Lorenzo Marchetti

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.

Revision of Late Permian tetrapod tracks from the Dolomites (Trentino-Alto Adige, Italy)

Abstract The Val Gardena Formation of the Dolomites region in northern Italy preserves the most significant assemblage of Late Permian tetrapod footprints in the world. More than 120 years of collecting resulted in about 900 publicly accessible specimens from the study area. This huge amount of data is comprehensively revised in the light of recent advances in the study of Late Palaeozoic – Early Mesozoic tetrapod ichnofossils. According to our analyses, the Val Gardena Sandstone Formation includes tracks that can be assigned to cf. Batrachichnus isp. (temnospondyl amphibian), Capitosauroides isp. (amphibian), Dicynodontipus isp. (cynodont therapsid), Dolomitipes accordii n. igen. n. comb. (dicynodont therapsid), cf. Dromopus isp. (neodiapsid), Pachypes dolomiticus (pareiasaurian parareptile), Paradoxichnium problematicum (archosauromorph neodiapsid), Procolophonichnium tirolensis n. comb. (procolophonoid parareptile), cf. Protochirotherium isp. (archosauriform neodiapsid) and Rhynchosauroides pallinii (neodiapsid). The ichnoassociation is dominated by tracks of neodiapsid and parareptilian tetrapods, whereas synapsid and anamniote tracks are rather minor components. It includes 10 out of 12 tetrapod ichnogenera known from Lopingian deposits and thus it constitutes a reference for the Paradoxichnium biochron. It shows striking similarities with other low-latitude non-aeolian contemporaneous ichnoassociations of Europe and North Africa, differences may be linked to the palaeoenvironment. Moreover, it shows a clear Triassic affinity. The new ichnogenus Dolomitipes was registered in Zoobank.org. urn:lsid:zoobank.org:act:5B4D871C-D16A-4E93-8211-CEE08019BA60

Vertebrate and Invertebrate Trace Fossils in the Late Pennsylvanian (Carboniferous) Fluvio-Lacustrine San Giorgio Basin (South-West Sardinia): Remarks on the Oldest Continental Ichnoassociation of Italy

ABSTRACT A new study of the ichnotaxonomy and palaeoecology of the Late Pennsylvanian San Giorgio Basins trace fossils was carried out. The tetrapod tracks were attributed to Batrachichnus salamandroides and to indet. tracks with a possible small temnospondyl and/or lepospondyl affinity. The invertebrate trace fossils include locomotion traces (Diplichnites isp.), grazing traces (Cochlichnus anguineus), and feeding structures (Treptichnus bifurcus, Treptichnus isp.). The trace fossils were evaluated by means of ichnofacies, highlighting a transitional Scoyenia-Mermia ichnofacies, typical of Carboniferous freshwater settings. The trace fossil co-occurrence and taphonomy was utilized to give a new interpretation of the fossil-bearing lithofacies, which are dolomitic mudstones-fine sandstones expression of marginal lacustrine environments repeatedly subject to flooding (three different ichnoassociations highlight different bathymetry/emersion). This is the oldest continental ichnoassociation of Italy, and its moderately high diversity and complexity suggest further study of this important Carboniferous trace fossil locality.

TETRAPOD FOOTPRINT PALEOECOLOGY: BEHAVIOR, TAPHONOMY AND ICHNOFAUNA DISENTANGLED. A CASE STUDY FROM THE LOWER PERMIAN OF THE SOUTHERN ALPS (ITALY)

Abstract: Vertebrate tracks are linked to the depositional environment where they were formed. Several studies hypothesized a paleoenvironmental control on vertebrate track ichnocoenoses, although this issue was never analyzed thoroughly. A new study of the sedimentology and tetrapod ichnology of two key stratigraphic sections in the Pizzo del Diavolo Formation of the lower Permian continental Orobic Basin of Southern Alps (Italy) tested the link between tetrapod ichnocoenoses and depositional environment. Behavior, taphonomy, and ichnocoenoses of three different lithozones (P-PDV, U-PDVa, U-PDVb) were analyzed and compared, two new census methods for tetrapod tracks were tested (“track/slab” and “weighting size”) and the first was applied to our specimen sample. The possible biostratigraphic meaning of track occurrences/relative proportions were discussed and excluded. Results indicate a predominance of the ichnogenus Erpetopus in a distal floodplain environment (P-PDV), a diverse ichnocoenosis in a proximal floodplain environment (U-PDVa), and a predominance of the ichnogenus Dromopus in a scarcely diverse ichnocoenosis in a floodplain/marginal lacustrine environment (U-PDVb). This encourages further detailed studies on tetrapod track paleoecology, in order to refine and give utility to the concept of tetrapod ichnofacies.

Walk 'n Jump: Associated Insect Walking and Landing Trace Fossils from the Early Permian of the Southern Alps

ABSTRACT We describe a compound trace fossil Stiaria cf. intermedia C Avolatichnium isp. from the lower Permian of Southern Alps (North Italy) and confidently attribute it to a wingless (apterygote) jumping insect producer belonging to the order Monura (Insecta: Archaeognatha). We discuss the common features linking the ichnogenera Avolatichnium, Rotterodichnium and Tonganoxichnus, and suggest a close affinity for their producers. Grounded on previous studies and on some exceptional features preserved in the described material, we provide a biomechanical model for jumping in Archaeognatha and hypothesize that Paleozoic Archaeognatha performed jumps with high vertical and very low horizontal component and only later acquired the ability to heighten the horizontal component of their jumps, therefore, becoming more efficient in propelling themselves far ahead as extant species do.

A Rare Occurrence of Permian Tetrapod Footprints: Ichniotherium cottae and Ichniotherium sphaerodactylum on the Same Stratigraphic Surface

ABSTRACT Ichniotherium Pohlig, 1892 is a principal morphotype of Carboniferous-Permian tetrapod footprints referred to diadectomorphs. Though these tracks are relatively abundant in paleoequatorial regions of Pangea, the Cisuralian Bromacker locality in central Germany, is the only known place with co-occurring Ichniotherium ichnospecies. Ichniotherium cottae Pohlig, 1885 and Ichniotherium sphaerodactylum Pabst, 1895 are well studied from the German fossil site but tracks of the two ichnospecies have reported to be almost exclusively preserved on separate specimens. Here, we describe two rare cases where I. cottae and I. sphaerodactylum tracks occur close each other on the same slab coming from the Bromacker quarry. In order to explain the exceptional occurrence of the two Ichniotherium ichnospecies and the higher relative abundance of I. sphaerodactylum at the Bromacker site, various reasons are discussed, from which the paleoecological ones linked to the time of impression (Hypothesis A) or to the trackmaker areal distribution (Hypothesis B) seem to be the most likely.