Updated study of adult and subadult pectoral girdle bones from Sima de los Huesos site (Sierra de Atapuerca, Burgos, Spain). Anatomical and age estimation keys

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The forearm skeleton is composed of two bones: the radius and the ulna. This is closely related to manipulative movements. The ulna is part of the elbow joint, whereas the radius and ulna together with the scaphoid and lunate bones, form the wrist joints. Thus, morphofunctional analysis of the adult Sima de los Huesos (SH) forearm bones, provides clues about manipulative activities in one Pleistocene population. From 1976 to the present, over 7000 human fossils have been recovered from the SH site. The radial sample comprised 98 labeled fragments, of which 49 belonged to adult individuals, representing at least 7 individuals. The ulnar sample included 31 labeled adult fossils representing at least nine individuals. In this study, we describe the SH radii and ulnae and analyze their functional implications for manipulative and forearm movements. We confirmed that the SH radii are long and curved, with variations in robusticity and radial tuberosity orientation. The SH ulnae are characterized by an anteriorly oriented trochlear notch, a massive olecranon process, an obliquely oriented radial notch, a blunt and short supinator crest, a gracile and curved diaphysis, and a round and anteriorly oriented pronator crests. In general, they exhibit Neanderthal morphology. The SH collection provides a unique opportunity to conduct morphological analyses of these bones in the Middle Pleistocene population.

Section: Discussionsupporting

confidence: 63%

Uncovering the adult morphology of the forearm bones from the Sima de los Huesos Site in Atapuerca (Spain), with comments on biomechanical features

Rodríguez

García‐González

Arsuaga

et al. 2023

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“…From this point of view, the scapular position of Neandertals would be more posterior in the thorax and the glenoid cavity more lateral, and in this case, clavicular elongation was most directly related to dorsal repositioning of the scapula (Larson, 2007a(Larson, , 2007b(Larson, , 2009. As we can see, determining the scapular position (more posterior or more lateral) and the relative clavicular length in fossil specimens is a key issue not easy to resolve (Melillo et al, 2019;Voisin, 2006) and which we have discussed in García-Gonz alez et al (2024).…”

Section: Humeral Retroversion Anglementioning

confidence: 80%

“…As is the case for the previously mentioned shaft traits, the specific functional meaning, if any, of the transversely oval humeral head is not clear, but is likely linked with the shaft traits described above and overall, with the scapular glenoid fossa morphology. In SH (Carretero, 1994;Carretero et al, 1997;García-Gonz alez et al, 2024) and the Neandertals (Churchill & Trinkaus, 1990;Di Vincenzo et al, 2012;Trinkaus, 1983) this humeral head morphology is present along with a narrower glenoid cavity of the scapula. The most obvious effect of this morphology of the glenohumeral articulation is enhancing ranges of motion of external and internal rotation at the shoulder joint.…”

Section: The Proximal Epiphysismentioning

confidence: 98%

Main anatomical characteristics of the hominin fossil humeri from the Sima de los Huesos Middle Pleistocene site, Sierra de Atapuerca, Burgos, Spain: An update

Carretero¹,

García‐González

Rodríguez

et al. 2023

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Some of the Sima de los Huesos (SH) humeri have been previously studied and described elsewhere. Here we present an updated inventory and a review of the specimens recovered to the present day. The morphological key traits of the adult and subadult specimens are described, discussed, and illustrated. The SH humeri share with Neandertals many traits usually considered to be Neandertal specializations, thus, most of this morphological pattern is not exclusive to them. The variation found within fossil samples stresses the frequential nature of all these traits and in the specific case of the SH humeri, most of the traits considered as phylogenetically relevant are retained by their descendants, the Neandertals. Some traits are plesiomorphic for the entire genus Homo or are present in European hominins since the early Pleistocene. Finally, some other traits display high variability within the SH sample or different hominin samples and are of uncertain phylogenetic value. Altogether, this evidence is consistent with the hypothesis based on the overall cranial and postcranial morphology that the SH hominins are a sister group to the later Neandertals.

“…The cortical thickness is influenced by differential endosteal resorption and subperiosteal deposition during development, which reflects the hypertrophy of the Pleistocene human femoral diaphysis (Chevalier & de Lumley, 2022;Pearson & Lieberman, 2004;Shaw & Stock, 2010;Yoshikawa et al, 1994). Moreover, this increased cortical shaft thickness and larger absolute and relative bone volumes are not exclusive traits of the femora, but are observed in the entire lower and upper limb SH adult bones (Carretero et al, 2018) and even in upper limb subadult specimens (García-Gonz alez et al, 2024). This suggests that there is a strong genetic influence on these characteristics.…”

Section: On Morphological Traits Of the Central Diaphysismentioning

confidence: 99%

Main morphological characteristics and sexual dimorphism of hominin adult femora from the Sima de los Huesos Middle Pleistocene site (Sierra de Atapuerca, Spain)

Carretero,

Rodríguez,

García‐González

et al. 2023

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The excellent fossil record from Sima de los Huesos (SH) includes three well‐known complete adult femora and several partial specimens that have not yet been published in detail. This fossil record provides an opportunity to analyze the morphology of European pre‐Neandertal adult femur and its variation with different evolution patterns. Currently, there are a minimum of five adult individuals (males or females). In this study, we compiled previously published basic anatomical and biometric characteristics of SH adult femora, emphasizing the most relevant features compared to other recent and fossil hominins. The SH femora exhibited a primitive morphological pattern common to all non‐Homo sapiens femora, as well as most of the Neandertal traits. Therefore, the complete Upper Pleistocene Neandertal pattern was well‐established in Middle Pleistocene ancestors long before the proper Neandertals appeared. Additionally, we highlight that the SH and Neandertal femora share some morphological traits and proportions with modern humans that hold sexual significance in our species, regardless of size. Keeping this in mind, we discussed the sex determination of the complete SH specimens and re‐evaluated sex allocation in two of them.