Pterichnus, Hitchcock, 1865
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publication ID |
https://doi.org/ 10.4202/app.00467.2018 |
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persistent identifier |
https://treatment.plazi.org/id/03A1FA76-FFAC-1A04-E94C-8065FE67F913 |
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treatment provided by |
Felipe |
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scientific name |
Pterichnus |
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cf. Pterichnus isp.
Fig. 11A, B View Fig .
Material. —ZPAL Tf.8/2007.14, a slab of very fine-grained silty sandstone, middle–late Eocene, King George Island, Antarctica.
Description. —Hypichnial, winding trackway, 8–9 mm wide, composed of two rows of elongate ridges. The ridges are straight, curved or slightly sinuous, 1.5–3 mm long, about 1 mm wide. The ridges are inclined at an angle of 10–20° with respect to the course of the trackway. Locally, the ridges are slightly larger on one side than the other. At one place, three series of ridges are visible in the rows. Four ridges are clearly visible within each series ( Fig. 11A View Fig ). Ridges in the series are oriented in the same direction, which is inclined at an angle of 10–20° with respect to the course of the trackway. In another part of the same trackway, its elements are less ordered ( Fig. 11B View Fig ). Two rows of small ridges are accompanied by additional imprints on both sides.
Remarks. —The trackway was produced by a crawling animal that used at least four pairs of crawling appendages. Four imprints in a series are typical of Octopodichnus Gilmore, 1927 , which is typified by O. didactylus Gilmore, 1927 , and interpreted as a trackway of spider ( Abel 1935; Braddy 2003), which suggests arid continental environments. This large trackway is characterized by two pairs of anterior bifid imprints. Bifid imprints are unclear in the described trace fossil and the rows with four imprints are visible only in a part of the trackway. The sinuous ridges (imprints) resemble the type 3 morphotype of Pterichnus isopodicus Gaillard, Hantzpergue, Vannier, Margerard, and Mazin, 2005 , which is an isopod trackway from Upper Jurassic tidal flat sediments of France ( Gaillard et al. 2005). The type 1 morphotype of this trace fossil also displays four imprints in per at least some series, Moreover, the inclination of imprints in respect to the course of the trackway (10–20°) is close to the value (15–20º) provided in the diagnosis of Pterichnus ( Häntzschel 1975; Gaillard et al. 2005). It is not excluded that an isopod could be a candidate for the tracemaker of the trace fossil described.
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