Three adult parietal fragments allow estimation of cranial thickness in Homo antecessor
L’IPHES-CERCA participates in research providing new data on the cranial vault of this species found at the Gran Dolina site (Atapuerca), reinforcing its characterization as a mosaic anatomy, with both ancestral and derived traits
IPHES-CERCA is participating in an article published in the Journal of Human Evolution, which provides unprecedented quantitative data on the cranial thickness of Homo antecessor, based on the analysis of three parietal fragments found at the Gran Dolina site in the Sierra de Atapuerca (Burgos).
The research, supported by the Atapuerca Foundation/Reale Foundation and the Atapuerca Project, is part of a doctoral thesis focused on the cranial microstructure of this species and its comparison with other humans—both modern and extinct—conducted by Rafael Gallareto-Sande, a predoctoral researcher at CENIEH, under the direction of María Martinón-Torres (CENIEH), Emiliano Bruner (MNCN, CSIC), and Palmira Saladié (IPHES-CERCA).
The results show that the total cranial thickness in these adult individuals falls within the range of modern humans and Neanderthals, and is clearly lower than that of Homo erectus and other Early Pleistocene human species.
Layer by layer
Until now, the only Homo antecessor parietal studied in detail was described by Emiliano Bruner and colleagues in 2017 and belonged to a juvenile individual. The three fragments analyzed in this new study (identified as ATD6-115, ATD6-128, and ATD6-401) correspond to adult individuals.
The analysis was performed using micro-computed tomography, a technique that allows for the separate measurement of the three layers composing the cranial bone (the outer table, the diploë, and the inner table) and detailed examination of other bone surface features, such as vascular canals and microforamina.
When analyzing each layer separately, the diploë (the inner spongy tissue of the bone) proved to be the thickest in all cases, accounting for between 41% and 50% of the total thickness, consistent with observations in Neanderthals and modern humans. Furthermore, the Homo antecessor fragments show a different proportion between the other two layers: a relatively thinner outer table and a relatively thicker inner table than in the other two species.
"It is the first time we can quantitatively compare the cranial thickness of this species, layer by layer, with the rest of the available data for the genus Homo, providing very valuable information that helps interpret the evolutionary position of this species," states Gallareto-Sande.
Mosaic characteristics
Homo antecessor was originally described from remains found at level TD6 of Gran Dolina as a species featuring mosaic characteristics—combining derived facial and neurocranial traits with more primitive postcranial and dental traits—and is considered today a group close to the common evolutionary root of Neanderthals and modern humans.
The results of this work corroborate that characterization, adding parietal bone thickness and internal architecture to the traits defining that combination of the ancestral and the derived. However, this represents a trend rather than a definitive conclusion, given that the current Homo antecessor sample size is small.
"The available sample is still limited and fragmented, so any new fragment could nuance these results. We trust that upcoming field campaigns will continue to recover new cranial remains that allow us to test our observations and deepen their interpretation," concludes Gallareto-Sande.
Bibliographic reference
Gallareto-Sande, R., Bruner, E., Saladié, P., Martinón-Torres, M. (2026). Parietal thickness and Homo antecessor: A description of three new fragments from Gran Dolina, Atapuerca, Spain. Journal of Human Evolution, 218. https://doi.org/10.1016/j.jhevol.2026.103870
