RIVISTA ITALIANA DI PALEONTOLOGIA E STRATIGRAFIA

COMMON AND RARE LOWER PLIOCENE AGGLUTINATED FORAMINIFERS OF PIEDMONT (NORTHWESTERN ITALY): DISTRIBUTION, TAXONOMY AND PALEOENVIRONMENT

DONATA VIOLANTI — 2023-09-05

Agglutinated foraminiferal taxa from five stratigraphic sections and eightheen small outcrops of Lower Pliocene deposits were quantitatively analyzed for paleoenvironmental purposes. The studied area is located in Piedmont, northwestern Italy, and includes the northeastern Monferrato, the southern margins of the Turin Hill, the Astigiano, the Albese and part of the Langhe. Studied samples were mainly collected in the marine Argille Azzurre (AA) Formation, and cover a time interval ranging from the MPl1 zone to the MPl4a subzone in the Pliocene Mediterranean Foraminiferal Zonation. Most of the agglutinated assemblages are dominated, or exclusively made, by calc-agglutinated infaunal species of elongated tapered or subcylindrical shape, mainly represented by Bigenerina nodosaria and Martinottiella communis. The deep-water infaunal Cylindroclavulina rudis, Eggerella bradyi and Martinottiella perparva characterized the open-sea basinal facies deposited in the central part of the Piedmont region during the earliest Pliocene. These taxa progressively decreased in abundance until to disappear, and were replaced in the upper silty succession by shelf taxa, dominated by Bannerella gibbosa and Textularia aciculata. In particular, T. aciculata showed its highest abundances in infralittoral to shallow circalittoral muddy sediments of probable fluvial origin, widespread in the Astigiano area, and could be suggested as a typical species of shallow marine delta deposits. Among the 42 agglutinated species here determined, Cyclammina cancellata and Reophax scorpiurus were seldom reported in previous works, Ammobaculites agglutinans, Ammoscalaria spp., Cribrostomoides subglobosus subglobosus, Haplophragmoides canariensis, Psammosphaera spp., and Psammolingulina papillosa were not previously found. The occurrence of these rare taxa could be the proxy of particular sea-floor conditions during the MPl3 zone, characterized by a locally active bottom circulation and mesotrophic waters.

CARNIVORA FROM THE EARLY PLEISTOCENE OF GRĂUNCEANU (OLTEŢ RIVER VALLEY, DACIAN BASIN, ROMANIA)

LARS WERDELIN — 2023-09-06

The Grăunceanu site in the Olteţ River Valley has yielded a rich carnivoran assemblage including at least 10, possibly 11 species: Vulpes alopecoides, Nyctereutes megamastoides, Ursus etruscus, Meles thorali, Lutraeximia sp., Pliocrocuta perrieri, Lynx issiodorensis, Puma pardoides, Megantereon cultridens, Homotherium latidens and possibly Pachycrocuta brevirostris. The faunal assemblage is compared with approximately coeval sites Europe and western Asia. This comparative analysis shows that the Grăunceanu assemblage shows the greatest similarities with sites to the west such as Senèze and, particularly, Saint-Vallier, rather than more easternly ones such as Liventsovka and Dmanisi. The relative abundance of the taxa at Grăunceanu was compared to that of Saint-Vallier and broad similarities were found, except for the absence of some cursorially adapted taxa present at Saint-Vallier but absent from Grăunceanu. The absence at Grăunceanu of taxa with a reconstructed cursorial hunting strategy, such as Chasmaporthetes and Acinonyx, may suggest less open habitat at Grăunceanu than indicated in previous paleoenvironmental reconstructions.

SIDELINED SEASHELLS: REAPPRAISAL OF THE MIDDLE TRIASSIC AMMONOIDS OF SAMOBOR AND ŽUMBERAK MTS. (NORTH-WESTERN CROATIA) AND THEIR SYSTEMATICS AND BIOSTRATIGRAPHIC IMPLICATIONS

FRAN VIDAKOVIĆ — 2023-09-07

Basinal Middle Triassic successions of the Samobor and Žumberak Mts. (north-western Croatia) have historically produced fossils of ammonoids. These finds have, however, largely been neglected in the later literature. This paper describes and redescribes a large collection of ammonoids, most of which were collected by previous researchers throughout the 20^th century. Aside from the detailed taxonomic descriptions and revisions, several taxa previously unknown from these localities were identified. Of the species whose holotypes were designated at the Gregruć Breg locality, some are found to be dubious, with validity of other remaining inconclusive and a single taxon, Eoprotrachyceras dorae comb. nov., being treated as valid. Certain Middle Triassic ammonoid genera may also require future comprehensive revisions. A preliminary, modified ammonoid zonal/sub-zonal scheme for the Ladinian of the Tethyan province is proposed, to be inclusive of most of the data from the literature. The need for improvement of the subdivision of this stage is recognized. Based on ammonoids, condensed red nodular limestones of the Gregurić Breg locality (Samobor Mts.) most likely span the Avisianum subzone (upper Illyrian) – Longobardicum subzone (“middle” Longobardian), indicating that subsidence began in the earlier part of the Illyrian. At Mt. Žumberak, scant ammonoid remains indicate that the upper, limestone-rich portion of this succession spans at least the Avisianum subzone (upper Illyrian) – Longobardicum subzone (“middle” Longobardian), but additional data is needed for drawing more robust conclusions. Overall, the timing of basinal deposition is well correlated between Gregurić Breg and Žumberak localities (lower Illyrian – upper Longobardian).

AN INSIGHT INTO THE SYSTEMATICS OF PLICATOSTYLIDAE (BIVALVIA), WITH A DESCRIPTION OF PACHYGERVILLIA ANGUILLAENSIS N. GEN. N. SP. FROM THE LITHIOTIS FACIES (LOWER JURASSIC) OF ITALY

RENATO POSENATO — 2023-09-13

The Lithiotis facies represents an Early Jurassic global bioevent characterized by a remarkable spread of gregarious bivalves, which produced large sedimentary bodies in tropical shallow-water marine environments. The most peculiar and common genera Lithiotis, Cochlearites and Lithioperna, with aberrant and extremely elongated or strongly flattened shells, have been studied since the second half of the nineteenth century. Despite numerous systematic studies, their phylogenetic relationship with the other bivalve families is still uncertain. The Lithiotis facies yields other bivalve genera, among which a large multivincular mytiloid, provisionally determined as Isognomon (Mytiloperna) sp. ind. or Mytiloperna sp., is recorded in the literature. This taxon is here studied from a systematic point of view to clarify its taxonomic position and solve the open nomenclature adopted in the past. Here, we propose a new genus Pachygervillia and a new species Pachygervillia anguillaensis. The stratotype is located in the lower part of the Rotzo Formation (Calcari Grigi Group, Lower Jurassic), while the type locality is in the Lessini Mountains (Verona Province, Trento Platform, Southern Alps). This new species is characterized by a thick aragonitic inner shell layer with a fibrous, irregular, spherulitic, prismatic microstructure combined with a nacreous middle layer, both also occurring in species of the genera Lithiotis and Cochlearites of the family Plicatostylidae. This microstructural layering is here proposed as the main taxonomic character of the family, which is here emended and divided into the following two subfamilies: Plicatostylinae, yielding Lithiotis and Cochlearites with stick-like shells, and Pachygervilliinae nov. subfam., yielding Gervilleioperna, Lithioperna, Pachygervillia n. gen., and Pachyperna, previously placed within the subfamily Isognomoninae.