Initiation and early development of the postcanine deciduous dentition in the dasyurid marsupial Dasyurus viverrinus

There has been disagreement for more than 100 years concerning the presence or absence of deciduous and successional third premolars in the dentition of the Australian dasyurid marsupial Dasyurus viverrinus as well as in other species of the genus Dasyurus. Most authors during the 19th and 20th centuries have considered the missing premolar in Dasyurus to be the third premolar family in both jaws, in part because of the reduction in size of the third deciduous premolar in many other genera of dasyurids. While other authors, found “the deciduous premolar to be constantly present in the young mammary foetus as a small and precociously calcified vestigial tooth”. However, the fate of this deciduous tooth, and its possible successor in later developmental stages, was never described; and the vestigial dp3 and its possible successor were assumed to undergo absorption during foetal life. With access to later developmental stages of Dasyurus viverrinus, via the extensive collections of Professor J.P. Hill, we present new evidence for the later development of dP3 and P3 in both jaws, the probable eruption of the successional P3 in both jaws and evidence that dP2 is the missing tooth in both jaws of this dasyurid species.