Possums and gliders are members of the diverse Order Diprotodontia, which contains 10 extant and 8 extinct Families (Kirsch et al. 1997).
Metatherian mammals separated from their eutherian counterparts ~104 million yr ago, with emergence of the Diprotodontia occurring ~60 million yr ago. The first Phalangeriforms arose 54 million yr ago, with radiation of the pseudocheirids and separation of the phalangerine tribes occurring at 36 and 20 million yr ago, respectively (Kirsch et al.
1997). Today, all possums and gliders fall under the Suborder Phalangeriformes, of which there are 6 Families, and 27 species.Like other diprotodonts, possums and gliders are characterised by diprotodonty (first pair of lower incisors enlarged and procumbent), a superficial thymus gland, a fasciculus aberrans connecting the two hemispheres of the brain, syndactyly and a continuous lower ankle joint pattern (Springer et al. 1998).
This chapter is an extension of the information in the first edition of Medicine of Australian Mammals and should not be read in isolation (Johnson and Hemsley 2008). Only additional information published since the first edition is covered here. Other useful texts and references that cover information not included in this chapter are Ladds (2009); Clarke (2011); Vogelnest and Allen (2015); and Reiss et al. (2015).
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