Evolution of the Pectoral Lunula in Portugal? (Valera)

This is an older paper from 2010, but relevant for the story on lunulae from its roots in the boar's tusk tradition in the Late Neolithic and its continued evolution into golden lunulae.

Early on, you can see Perdigoes tusks are pairs or halved pairs which are connected together and worn in the shape of a pectoral lunula.  They are depicted both on the anthropomorphic Late Neolithic menhirs (in the paper) and also within the burial deposits.

In a comparative, proto-historical mythology, boar's tusks were associated with the moon goddess who was variously associated with the bow, the boar hunt, cow horns and the crescent shape.  Although a feminine symbol, both boar's tusks, boar's tusk pendants and lunulae appear to be mostly associated with men at first, but may have been expressed by both sexes at different times and places.
(jet spacer lunulae appear to have been worn exclusively by British women)

Perforations for connecting

One important difference between a pectoral lunula and a boar's tusk pendant of Central Europe is that pectoral lunulae face up and the suspended pendants face down.  The suspended pendants probably mimic flatbows or composite bows as believed by Stuart Piggott [Pendants], and the later golden lunulae probably represent "solar boats" or "moon boats" [Pendants]. 

A Late Neolithic Iberian figure with the typical 'facial tattoos' or 'mustache' of that era.

Boar's tusks have a symbolic value that transcend any sort of compositional worth.  As you can see in this ivory burial amulet, several reoccurring 'protective' features seem to be built in, including a boar's tusk lulula.  Boar's tusks and cornos have been until recently were fashioned into lunar shapes for the protection of horses or barns.  It's possible that the lunulae originally protected high status individuals from jealous and strange looks.

Marfim No Recinto Calcolitico Dos Perdigoes (1): "Lunulas", Fragmentacao E Ontologia Dos Artegactos.  Apontamentos de Arqueologia e Patrimonio - 5/2010 (www.nia-era.org) Antonio Carlos Valera.  [Link]