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First Upper Cretaceous dinosaur track assemblage from Jordan (Middle East) : preliminary results

Klein Hendrik, Gierliński Gerard, Lallensack Jerns N., Abu Hamad Abdalla, Al-Mashakbeh Habes, Alhejoj Ikhlas, Konopka Marcin, Błoński Marcin

Annales Societatis Geologorum Poloniae

2020

Vol. 90, No. 3

331--342

Dinosaur tracks from Jordan (Middle East) have only been briefly reported in geological overview papers and books. We present here the first description and documentation of Jordanian dinosaur tracks based on a new tracksite from the south-central part of the country. The track-bearing strata belong to marginal marine (tidal flat) deposits of the Na’ur Formation (Upper Cretaceous, Cenomanian). This unit largely consists of well-bedded limestones, dolomites and marls that contain abundant marine invertebrate fossils such as bivalves, ammonites and foraminifers. The dinosaur ichnofauna occurs on four different levels and comprises abundant theropod tracks and trackways as well as isolated sauropod and ornithopod tracks. Theropod trackways consist of two different morphotypes. Morphotype 1 is tridactyl (26 cm pes length) and with a broad, but short metatarsal area and resembles the ichnogenus Picunichnus from the Lower Cretaceous (Albian) of Argentina. Morphotype 2 (36 cm pes length) has extensive and narrow metatarsal impressions continuously occurring along regularly-spaced trackways. This suggests either a plantigrade movement of the trackmaker or reflects preservational factors. By their over-all-shape with thin digits, Morphotype 2 resembles described penetrative tracks suggesting a strong influence of the substrate. Sauropod tracks are relatively small (40 cm pes length) and show low heteropody with a kid-ney-shaped manus imprint, pointing to a Sauropodichnus-like form. The single ornithopod pes track (18 cm in length) is similar to material described as Ornithopodichnus from the Lower Cretaceous of Korea. Due to the incomplete material of sauropod and ornithopod prints, no concrete assignment is given to this material and further study is needed. The presence of dinosaur tracks proves a temporary subaerial exposure of the surface whereas the main part of the Na’ur Formation is dominated by subaqueous activity of marine faunas.

Healed or non-healed? Computed tomography (CT) visualisation of morphology of bite trace ichnotaxa on a dinosaur bone

Jacobsen A. R., Lauridsen H., Fiirgaard B., Boel L. W. T., Hansen K.

Annales Societatis Geologorum Poloniae

2015

Vol. 85, No. 3

457--464

Bite traces on fossilised bones can provide important information on predator-prey relations and interactions in ancient environments. In 2009, two new ichnotaxa, Linichnus serratus and Knethichnus parallelum, were introduced to develop the application of bite traces as an ichnological tool. Ichnotaxa defined by theropod bite traces can provide useful information for understanding feeding behaviour. However, objective interpretation of possible bite traces can be difficult using traditional visual inspection. In this study, the bite traces on a fossilised dinosaur bone were comprehensively examined by correlating traditional naked-eye in spection with computed tomography (CT) imaging, used to visualise the internal morphology of the bite traces and in particular, to clarify the appearance of one possibly healed bite trace. A forensic pathologist visually examined the bone with the aid of stereomicroscopy and a radiologist analysed the CT scans. Sixteen different scanner settings were used to optimise the CT parameters and avoid signal at tenuation, in the form of hypointense artefacts in the central trabeculated part of the bone fragment. The use of CT scanning provided information on internal morphology from the vicinity of the bite trace, including hyperdense zones, not identified using visual inspection alone. By applying the extended CT scale, the dense and radiopaque cortical bone layer could be clearly identified and applied as a pathomorphological marker to correctly distinguish non-healed from healed wounds. In conclusion, the authors demonstrate that external visual examination of trace fossils by ichnologists in combination with interior examination using CT imaging can be applied to characterise ichnotaxa defined by bite traces and potentially provide clues on ancient feeding behaviour.

New ichnotaxa based on tooth impressions on dinosaur and whale bones

Jacobsen Aa. R., Bromley R. G.

Geological Quarterly

2009

Vol. 53, No 4

373-382

Traces produced by teeth on bones provide a source of information on the feeding behaviour, predator-prey relationships, and tooth morphology of the tracemaking carnivores and scavengers involved. Studies on mammals, both fossil and recent, have used tooth-scratched bones as clues to the feeding behaviour of carnivorous, scaveng ing, mineral-seeking and tooth-sharpening mammals in various ecosystems. Similarly, theropod tooth traces have the potential of being important for studying the ecology and ethology of both carnivorous and herbivorous dinosaurs. This paper augments the ichnological nomenclature for traces made by teeth on bones. Two new ichnogenera and ichnospecies, Linichnus serratus and Knethichnus parallelum, are introduced on the basis of the morphology of theropod biting damage, to focus on the resulting trace fossils as an ichnological feature and to encourage further observation and studies of distrtibution. Using similar ichnological terminology for both theropod and mammalian feeding traces, and even those of selachian sharks preying on whales or scavenging their corpses, will help coordinate biting strategies, jaw mechanism and feeding behaviour for both recent and ancient carnivores and scavengers.