CTENOGNATHICHTHYS BELLOTTII (DE ALESSANDRI, 1910): NOMENCLATURAL PROBLEMS AND STRATIGRAPHICAL IMPORTANCE OF THIS MIDDLE TRIASSIC ACTINOPTERYGIAN FISH

The existence of one of the original specimens of Ctenognathichthys bellottii (De Alessandri 1910), figured and labelled as ‘type specimen’ by De Alessandri himself, raises a nomenclatural question as there is also a neotype designated by Bürgin (1992). The International Commission of Zoological Nomenclature has been asked to rule on the validity of the neotype. As some of the requirements for the designation of a neotype were not met, the holotype should be treated as the name-bearing type. The discovery of this species in both the Besano Formation (Grenzbitumenzone Auct.) and the Perledo-Varenna Formation is very important from a stratigraphic point of view, confirming that the so called Perledo fish-fauna is composed of different assemblages. In fact, the Perledo fauna has most species in common with the Ca’ del Frate (Viggiù, Varese, Italy) fauna from the Kalkschieferzone (uppermost Meride Limestone), which is latest Ladinian in age, while a few of the Perledo species have been found also in the Grenzbitumenzone and/or in the lower Meride Limestone of Lower Ladinian age.&nbsp

FIRST AMPHIBIAN FIND IN EARLY PERMIAN FROM SARDINIA (ITALY)

An amphibian fauna from Permo-Carboniferous boundary beds is recorded for the first time in Italy. A thin fossiliferous level has been found in the Perdasdefogu Basin in southeastern Sardinia;it yields several speciments of Branchiosaurus cf."B." petrolei Gaudry 1875), often in mass mortality assemblages.Repeated mass mortality events testify to sudden changes in the environment of the basin, possibly due to seasonal variations. The finding of speciments very close to Branchiosaurus petrolei,which is a common species in the Central France basins,confirms that Sardinia at the time belonged to the same hydrographic basin of continental Europe, with no seaway in between.Furthermore, though not the primary focus of this note, we report the first discovery of the xenacanth teeth and acanthodian spines in Italy. &nbsp

GABANELLIA AGILIS GEN. N. SP. N., (ACTINOPTERYGII, PERLEIDIFORMES) FROM THE CALCARE DI ZORZINO OF LOMBARDY (NORTH ITALY)

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LATE DEVONIAN (FRASNIAN) CORALS FROM CENTRAL DOLPO, NEPAL

Rugosa and Tabulata from the Late Devonian of central Dolpo (Nepal) belong to the genera Kuangxiastraea, Scruttonia, Sinodisphyllum, Tabulophyllum (?), Fruehwirthia gen. n., Thamnopora, Cladopora, Alveolites and Alveolitella. The calcarenitic beds yielding the fossils are overlain by a prominent oolitic ironstone with thick ferruginous nodules and crusts. The age of the corals is probably Early Frasnian, thus younger than the Givetian fauna previously reported from eastern Dolpo. Biogeographic relations of the new fauna are with Western Europe and South China

LOCOMOTOR FUNCTION OF SCALES AND AXIAL SKELETON IN MIDDLE–LATE TRIASSIC SPECIES OF SAURICHTHYS (ACTINOPTERYGII)

Starting in the Late Permian, the “Triassic osteichthyan revolution” gave rise to several new morphotypes of actinopterygians, including the iconic barracuda-shaped predator Saurichthys. About 50 species, from 10 cm to over 1.5 m long, are known from mainly marine deposits worldwide. Despite current interest in Saurichthys, freshwater species and those from late Middle to early Late Triassic remain understudied. We document the postcranial morphology of three small to mid-sized (15–45 cm) species from this timeframe represented by sufficiently complete individuals: Saurichthys orientalis Sytchevskaya, 1999, from lacustrine deposits of the Madygen Formation (late Ladinian/Carnian); S. striolatus (Bronn, 1858) from the fully marine Predil Limestone (early Carnian); and S. calcaratus Griffith, 1977, from the terrigenously influenced coastal environment of the Lunz Formation (middle Carnian). S. orientalis resembles early saurichthyids in having six rows of large, thick ganoid scales; fins with segmented lepidotrichia; and flank scales relating to dorsal vertebral elements as 1:2. S. calcaratus and S. striolatus share unsegmented fin rays and a reduced scale cover with well-ossified but narrow mid-dorsal and mid-ventral scales and small, thin flank scales, relating to the dorsal arcualia as 1:1. Ventral arcualia are first described for S. calcaratus and S. striolatus, where they change in shape and number at the abdominal-caudal transition. In all three species, force transmission to the tail fin is enhanced by the caudal peduncle strengthened by a stiff structure arising from interlocking or fusion of the last enlarged mid-dorsal and mid-ventral scales (scutes), while the vertebral column remains rather lightly built

BIOMECHANICAL FRAGMENTATION IN SHELL-BEDS FROM THE LATE TRIASSIC OF THE LOMBARDIAN BASIN (NORTHERN ITALY). PRELIMINARY REPORT

Shell-beds rich in shell fragments are very common in the Lombardia basinal facies in the Late Triassic. Biofragmentation by durophagous fishes, which were very common, must be regarded as the main taphonomic process on the basis of the shape of fragments and the presence of predatory traces, such as semicircular notches on the fragment edges or punctures on whole valves. Scattered patches of shell-fragments are also common and are considered as ejecta and/or coprolites from durophagous fishes. Funhermore, shell material fragmented by living fish (Pogonias cromis and Diplodus sargus among others) is comparable in shape with the Triassic material presented here. The shell-beds here described were deposited in a low energy environment, which precludes waves or currents mechanical damages. Paralepidotus ornatus, the most common Triassic duropagous fish, pycnodonts, other semionotids and the placodont reptile Psephoderrna  alpinum, are the most important shell-predators in the Late Triassic.  Modiolus, Laternula and Protocardia were the more commonly preyed  molluscs

PREDATORS AND PREYS: A CASE HISTORY FOR <em>SAURICHTHYS (COSTASAURICHTHYS) COSTASQUAMOSUS</em> RIEPPEL, 1985 FROM THE LADINIAN OF LOMBARDY (ITALY)

A large specimen of Saurichthys (Costasaurichthys) costasquamosus from the lower Ladinian of the Northern Grigna mountain is described. It is an incomplete specimen, lacking the caudal region, and showing gut content. This latter consists of totally scattered remains of at least two specimens of adult Ctenognathichthys bellottii, a medium size fish quite common in this fossil assemblage. Saurichthys has been always considered an active predator on small fishes, but it cannot be the case for this specimen, with remains in the gut are totally disarticulated and evenly scattered all along the abdomen. Scavenging on floating carcasses is proposed, the hypothesis being also supported by the common preservation of Ctenognathichthys as incomplete individuals. Although the Saurichthys specimen shows some ‘in situ’ disarticulation, caudal region elements are totally missing on the slab yielding the anterior part of the fish. As for other large Saurichthys specimens from the same site, it is supposed that this is the result of a predation by a much larger marine organism, possibly an ichthyosaur

FISH TAPHONOMY AND TRIASSIC ANOXIC BASINS FROM THE ALPS: A CASE HISTORY

Anoxic basins, rich in fossil vertebrates, are frequently represented in the Middle and Upper Triassic rocks of both Southern and Northern Calcareous Alps. Some of the localities have been known since the second half of the XIX century and have yielded a great deal of specimens (Formazione di Besano, Seefelder Schichten), some others have been only recendy found (Calcare di Zorzino). In the past times, these sites have generally been the object of economical rather than paleontological interests: their bituminous levels, in fact, were mainly exploited for pharmaceutical purposes. Their present economical interest resides in that they may have been oil source-rocks. The formations in question have a medium/high total organic matter content (TOC, up to 40%). This, together with the presence of abundant, well preserved fossil vertebrates, have always led the previous Authors to think the basins bottom was anoxic; they assumed, in fact, that marine vertebrates fossilizate mainly under anoxia. Nonetheless, the taphonomic study of these vertebrate remains, here carried on for the first time, only in some cases supports this idea; in the others, most of all as concerns the Formazione di Besano, it has allowed the proposition of a different model. Fossils, in fact, often lie isooriented and disarticulate, with unimodal dispersal of the single elements. This implies the presence of light bioturbation and currents at the bottom and thus a disaerobic, rather than anoxic environment. Regarding other units, such as the Calcare di Zorzino and the Kalkschieferzone, the anoxic bottom conditions are well supported by the preservation of very small sized, completely articulated specimens, though the TOC shows remarkably lower rates than in the Formazione di Besano

NEW TRIASSIC ASTEROIDEA (ECHINODERMATA) SPECIMENS AND THEIR EVOLUTIONARY SIGNIFICANCE

The Paleozoic-Mesozoic transition saw the disappearance of asteroid stem groups and the ascent of the crown group, but late Paleozoic and Triassic asteroids are rare and transition events are poorly documented. Three new Middle and Late Triassic specimens augment existing data; included are a specimen of Trichasteropsis weissmanni from Germany, a specimen of Trichasteropsis? sp. indet. from Italy, and a possible member of the extant Poraniidae from Slovenia. Presence of a small ossicle at the interbrachial midline and adjacent to the marginal series of the new T. weissmanni specimen is consistent with similar expressions not only of other trichasteropsids but also occurrence of two interbrachial ossicles in Paleozoic, stem-group asterozoans; presence is in turn consistent with a hypothesis of derivation of the axillary/odontophore coupling from two ossicles rather than direct derivation of the crown-group odontophore from a single stem-group axillary. Morphology of Trichasteropsis? sp. indet., including, for example, the evenly-tapering arms are reminiscent of those of diverse crown-group asteroids whereas the enlarged distal arms of T. weissmanni are unique, the morphology of T? sp. indet. thereby potentially indicative of a plesiomorphic, stemward positioning within the Trichasteropsiidae. The range of the Poraniidae is tentatively extended to the Carnian. Similarities shared by the Poraniidae and the Trichasteropsiidae suggest stemward positioning within crown-group diversification; however, known Triassic fossils do not appear closely related to extant taxa identified in recent molecular studies as basal within the crown-group. A temperate climate is suggested as preferred by the Triassic asteroids rather than a tropical, warmer one