Matteo Belvedere

Comparative analysis of Late Jurassic sauropod trackways from the Jura Mountains (NW Switzerland) and the central High Atlas Mountains (Morocco): implications for sauropod ichnotaxonomy

Late Jurassic sauropod trackways from the Jura Mountains (NW Switzerland) and the central High Atlas Mountains (Morocco) are described and compared. Emphasis is put on track preservation and trackway configuration. The trackways are similar with respect to preservation and the pes and manus track outlines, but they show a large range of trackway configuration. Only one of the trackways reveals digit and claw impressions, and thus differences in trackway gauge and the position of pes and manus tracks are the most explicit characters for their distinction. The Late Jurassic to Early Cretaceous ichnotaxa Brontopodus, Parabrontopodus and Breviparopus are reviewed and a differential diagnosis is given for the trackways studied. The reference trackway of Breviparopus corresponds to one of the studied trackways of Morocco. Parabrontopodus and Breviparopus are considered to be both valid ichnotaxa, even though we recommend the latter to be formally erected based on better-preserved tracks than those currently exposed. The analysed trackways and ichnotaxa suggest that trackway configuration, notably trackway gauge (width), is not decisively influenced by extrinsic factors such as ontogenetic stage, locomotion speed and substrate properties. However, it cannot be excluded that it is related to other factors such as individual behaviour or even sexual dimorphism.

The tracks of giant theropods (Jurabrontes curtedulensis ichnogen. & ichnosp. nov.) from the Late Jurassic of NW Switzerland: palaeoecological & palaeogeographical implications

Abstract Jurabrontes curtedulensis, a new ichnogenus and species of Late Jurassic giant theropod dinosaur track is described based on very well-preserved and morphologically-distinct tracks, all carefully excavated along federal highway A16 (Canton Jura, NW Switzerland). All trackways were systematically documented including parameter measurements, descriptions, outline drawings, orthophotos and laserscans. Jurabrontes is characterised by sub-equal track length and width, a small anterior triangle, weak mesaxony, three blunt digits (dII-III-IV) with pronounced (sub)triangular claw marks, a rounded heel, and clear phalangeal pad impressions. The combination of features of Jurabrontes is typical for a theropod (and not ornithopod) trackmaker. Jurabrontes is compared to other similar ichnotaxa and unnamed tracks of large theropods from the Early Jurassic to Late Cretaceous, from which it is clearly different. The sheer size of the largest tracks, that are amongst the largest worldwide and of similar size to Tyrannosauripus from the Late Cretaceous, suggests a ‘megalosaurid’ or large allosaurid theropod as a trackmaker. The presence of such large theropod tracks in tidal-flat deposits of the Jura carbonate platform and associated with small to large sauropod tracks has important palaeoecological implications for the dinosaur community and for palaeoenvironmental and palaeogeographical reconstructions. Jurabrontes - urn:lsid:zoobank.org:act:B482D2AF-637A-4B2D-8B0B-FEAD54CA2A26 J. curtedulensis- urn:lsid:zoobank.org:act:30D45944-5A2B-45E1-89B9-20298E475D51

Megalosauripus transjuranicus ichnosp. nov. A new Late Jurassic theropod ichnotaxon from NW Switzerland and implications for tridactyl dinosaur ichnology and ichnotaxomy

A new ichnospecies of a large theropod dinosaur, Megalosauripus transjuranicus, is described from the Reuchenette Formation (Early–Late Kimmeridgian, Late Jurassic) of NW Switzerland. It is based on very well-preserved and morphologically-distinct tracks (impressions) and several trackways, including different preservational types from different tracksites and horizons. All trackways were excavated along federal Highway A16 near Courtedoux (Canton Jura) and systematically documented in the field including orthophotos and laserscans. The best-preserved tracks were recovered and additional tracks were casted. Megalosauripus transjuranicus is characterized by tridactyl tracks with clear claw and digital pad impressions, and notably an exceptionally large and round first phalangeal pad on the fourth digit (PIV1) that is connected to digit IV and forms the round heel area. Due to this combination of features, M. transjuranicus clearly is of theropod (and not ornithopod) origin. M. transjuranicus is compared to other Megalosauripus tracks and similar ichnotaxa and other unassigned tracks from the Early Jurassic to Early Cretaceous. It is clearly different from other ichnogenera assigned to large theropods such as Eubrontes–Grallator from the Late Triassic and Early Jurassic or Megalosauripus–Megalosauropus–Bueckeburgichnus and Therangospodus tracks from the Late Jurassic and Early Cretaceous. A second tridactyl morphotype (called Morphotype II) is different from Megalosauripus transjuranicus in being subsymmetric, longer than wide (sometimes almost as wide as long), with blunt toe impressions and no evidence for discrete phalangeal pad and claw marks. Some Morphotype II tracks are found in trackways that are assigned to M. transjuranicus, to M.? transjuranicus or M. cf. transjuranicus indicating that some Morphotype II tracks are intra-trackway preservational variants of a morphological continuum of Megalosauripus transjuranicus. On the other hand, several up to 40 steps long trackways very consistently present Morphotype II features (notably blunt digits) and do not exhibit any of the features that are typical for Megalosauripus (notably phalangeal pads). Therefore, it is not very likely that these tracks are preservational variants of Megalosauripus transjuranicus or Megalosauripus isp. These trackways are interpreted to have been left by an ornithopod dinosaur. The high frequency of large theropod tracks in tidal-flat deposits of the Jura carbonate platform, associated on single ichnoassemblages with minute to medium-sized tridactyl and tiny to large sauropod tracks has important implications for the dinosaur community and for paleoenvironmental and paleogeographical reconstructions. As with most other known occurrences of Megalosauripus tracks, M. transjuranicus is found in coastal settings, which may reflect the preference of their theropod trackmakers for expanded carbonate flats where food was abundant.

Stat-tracks and mediotypes: powerful tools for modern ichnology based on 3D models

Vertebrate tracks are subject to a wide distribution of morphological types. A single trackmaker may be associated with a range of tracks reflecting individual pedal anatomy and behavioural kinematics mediated through substrate properties which may vary both in space and time. Accordingly, the same trackmaker can leave substantially different morphotypes something which must be considered in creating ichnotaxa. In modern practice this is often captured by the collection of a series of 3D track models. We introduce two concepts to help integrate these 3D models into ichnological analysis procedures. The mediotype is based on the idea of using statistically-generated three-dimensional track models (median or mean) of the type specimens to create a composite track to support formal recognition of a ichno type. A representative track (mean and/or median) is created from a set of individual reference tracks or from multiple examples from one or more trackways. In contrast, stat-tracks refer to other digitally generated tracks which may explore variance. For example, they are useful in: understanding the preservation variability of a given track sample; identifying characteristics or unusual track features; or simply as a quantitative comparison tool. Both concepts assist in making ichnotaxonomical interpretations and we argue that they should become part of the standard procedure when instituting new ichnotaxa. As three-dimensional models start to become a standard in publications on vertebrate ichnology, the mediotype and stat-track concepts have the potential to help guiding a revolution in the study of vertebrate ichnology and ichnotaxonomy.

A walk in the maze: variation in Late Jurassic tridactyl dinosaur tracks from the Swiss Jura Mountains (NW Switzerland)

Background Minute to medium-sized (footprint length (FL) less than 30 cm) tridactyl dinosaur tracks are the most abundant in the Late Jurassic tracksites of Highway A16 (Reuchenette Formation, Kimmeridgian) in the Jura Mountains (NW Switzerland). During excavations, two morphotypes, one gracile and one robust, were identified in the field. Furthermore, two large-sized theropod ichnospecies (Megalosauripus transjuranicus and Jurabrontes curtedulensis) and an ornithopod-like morphotype (Morphotype II) have recently been described at these sites. Methods The quality of morphological preservation (preservation grade), the depth of the footprint, the shape variation, and the footprint proportions (FL/footprint width (FW) ratio and mesaxony) along the trackways have been analyzed using 3D models and false-color depth maps in order to determine the exact number of small to medium-sized morphotypes present in the tracksites. Results The study of footprints (n = 93) recovered during the excavations has made it possible to identify and characterize the two morphotypes distinguished in the field. The gracile morphotype is mainly characterized by a high FL/FW ratio, high mesaxony, low divarication angles and clear, sharp claw marks, and phalangeal pads (2-3-4). By contrast, the robust morphotype is characterized by a lower FL/FW ratio, weaker mesaxony, slightly higher divarication angles and clear, sharp claw marks (when preserved), whereas the phalangeal pads are not clearly preserved although they might be present. Discussion The analysis does not allow the two morphotypes to be associated within the same morphological continuum. Thus, they cannot be extramorphological variations of similar tracks produced by a single trackmaker. Comparison of the two morphotypes with the larger morphotypes described in the formation (M. transjuranicus, J. curtedulensis, and Morphotype II) and the spatio-temporal relationships of the trackways suggest that the smaller morphotypes cannot reliably be considered as small individuals of any of the larger morphotypes. The morphometric data of some specimens of the robust morphotype (even lower values for the length/width ratio and mesaxony) suggest that more than one ichnotaxon might be represented within the robust morphotype. The features of the gracile morphotype (cf. Kalohipus isp.) are typical of “grallatorid” ichnotaxa with low mesaxony whereas those of the robust morphotype (cf. Therangospodus isp. and Therangospodus? isp.) are reminiscent of Therangospodus pandemicus. This work sheds new light on combining an analysis of variations in footprint morphology through 3D models and false-color depth maps, with the study of possible ontogenetic variations and the identification of small-sized tridactyl ichnotaxa for the description of new dinosaur tracks.

FISH FEEDING TRACES FROM MIDDLE EOCENE LIMESTONES (GARGANO PROMONTORY, APULIA, SOUTHERN ITALY)

ABSTRACT More than two hundred subcircular to crescent-shaped depressions, often with radiating markings, were discovered on a 120 m2 bedding plane interpreted as base-of-slope carbonate deposits and belonging to the Lutetian–Bartonian Peschici Formation at San Lorenzo (Vieste, Gargano Promontory, Italy). The area was mapped using a high-resolution aerial camera (mounted on a kite) and a terrestrial laser scanner. The survey allowed detailed morphologic analysis and topographic mapping of the traces, in order to analyze the very regular distribution pattern. The ichnological study, combined with sedimentologic and stratigraphic analyses, identifies the depressions as fish feeding traces. Although the tracemaker cannot be definitely identified, the comparison with modern and fossil fish excavations suggests a higher affinity with bony fishes (e.g., sturgeons) than with rays. The trace fossils are here attributed to the ichnogenus Piscichnus and constitute the first discovery of this ichnotaxon in the middle Eocene of the Apulia Carbonate Platform and of Italy.

Is It Human? Discriminating between Real Tracks and Track-Like Structures

ABSTRACT Some human footprints-like hollows in the tuffaceous ground of an ancient quarry and of a recent anthropic path, created by the inhabitants no more than 30 years ago near the small village of Carangi (Caserta province, Southern Italy), allowed scientists to study some of the most misleading alteration processes of the volcanic tuff formations. The closeness of this site to the “Ciampate del Diavolo” ichnosite, bearing some of the oldest human fossil footprints, and the common stratigraphical and sedimentological background permitted accurate comparisons between actual human fossil footprints and footprint-like depressions, which can be easily mistaken for actual fossil evidence. This comparative study has permitted the reporting of some useful features and advice on distinguishing actual fossil footprints from natural and/or anthropic pseudo-tracks.

Anthropic artifacts and donkey horseshoe traces looking like fossil human footprints: a case study from the Roccamonfina volcano (central Italy) with implication for human ichnology

Fossil footprints of Middle Pleistocene hominids, locally known as “Ciampate del Diavolo”, were discovered in 2001 on the North-Eastern slope of the Roccamonfina volcano (central Italy, municipality of Tora and Piccilli, Caserta). The imprints occur on a surface of Brown Leucitic Tuff (BLT), dated to 349 ± 3 ka. After this discovery, e this tuffaceous formation was investigated in more detail on the North-Eastern, Eastern and South-Eastern side of the Roccamonfina volcano, with the aim of locating other fossil footprints. In 2003 another succession of nine hollows fully compatible with human fossil footprints for stratigraphic position, pattern and dimensional range was found on the same ridge but at a higher level. This second site, known locally as Cantarelle di Carangi, is positioned at a distance of about 1.8 km from the first fossiliferous area (municipality of Marzano Appio, middle-central Italy, Caserta province). Further surveys and archaeological excavations were carried out in the Cantarelle di Carangi site during 2008 to better understand, contextualize and confirm the potential ichnological value of the findings of 2003. Ichnological and stratigraphical analyses, combined with findings during the excavations and historical data, however, tell a different story. What was supposed to be a new ichnosite with Pleistocene fossil footprints, is very likely the result of anthropic digging, erosion made by animals, and weathering. In any case, the discovery shows how careful researchers have to be in interpreting possible fossil footprints, especially in conditions of poorly preserved traces. RIASSUNTO [Impronte umane simulate da artefatti e ferri d’asino: un caso-studio dal vulcano di Roccamonfina (Italia centrale) con implicazioni per l’icnologia umana] Nel 2001, sul versante nord-orientale del vulcano Roccamonfina, nel Comune di Tora e Piccilli (provincia di Caserta, Italia centrale), furono scoperte orme umane fossili del Pleistocene Medio, le quali erano note localmente con il nome di “Ciampate del Diavolo”. Esse sono impresse su una superficie di Tufo Leucitico Bruno (BLT), che è stata datata a 349 ± 3 ka. Dopo questa scoperta la stessa formazione è stata oggetto di indagini accurate sui versanti nord-orientale, meridionale e sud-orientale del vulcano Roccamonfina, con il proposito di individuare altre orme fossili. Nel 2003, sullo stesso crinale ma ad una quota più elevata, è stata trovata un’altra successione di nove cavità completamente compatibili con impronte fossili umane per la loro posizione stratigrafica, per lo schema d’andatura da loro disegnato e per il loro range dimensionale. Questo secondo sito, conosciuto localmente come “Cantarelle” di Carangi (Comune di Marzano Appio, provincia di Caserta, Italia centrale), si trova a circa 1,8 km dal sito delle “Ciampate del Diavolo”. In questo secondo sito, nel corso del 2008 sono state effettuate ulteriori indagini e lavori di pulizia per avere un quadro più chiaro e per contestualizzare e confermare l’eventuale potenziale icnologico delle evidenze ritrovate. Le analisi icnologiche e stratigrafiche, in combinazione con i risultati dei lavori di pulizia del sito e dei dati storici disponibili, tuttavia, raccontano una storia diversa. Quello che doveva essere un nuovo icnosito con impronte fossili del Pleistocene, è molto probabilmente il risultato di scavi antropici e di azioni erosive ad opera di animali e di agenti atmosferici. In ogni caso, la scoperta è di grandissima importanza perché mostra quanto attento dev’essere un ricercatore per evitare di essere ingannato, nel momento in cui interpreta possibili impronte fossili, specialmente quando esse si presentano in un pessimo stato di conservazione. Quello di “Cantarelle” di Carangi è un caso-studio di fondamentale importanza per tutti coloro che si accingono a studiare le impronte fossili di ominidi e animali.

An artiodactyl tracksite at Musandam Peninsula, Sultanate of Oman

Here we report an artiodactyl trackway from Musandam Peninsula, Sultanate of Oman. Epireliefs of the tracks are preserved in poorly consolidated aeolian deposits now making up the ceiling of a coastal cave. As an interesting morphological feature, the trackway documents the trackmaker negotiating a slippery dune slope at an angle.