Burramyoidea Broom, 1898

Beck, Robin M. D., Voss, Robert S. & Jansa, Sharon A., 2022, Craniodental Morphology And Phylogeny Of Marsupials, Bulletin of the American Museum of Natural History 2022 (457), pp. 1-353 : 235-237

Burramyoidea Broom, 1898

CONTENTS: Burramys (fig. 46) and Cercartetus .

STEM AGE: 29.9 Mya (95% HPD: 25.8–35.4 Mya).

CROWN AGE: 21.6 Mya (95% HPD: 13.5–26.2 Mya).

UNAMBIGUOUS CRANIODENTAL SYNAPOMORPHIES: Scars of M. temporalis origin on braincase not fused middorsally to form sagittal crest in adults (char. 27: 1→0; ci = 0.059) and presphenoid exposed in roof of nasopharyngeal fossa above posterior palate (char. 43: 1→0; ci = 0.091).

COMMENTS: Archer (1984c) and Aplin and Archer (1987) gave detailed summaries of the various attempts to unravel the affinities of “pygmy possums.” Briefly, Burramyidae was first recognized as a distinct family by Kirsch (1968 a, 1968b), who included within it Burramys , Cercartetus , and Acrobates . Kirsch and Calaby (1977) subsequently also classified Distoechurus as a burramyid, based on its morphological resemblance to the other three genera. However, Aplin and Archer (1987) removed Acrobates and Distoechurus to their newly created family Acrobatidae (see Acrobatidae below), leaving Burramys and Cercartetus as the sole known constituent genera of Burramyidae . Aplin and Archer (1987) placed Burramyidae in its own superfamily, Burramyoidea, based on “the degree of morphological distinction of the burramyids and of their apparently wide phyletic separation from other possums” ( Aplin and Archer, 1987: lxi). Aplin and Archer (1987: lx) remarked that monophyly of Burramys + Cercartetus was “not certainly known” at that time, but subsequent molecular studies have consistently recovered this clade with strong support ( Phillips and Pratt, 2008; Meredith et al., 2009a; Mitchell et al., 2014; May-Collado et al., 2015; Duchêne et al., 2018; Álvarez-Carretero et al., 2021), and it is strongly supported in our molecular (figs. 27–29) and total-evidence (figs. 32, 33) analyses, although not in our craniodental analyses (figs. 30, 31).

Fragmentary remains of burramyids are known from the late Oligocene of Australia, and these have been referred to the modern genus Burramys ( Pledge, 1987b; Brammall and Archer, 1997). Fossil material of Cercartetus has not been formally described to date, but fossils have apparently been recovered from early to middle Miocene deposits at Riversleigh World Heritage Area ( Brammall and Archer, 1999; Archer and Hand, 2006; Black et al., 2012b). Earlier reports of Cercartetus -like fossils from the late Oligocene of central Australia (e.g., Tedford et al., 1977; Rich et al., 1982; Woodburne et al., 1985) actually represent † Pilkipildridae , an extinct phalangeridan family of uncertain relationships ( Archer et al., 1987; Brammall and Archer, 1999; Long et al., 2002; Archer and Hand, 2006; Black et al., 2012b). The apparent presence of as yet undescribed Cercartetus specimens in the early or middle Miocene, as discussed above, is roughly congruent with our late Oligocene to middle Miocene estimate for the time of divergence between Burramys and Cercartetus . The late Oligocene Burramys specimens may predate our estimate, but their phylogenetic relationship to extant Burramys and Cercartetus species has not been rigorously tested (the phylogenetic analysis presented by Brammall and Archer, 1997, assumed a priori that Burramys , including the fossil species, is monophyletic to the exclusion of Cercartetus ).