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Friday, September 11, 2015

Postcranial morphology of the middle Pleistocene humans from Sima de los Huesos, Spain

Postcranial morphology of the middle Pleistocene humans from Sima de 
los Huesos, Spain. 

Current knowledge of the evolution of the postcranial skeleton in the 
genus Homo is hampered by a geographically and chronologically 
scattered fossil record. Here we present a complete characterization 
of the postcranium of the middle Pleistocene paleodeme from the Sima 
de los Huesos (SH) and its paleobiological implications. The SH 
hominins show the following: (i) wide bodies, a plesiomorphic 
character in the genus Homo inherited from their early hominin 
ancestors; (ii) statures that can be found in modern human 
middle-latitude populations that first appeared 1.6–1.5 Mya; and (iii) 
large femoral heads in some individuals, a trait that first appeared 
during the middle Pleistocene in Africa and Europe. The 
intrapopulational size variation in SH shows that the level of 
dimorphism was similar to modern humans (MH), but the SH hominins were 
less encephalized than Neandertals. SH shares many postcranial 
anatomical features with Neandertals. Although most of these features 
appear to be either plesiomorphic retentions or are of uncertain 
phylogenetic polarity, a few represent Neandertal apomorphies. 
Nevertheless, the full suite of Neandertal-derived features is not yet 
present in the SH population. The postcranial evidence is consistent 
with the hypothesis based on the cranial morphology that the SH 
hominins are a sister group to the later Neandertals. Comparison of 
the SH postcranial skeleton to other hominins suggests that the 
evolution of the postcranium occurred in a mosaic mode, both at a 
general and at a detailed level. Postcranial morphology of the middle Pleistocene humans from Sima de los Huesos, Spain
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