed.

Deep-sea Pleistocene Bryozoa of Southern Italy

Abstract The bryozoan communities contained in deep-sea Pleistocene sediments cropping out in several localities of Southern Italy appear richer and more diversified than those living in the Recent Mediterranean. They are characterized by several groups of species having different origin and meaning: a) eurybathic palaeomediterranean, probably Tethysian, species; b) bathyal Atlantic-Mediterranean species; c) species showing a clear affinity with (or having close counterparts in) Recent Atlantic species. The eurybathic species can be considered as “Northern Guests” or “Residual Northern Guests” whereas the bathyal ones are “Atlantic Guests”. The occurrence of such cold stenothermic species in the Mediterranean suggests that environmental conditions of this basin during the Early Pleistocene where markedly different from the Recent ones. The subsequent disappearance of those species seems to be linked to the climatic change but also to the hydrological changes undergone by the Mediterranean when it passed from an ocean-connected to a closed basin, the latter characterized by deep-water homothermy.

Paleoecological interpretation of a Holocene sand body in the coastal area of Phetchaburi, Gulf of Thailand

Faunal examination is made of 4 samples, 2 from the Recent Ban Laem Phak Bia sand spit, and 2 from the Holocene sand body of Ban Bang Ket. Fossil and modern assemblages are compared on the basis of overall composition, taxa abundances, and of autoecological investigation on life habit, substrate preference, feeding type, depth range and ecological meaning of the identified species. The Holocene assemblage of Ban Bang Ket, compared to the Recent one of Ban Laem Phak Bia, 1) exhibits generally similar overall composition and ecological structure, 2) contains much of the dominant species characterizing the modern assemblage, and 3) includes all taxa that are members of the living molluscan community. On this basis, the molluscan assemblage of Ban Bang Ket results to be the Holocene counterpart of the modern one of Ban Laem Phak Bia, and reflects the same environmental conditions recorded for the latter. Thus, the sand body near Ban Bang Ket is interpreted as a Holocene equivalent of the sand spit of Ban Laem Phak Bia.

Homalopoma emulum (a bathyal cold stenothermic gastropod in the Mediterranean Pleistocene

Abstract Homalopoma emulum Seguenza , 1876) is a poorly known gastropod from the bathyal deposits of the Mediterranean Lower Pleistocene (Strait of Messina area). Its affinity with Homalopoma globuloides ( Dautzenberg & Fischer , 1896 ) living on the bathyal bottoms of the Northeast Atlantic Ocean (Azores and Gulf of Biscay) is very high and the two species are more closely related than two simply congeneric species. Homalopoma emulum belongs to a category of Mediterranean Plio-Pleistocene deep-water species characterized by remarkable taxonomic, morphologic and ecologic affinities with deep-water species from the Atlantic Ocean, or extra-Mediterranean areas in general. Such affinities seem to indicate a cold-stenothermic character, incompatible with the present deep homothermy in the Mediterranean Sea. The reason for the extinction of these species is referred to homothermic episodes which took place cyclically during the interglacial phases of the Upper Pleistocene. A progressive and selective extinction of these species led to the present lack of cold-stenothermic species in the Mediterranean deep benthos.

Homalopoma emulum (Seguenza, 1876)a bathyal cold stenothermic gastropod in the Mediterranean PleistoceneHomalopoma emulum (Seguenza, 1876) un gastéropode bathyal sténothermefroid dans le Pléistocène méditerranéen

Abstract Homalopoma emulum Seguenza , 1876) is a poorly known gastropod from the bathyal deposits of the Mediterranean Lower Pleistocene (Strait of Messina area). Its affinity with Homalopoma globuloides ( Dautzenberg & Fischer , 1896 ) living on the bathyal bottoms of the Northeast Atlantic Ocean (Azores and Gulf of Biscay) is very high and the two species are more closely related than two simply congeneric species. Homalopoma emulum belongs to a category of Mediterranean Plio-Pleistocene deep-water species characterized by remarkable taxonomic, morphologic and ecologic affinities with deep-water species from the Atlantic Ocean, or extra-Mediterranean areas in general. Such affinities seem to indicate a cold-stenothermic character, incompatible with the present deep homothermy in the Mediterranean Sea. The reason for the extinction of these species is referred to homothermic episodes which took place cyclically during the interglacial phases of the Upper Pleistocene. A progressive and selective extinction of these species led to the present lack of cold-stenothermic species in the Mediterranean deep benthos.

Circalittoral to infralittoral communities encrusting the Pleistocene gravels of Motta S. Giovanni (Reggio Calabria, Italy)

Abstract Several separated layers of the Pleistocene series of the “Messina gravels” have been studied. The outcrop, 50 metres thick, is made of various clinostratified gravelly-conglomeratic layers, with inverse gradation, whose upper part, more or less cemented, generally has no matrix. The cobbles and pebbles which make up the top part of some layers are encrusted by palaeocommunities, mainly formed by bryozoans and serpuloideans and subordinately by forams, mollusks and calcareous algae. The state of preservation of the external morphology is exceptional though not showing internal structures due to micritization and recrystallization. The organisms composition records a regressive evolution with sciaphilous and rheophilous palaeocommunities referable to biocoenoses from circalittoral to infralittoral zone. The structure, texture, setting and taphonomic arrangement of the sediments record a rhythmic sedimentation of the gravels and an immediate burial of the fossiliferous layers.