Browsing by Autor "Christian A. Meyer"

Now showing 1 - 6 of 6

Differentiating sauropod from thyreophoran tracks: insights from the Late Jurassic Villette Tracksite (Jura, France)
(Società geologica italiana, 2025) Lara Sciscio; Christian A. Meyer; Emmanuel Fara; Patrice Landry; Jean‐David Moreau; Nicolas Olivier
Sauropod trackways are extensively reported from Upper Jurassic deposits, whereas thyreophoran tracks seem to be rarer and often overlooked or misidentified due to their morphological similarity to sauropod tracks. This overlap complicates ichnological interpretations, leaving several occurrences unresolved. Here, we analyse an ambiguous trackway from the Late Jurassic (Kimmeridgian) Villette tracksite in eastern France (Jura Mountains), part of a sauropod-dominated ichnoassemblage. The trackway displays morphological features typical of Deltapodus, an ichnogenus attributed to thyreophoran (stegosaur) trackmakers, including the size, overall gross pes and manus morphology, and track orientation. Using photogrammetry and morphometric analyses, we compare the Villette trackway with contemporaneous Deltapodus and Deltapodus-like trackways and sauropod trackways of the Swiss Jura mountains. Considering this, despite notable similarities, key differences, such as the shape of the pes tracks, presence of a strong heel impression, and the absence of three-toed digit impressions, exclude assignment to Deltapodus and support attribution to a small-bodied sauropod trackmaker. This conclusion is consistent with the ichnoassemblage at Villette, where other tracks correspond to Parabrontopodus-like ichnotaxa, reinforcing a sauropod attribution. More broadly, this study also synthesizes key diagnostic criteria and methodological approaches that help in distinguishing thyreophoran from sauropod tracks. By integrating these methods, we highlight their potential as reliable tools for ichnological interpretation, providing a framework for future studies addressing similar challenges.
Diverse dinosaur tracks from the Upper Jurassic – Lower Cretaceous Chacarilla Formation of Quebrada de Arcas, northeast Chile: Evidence of high ichnodiversity in an arid palaeoenviroment
(Elsevier BV, 2025) Vincenzo Gesualdi; Matteo Belvedere; Marko Yurac; Dorothee Hippler; Nejla Hurem; Christian Salazar; Jose Nicanor Mendez; Christian A. Meyer
We report diverse dinosaur tracks from siltstone to fine-grained sandstone facies of the Chacarilla Formation, Quebrada de Arcas of northeast Chile. Track-bearing surfaces were studied using 3D modelling and false-colour depth maps, derived from UAV photographs. Five morphotypes are identified based on morphology and morphometric criteria. Morphotype I comprises rounded tracks with a consistent narrow-gauge and resembles the sauropod ichnogenus, Parabrontopodus ; diplodocids or titanosaurids are probable trackmakers. Morphotype II is assigned to the theropod ichnotaxon Abelichnus astigerrae and comprises some of the largest theropod tracks ever recorded from South America with a maximum footprint length of 51 cm; the trackmaker was most likely a large carcharodontosaurid, such as Giganotosaurus carolinii . Morphotype III is an indeterminate theropod track, which shows a distinctive and prominent metatarsal impression, but does not closely match any ichnotaxon although it bears some morphometrical affinity to Changpeipus carbonicus . The Morphotypes IV and V both belong to small-sized theropod trackmakers, and resemble Grallatoridae and Kayentapus -like forms, respectively. Additional theropod material cannot be assigned to specific morphotypes or trackmakers, due to poor preservation. Our findings show the existence of three distinct size classes (small, medium and large) of theropod morphotypes and point to a high ichnodiversity at the Jurassic-Cretaceous transition in the subtropical arid environments of Gondwana. • New track-bearing surfaces are found in the Chacarilla Fm. in Quebrada des Arca. • Five morphotypes: one of sauropod and four for different size theropod tracks are defined. • Huge theropod tracks have been found and identified.
New dinosaur tracks from the Middle Jurassic red beds of the Middle Atlas (Morocco): Application of photogrammetry to ichnology and conservation of geological heritage
(Elsevier BV, 2024) Mustapha Amzil; Mostafa Oukassou; Jens N. Lallensack; Hendrik Klein; Omar Zafaty; Hafid Saber; André Charrière; Christian A. Meyer; Gerard D. Gierliński
The abundance and diversity of penetrative tracks: a critical re-evaluation of theropod ichnotaxa
(Taylor & Francis, 2026) Jens N. Lallensack; Félix Pérez‐Lorente; Mustapha Amzil; Mostafa Oukassou; Christian A. Meyer; Hafid Saber; Hendrik Klein; André Charrière; Omar Zafaty; Peter Falkingham
Tetrapod ichnotaxonomy aims to classify tracks based on features that reflect trackmaker anatomy. Consequently, distinct ichnotaxa are assumed to represent distinct (though often unidentified) biological taxa. However, track shape is not only determined by trackmaker anatomy, but also by the properties of the substrate, the movements of the foot, the level of exposure, and any post-formational alteration. Because of these multiple sources of variation, determining if, and to what degree, a particular feature conveys anatomical information remains a major challenge. A major source of confusion has been penetrative tracks, which form when the foot sinks deeply into soft sediment, causing sediment to flow around the foot to seal its path. Penetrative tracks of long-toed, tridactyl trackmakers often show conspicuous features that appear to reflect foot anatomy but do in fact reflect the penetrative nature of the tracks. We studied dozens of tracksites in the Middle Jurassic of El Mers, Morocco and the Early Cretaceous Cameros Basin, Spain, showing that penetrative tracks are much more diverse and common than previously thought. We discuss formational mechanisms that explain the variation of several features commonly used to define ichnotaxa. We conclude that the type ichnospecies of Saurexallopus, Magnoavipes, Theroplantigrada, Ordexallopus, and Archaeornithipus are probably based on penetrative tracks and therefore nomina dubia.
Titanosaurid trackways from the Upper Cretaceous of Bolivia: evidence for large manus, wide-gauge locomotion and gregarious behaviour
(Elsevier BV, 2002) Martin G. Lockley; Anne S. Schulp; Christian A. Meyer; Giuseppe Leonardi; David Kerumba Mamani
Upper Jurassic dinosaur tracks from the Majala Formation in the Huatacondo area (Tarapacá Basin, Chile): reappraisal of known localities and new tracksite discoveries
(Springer Nature, 2025) Marko Yurac; Matteo Belvedere; Christian Salazar; Jose Nicanor Mendez; Christian A. Meyer
Abstract The bone record of non-avian dinosaurs from Chile consists of sauropods, theropods, ornithopods, and rare thyreophorans. However, the ichnological record is potentially even more abundant and plays a significant role in supplementing and enlarging the Chilean dinosaur record. Rich track-bearing levels, dated from the Upper Jurassic to the Lower Cretaceous, are known mainly from northern Chile. This study describes for the first time a stratigraphic section of the Majala Formation (late Oxfordian) in the Quebrada Huatacondo. In this section, five track-bearing levels were recorded confirming the presence of ichnites of giant (lengths between 51 and 52.8 cm), large (lengths between 43.5 and 46.5 cm) and medium (lengths between 25 and 27 cm) theropods. One surface (Maj5) has more than 25 footprints of minute to small theropods (footprints lengths ranging from 8 to 13 cm). Morphological parameters from the small footprints are similar to Carmelopodus , Grallator , and Therangospodus . Meanwhile, some similarities were observed with Kayentapus and Megalosauripus for the range of medium to giant footprints. When comparing track sizes from Quebrada Huatacondo with other theropod tracks from the Tarapacá Basin (Quebrada Chacarilla and Río San Salvador localities), their dimensions and morphology are similar, but the small tracks are substantially smaller than those from the other localities and constitute to the smallest footprints found on the western margin of Gondwana for this time. These tracks and trackways represent the oldest dinosaur footprints reported for Chile and the western margin of Gondwana.