Recursive anisotropy: a spatial taphonomic study of the Early Pleistocene vertebrate assemblage of Tsiotra Vryssi, Mygdonia Basin, Greece

Abstract

By applying advanced spatial statistical methods, spatial taphonomy complements the traditional taphonomic approach and enhances our understanding of biostratinomic and diagenetic processes. In this study, we elaborate on a specific aspect – spatial anisotropy – of taphonomic processes. We aim to unravel the taphonomic history of the Early Pleistocene vertebrate assemblage of Tsiotra Vryssi (Mygdonia Basin, Greece). Circular statistics are used for the fabric analysis of elongated elements; geostatistics (directional variograms), wavelet and point pattern analyses are applied for detecting anisotropy at the assemblage level. The anisotropy of magnetic susceptibility (AMS) of sedimentary magnetic minerals is also investigated. The results, integrated with preliminary remarks about the differential preservation of skeletal elements, sedimentological and micromorphological observations, suggest multiple dispersion events and recurrent spatial re‐arrangement of a lag, (peri)autochthonous assemblage, consistent with the cyclical lateral switching of a braided fluvial system. Furthermore, this study offers a contribution to the building of a spatial taphonomic referential framework for the interpretation of other fossil vertebrate assemblages, including archaeo‐palaeontological ones.

Bone modifications by the giant hyaenaPachycrocuta brevirostrison large-sized ungulate carcasses from the Lower Pleistocene site of Tsiotra Vryssi (Mygdonia Basin, Greece)

“…Specimens that could not be identified taxonomically but belong to the aforementioned size groups are also included in some of the analyses (n = 77). Concerning the collection protocol of fossils during the excavation, collected were all diagnostic (to skeletal element) bones and teeth, as well as carnivore modified bones, regardless of their preserved size; not collected, yet recorded (location, dimensions) with the total station were non-diagnostic bone fragments with length of ≥50 mm, while non-diagnostic and non-carnivore modified fragments ≤50 mm were not recorded (Giusti et al 2019). Although this sampling protocol introduces few limitations in some of the analyses included in this study, we believe that these are only minor and that the studied sample is sufficient for a safe interpretation of the site.…”

“…Two main depositional units have been identified at TSR, Geo 1 and Geo 2, of which the ~1 m thick fossiliferous Geo 2a consists of pale brown-to dark yellowish brown very fine sandy silts, locally intercalated by cm-thick lenses of medium-coarse grained sands (Giusti et al 2019). Previous spatial taphonomic analyses of the vertebrate assemblage, in agreement with sedimentological and micromorphological observations, suggested that multiple dispersion events occurred in the formation of the deposit: the recurrent spatial rearrangements of a lag, (peri)autochthonous assemblage being consistent with the cyclical lateral switching of a braided fluvial system (Giusti et al 2019). Cosmogenic radionuclides, magnetostratigraphy and biochronological data indicate an age between 1.78 and ~1.5 Ma (late Villafranchian, Lower Pleistocene) for the site (Konidaris et al , 2022.…”

“…Although ribs cannot be taken into consideration, since their collection was not systematic during the early years of excavation, MAU values of vertebrae and long bones (Table 1, Figure 2A) show that axial elements are underrepresented in the assemblage, while limb bones are abundant (see also Giusti et al 2019). These values could suggest hyaena involvement, as it has been observed that spotted hyaenas consume the axial skeleton at kill sites, thus creating assemblages where limb bones are predominant (e.g., Skinner et al 1986;Capaldo 1998), whereas felids have been mostly shown to modify axial bones without deleting them (e.g., Domı ńguez-Rodrigo 1999).…”

“…The present study aims to contribute to the taphonomic interpretation of the Lower Pleistocene site Tsiotra Vryssi in the Mygdonia Basin (Greece). Previous studies have recognized that carnivores had an important role in the modification, and possibly the primary accumulation of the skeletal remains (Konidaris et al 2015;Giusti et al 2019). In the present study, we perform a multitude of taphonomic analyses in order to thoroughly investigate the extent to which carnivore alteration is present, as well as to identify the main biotic agent responsible for the bone modifications of large ungulate carcasses.…”

Burning, dumping, and site use during the Middle and Upper Palaeolithic at Hohle Fels Cave, SW Germany

“…For example, fabric analysis on natural clasts within a debris flow reveals that the long axes of clasts are often oriented parallel to the slope direction (Bertran et al 1997;Lenoble and Bertran 2004), to the extent that the clast in these deposits show weak or strong imbrication, as is the case in grain flows (Bertran and Texier 1999). Therefore, by recording the orientation (trend and bearing) of elongated artefacts and natural clasts during excavation, researchers can use fabric analysis to reconstruct potential modes of deposition (Benito-Calvo et al 2009;Sánchez-Romero et al 2016;McPherron 2018;Giusti et al 2019;Li et al 2021) and also investigate the impacts that previous substrate morphologies have on the clast orientation (Li et al 2021). Despite the increasing regularity with which fabric analysis has been employed for the reconstruction of site formation processes, little work to date has focused on the analysis of fabrics internal to combustion features.…”