Bollettino SPI Vol. 26 - Issues 1-2, 3
Issues 1-2
Published in September 1987
- Malaroda R. (1987)
The fossils of the Annot Flysch and the new fossiliferous deposit of Col de Turini
pp. 11-20
Certainly not reworked significant fossils of the autochtonous Tertiary flysch of the Maritime Alps (Protula septaria (Giebel), Anellida Sedentaria) and the trace fossil Zoophycos circinatus (Brongniart) are described and their finding localities pointed out. A complete list of all fossils of the formation is also given.
- Clari P. & Pavia G. (1987)
Omission surfaces and stratigraphic gaps in the lower Cretaceous of Mizzole (Lessini Veronesi)
pp. 21-38
Some omission surfaces and the related gaps recognized in the basal layers of the Biancone Formation in the Southern Alps are described. In the study area (Lessini Veronesi) this formation, consisting of white, micritic, pelagic limestones of Lower Cretaceous age, rests at the top of a condensed section of red nodular limestones (Rosso Ammonitico Veronese) deposed on a submerged structural high (Trento Plateau) during the Middle and Upper Jurassic. From the sedimentological point of view, the omission surfaces are quite similar to the ones present in the underlying “Rosso Ammonitico” and are represented by planar erosional surfaces covered by thin stromatolitic horizons or by lag deposits. The detailed study of the Calpionellid associations consented to recognize the presence of other sedimentary gaps underlined only by simple bed surfaces showing no sedimentological evidence of omission. Some of the hiatuses lasted some millions years and the most important embraces the middle and upper Berriasian and the base of the Valanginian. The genesis of the omission surfaces is related to a periodic strong activity of bottom currents which slowed down or halted the deposition of pelagic, biogenic sediments and favoured the processes of sea floor lithification. These in turn gave origin to the lithified bottoms (hard ground) cut by the omission surfaces and to early diagenetic nodules many of which were later reworked as intraclast by bottom currents.
The morphological variations of several species the genus Remaniella and Tintinnopsella are also briefly discussed. A biostratigraphic zonation was attempted, based on the abundant Calpionellid faunas and compared, at least in one case, with the data furnished by a scanty ammonite fauna in which was recognized the presence of Spiticeras of the Boissieri zone, Picteti Subzone.
- Dodona E. & Farinacci A. (1987)
Radiolarites in the Spiten lacunose sequence: a Mesozoic non-subsiding structural high of Albania
pp. 39-46
Mesozoic sedimentary sequences of Albania show the same features as those in Apennines. The preliminary study of the Spiten outcrop provides evidence for a very thin sequence of limestones and cherts with remarkable breaks in deposition. The sequence, 70 m thick, was laid down during the time from the Domerian to the Eocene, over 120 m.y.
The radiolarites of Krasta-Cukali area, represented by the Spiten sequence, are related to the emplacement of ophiolites in the adjoining Mirdita area.
- Elmi S. & Benshili K. (1987)
Relation between structural framework, composition of populations and evolution: examples from the Toarcian of Southern Middle Atlas, Morocco
pp. 47-62
During the Toarcian, schelves undergo block-faulting with rotational mechanisms of lifting which originate sometimes very marked differentiations in submarine morphology. Dwira and Tizi Nehassa regions (Middle Atlas) offer the example of narrow and shallow shelves swept by currents which assure good oxygenation; trophic components are diversified and well distributed. In such environments Ammonites develope large sizes, but populations are little diversified even when individuals are abundant. On the other side, the associated faunas are very diversified (bivalves, brachiopods). Some structural highs, narrow and sometimes emergent, divide these zones from contiguous basins; in particular, to the North, restricted and very subsiding basins develope: they are markedly deeper with very different fauna (little sized ammonites, often lacking benthos). These situations illustrate the environmental influence over Ammonites morphology and size: Hildoceratids and Dactylioceratids, in fact, may show environmentally controlled “morphologic plasticity”.
Some examples have been chosen between Crassiceras and Dactylioceratidae from Variabilis zone and from its Tethysian equivalent (Gradata zone). Figured specimens are from northern (SE France) and southern (Maroc, Algeria) margin of western Tethys. A scheme (fig. 5) shows relations between ammonites populations and environment from the point of view of this variability and evolution. Ecologic, biologic and geographic diversifications are the product of Tethys break up in a mosaic of basins with complex and changing relations.
- Pavia G., Benetti A. & Minetti C. (1987)
The Rosso Ammonitico formation in the Lessini Veronesi mountains (N.E. Italy). II. Ammonite faunas and stratigraphic gaps of the Lower Kimmeridgian
pp. 63-92
The outcrops at the Bocca di Selva farm, a few kilometers from San Giorgio, and of the Valle delle Sfingi, in the neighbourhood of Camposilvano, are used to describe depositional and structural differences in the Rosso Ammonitico sequences (Upper Bajocian-Middle Tithonian) of the northern Monti Lessini. The reduced horizons of the Rosso Ammonitico Superiore (Malm), ranging from the stromatolitic facies (Middle Oxfordian in age, Antecedens/Transversarium Zones) to the “nodular” limestones of the Lower Kimmeridgian (Divisum Zone), are biostratigraphically analysed. A sharp stratigraphic break is recognized in the outcrops of Camposilvano, where “nodular” limestones with ammonites of the Divisium Zone, Uhlandi Subzone directly overlie the stromatolitic Transversarium Zone. In the Bocca di Selva section the same paraconformity is still recognizable, despite episodic fossil records. The gaps usually correspond to planes of early lithification, on which stromatolitic horizons made up of laterally-linked hemispheroids are developed; we could only find thin condensed layers representing Platynota, Strombecki and Divisium (pars) Zones in one of the Camposilvano sections. The Oxfordian-Kimmeridgian paraconformity has a regional significance, but there is no direct evidence of any connection with sea-level changes.
Figure 3 and 5 summarize the biostratigraphy. 111 ammonites were analysed, 74 of these are Kimmeridgian in age. In this work we have described those taxa which give some new information about the ammonite faunas of the mediterranean Lower Kimmeridgian. In particular:
– Genus Idoceras, Subgenus Lessiniceras nov. subgen. – The species I. (L.) ptychodes and I. (L.) raschii are separated as a primitive “idoceratoid” group of the Platynota (?) and Strombecki Zones with the newly named Lessiniceras (type-species: Perisphinctes ptychodes Neumayr, 1873). The change of ribbing on the body chamber and the discovery of a “passendorferioid” I? (Lessiniceras?) n.sp.ind. in the Platynota Zone suggest a possible origin for Idoceras l.s. from the Passendorferiinae of the Upper Oxfordian. I. (Idoceras?) dedaloides from the Platynota/Strombecki Zones may be regarded as an intermediate form between Lessiniceras and Idoceras.
– Genus Orthosphinctes -Two new microconchs of the subgenus O. (Orthosphinctes) are frequently found in the Strombecki Zone of the Bocca di Selva section. Their “primitive” features (great diameter, monoschizotome bifurcation with intercalatory ribs, horizontal ribbing curve above diameters of mm 60) connect them to the conservative, already documented mediterranean stock of Orthoshinctes.
– Genus Crussoliceras -Four species were indentified in the Lower Kimmeridgian. Two of these (Crussoliceras (?) sp.ind. from the Platynota and (?) Strombecki Zones, C. aff. divisum from the lowermost Strombecki Zone) confirm the mediterranean origin of this genus, probably from the Passendorferiinae of the Upper Ox/ordian, via a palingenetic process of gradual coarsening of ribbing and whorl. The genus Pseudosimoceras can be placed in this morphological trend; it is limited to the type-species P. stenonis from the upper Strombecki Zone of the Bocca di Selva section.
The following mediterranean biozones are recognized:
MIDDLE OXFORDIAN -Antecedens Zone: this is defined by the presence of Kranaosphinctes gr. promiscuus in association with Passendorferia tenuis and Euaspidoceras cf. acuticostatum. Transversarium Zone: this is represented by rich faunas of Passendorferia, Gregoryceras and Euaspidoceras. The association of Passendorferia cf. torcalensis, P. (Dichotomosphinctes) elisabethae and Gregoryceras fouquei in the sections of Camposilvano seems to belong to the Schilli Subzone. Bifurcatus Zone: we have been able to refer to this zone only one specimen of Perisphinctes aff. variocostatus from the section of Bocca di Selva.
UPPER OXFORDIAN –Bimammatum Zone: the association of O. (Pseudorthosphinctes) cf. alternans and Euaspidoceras wildenbergense in layer 3 of the Bocca di Selva section should belong to this zone, but Epipeltoceras are absent. E. (Epaspidoceras) mamillanum, Aspidoceras binodum, Physodoceras gr. circumspinosum and P. wolfi make their appearance. Planula Zone: this is documented by the presence of Subnebrodites planula in the section of Bocca di Selva (layer 4), associated with T. (Metahaploceras) tenuisculptum, Orthosphinctes cf. freybergi, O. polygyratus, Benetticeras benettii and Aspidoceratidae, like Physodoceras altenense.
LOWER KIMMERIDGIAN –Platynota Zone: we can confirm that it is difficult to distinguish Planula and Platynota Zone faunas, in the absence of Sutneria and Ataxioceratinae. In our sections we have attributed to the Platynota Zone, which is poorly represented, a fauna of Orthosphinctes polygyratus, O. (Lithacosphincres) evolutus and Aspidoceratidae; I? (Lessiniceras?) n.sp.ind., I. (Idoceras?) dedaloides and Crussoliceras (?) sp.ind are associated. Strombecki Zone: this corresponds to the submediterranean Hypselocyclum Zone. Its lower boundary is arbitrarily recognized by the FADs of Taramelliceras trachinotum and L. (Lessiniceras) ptychodes. T. (Metahaploceras) strombecki, Pseudosimoceras stenonis, Orthosphinctes n.sp.ind. 1, Crussoliceras aff. divisum are restricted to it; in addition T. (Metahaploceras) nodosiusculum, I. (L.) ptychodes, I. (L.) raschii, Orthosphinctes n.sp.ind. 2, Progeronia progeron also characterize this zone. Two horizons have been separated: an “Orthosphinctes horizon” with the last Physodoceras altenense and a “Stenonis horizon” with the last Physodoceras wolfi and first Nebrodites, Mesosimoceras and Crussoliceras aceroides. The latter may correspond to the submediterranean Lothari Subzone.
Divisum Zone: its lower boundary is defined by the first appearance of Crussoliceras tenuicostatum together with Progeronia unicompta, P. (Hugueninsphinctes) spp. and a rich fauna of Mesosimoceras. The ammonite associations (fig. 6) allow us to separate two subzones:
Tenuicostatum Subzone (nov.): we note here the disappearance of I. (Lessiniceras) ptychodes and the ultimate reduction of T. (Metahaploceras), still present with T. (M.) nodosiusculum and T. (M.) cf. semibarbarum; on the other hand, some morphological trend typical of the next Uhlandi Subzone, like the increase of Progeronia l.s. and the appearance of Idoceras balderum, are already present.
Uhlandi Subzone: its lower boundary is marked by the FAD of Orthaspidoceras gr. uhlandi, which is limited to the lower part of the subzone in our sections (“Uhlandi horizon”). Features of the Uhlandi Subzone are the increase of Taramelliceras s.s. and Nebrodites faunas (T. compsum, T. plaryconcha, T. pseudoflexuosum, N. agrigentinus, N. favarensis, N. peltoideus), the presence of Simaspidoceras irregulare and S. bucki, with the first appearance of Aspidoceras acanthicum and Physodoceras contemporaneum.
UPPER KIMMERIDGIAN – Acanthicum Zone: the presence of this zone is confirmed by the frequence of A. acanthicum and by the appearance of Aspidoceras longispinum and Orthaspidoceras liparum. Taramelliceras trachinotum does not seem to occur above the lower boundary of this zone.
- Torrens H. (1987)
Ammonites and stratigraphy of the Bathonian rocks in the Digne-Barrême
area (South-Eastern France, Dept. Alpes de Haute Provence)
pp. 93-108
Some of the results of a never-completed revision of Bathonian ammonite-rich sections in the Digne-Barrême area of South
Eastern France, made by Carlo Sturani over 1972-75, are presented. These draw on materials left at his death. This area is important as, by
general agreement, it is seen to provide an ideal type section for the international typological definition of the basal subzone and zone of the
Bathonian stage and thus for the Bathonian stage of the Middle Jurassic itself.
The Lithostratigraphic sequence at Bas Auran first published in 1967 is reviewed and important modifications made to the numbering of the
uppermost Limestone beds. The faunas yielded by these beds numbered now 4 to 0 are re-evaluated and the topmost laterally continuous
limestone bed in all sections (Bed 1) is in particular re-considered on the basis of both previous, sometimes corrected, discoveries and new discoveries of ammonites. These are listed with notes on each species present, many of which are illustrated on the first seven of nine plates.
The age of the assemblage from Bed 1 is then discussed. It is placed in the topmost zone of the Lower Bathonian – the Tenuiplicatus Zone –
some of the characteristic Asphinctites ammonites of which are figured on plate 2. The possibility that younger horizons are represented within
the fauna from Bed 1, and thus the extent to which this bed might be condensed, are also discussed.
The phylogeny of some Lower Bathonian Perisphinctidae is also revised. The macroconch genus Procerites is shown to include two
phylogenetically separate homeomorphs, often confused before because of their common condensed occurrence together. The earliest of these is
placed in Lobosphinctes (M) of Parkinsoni to basal Zigzag Zone age. The corresponding microconch is Planisphinctes (m). Forms are illustrated on plate 4. The later homeomorph only now remains in Procerites (M) – Siemiradzkia (m) which range up, only from the very top of the Macrescens subzone. Forms are illustrated on plates 6 and 7 and the phylogeny of the latter group from Procerozigzag (M) – Zigzagiceras
(m) illustrated on plates 8 and 9. A schematic phylogeny of the two homeomorphs is also given in figure 2.
Other forms from Lower beds at Bas Auran, as well as material from nearby localities (e.g. Strigoceras from Castellane) with some Upper Bathonian ammonites from Chaudon, are also illustrated. No formally named new species are described but a number of new forms which will
need separation in future, when further material becomes available, are illustrated.
- Clari P., Proto Decima F., Ricci B. & Sampò M. (1987)
Shelf facies in the Middle Oligocene of the Monferrato Hills
pp. 109-118
Inner-shelf and continental (?) deposits of Middle Oligocene age have been recognized in the middle eastern Monferrato Hills and named “unità di Cardona”. This unit consists of a fining and
thinning upward sequence of conglomerates, sandstones and pelites with abundant trace fossils (Ophiomorpha, Thalassinoides) suggesting an
inner shelf environment. These sediments may be referred to the submerged front of a fan delta. In the study area this sequence has been strongly tectonized and eroded before the deposition of the so-called “molassic seguence” of Oligo-Miocene age which rest unconformably on it.
Farther to the North the uncomformity seems to die out.
- Ferrero Mortara E. (1987)
Miogypsinids of Oligo-Miocene from Turin Hill area (NW Italy)
pp. 119-150
A biometric research has been performed on 23 populations of Miogypsinids from samples collected in stratigraphic sequence on both sides of Gassino anticline, Collina di Torino, NW Italy. On the base of counts and measurements the following taxa were recognized: Miogypsina (Miogypsinoides) complanata Schlumberger, Miogypsina (Miogypsinoides) ex. interc. complanata–formosensis, Miogypsina (Miogypsinoides) formosensis Yabe & Hanzawa, Miogypsina (Miogypsinoides) bantamensis Tan, Miogypsina (M.) septentrionalis Drooger, Miogypsina (M.) ex. interc. basraensis–gunteri, Miogypsina (M.) gunteri Cole.
The occurrence of some of the cited species (M. formosensis, M. bantamensis, M. septentrionalis, M. basraensis) in Piedmont Tertiary Basin had never been reported before. Species distribution is in good agreement with the phyletic sequence recognized in Europe and the Mediterranean area, based on the principle of nepionic acceleration.
Statistic treatment of significant parameters in primitive singlespiralled Miogypsinids indicates strong correlation between X/γ, X/Y, DII/DI. Mean values of embrionic diameters increase with decreasing X and abruptly decrease as lateral chambers appear in M. septentrionalis.
Correlation with planctonic Foraminifera associations indicates that the examined stratigraphic sections represent the Chattian-Aquitanian transition (biozones P22/N3 and N4 – N5, Bloux. 1969).
- Cavallo O. & Galletti P.A. (1987)
Carlo Sturani’s studies on fossil dragonflies and other insects from the Messinian of Alba region (Piedmont) and description of Oryctodiplax gypsorum n. gen. n. sp.
pp. 151-176
The reading of the unpublished manuscripts of Carlo Sturani (1938-1975) on the Messinian paleoentomology allows to recognize the main stages through which the Author dealt with the systematic of the fossil insect remains; in particular, he started to describe and made camera-lucida drawings of more than one hundred impressions of dragonfly wings, collected from the gypsiferous marls outcropping from Santa Vittoria d’Alba to Costigliole d’Asti, in southern Piedmont. We thought that entomologists would be interested to know this spectacular dragonflies fauna through Sturani’s drawings, which are the best way to study these fossil specimens because the wing impressions are now partially obscured by gypsum recrystallization. This work assembles all Sturani’s writings and drawings on the subject and formalizes the new dragonfly genus Oryctodiplax (Odonata, Libellulidae), already outlined by C. Sturani in his unpublished manuscript.
The wing venation of Oryctodiplax n. gen. shows the joint occurrence of both archaic and recent characters: the arculus situated between the 1st and 2nd antenodals (recent); the sectors of arculus usually diverging at origin or in mutual contact in the forewings (archaic); the distal antenodal of forewings complete (archaic); the triangle of forewings moderately broad, its coastal side often slightly angulated distally (archaic); the well developed, stocking-shaped, anal loop (recent); the absence of accessory cross-veins to the bridge (recent); the base of triangle in the hindwings slightly distal to the level of arculus (archaic); the strongly oblique small reverse cross vein r between R2 and R3 (recent); the Rspl of rather primitive build and the Mspl absent or of very primitive build (archaic).
Systematic position and affinities of Oryctodiplax n. gen. are discussed.
- Cavallo O. & Gaudant J. (1987)
Complementary observations on the fish-fauna of the Messinian marls from Cherasco (Piedmont): geodynamic implications
pp. 177-198
The detailed description of the evaporitic Messinian series outcropping on the right bank of the Tanaro river, near Cherasco (Piedmont, Italy) gives occasion for a complementary study of the fish-fauna from the marly sequence overlying the upper gypsum. Two new species are described in this locality: a Clupeid, Clupeonella macagnoi nov. sp. and a Salmonid, Salvelinus oliveroi nov. sp. Moreover, the occurrence of a Cyprinid, originally reported by Sturani, is confirmed.
The geodynamical significance of the Messinian fish-fauna from Cherasco is-reexamined. This community is characterized by the affluence of the species Aphanius crassicaudus (Agassiz) which peopled lagoonal environments with a variable salt-content, during the Messinian. The species Gobius ignotus Gaudant is also frequent enough, white Atherina cavalloi Gaudant is more scarce. The four other species are only represented by one specimen. The brackish lagoon of Cherasco was related to the sea, as demonstrated by the occurrence of Mugil (?) nov. sp. and, also probably, by those of Atherina cavalloi Gaudant, Salvelinus oliveroi nov. sp. and Gobius ignotus Gaudant. Moreover, this lagoon was probably established near the estuary of a coastal river where Leuciscus cf. oeningensis Agassiz was normally living and in which Salvelinus oliveroi nov. sp. used probably to spawn.
Finally, the discovery of a fossil charr is interpreted as an index of climatic cooling.
- Fontes J.C., Filly A. & Gaudant J. (1987)
Deposition conditions of the Messinian evaporites near Alba (Piedmont): Paleontological and isotopic evidences
pp. 199-210
The detailed study of the evaporitic Messinian section exposed at Scaparoni, near Alba (Piedmont, Italy) allows to point out significant variations of the conditions of deposition. The bed of thinly laminated “primary gypsum” has produced dragonfly nymphs and, according to Sturani, remains of Cyprinodontid fishes. The evaporitic environment underwent seasonal variations of salt-content. Above, the thinly laminated marls have yielded a diversified fish-fauna in which is described a new species of Serranid: Tavania sturanii nov. sp. The occurrence of several typically marine genera demonstrates that the sedimentary basin was connected with the open sea. Still higher, the oligotypic community with Aphanius crassicaudus and dragonfly nymphs attests of the recurrence of an environment with seasonal variations of the salt content.
The carbonate phase associated with the evaporitic facies is mainly made of dolomite. This mineral displays large variations in 18O contents which indicate major fluctuations in the hydrological balance of the basin.
The base of the evaporitic layers shows a calcitic level highly depleted in carbon 13. This calcite crystallized out of any contact with dissolved CO2 of atmospheric origin. The dissolved carbon could have been produced through sulphato-reduction in the presence of continental solutions rather than marine ones.
Sulphur 34 and oxygen 18 contents from the sulphate of the gypsum samples suggest various stages of reduction from a unique source. This reservoir of sulphate would have had a Permian or Triassic signature. The sulphate supply would have implied a redissolution process but leaves open the question of the origin of the chloride.
The presence of stenohaline marine organisms and especially of fishes together with palaeoecological and geochemical arguments for supplies of continental solutions is discussed. We propose the concept of a coastal basin with reduced communications with the open sea. The hydraulic confinement allowed the continental supplies to evaporate until a salt concentration compatible with living conditions of the most stenohaline marine organisms.
- Romeo M. (1987)
Presence of Polyperibola christiani Liska in the Tortonian of central-southern Sicily
pp. 211-218
The presence of Polyperibola christiani Liska (Globigerinacea) is pointed out in the lower Tortonian of central-southern Sicily with the same morphological modifications found in Venezuela. As a result of paleoclimatic controls, this species could be considered as a cold indicator of the basis of the Upper Miocene.
Issue 3
Published in November 1987
- Mazza P. & Zafonte F. (1987)
Phyletic and ecologic considerations on the Gargano (Southern Italy) Prolagus (Ochotonidae, Lagomorpha, Mammalia)
pp. 221-231
The need to deepen the knowledge of the phylogenesis and the ecology of the Gargano Ochotonids led to the study of the enamel structure and general jaw morphology of Prolagus specimens.
The microstructural analysis seems to corroborate the opinion of the existence of two distinct Gargano Prolagus populations in the more recent fissure filling samples.
This study as a whole allowed a clearer definition of the environment of life of those animals.
- Mazza P. (1987)
Prolagus apricenicus and Prolagus imperialis: two new Ochotonids (Lagomorpha, Mammalia) of the Gargano (Southern ltaly)
pp. 233-243
Two new species, Prolagus apricenicus and P. imperialis, are described. This formalization must be seen as a step on the way of wider knowledge of the Gargano fossil community. The two species seem rather closely related. P. apricenicus is a small-size form, characterized by low size growth rate. In the fossil record here studied, P. apricenicus shows a progressive increase of specialized characters as those possessed by P. imperialis. The latter species appears rather late in the Gargano fossil record. It is very large-sized, more than any other known Prolagus species, and strongly endemized. Its size growth rate seems rather higher than that of P. apricenicus.
- Gnoli M. (1987)
Revision and autecological remarks of the species Columenoceras grande (Meneghini, 1857) (Nautiloidea, Orthocerida)
pp. 245-250
New specimens of “Orthoceras” grande Meneghini, collected in the type-locality from the Upper Wenlock of the Fluminese area (Silurian, SW Sardinia), permit a better knowledge of this species and its different taxonomic assignment. O. grande is now considered to belong to the genus Columenoceras (Geisonoceratidae) instead of to the genus Michelinoceras (Orthoceratidae), as previously supposed by Serpagli & Gnoli (1977). Also the synonymy, proposed by the same authors, between M. grande Meneghini and M. michelini Barrande, type-species of the genus Michelinoceras, must be revised. Besides the complete redescription of the species, remarks on its autecology and a wide discussion on the diagnostic features of the genus Columenoceras are also given.
- Bonaduce G., Ruggieri G. & Russo A. (1987)
The ostracode genus Mutilus and some so-called Mutilus from the Mediterranean Miocene-Pleistocene
pp. 251-268
The genus Mutilus is represented in the Mediterranean Pliocene-Early Pleistocene by 5 species belonging to 2 subgenus: Mutilus (Mutilus) and Mutilus (Obtusomutilus).
The 3 species belonging to the subgenus Mutilus (Mutilus) can be arranged in a phyletic series: elegantulus, laticancellatus, evolutus, the ancestral form of which must be searched in the Atlantic Miocene. All Miocene Mediterranean species previously described as Mutilus don’t belong in fact to this genus. Some of these species are here assigned to 2 new genera: Flabellimutilus n. gen. (Middle-Upper Miocene), type-species Mutilus (M.) keiji Ruggieri, represented by 2 species, one of which, F. flabellum, is described as new; and Arutella, n. gen., type-species Mutilus cimbaeformis saheliensis Aruta, occurring exclusively in the Upper Miocene. The systematic position of this last genus appears still questionable.
- Sirotti A. (1987)
Ontogeny in Tethyan Discocyclinidae and Orbitoclypeidae (Foraminifera)
pp. 269-278
Discocyclina Gumbel and Orbitoclypeus Silvestri, homeomorphic taxa of Paleocene and Eocene macroforaminifera misinterpreted by some Aa. as synonyma, are here analyzed and their microspheric morphogenetic pattern recognized. On this basis the two taxa are acknowledged phylogenetically unrelated. From the ontogenetic development of the microspheric generation in the two taxa, their respective megalospheric nepionic stages are interpreted so to differentiate them structurally.
- Vazzana A. (1987)
Cenomanian Cephalopoda from Brancaleone Marina, Calabria (Italy)
pp. 279-286
Twelve species of Cenomanian Cephalopoda are discovered near Brancaleone Marina (Calabria, Italy). Once more the presence of the Cenomanian stage surrounded of the Tertiary formations not directly connected in the vertical succession, nor contiguous with the South-East Calabria is confirmed.
- Pavia G. & Sarti C. (1987)
Ammonite biostratigraphy of the Italian Jurassic
pp. 289-293
A general picture of the up-to-date knowledge is outlined with the main aim to suggest which sections can be used as references for Italian Jurassic biostratigraphy, stage by stage. The paleobiogeographic difference between the south-western Alps (Argentera district) and Sardinia, submediterranean in character, and the main part of Italy from Meridional Alps to Apennines and Sicily, with typically mediterranean ammonite faunas, is pointed out. Our knowledge is far to be exhaustive: whilst some stage like Domerian, Toarcian, Bajocian, Kimmeridgian are well or sufficiently known, we need larger and greater researches on Hettangian, Aalenian, Bathonian and Oxfordian.
- Farinacci A. (1987)
Italian Jurassic facies in the framework of the Tethys realm
pp. 295-301
Sedimentary facies in the Tethyan realm are characterized, during Jurassic, by two main types: 1) carbonates in very thick sequences sedimented on the shelves where the carbonate productivity was very high (Bahamian type); 2) marly limestone, often with chert, in thin sequences, without deep-sea bottom features, but with emersion facies and sedimentary gaps (actually unknown type).
In the first sedimentary type the subsidence proceeded fastly, foot by foot, according to the sedimentation rate. In the second type the subsidence was very slow, as on a non-subsident plateau.
For the second type basin the model shown in the Rosso Ammonitico Symposium is explaned. The old model-building, assuming the sedimentation below CCD, is refused by the new data drawn from paleontology and sedimentology.
- Chiocchini M. (1987)
Carbonatic platform shelf-edge facies in the Central-Southern Apennines, during the Jurassic time interval: a summary of the paleontological and stratigraphical data
pp. 303-308
The paleontological and stratigraphical data regarding the carbonatic platform shelf-edge facies during Jurassic time interval in the Central-Southern Apennines are summarized in this work.
The main data concern the most recent researches in the Abruzzi area. In fact the knowledges about these facies in the other Apenninic areas are not stili completed.
The Upper Sinemurian-Portlandian sequence of the Gran Sasso d’Italia and Marsica areas are characterized by the presence of large amount of building organisms (Antozoa, Idrozoa, Briozoa and so on) and typical benthic microfossils. These sequences have been subdivided into four biozones and a subzone, based on different types of characteristic associations.
The stratigraphic range of the identified benthic species in this area is established. Some remarks about the paleoecologic significance of the benthic species and associations are also exposed.
- De Castro P. (1987)
Jurassic carbonate platform facies in Italy: areal distribution and biostratigraphic outline
pp. 309-325
The most important results of Italian Jurassic carbonate platform studies are outlined, and the state of knowledge is presented. After an historical review, essential stratigraphic and paleontological data are illustrated for Western and Southern Alps, Apennines, Calabrian Arc, Sicily and Sardinia.