Maria Alessandra Conti

Dinosaur Tracks as Paleogeographic Constraints: New Scenarios for the Cretaceous Geography of the Periadriatic Region

A really unexpected finding of sauropod and theropod footprints in southern Latium raises to four the number of the trampled levels recognized in central and southern Italy. After the recent findings in Latest Jurassic and Early, mid and Late Cretaceous carbonate platform deposits of the Periadriatic region, dinosaur footprints seem to provide very important paleogeographic constraints for reconstructing the geodynamic history of the Mediterranean area. The presence of a varied ichnoassociation makes acceptance of the current paleogeographic models concerning the relative and absolute position of the Laziale-Abruzzese-Campano and of Apulian-Dinaric domains during the Late Cretaceous more and more problematic. Dinosaur footprints, combined with other paleontological data, demonstrate that these areas were never completely pulled apart by deep seaways, while frequent or continuous links between them, and to southern and northern mainlands, probably persisted. These data also allowed us to improve our understanding of the timing of the Mesozoic plate motion in this segment of the Western Tethys.

Jurassic Dinosaur Footprints from Southern Italy: Footprints as Indicators of Constraints in Paleogeographic Interpretation

Abstract Three loose blocks, rich in dinosaur footprints, were found in a small pier at Mattinata (Gargano Promontory, Foggia, Italy), most probably quarried from the Upper Jurassic Sannicandro Formation. All of the footprints in the blocks are ascribed to medium-sized theropod trackmakers. Recent track discoveries from both the Early Cretaceous San Giovanni Rotondo Limestone and the Late Cretaceous Altamura Limestone, as well as this new discovery, reveal the consistency of terrestrial associations along the southern margin of the Tethys Ocean in the peri-Mediterranean area at the end of Jurassic through Cretaceous times. The presence of these dinosaur-track-rich levels within marine sediments of the Apulia Platform underlines the relevance of dinosaur footprints as a means of constraining paleogeographic reconstructions.

Lacertoid Footprints of the Upper Permian Arenaria di Val Gardena Formation (Northern Italy)

Lacertoid footprints are the largest component of the Upper Permian Arenaria di Val Gardena Formation ichnofauna that contains hundreds of specimens mostly referred to the ichnogenus Rhynchosauroides Maidwell 1911. In this paper, we analyzed unpublished material and re-examined the Rhynchosauroides footprints of that ichnofauna, in particular the figured specimens. Analysis of Rhynchosauroides and its type ichnospecies R. rectipes Maidwell 1911 was first necessary. This preliminary investigation highlighted several problems, including ichnospecies named on the basis of poorly preserved material and in some cases significantly different from the type ichnospecies. The study allowed for recognition of three ichnotaxa referred to Rhynchosauroides: Rhynchosauroides pallinii Conti et al., 1977, Rhynchosauroides isp.1 and Rhynchosauroides isp.2 and Ganasauripus ladinus igen. et isp. nov. Other material previously referred to Rhynchosauroides is herein regarded as unclassifiable, in the light of present ichnological knowledge and procedures.

Middle Jurassic Gastropods from the Central High Atlas, Morocco

This systematic study considers twenty-four gastropod species recovered in the Upper Aalenian-Lower Bajocian sediments of the Central High Atlas. Twenty-one species belong to archaeogastropod groups and three species are assigned to two caenogastropod families. A new genus, Sadkia nov. gen. (family Eucyclidae), and two new species, Sadkia richensis nov. sp. and Pirper ouchenensis nov. sp., are described. This gastropod fauna is compared with the coeval faunas known from other regions in order to define better the palaeobiogeographical history of the western Tethyan gastropods during the Jurassic. The generic/subgeneric and specific palaeogeographical distributions indicate a close resemblance between the gastropod faunas of the Central High Atlas and those of the European continental seas. On the other hand, there are no evidences of relationships with the faunas of the inner area of the western Tethys.

Hyloidichnus bifurcatus Gilmore, 1927 and Limnopus heterodactylus (King, 1845) from the Early Permian of Southern Alps (N Italy): A New Equilibrium in the Ichnofauna

Studies on Early Permian tetrapod ichnofauna emphasized the scarcity of forms from Italian sites. A revision work on the entire collections revealed the presence of Hyloidichnus bifurcatus Gilmore, 1927 and Limnopus heterodactylus (King, 1845). The ichnoassociation now lists seven ichnogenera: Amphisauropus, Batrachichnus, Dromopus, Erpetopus, Hyloidichnus, Limnopus, Varanopus. These new data enlarge the ichnoceonosis, adding tracks of medium-size captorhinomorphs (Hyloidichnus) and temnospondyls (Limnopus) to the Italian ichnofauna, previously characterized by scarcity of predators and amphibians. Radiometric ages give a strong age constraint to the ichnoassociation (Early Kungurian), allowing useful correlations to contemporary successions all over the world. The main difference is the absence of Ichniotherium and Dimetropus, and this could have a stratigraphic or paleoenvironmental significance. The fauna is similar in two main basins, Collio and Orobic. It differs solely in the proportions between ichnotaxa, with a predominance of areoscelid traces (Dromopus) in the Collio Basin and of captorhinomorph traces (Erpetopus, Varanopus, Hyloidichnus) in the Orobic Basin. This datum could reflect slightly different environments, seasonal in the Collio Basin (alluvial plain) and more arid in the Orobic Basin (playa-like). The lack of some forms in smaller basins of the Athesian Volcanic Complex is probably due to a bias.

Earliest Jurassic patellogastropod, vetigastropod, and neritimorph gastropods from Luxembourg with considerations on the Triassic–Jurassic faunal turnover

The Hettangian to earliest Sinemurian Vetigastropoda, Patellogastropoda, and Neritimorpha housed in the National Museum of Natural History of Luxembourg are studied. Most of the species comes from the Luxembourg Sandstone Formation. This deposit formed along the southern margin of the London-Brabant-Ardennes Landmass, in a region that during the earliest Jurassic constituted a seaway connecting the Paris Basin with the epicontinental seas of the Netherlands and northern Germany. The systematic analysis revealed high diversity of the studied fauna; we identified twenty-two species, eleven genera, nine families, and six superfamilies. A new genus, Meiersia gen. nov., and three new species, Anodomaria schroederi sp. nov., Meiersia disarmata sp. nov., and Spirocirrus weisi sp. nov. are described. The fauna is dominated by pleurotomarioideans representing the genera Ptychomphalus, Pleurotomaria, and Trochotoma, and by the patellogastropod genus Scurriopsis both in number of species and specimens. The neritimorph genus Neridomus is also well represented. Among the accessory taxa, Anodomaria and Spirocirrus first appeared in the Late Hettangian of the Luxembourg area. Most of these genera show a species radiation in the Early Jurassic and are distributed over the western European epicontinental shelf, probably favoured by an east to west marine transgression which influenced wide areas from the basins of the northern Germany to the Paris Basin through the Luxembourg seaway. The evolutionary and palaeobiogeographical data demonstrate that this radiation was already considerably advanced in the Late Hettangian. This suggests that the recovery of the gastropod diversity after the end-Triassic crisis was relatively fast in western Europe.

AN OVERVIEW OF THE JURASSIC GASTROPODS FROM ROCCA BUSAMBRA (NORTH-WESTERN SICILY, ITALY)

This paper is an overview of the gastropods from the Toarcian to Lower Kimmeridgian fissure fillings of Rocca Busambra. They are the most diverse and richest Jurassic faunas known from the pelagic sediments of the western Tethys. 224 species, 137 of them new, were recognized. The main feature of the structure of these assemblages is the high number of new taxa and the concomitant presence of an archaic stock with Triassic affinities, and a group advancing the appearance of the modern caenogastropod taxa. These features give these assemblages an important place in the reconstruction of the evolution of the whole class.

The Jurassic Pleurotomarioidean Gastropod Laevitomaria and Its Palaeobiogeographical History

The genus Laevitomaria is reviewed and its palaeobiogeographical history is reconstructed based on the re-examination of its type species L. problematica, the study of material stored at the National Natural History Museum of Luxembourg, and an extensive review of the literature. The systematic study allows ascribing to Laevitomaria a number of Jurassic species from the western European region formerly included in other pleurotomariid genera. The following new combinations are proposed: Laevitomaria allionta, L. amyntas, L. angulba, L. asurai, L. daityai, L. fasciata, L. gyroplata, L. isarensis, L. joannis, L. repeliniana, L. stoddarti, L. subplatyspira, and L. zonata. The genus, which was once considered as endemic of the central part of the western Tethys, shows an evolutionary and palaeogeographical history considerably more complex than previously assumed. It first appeared in the Late Sinemurian in the northern belt of the central western Tethys involved in the Neotethyan rifting, where it experienced a first radiation followed by an abrupt decline of diversity in the Toarcian. Species diversity increased again during Toarcian—Aalenian times in the southernmost part of western European shelf and a major radiation occurred during the Middle Aalenian to Early Bajocian in the northern Paris Basin and southern England. After a latest Bajocian collapse of diversity, Laevitomaria disappeared from both the central part of western Tethys and the European shelf. In the Bathonian, the genus appeared in the south-eastern margin of the Tethys where it lasted until the Oxfordian.

A THEROPOD DOMINATED ICHNOCOENOSIS FROM LATE HAUTERIVIAN-EARLYBARREMIAN OF BORGO CELANO (GARGANO PROMONTORY, APULIA, SOUTHERN ITALY)

Several dinosaur footprints were discovered on three different levels cropping out in the CO.L.MAR quarry, south of the village of Borgo Celano in the Gargano Promontory (Apulia, southern Italy). The track-bearing levels belong to a carbonate inner platform succession referred to the Lower Cretaceous (upper Hauterivian-lower Barremian). This paper describes only the lowest dinoturbated bed, where footprints are preserved as natural cast. Forty footprints, mostly tridactyl, have been attributed to medium-sized theropods. Tridactyl tracks are similar to Kayentapus Welles, 1971 regarding ichnotaxonomy. Round shaped footprints, previously not described from this site, are found in association with tridactyl footprints and are related to ornitischian dinosaurs.