New Late Devonian phacopid trilobites from Marhouma, SW Algerian Sahara

Phacopid trilobites in post-Taghanic Givetian through Frasnian cephalopod limestones, Montagne Noire (France) and related areas (Thuringia, Morocco)

“…for North African occurrences, Bault et al 2021). In phacopids the curve of low diversity trends greatly changes when two genera, Chlupacops and Magreanops, appear at the base of the middle Frasnian (Feist et al 2016, Van Viersen & Vanherle 2018. Together with the reappearance of Cronierella and the appearance of the new genus Acutiphacops in the higher part of the substage, there are four genera with 18 species present in the middle Frasnian.…”

“…However, these taxa exhibit markedly smaller and more advanced eyes than the typical Eifelian species and allies. By these features the koeneni group is closest to representatives of Chlupacops and as such was questionably included in the latter by Feist et al (2016). However there is a considerable time interval of some 3 Ma between the late mid-Givetian Taghanic extinction of the koeneni group and the first Chlupacops in the mid-Frasnian (FZ 5), devoid of any morphologically intermediate taxa that would testify to possible direct evolutionary links between Chotecops and Chlupacops.…”

“…Varia bility in the ratio of dimensions, parameters of glabella divergence, number of lens rows, lenses, pygidial axial rings and position of maximum pygidial width are listed in Table 1. Feist et al (2016) questionably assigned the Givetian taxa Eocryphops? reichi (Kegel, 1932) and Chotecops?…”

Frasnian (Upper Devonian) integrated facies analysis, magnetic susceptibility and sea-level fluctuations in the NW Algerian Sahara

“…The limestones are wackestones with Styliolina (tentaculites) coquinas; they yield phacopid trilobites and cephalopods (Mesobeloceras sp.) on the surface of bed MH9 (Feist et al 2016). Mahboubi et al (2015).…”

“…A Mahboubi et al (1987) and trilobites by Feist et al (2016), and ichnological analyses were performed by Bendella & Mehadji (2014). The first conodont research was conducted by Mahboubi & Gatovsky (2014) and revealed a rather moderate yield of often insignificant conodont elements (less than 10 conodonts per kilogram in most samples), preventing a fine-scaled biostratigraphic framework from being established.…”