Paolo Citton

Dimetropus osageorum n. isp. from the Early Permian of Oklahoma (USA): A Trace and its Trackmaker

A new ichnospecies is named as Dimetropus osageorum n. isp. within the ichnogenus Dimetropus Romer and Price, 1940. The new ichnotaxon comes from the Lower Permian Midco Member of the Wellington Formation, cropping out near Perry, Noble Co. (Oklahoma, USA), and differs from congeneric ichnospecies in the apparent heteropody and in the proportionally shorter digits. The characters of the new ichnotaxon, together with comparative analysis of footprints and of known skeletal remains, suggest referral of the trackmaker to the Caseidae, although edaphosaurid affinities cannot be excluded. Tracks referred to Dimetropus exhibit wide variation, and their respective trackmakers may be ascribed to an accordingly wide range of different zoological taxa among non-therapsid Synapsida and not only to Sphenacodontidae as has been generally believed. At the same time, the process of attributing ichnotaxa, on the basis of well preserved tracks and by comparison with known skeletal remains, is validated.

Testing two open-source photogrammetry software as a tool to digitally preserve and objectively communicate significant geological data: the Agolla case study (Umbria-Marche Apennines)

The digital storage and communication of significant geological data became increasingly more objective and accessible through the development of new technologies or the implementation of already well-known techniques as photogrammetry. Digital acquisition of geometries (both structural and depositional) of significant geological outcrops is deemed necessary, especially if the site concerned is liable to be damaged or hopelessly involved in natural processes of geological and geomorphological evolution. In this paper, we tested the performances of two different open-source software (i.e. VisualSFM and ARC3D) on a small-scale but paradigmatic outcrop in the Umbria-Marche Apennines (Italy). The test showed that ARC3D provides an high-resolution model, employing a relatively short time and requiring inexpensive hardware support for processing hundreds of photos. In the text, 3D models of the selected outcrop are reported and discussed emphasizing the potential of the method to highlight structural, sedimentological and paleontological details. As a result, 3D photogrammetry proved to be a powerful and effective tool to digitally conserve and objectively communicate important geological observations and to facilitate accessibility and dissemination of the collected data within the scientific community.

Elongated theropod tracks from the Cretaceous Apenninic Carbonate Platform of southern Latium (central Italy)

New dinosaur footprints were recently discovered in southern Latium (Italy). The tracks all appear slightly differently preserved and are characterized by elongated metatarsal impressions, recording the complex locomotor behaviour of a medium-sized theropod. The spatial distribution and the features of the footprints indicate that the trackmaker adopted a “crouched” position as part of an activity as well as a resting phase suggested by sub-parallel, calcigrade tracks. These new data once again highlight the great potential of ichnological evidence in the study of the biology and behaviour of extinct tetrapods. Paolo Citton. Dipartimento di Scienze della Terra, “Sapienza” Università di Roma, Piazzale Aldo Moro 5, 00185, Rome, Italy. paolo.citton@uniroma1.it Umberto Nicosia. Dipartimento di Scienze della Terra, “Sapienza” Università di Roma, Piazzale Aldo Moro 5, 00185, Rome, Italy. umberto.nicosia@uniroma1.it Iacopo Nicolosi. Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Roma, Italy. iacopo.nicolosi@ingv.it Roberto Carluccio. Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Roma, Italy. roberto.carluccio@ingv.it Marco Romano. Dipartimento di Scienze della Terra, “Sapienza” Università di Roma, Piazzale Aldo Moro 5, 00185, Rome, Italy; Sam Noble Museum, 2401 Chautauqua Ave., Norman, Oklahoma 73072, USA. marco.romano@uniroma1.it (corresponding author)

Re-evaluation of Chelichnus tazelwürmi, a non mammalian therapsid-grade track from the Upper Permian Arenaria di Val Gardena

Abstract In this paper, a revision of tracks referred to as Chelichnus tazelwürmi is reported. The performed analysis, consisting of a holistic approach by means of a mainly morphological analysis, and a secondarily functional one, led to the proposal of a new ichnogenus, named as Contiichnus tazelwurmi. The three dimensional morphology of the tracks allows for the inference of a complex cycle of locomotion by the trackmakers. The tracks were formed in the main phases (i.e. touch-down, weight-bearing and kick-off) by different axes of body load and transference, indicating that the whole fore autopod was involved in the cycle of locomotion and actively contacted the substrate, while for the hind autopod the functional prevalence was markedly centro-medial. Some track features suggest a therapsid-grade synapsid as potential trackmaker. However, the reconstructed autopodial structure does not correlate with known autopods from the Late Permian body fossil record. These observations stress the importance of tetrapod ichnology studies in improving knowledge in the field of vertebrate palaeontology. http://www.zoobank.org/urn:lsid:zoobank.org:pub:B4EB4D42-1A3B-48EC-B83F-6942F741AF30 http://www.zoobank.org/urn:lsid:zoobank.org:pub:B4EB4D42-1A3B-48EC-B83F-6942F741AF30

First report of hybodont shark from the Toarcian Rosso Ammonitico Formation of Umbria-Marche Apennine Polino area, Terni, Central Italy)

In this contribution we present the first material referable to hybodont shark from the Rosso Ammonitico Formation (Umbria-Marche-Sabina Palaeogeographic Domain). Two teeth were recovered isolated within Toarcian red marly-limestone (Bifrons Zone). The best-preserved tooth is characterized by a general structure well in accord with the classic crushing dentition typical of hybodont sharks within the Subfamily Acrodontinae. The gently domed occlusal surface of the tooth does not show any trace of occlusal crest and of wrinkles, and is characterized by densely pitted, finely reticulated ornamentation. The available characters allow a conservative classification of the material at the genus level as Asteracanthus sp. The best-preserved tooth can be referred to the most mesial area of the first row of lateral teeth, using as a reference the holotype of Asteracanthus medius. The new material represents the earliest evidence of Asteracanthus and the second one from the whole Northern Apennines (Central Italy), throwing new light on the dispersal of the genus on the Jurassic Tethys.

Sometimes They Come Back: Recovery and Reinterpretation of a Trackway Slab from the Permian Coconino Sandstone of the Southwestern United States

When a fossil vanishes to a private collection, it must be considered lost to science because, frequently, it is no longer available for study. Fortunately some fossils occasionally are regained. We had the opportunity to recoup an interesting footprint-bearing slab that was part of a private collection in Italy. The specimen, found in 1992 near Seligman, Arizona (USA) was described, before disappearing, as one of the best fossil examples of vertebrate (Chelichnus [Laoporus])-on-invertebrate (Octopodichnus) predation. After a careful re-examination of the slab, the primary conclusions of the former describers are demonstrably groundless. The reanalysis of the tracks, as well as peculiar sedimentary structures associated with the tracks, allowed obtaining new information about the depositional environment and the complex interactions between the type of substrate and trackmaker behavior. The re-examination of the specimen also revealed interesting aspects about trackmaker biomechanics.

Triassic pentadactyl tracks from the Los Menucos Group (Río Negro province, Patagonia Argentina): possible constraints on the autopodial posture of Gondwanan trackmakers

The Los Menucos locality in Patagonia, Argentina, bears a well-known ichnofauna mostly documented by small therapsid footprints. Within this ichnofauna, large pentadactyl footprints are also represented but to date were relatively underinvestigated. These footprints are here analyzed and discussed based on palaeobiological indications (i.e., trackmaker identification). High resolution digital photogrammetry method was performed to achieve a more objective representation of footprint three-dimensional morphologies. The footprints under study are compared with Pentasauropus from the Upper Triassic lower Elliot Formation (Stormberg Group) of the Karoo Basin (Lesotho, southern Africa). Some track features suggest a therapsid-grade synapsid as the potential trackmaker, to be sought among anomodont dicynodonts (probably Kannemeyeriiformes). While the interpretation of limb posture in the producer of Pentasauropus tracks from the Los Menucos locality agrees with those described from the dicynodont body fossil record, the autopodial posture does not completely agree. The relative distance between the impression of the digital (ungual) bases and the distal edge of the pad trace characterizing the studied tracks likely indicates a subunguligrade foot posture (i.e., standing on the last and penultimate phalanges) in static stance, but plantiportal (i.e., the whole foot skeleton and related soft tissues are weight-bearing) during the dynamics of locomotion. The reconstructed posture might have implied an arched configuration of the articulated metapodials and at least of the proximal phalanges, as well as little movement capabilities of the metapodials. Usually, a subunguligrade-plantiportal autopod has been described for gigantic animals (over six hundreds kilograms of body weight) to obtain an efficient management of body weight. Nevertheless, this kind of autopod is described here for large but not gigantic animals, as the putative trackmakers of Pentasauropus were. This attribution implies that such an autopodial structure was promoted independently from the body size in the putative trackmakers. From an evolutionary point of view, subunguligrade-plantiportal autopods not necessarily must be related with an increase in body size, but rather the increase in body size requires a subunguligrade or unguligrade, plantiportal foot. Chronostratigraphically, Pentasauropus was reported from Upper Triassic deposits of South Africa and United States, and from late Middle Triassic and Upper Triassic deposits of Argentina. Based on the stratigraphic distribution of the ichnogenus currently accepted, a Late Triassic age is here proposed for the Pentasauropus-bearing levels of the Los Menucos Group.

A review of the concepts of ‘axony’ and their bearing on tetrapod ichnology

ABSTRACT Two meanings of the term axony are found in the ichnological literature. Multiple meanings may prove to be a double-edge sword, complicating scientific communication. In vertebrate ichnology the first meaning of axony relies on aspects of locomotion related to the body weight support and propulsive thrust. A second one concerns axony as a purely geometric and dimensional descriptor. These approaches are based on a static view of the impression process, implying the loss of much important information. Here we report an analysis of shallowly impressed footprints referred to the ichnotaxa Ichniotherium sphaerodactylum and Dimetropus osageorum. The analysis was carried out by considering the track registration as a dynamic process and attempting to identify and describe axony conditions during movements. Variations in the axony conditions can be understood in the light of the producer’s foot anatomy and the reciprocal relations between foot bone elements. The concept of axony can be a useful tool in ichnological practice only when it is related to the complex dynamic of locomotion and the resulting track registration. It can help in restoring the interconnections between track and trackmaker, re-establishing the biological significance of tetrapod footprints.

First remains of neoginglymodian actinopterygians from the Jurassic of MonteNerone area (Umbria-Marche Apennine, Italy)

Since the early nineteenth century, the structural high of Mt. Nerone in the Umbria-Marche Sabina Domain (UMS – Central/Northern Apennines, Italy) attracted scholars from all over Europe due to the wealth of fossil fauna preserved in a stunningly well-exposed Mesozoic sedimentary succession. Several geopalaeontological studies were focused on the abundant and diverse invertebrate fauna, whereas contributions dealing with Mesozoic vertebrates were to date virtually lacking. Recently, the first material referable to hybodont sharks, consisting of an articulated crushing dentition, was described from the area and referred to Asteracanthus cf. A. magnus. In this contribution, we report the first evidence of ginglymodians actinopterygians from the Upper Jurassic of Mt. Nerone. The material is represented by seven highly tritorial isolated teeth collected from three classic fossiliferous localities of the area (i.e. Pian del Sasso, Fosso Pisciarello, I Ranchi). The general morphology of the material under study allow us to conservatively refer the teeth to the Neoginglymodi, a clade formed by Lepisosteiformes and Semionotiformes. The occurrence of durophagous organisms, to date represented by hybodont sharks and lepisosteiformes fishes, reveals interesting palaeoecological scenarios characterizing the pelagic carbonate platform-basin system of Mt. Nerone, which were most likely triggered by large-scale geodynamic processes. The complex submarine palaeotopography, inheritance of the Western Tethys Early Jurassic rifting, aroused the establishment of new infaunal and epifaunal communities opening up unexplored trophic niches for durophagous predators. The particular geodynamic setting of the UMS Domain, consisting of predominantly interconnected structural highs and lows, and the relative evolution of a diverse invertebrate fauna characterized by terebratulid, ostreids, limids, brachiopods, crustaceans, and gastropods, attracted both hybodontids anddurophagous ginglymodians in the Tethyan Realm, influencing their dispersal during the Late Jurassic.