Garilli V.,APEMA Research and Educational Service |
Parrinello D.,University of Palermo
Molluscan Research | Year: 2010
Alvania baldoi n. sp. and A. dimitrii n. sp. are described from the Plio-Pleistocene of Italy. A. baldoi n. sp. is characterized by clathrate/cingulated sculpture of delicate axial and spiral elements forming knobs. It is closer to the species placed in Alvania Risso, 1826 s.s. than to those grouped within Acinopsis Monterosato, 1884 which is usually treated as a subgenus or synonym of Alvania. A. dimitrii n. sp. is characterized by an almost globose, conical shell bearing a clathrate pattern of subequal spiral and axial elements forming rounded tubercles. It also shows pronounced denticles and a crenulated outer lip. It is intermediate in shell characters between Alvania s.s. and Acinopsis, and closely resembles A. baldoi n. sp. Both the described species have a paucispiral protoconch indicating a non-planktotrophic larval development. Taphonomic and taxonomic information on the fossil sites indicates that A. baldoi n. sp. lived on the mid to lower shelf, whereas A. dimitrii n. sp. presumably inhabited lower shelf to upper slope environments. The morphological features of the new species described are an example of the difficulties in separating some of the nominal genus-group taxa previously recognized that are now usually treated as synonyms of Alvania. © 2010 Malacological Society of Australasia & Society for the Study of Molluscan Diversity.
Garilli V.,APEMA Research and Educational Service
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2011
The analysis of several central to eastern Mediterranean shallow-water deposits, mostly related to Posidonia oceanica palaeocommunities, sheds light on the presence of thermophilic molluscan assemblages throughout the Mediterranean Pleistocene. The taxonomic composition of these assemblages is totally different from that of the well-known Senegalese molluscan fauna and they play an important role in understanding some of the hydroclimatic conditions during Quaternary interglacial episodes in the central-eastern Mediterranean basin. Two of these assemblages from the Kyllini-Trypiti sequence (NW Peloponnesus) can be referred to the Upper Pleistocene interglacial marine isotope (sub)stage (MIS) 5e and 5a, on the basis of U/Th dating of corals (Cladocora coespitosa). Other assemblages belong to Lower Pleistocene (mainly Emilian substage, possible MIS 37), late Lower (Sicilian substages)-early Middle Pleistocene and late Middle-Upper Pleistocene (MIS 7 and MIS 5e). As a whole, these assemblages consist of 15 species of palaeoclimatic and stratigraphic value. Among these, Craspedochiton altavillensis (Polyplacophora), Jujubinus? bullula, Ersilia aliceae, Haedropleura bucciniformis, Strioterebrum basteroti (Gastropoda), and Plicatula mytilina (Bivalvia) are (Euro)Mediterranean strictly endemic extinct species, whereas Rissoina decussata, Niso terebellum, Kyllinia parentalis, Strioterebrum grayi, Terebra corrugata, Terebra reticularis (Gastropoda), Anadara sp., Chama placentina, and Corbula revoluta (Bivalvia) can be regarded as closely related to recent tropical West African taxa or as species living in tropical waters. The latter stock is useful for reconstructing palaeoclimatic conditions, suggesting winter sea surface temperatures 4-6°C and 2-4°C warmer than today in western Sicily and the easternmost part of the Mediterranean Sea, respectively. In contrast with Pleistocene glacial settings, detected warm episodes are characterized by a lower degree of seasonality, with a difference between summer and winter sea surface temperatures of 6-7°C vs. 10-11°C recorded at present in the Mediterranean. The molluscan assemblages also indicate that central to eastern Mediterranean salinity was lower than today, suggesting that a different hydrological regime, triggered by increase in rainfall/runoff, was manifested during warmer Pleistocene periods in that area. The distribution of some of the most meaningful taxa studied here indicates that the Mediterranean Sea was divided into two palaeobioprovinces, a cooler western and a warmer eastern one, with a boundary zone possibly located near the present Sicilian-Tunisian Strait.The Anadara sp.- Jujubinus? bullula association is a meaningful ecobiostratigraphical marker for recognizing warm Lower Pleistocene-Upper Pleistocene events. The youngest occurrence of this association has been detected in MIS 5a, in the uppermost part of the Kyllini-Trypiti sequence. Craspedochiton altavillensis, J.? bullula, Ersilia aliceae, Anadara sp., Chama placentina and Plicatula mytilina became extinct during the MIS 5a. Kyllinia parentalis and Terebra corrugata became extinct during MIS 5e. The disappearance of Niso terebellum took place during the Emilian substage (Lower Pleistocene). The gastropod Nassarius musivus musivus, previously considered as becoming extinct at the top of the Gelasian stage, has been recorded in the eastern Mediterranean deposits younger than MIS 5a and older than MIS 3. © 2011 Elsevier B.V.
First record of the sand dollar amphiope agassiz, 1840 (Echinoidea: Astriclypeidae) from the Miocene of Sicily [Prima segnalazione di amphiope agassiz, 1840 (Echinoidea: Astriclypeidae) nel miocene della sicilia] - si descrive unatafocenosi dominata da amphiope bioculata (des Moulins, 1837)]
Garilli V.,APEMA Research and Educational Service |
Borghi E.,Societa Reggiana di Science Naturali |
Galletti L.,APEMA Research and Educational Service |
Pollina F.,APEMA Research and Educational Service
Bollettino della Societa Paleontologica Italiana | Year: 2010
The first Sicilian record of the sand dollar Amphiope is reported on the basis of the occurrence of the species A. bioculata (des Moulins, 1837), recovered from a previously unreported sandy deposit cropping out near Case Genna (western Sicily). The best preserved tests are described and compared with similar congeners. Taphonomic and palaeoecological observations on the A. bioculata-thaphocenoses, and granulometric characterizations indicate that the sand dollar-bearing deposit formed in very shallow, nearshore environments subjected to bottom current. This deposit, if considered as a subunit of the deltaic upper Tortonian-lower Messinian "Molassa" of the Terravecchia Formation, would have a late Miocene age (upper Tortonian). In this case the Mediterranean distribution of A. bioculata, previously known from the Aquitanian to the lower Tortonian, should be extended to the upper part of the latter stage.