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Coupling geometric morphometrics and machine learning for mandibular sex estimation in late pleistocene and late modern populations
Publication . Godinho, Ricardo Miguel; Crevecoeur, Isabelle; Garcia, Susana; Whiting, Rebecca; Aramendi, Julia
Accurate sex estimation is crucial for studying both modern and ancient human populations, yet methods are often limited to well-preserved skeletons. Here, we combine Geometric Morphometrics (GM) and Machine Learning (ML) to assess mandibular sexual dimorphism and classify sex across a wide chronological and geographic range to bracket the potential of this approach. Sixty-seven individuals from the modern, identified Luis Lopes collection (Portugal) and 18 Late Pleistocene individuals from Jebel Sahaba (Sudan) were surface scanned. Anatomical landmark coordinates were extracted and analyzed with GM, and ML models were trained on a subset of the modern sample to predict sex in both the remaining modern individuals and the Late Pleistocene specimens. GM revealed significant sexual dimorphism in all samples, and ML achieved high intrapopulation classification accuracy. However, predictions were less reliable when applied across the temporally and geographically distant Jebel Sahaba population, reflecting interpopulation differences in mandibular size and shape. These results demonstrate that while GM-ML approaches are powerful tools for sex estimation within populations, caution is required when extending models to other populations.
A Santacrucian record of Acarechimys minutus (Octodontoidea) from Laguna del Laja (Cura-Mallín Formation, Chile; late Early Miocene) and its biogeographic implications
Publication . Solórzano, Andrés; Encinas, Alfonso; Núñez-Flores, Mónica; Carrasco, Gabriel; Buldrini, Karina; Campos-Medina, Jorge; Bobe, René
The fossil record of pre-Quaternary continental mammals from Chile remains less well-documented than that of neighboring Argentina and Bolivia. Among the most promising successions is the Miocene Cura-Mallin Formation at Laguna del Laja (37.5 degrees S), which preserves diverse mammalian assemblages spanning nearly 10 million years. One of the rodents previously reported from this locality is Acarechimys, a small octodontoid widely documented in Late Oligocene to Late Miocene continental deposits of South America. However, records from Laguna del Laja were based exclusively on fragmentary and undescribed material, leaving their taxonomic identity uncertain. Here, we describe a Santacrucian (late Early Miocene) occurrence of a caviomorph rodent from Laguna del Laja, represented by a partial mandible preserving m1-m3 and a fragment of the dp4. Dental traits, including a laterally compressed lower incisor and a developed posterior arm of the metaconid, support referral to Acarechimys minutus. This well-dated record provides a stratigraphically constrained occurrence of the species in south-central Chile and narrows the geographic gap between Chilean localities of Chucal in the north and Aysen in the south. The new evidence supports the hypothesis that the Laguna del Laja assemblage was not fully endemic, but rather integrated into the broader Santacrucian biogeographic continuum, reinforcing its value as a key reference point for Neogene faunal and biogeographic studies in the south-central Andes.
Earliest evidence for intentional cremation of human remains in Africa
Publication . Cerezo-Román, Jessica I.; Sawchuk, Elizabeth; Schilt, Flora Cecilia; Bertacchi, Alex; Buckley, Gina; Chibisa, Edwin; Fahey, B. Patrick; Falchenberg, Sofia Gunilla Hedman; Kaliba, Potiphar; Kennett, Douglas J.; Mercader, Julio; Pargeter, Justin; Stock, Jay; Szymanski, Ryan; Thompson, Jessica C.
Human cremation on an open pyre demands intensive labor, communal resources, and sensory exposures. We report the earliest evidence for intentional cremation in Africa, the oldest in situ adult pyre in the world, and one of only a few associated with hunter-gatherers. A large cremation feature at Hora 1 in Malawi dates to similar to 9500 years ago and contains the remains of a small, gracile adult with evidence for perimortem defleshing and postcremation manipulation. Subsequent revisiting of the site to build fires in the same place provided additional pyrotechnological spectacles. High-resolution, multiproxy reconstruction of the ritual associated with cremation and its subsequent deposition demonstrates complex mortuary practices among ancient African foraging groups with substantial social investment and use of natural landscape features as persistent mortuary monuments.
Towards a formation model of the Neanderthal symbolic accumulation of herbivore crania: spatial patterns shaped by rockfall dynamics in level 3 of des-cubierta cave (Lozoya valley, Madrid, Spain)
Publication . Villaescusa, Lucía; Baquedano, Enrique; Martín-Perea, David M.; Márquez, Belén; Galindo-Pellicena, M. Ángeles; Cobo-Sánchez, Lucía; Ortega, Ana Isabel; Huguet, Rosa; Laplana, César; Ortega, M. Cruz; Gómez-Soler, Sandra; Moclán, Abel; García, Nuria; Álvarez-Lao, Diego J.; García-González, Rebeca; Rodríguez, Laura; Pérez-González, Alfredo; Arsuaga, Juan Luis
Understanding formation processes is crucial for interpreting sites with complex sedimentary histories and exceptional archaeological records, such as Level 3 of Des-Cubierta Cave. This Middle Paleolithic unit contains an assemblage of anthropically modified ungulate horned crania, Mousterian lithics, and evidence of fire use, all preserved in a clast-supported gravel deposit shaped by successive rockfalls. This study integrates geostatistical analyses with traditional spatial and taphonomic methods to examine the cone-shaped sedimentary structure that dominates the level and its influence on the spatial distribution and preservation of archaeological materials. The results reveal distinct spatial patterns for geological and archaeological materials, indicating separate formation dynamics. Size-based spatial analyses of boulders characterize the morphology of the conical structure, highlighting size sorting and intensity variations that may indicate sedimentary hiatuses. Bone refitting analysis suggests limited post-depositional movement, with material distribution shaped by the conical sedimentary structure and karst gallery morphology. Variability in crania preservation correlates with proximity to the cone's apex and elevation, with better-preserved specimens in central areas and more fragmented remains in zones affected by erosive and edaphic processes. These findings underscore the value of integrating geostatistical and traditional archaeological approaches to advance interpretations of spatial and temporal patterns in karst environments and provide a methodological approach for examining sites with similar sedimentary histories. Moreover, the results support the interpretation of a recurrent, culturally motivated Neanderthal behaviour centred on the deliberate accumulation of large ungulate crania, pointing to a symbolic dimension in these practices.
Spatiotemporal patterns and environmental drivers of Physalia physalis strandings along mainland Portugal (northeastern Atlantic)
Publication . Carvalho, Patrícia; Henrique Cordeiro, Clara Maria; Pereira, Soraia; Santos, Antonina dos
Physalia physalis is a cosmopolitan colonial organism frequently observed in Portuguese waters. The species has long tentacles, provided with cnidocytes, which release a strong poison when in contact with other organisms, and cause skin reactions and severe pain in humans. Events of rapid reproduction, common in these species, may have important economic and social consequences. This study explores for the first time, the relationships between long-term assessment of P. physalis strandings, using data from the GelAvista citizen science project, and environmental variables - Sea Surface Temperature (SST), wind direction and intensity, the North Atlantic Oscillation (NAO), and upwelling indices - along the Portuguese coast, using a Generalized Linear Mixed-Effects Model. Strandings of P. physalis were concentrated along the western coast and were rare in the south. More than 54 % of the records corresponded to a single individual. Sightings peaked from November through May (winter and spring), mirroring the negative correlation with SST. Wind patterns strongly influenced stranding events: winds likely pushed colonies toward the shore, while calm conditions facilitated their arrival on beaches. In March 2018, an upwelling event in the south coast combined with a series of storms likely underlay the high stranding numbers observed in the southern area, with more than 50 individuals of P. physalis per record. A positive trend in sightings over the study period suggests that P. physalis occurrences may be rising, even after accounting for wind and SST, which might be linked to climate change. Our findings underscore the value of ongoing jellyfish monitoring via citizen science platforms like GelAvista and highlight the need for expanded high-resolution environmental datasets. Moreover, this work establishes a foundation for experimental studies to elucidate the mechanisms behind P. physalis strandings. For future research, time series techniques for imputing missing values may be utilized to enhance the completeness of environmental datasets and strengthen analytical robustness in subsequent studies focused on time series analysis.