Middle Devonian trilobites of the Saoura Valley, Algeria: insights into their biodiversity and Moroccan affinities

Crônier, Catherine; Abbache, Abdelkader; Khaldi, Ahmed Yacine; Oudot, Morgane; Maillet, Sébastien; Mehadji, Abdelkader Ouali

doi:10.1017/s001675681600100x

Cited by 8 publications

(6 citation statements)

References 41 publications

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“…The Late Devonian period marked the most important phase of epeirorgenic movements in the Saoura, leading to an important subsidence (Benhamou et al 2004). The Upper Devonian is characterized by alternate deposits of clay-sand and limestone, especially including 'griotte' nodular limestones with benthic and pelagic faunas, which indicates an opening to marine environments (Crônier et al 2018a;Abbache et al 2019).…”

Section: C Late Devonianmentioning

confidence: 99%

“…The Chotecops Association was encountered in Ougarta and Tafilalt (Fig. 7) in marls or in thin limestone layers in marl deposits from the quiet environments of a distal platform or basin (Feist & Orth, 2000;Crônier et al 2018a).…”

Section: Palaeoenvironments Of Trilobite Associationsmentioning

confidence: 99%

“…While no connection existed to the west of Tafilalt, trilobite exchanges still occurred to the east. Indeed, Chotecops, present in deep environments (Feist & Orth, 2000;Crônier et al 2018a), occurred in both the Tafilalt and Ougarta areas. The Variscan orogeny created a basin between the Tafilalt and the Ougarta areas, but this basin seems shallower than the Maïder Basin (Kaufmann, 1998), thus enabling Chotecops to cross this basin to invade new localities but not Piriproetus.…”

Section: D Eifelianmentioning

confidence: 99%

“…Wendt et al (1984) specified that the Maïder Basin was deeper than the Tafilalt Basin. In Algeria, the Ougarta Basin became deeper during Eifelian time, from a foreshore environment at the end of Emsian time to a distal platform (Maillet et al 2013;Crônier et al 2018a). Henceforth, hemipelagic deposits were found as marlstones interbedded with thin-bedded limestones.…”

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confidence: 99%

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The influence of palaeogeography and tectonic events on trilobite distributions in Morocco and northwestern Algeria

2022

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The effects of sea-level changes and anoxia on Devonian trilobites have been studied for a long time, but the importance of palaeogeographic and tectonic events in this key-period is still not well understood. In the Devonian Period, trilobites invaded many different marine environments and areas in North Africa where important palaeogeographic changes occurred. Distribution patterns of trilobites through time and space have been analysed using a hierarchical cluster analysis and diversity indices. Our examination of the literature suggests that trilobites were scarce during Lochkovian time before an important diversification in Pragian time. Trilobites flourished in many North African regions without there being important taxonomic differences between basins, because of free migration in relatively flat palaeo-topography and homogeneous environments. During Middle Devonian time, early Variscan tectonic movements transformed the eastern Anti-Atlas area into a basin with a platform topography. Geographical barriers such as deep basins prevented trilobite migrations. At the beginning of Eifelian time, the reduction in migration between the different regions of this area coincided with a decrease in diversity. Consequently, tectonic events played an important role in the decline of trilobites during Middle Devonian time, especially when these were combined with sea-level changes and anoxic/hypoxic events. A recovery occurred in Famennian time involving only new genera. As at the global scale, cyrtosymbolines developed in shallow seas, whereas phacopids evolved in deeper environments. The basin and platform system still hampered migrations, although sea-level variations led to episodic exchanges. The late Famennian regression reduced trilobite diversity dramatically in the study area.

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Section: C Late Devonianmentioning

confidence: 99%

Section: Palaeoenvironments Of Trilobite Associationsmentioning

confidence: 99%

Section: D Eifelianmentioning

confidence: 99%

mentioning

confidence: 99%

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The influence of palaeogeography and tectonic events on trilobite distributions in Morocco and northwestern Algeria

2022

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“…Reed, 1898Reed, , 1905Reed, , 1927Reed, , 1928Swinnerton, 1915Swinnerton, , 1919, extensive taxonomic works (e.g. Woodward, 1883Woodward, , 1884bThomas & Narbonne, 1979;McNamara, 1980;Rushton & Hughes, 1981;Fortey & Owens, 1991;Edgecombe et al 1994;Adrain & Westrop, 2005;Feist & McNamara, 2007;Żylińska & Masiak, 2007;Feist et al 2009;Lerosey-Aubril, 2012;Crônier et al 2018), and key papers that have attempted to reveal, support or dispute the relationships between groups (e.g. Temple, 1956;Lane & Thomas, 1978;Ludvigsen & Chatterton, 1980;Fortey, 1981;Tripp & Evitt, 1981;Whittington, 1981;Park & Choi, 2011a;Park, 2018), as well as the affinities of trilobites with other arthropods (e.g.…”

Section: Introductionmentioning

confidence: 99%

The trouble with trilobites: classification, phylogeny and the cryptogenesis problem

Paterson

2019

Geol. Mag.

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Trilobites are an iconic group of extinct arthropods that lived in Palaeozoic oceans for c. 270 Ma, before their demise at the end of the Permian Period. Despite their considerable diversity (> 22 000 species) and abundance, particularly in Cambrian and Ordovician rocks, as well as intensive study for well over 200 years, trilobite systematics remains in a state of flux. In this contribution, the complex history of trilobite classification over the last century is briefly reviewed, including the seminal scheme published by Henry Swinnerton in 1915. The cryptogenesis problem, which relates to the supposedly obscure phylogenetic links between major post-Cambrian trilobite clades and their Cambrian sister taxa, is also discussed. Previous studies have suggested that the cryptogenesis problem is largely a taxonomic artefact, but the Cambrian origins of some post-Cambrian groups, such as the orders Proetida and Odontopleurida, are still unclear. Future directions for research on trilobite systematics are outlined, from taxonomic studies involving comprehensive documentation and extensive illustration of morphology at the species level, through to broad-scale phylogenetic analyses that initiate or test hypotheses about relationships across the major groups. Other ongoing issues to be addressed include identifying the sister group of Trilobita, and determining whether certain taxa, such as the suborder Agnostina and Cambrian family Burlingiidae, represent trilobites.

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The Chefar El Ahmar Formation (late Emsian-Frasnian Ib) in the Marhouma section (Saoura, Algerian Sahara): insights from ichnology and sedimentology

2021

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Middle Devonian trilobites of the Saoura Valley, Algeria: insights into their biodiversity and Moroccan affinities

Cited by 8 publications

References 41 publications

The influence of palaeogeography and tectonic events on trilobite distributions in Morocco and northwestern Algeria

The influence of palaeogeography and tectonic events on trilobite distributions in Morocco and northwestern Algeria

The trouble with trilobites: classification, phylogeny and the cryptogenesis problem

The Chefar El Ahmar Formation (late Emsian-Frasnian Ib) in the Marhouma section (Saoura, Algerian Sahara): insights from ichnology and sedimentology

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