Metatarsals and foot phalanges from the Sima de los Huesos Middle Pleistocene site (Atapuerca, Burgos, Spain)

Abstract

This study provides a complete, updated and illustrated inventory, as well as a comprehensive study, of the metatarsals and foot phalanges (forefoot) recovered from the Middle Pleistocene site of Sima de los Huesos (SH, Atapuerca, Spain) in comparison to other Homo comparative samples, both extant and fossils. This current updated review has established a minimum number of individuals (MNI) of 17, which represent 58.6% of the 29 dental individuals identified within the SH sample. An exclusive or autoapomorphic combination of traits can be recognized within the SH hominin foot sample. A few traits appear primitive or plesiomorphic when compared with earlier Homo individuals and other recent modern humans. There are other metrical and morphological traits that SH hominins and Neandertals have in common that sometimes represent shared derived traits in this evolutionary line, most of which are probably related to robusticity. Furthermore, some exclusive autoapomorphic traits are observed in the SH sample: a very broad first metatarsal, long and broad hallucal proximal foot phalanges and possibly extremely robust lateral distal foot phalanges compared to those of Neandertals and modern humans. In these last traits, the SH metatarsals and pedal phalanges are even more robust than in Neandertals. They are herein named as “hyper‐Neandertal” traits, which could suggest a slight gracilization process in this evolutionary line, at least in the hallux toe. Finally, some paleobiological inferences are made in relation to body size (stature and body mass) and some associations are proposed within the SH sample.

Tarsals from the Sima de los Huesos Middle Pleistocene site (Atapuerca, Burgos, Spain)

“…Although these are just a few characters, in some ways, the SH tarsals are even more robust than Neandertals (Table 13). Something similar is observed in metatarsals and phalanges, especially in the hallucal elements (Pablos & Arsuaga, 2024).…”

“…In general, the SH tarsal collection displays both complete bones and fragments in different stages of preservation corresponding to both juvenile and adult individuals. Over more than 40 years of excavation and laboratory work, some of the fragments are glued together to make complete bones (e.g., the cranium and other postcranial bones; Arsuaga et al, 2014Arsuaga et al, , 2015Bonmatí et al, 2010;G omez-Olivencia et al, 2007;Pablos & Arsuaga, 2024;Pantoja-Pérez et al, 2016;Rodríguez et al, 2016). The tarsals sometimes also underwent this gluing process, as indicated below.…”

“…In spite of this, here we try to make initial and approximate assignments to sex based on general size of the tarsals, despite the dependence on a reference population. For sex assignments, we used similar methods to those used to establish sex from the metatarsals and phalanges from SH (Pablos & Arsuaga, 2024). The method consists of performing a principal component analysis (PCA) on the raw variables of each element.…”

“…See Table 11 for details about the identification. García-Gonz alez et al, 2024;G omez-Olivencia et al, 2007;Pablos & Arsuaga, 2024;Rodríguez et al, 2024aRodríguez et al, , 2024b.…”

“…They belonged to a minimum of 29 individuals from both sexes, mostly corresponding to late adolescents or young adults (Bermúdez de Castro et al, 2021). They are closely related to Neandertals, both genetically (Meyer et al, 2014(Meyer et al, , 2016, and morphologically, in spite of some exclusive or autapomorphic traits present in this Middle Pleistocene population (Arsuaga et al, 2014(Arsuaga et al, , 2015Bermúdez de Castro et al, 2024;Carretero et al, 1997;Pablos et al, 2017;Pablos & Arsuaga, 2024;Pantoja-Pérez et al, 2015;Rodríguez et al, 2016). It has previously been proposed that the SH sample is phylogenetically related to Neandertals, suggesting that this Middle Pleistocene population, or other similar, could be the paleodeme that gave rise to Neandertals in Europe (Arsuaga et al, 2014(Arsuaga et al, , 2015.…”