Simosthenurus sp.

Piper, Katarzyna J., 2016, The Macropodidae (Marsupialia) of the early Pleistocene Nelson Bay Local Fauna, Victoria, Australia, Memoirs of Museum Victoria 74, pp. 233-253 : 233-234

Simosthenurus sp. cf. S. occidentalis Glauert, 1910

Referred material. NMV P216045, anterior half right I3; NMV P216047, posterior fragment left I3; NMV P216048, left I3; NMV P218251, talonid right m1?; NMV P216042, worn right dp2; NMV P173664, proximal phalanx IV; NMV P216147, proximal phalanx IV. Note: NMV P173639, a left i1 identified by Hann (1983) as Simosthenurus sp. cf. S. occidentalis has been re-identified during this study as the very worn i1 of Palorchestes pickeringi Piper, 2006a .

Remarks. The molar, although poorly preserved, is clearly identifiable as a simosthenurin owing to the presence of numerous fine enamel crenulations, straight lophs, a divided cristid obliqua and being low crowned ( figs. 1B–D ) ( Prideaux, 2004). Both the molar and premolar ( fig. 1A ) fall within the size range of the southeastern population of S. occidentalis and are also similar to this species in overall morphology, in particular the development of the molar enamel crenulations. However, Prideaux (2004) stated that the molars of S. occidentalis are inseparable from S. euryskaphus ; therefore, they are only tentatively referred to Simosthenurus sp. cf. S. occidentalis pending the discovery of more complete material.

Although they cannot be positively identified, as no other sthenurines have so far been identified in the Nelson Bay LF, and their overall morphology is consistent with that of S. occidentalis , it is most parsimonious to refer the I3 ( fig. 1E ) and postcranial elements ( figs. 1I–N ) to the same species as the other dental elements until such alternative evidence arises.

Simosthenurus occidentalis is one of the most common and widespread species of sthenurine in the mid to late Pleistocene. A single tooth from the late Pliocene Dog Rocks LF, Victoria, is referred to Simosthenurus sp. cf. S. occidentalis ( Prideaux, 2004) . Like this specimen, the Nelson Bay material is evidence for the presence of an occidentalis -like simosthenurin prior to the mid Pleistocene.

Figures

Figure 1. Simosthenurus sp. cf. Si occidentalis: a, NMV P216042, right dp2, occlusal view; b–d, NMV P218251, right m1?, occlusal, labial and posterior views; e, NMV P216048, left I3, labial view. Simosthenurin sp. indet.: f–h, NMV P216899, left I1, labial, lingual and posterior views. Simosthenurus sp. fourth proximal phalanges: i–k, NMV P216147, proximal, dorsal and plantar views; l–n, NMV P173664, proximal, dorsal and plantar views. Scale bars = 10 mm.