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Geographic setting. (1) Simplified geologic map of the Anti-Atlas Mountains and localities of recovered olenid trilobites in Morocco. Previously reported specimens identified as Beltella sp. were found at localities 26 and 808 (yellow stars) in the Zagora area (Destombes, 2006c). The specimens described in this paper were found in the N'kob area (red square). Modified from Álvaro et al. (2022). (2) Lower Tremadocian exposures of the Fezouata Shale Formation in the N'kob area. Mountainous area in background represents the First Bani Group. (3) Bedding-plane accumulations of the graptolite Rhabdinopora cf. R. socialis (Salter) in the Akka n'Ousdidene locality east of N'kob, ∼12 m above the base of the Fezouata Shale Formation. Diameter of coin is 24 mm.
Source publication
Here we describe the first articulated olenid trilobite specimens recovered from the lowermost Fezouata Shale Formation (lower Tremadocian, Ordovician) of Morocco. Prior to the discovery of this sample, only two partial olenid trilobite specimens had been found from this part of the rock record. The specimens are well preserved enough to confidentl...
Contexts in source publication
Context 1
... specimens were found by locals near N'kob village ( Fig. 1.1) and acquired in 2019. In the N'kob area, the Fezouata Shale Formation crops out extensively across the southern flank of the Precambrian antiform of the Jbel Saghro (also known as the Saghro Massif), but there are no complete stratigraphic sections because the unit is regularly covered by Quaternary sediments. Partial exposures exist ...
Context 2
... Formation crops out extensively across the southern flank of the Precambrian antiform of the Jbel Saghro (also known as the Saghro Massif), but there are no complete stratigraphic sections because the unit is regularly covered by Quaternary sediments. Partial exposures exist on hillsides, where they are topped with Pleistocene terrace deposits ( Fig. 1.2). In the plains, Holocene deposits are thin enough (1 meter or less) that any small excavation has the potential to expose Fezouata Shale Formation layers. Although the exact location where these specimens were found is unknown, outcrops of the Fezouata Shale Formation around *Corresponding author. N'kob preserve the graptolites ...
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... include an internal mold of a cranidium with four partial thoracic tergites and an internal mold of a pygidium and partial thorax (Destombes, 2006c, pl. 1, figs. 1, 2). These two specimens were collected from localities 808 and 26 in the Zagora area (Destombes, 2006b) in 1959 and 1961, respectively (Destombes, personal communication, 2009) ( Fig. 1.1), about 50−100 km south of the N'kob area. Although one of us (JCG-M) has been to locality 808, no new olenid trilobites were recovered. Although the specimens figured by Destombes are not complete, there is no aspect of the preserved exoskeleton that provides conclusive evidence that these are not L. salteri. Destombes may have ...
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... that the spines are not well preserved on molds, especially on convex internal molds, and the axial rings can appear smooth (Lake, 1919); the spines also break easily (Mån- sson and Clarkson, 2020). There is at least one axial ring with what could be the base of a spine on the cranidium with partial thoracic tergites (Destombes, 2006c, pl. 1, fig. ...
