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<p>The Oxfordian‒lower Kimmeridgian Laguermi and the upper Kimmeridgian‒lower Tithonian Sfissifa Formation from the Saharan Atlas of Algeria have been studied for their fossil content. These two marine formations yielded cm- to dm-thick layers and lenses of shell concentrations composed essentially of oysters, new to science (<i>Pseudexogyra euryhalina</i> n. gen. et n. sp. and ?<i>Africogryphaea geniculata</i> n. sp.). Two levels of the Sfissifa Formation contain concentrations of terebratulid brachiopods; the lower one composed of the late Kimmeridgian <i>Xestosina arguta</i> and the upper one of the early Tithonian <i>Xestosina sera</i>. <i>Xestosina sera</i> is recorded for the first time from Africa. Based on petrographic features, taphonomic data, and sedimentary structures, the oyster concentrations are autochthonous to parautochthonous and formed in a lagoonal environment under the influence of episodic storms. The paucispecific nature of these shell beds is interpreted to reflect adverse environmental conditions, in particular hypersalinity, although selective early diagenetic dissolution of shells may also have played some role.</p>

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Taxonomy, palaeoecology, taphonomy, and palaeoenvironments of paucispecific macrobenthic assemblages from the Upper Jurassic of the Saharan Atlas, Algeria

  • 期刊论文

  • 发表日期：

    2026年4月1日

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  • Radouane Sadji,
  • Franz Fürsich,
  • Barbara V. Radulović,
  • Wagih Ayoub-Hannaa,
  • Salim Belkhedim,
  • Axel Munnecke

摘要

The Oxfordian‒lower Kimmeridgian Laguermi and the upper Kimmeridgian‒lower Tithonian Sfissifa Formation from the Saharan Atlas of Algeria have been studied for their fossil content. These two marine formations yielded cm- to dm-thick layers and lenses of shell concentrations composed essentially of oysters, new to science (Pseudexogyra euryhalina n. gen. et n. sp. and ?Africogryphaea geniculata n. sp.). Two levels of the Sfissifa Formation contain concentrations of terebratulid brachiopods; the lower one composed of the late Kimmeridgian Xestosina arguta and the upper one of the early Tithonian Xestosina sera. Xestosina sera is recorded for the first time from Africa. Based on petrographic features, taphonomic data, and sedimentary structures, the oyster concentrations are autochthonous to parautochthonous and formed in a lagoonal environment under the influence of episodic storms. The paucispecific nature of these shell beds is interpreted to reflect adverse environmental conditions, in particular hypersalinity, although selective early diagenetic dissolution of shells may also have played some role.