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The Ordovician wave-dominated sandstones of the Daoura (Ougarta range, NW Algeria) contain shell beds with cornulitids in an exceptional state of preservation. The objective of this study, focused on the sandstone of the uppermost part of the Hassi Chaamba Fm. (Sandbian?), is to understand the shell beds from the hydrodynamic and stratigraphic perspective with the combined approach of facies sedimentology and taphonomy. A 40-m section encompassing the shell beds was studied in detail. The shell beds are preserved as dm-scale concentrations in transgressive deposits of 5 high-frequency sequences preserved at the turnaround from a regressive to a transgressive sequence set. The biota in shell beds are dominated by brachiopods, cornulitids and gastropods, suggesting that the related ecosystem extended to the offshore. Three types of shell beds are distinguished, ranging from a conglomerate in the foreshore to a hardground in the offshore transition. In the lower shoreface, the shell beds are interstratified with fine-sand SCS infilling large-scale (up to 20m in wavelength) troughs eroded in the foreshore by transgressive ravinement. The petrographic and tomographic analysis of a sample of these shell beds shows that cornulitids and, to a lesser extent, brachiopods of the shell beds are perfectly preserved within a matrix composed of bioclasts. This suggests that they were reworked from nearby areas and therefore were present in the foreshore. Aggregation of cornulitids in clusters of 4–5 individuals suggests an adaptation to loose grounds in a relatively high energy setting. The rhythmic alternation of shell beds and sandstones in these deposits suggests a possible role of tides in their formation. [ABSTRACT FROM AUTHOR]

The present study investigates the inner structural organization of the two mandible specimens Tighenif 1 and Tighenif 2 from the late early Pleistocene site of Tighenif, Algeria. Using (micro)tomographic scans, we built a new protocol to investigate the cortical bone topography at the post-canine level. We selected two cross-sectional slices placed between the P3/P4 and M1/M2 on the right and left sides and assessed the cortical bone thickness topography (CBT) on each slice. Our analyses demonstrate that the mandibles from Tighenif exhibit higher CBT and a different topographic distribution pattern at the molar level than in modern humans, resulting in a proportionally more robust inner structure, while a similar signal is observed between the fossil and extant specimens at the premolar level. Further studies need to be done in order to determine if this feature is related to functional constraints during mastication or paramasticatory activities; or if it is related to any independent evolutionary process. [ABSTRACT FROM AUTHOR]

Following the recent studies of East Asian mid-Middle to early Late Pleistocene hominin material, a large spectrum of morphological diversity has been recognized and the coexistence of archaic (' Homo erectus -like') and derived ('modern-like') dental morphological patterns has been highlighted. In fact, for most of these Chinese fossils, generally categorized as 'archaic Homo sapiens ' or 'post- H. erectus Homo' , the taxonomic attribution is a matter of contention. With the help of μCT techniques and a deformation-based 3D geometric morphometric approach, we focused on the morphological variation in the enamel–dentine junction (EDJ) of 18 upper and lower premolars from Chinese Middle Pleistocene hominins. We then compared our results with a number of fossil and modern human groups, including Early Pleistocene H. erectus from Sangiran; late Early Pleistocene hominins from Tighenif, Algeria; classic Neanderthals; and modern humans. Our results highlight an evolutionary/chronological trend of crown base reduction, elevation of EDJ topography, and EDJ surface simplification in the hominin groups studied here. Moreover, this study brings insights to the taxonomy/phylogeny of 6 late Middle Pleistocene specimens whose evolutionary placement has been debated for decades. Among these specimens, Changyang premolars show features that can be aligned with the Asian H. erectus hypodigm, whereas Panxian Dadong and Tongzi premolars are more similar to Late Pleistocene Homo. Compared with early to mid-Middle Pleistocene hominins in East Asia, late Middle Pleistocene hominins evince an enlarged morphological variation. A persistence of archaic morphotypes and possible admixture among populations during the late Middle Pleistocene are discussed. [ABSTRACT FROM AUTHOR]