Extended Data Fig. 7: PYS shell analysis.

a, Fragments of Achatina cf. fulica found in close association with the child’s skeleton. Observation of anatomical features allows precise identification of the provenance of the fragments on the shell. Fragments PYS-2017-200407 and PYS-2017-200404 come from the area of the body whorl adjacent to the middle portion of the parietal callus. Fragment PYS-2017-200405 must come from a portion of the shell close to that of the previous fragment and may derive from the same individual. Fragment PYS-2017-200406 comes from the middle of the body whorl, on its dorsal aspect. Although anatomically it is compatible with provenance from the same individual, its very dark colour, suggestive of a higher Mn intake, and different texture of the concretion coating its outer surface indicate that it had a different taphonomic history and may derive from a different shell. Fragment PYS-2017-200086.D comes from the middle of the body whorl, on its ventral aspect. b, Refitting of fragments PYS-2017-200407 and PYS-2017-200404. The two large fragments refit along an ancient fracture perpendicularly intercepting the shell growth lines. c, Modern striations on the inner surface of specimen PYS-2017-200406, probably produced during excavation or cleaning of the fragments. The modern origin of the striations is shown by their random orientation and absence of the thin manganese patina adhering to the inner surface of this specimen. d, Micrographs and 3D reconstruction of an area of the outer surface of fragment PYS-2017-200404 showing two grooves obliquely crossing the decussated sculpture of the outer shell surface. The internal morphology and outlines of the grooves indicate that they were made by a pointed agent, possibly a stone tool, following the irregular morphology of the shell natural surface and slightly changing direction when falling into concave areas. The antiquity of the lines is demonstrated by the red sediment coating the specimen, which fills in the striations and almost completely buries them when they run into natural grooves of the shell. e, Fragments of Achatina cf. fulica found in feature 809 (bottom) and their anatomical origin (top). The twelve fragments mostly come from body whorls and last whorls of the spire of Achatina snails, with only two from the parietal wall and the apex. They present a similar state of preservation, colour, taphonomic modifications and type of concretions to the five fragments found in direct association with the skeleton. None of them bears incisions similar to those recorded on specimen PYS-2017-200404. Fragments comprising the control sample from layer 18 are, in general, more free from concretions than those from the skeleton and feature 809. f, Biplot and linear regression correlating the length and width of Achatina cf. fulica fragments from the grave pit (n = 12) and the skeleton (n = 5) with those from layer 18 (n = 581) (top), and box plots of length and width distributions of Achatina cf. fulica fragments from these two contexts (bottom). Rectangles in the box plots show the second and third quartiles, central bar indicates the median, and whiskers the extreme values. The fragments from the burial pit are significantly larger in size (P = 0.001) while displaying the same length/width ratio. Incorporation in the grave infilling have preserved Achatina fragments from the higher levels of fragmentation that have affected fragments exposed to trampling on the occupation surface in layer 18.