The formation of the prechordal plate. The prechordal plate is a thickening of the endoderm at the cranial end of the primitive streak formed by the involution of Spemann's organizer cells. The prechordal plate and the notochord induce the formation of the neural plate from the overlying ectodermal cells. [ GOC:dgh GOC:dph GOC:cls GOC:jid http://purl.obolibrary.org/obo/go/references/0000021 ]