Nihilichnus nihilicus Mikuláš et al., 2006
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publication ID |
https://doi.org/ 10.26879/1315 |
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persistent identifier |
https://treatment.plazi.org/id/03BE87DE-FFFD-FFF5-9803-FB3F459AFA00 |
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treatment provided by |
Felipe |
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scientific name |
Nihilichnus nihilicus Mikuláš et al., 2006 |
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Nihilichnus nihilicus Mikuláš et al., 2006
( Figure 3A View FIGURE 3 )
Material. Three ellipsoid borings on a carapace fragment (NVP001).
Description. Circular, subcircular to ellipsoidal holes in outline, straight and perpendicular margin towards the outer and inner shell surfaces; not penetrating the cortical compact bone with minor irregular jags, diameter of holes ranges from 2 to 4 mm, situated 2 cm apart. No bioglyphes have been recorded.
Discussion. The presence of a set of grooves with irregular outlines in the studied specimen supports the assignment to the ichnofamily Machichnidae Wisshak et al., 2019 (which includes the ichnogenera Machichnus , Nihilichnus, Linichnus, Knethichnus , and Mandaodonites ). Due to subsequent erosion of the superficial layers of the studied bone that leaves the internal-most section of the exposed traces, each groove exhibits a circular outline with minor irregular jags, allowing its assignment to the ichnogenus Nihilichnus . The borings described show most of the morphological characters of the holotype described and illustrated by Mikuláš et al. (2006, p. 120, figure 6A–K). In general, Nihilichnus is known from terrestrial, palustrine, freshwater (reported herein), and marine environment ( Rasser et al., 2016). Although it most commonly occurs on vertebrate bone substrate, it has also been recorded in other invertebrate skeletal substrate (molluscan shells) ( Rasser et al., 2016; Ahmed et al., 2022).
Producer. The ichnogenus Nihilichnus represents putative bite marks on fossil bone. Crocodiles may be considered potential makers, as crocodylian remains are documented from the Quseir Formation (Abu El-Kheir, 2020). Similar cases have been reported previously by other authors (e.g., Milàn et al., 2011; Schwarz-Wings et al., 2014). Additionally, marine mammals, reptiles, and bony fish could be responsible for N. nihilicus ( Irazoqui and Acosta Hospitaleche, 2022) .
Stratigraphic and geographic distribution. Campanian of the Qarn Ganah, Kharga Oasis (this study). It is also recorded from the Middle Triassic of Germany ( Mujal et al., 2022), latest Triassic of Poland (Dzik et al., 2008; Niedźwiedzki et al., 2011), Kimmeridgian of Germany ( Karl and Tichy, 2004), Lower Palaeocene of Denmark ( Milàn et al., 2011), Eocene of Antractica ( Irazoqui and Acosta Hospitaleche, 2022), Lower Miocene of Czech Republic and Egypt ( Mikuláš et al., 2006; Zonneveld et al., 2022a), and Upper Miocene of Brazil (Di Gregorio et al., 2020).
Ichnogenus Karethraichnus Zonneveld et al., 2016
Type ichnospecies. Karethraichnus lakkos Zonneveld et al., 2016
Diagnosis. Circular to subcircular and oval pits and holes bored into bony substrates. The hole may penetrate fully through the substrate or terminate within the substrate as a shallow, bowl-shaped pit or as a deeper shaft with a rounded, blunt, or pointed terminus (Zonneveld et al., 2016).
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