Protemnodon, Kerr, Isaac A. R., Camens, Aaron B., Van Zoelen, Jacob D., Worthy, Trevor H. & Prideaux, Gavin J., 2024

Kerr, Isaac A. R., Camens, Aaron B., Van Zoelen, Jacob D., Worthy, Trevor H. & Prideaux, Gavin J., 2024, Systematics and palaeobiology of kangaroos of the late Cenozoic genus Protemnodon (Marsupialia, Macropodidae), Megataxa 11 (1), pp. 1-261 : 193-194

‘ Protemnodon n. sp. A’

Several specimens were referred to ‘ Protemnodon n. sp. A’ by Piper (2016), who described but did not formally name a taxon from mostly isolated upper cheek teeth from the early Pliocene Hamilton LF (4.46 ± 0.1 Ma) ( Turnbull et al. 2003), early mid Pleistocene Nelson Bay LF (0.78–1.77 Ma) ( Aziz-ur-Rahman & McDougall 1972; MacFadden et al. 1987), and the early Pleistocene Dog Rocks LF (2.06–2.58 Ma) ( Whitelaw 1991), southwestern Victoria. Piper (2016) included a complete description and diagnosis but refrained from assigning a formal name or type specimen due to the need for more complete material and for a taxonomic review of the genus. All specimens listed under Protemnodon n. sp. A are isolated upper cheek teeth with the exception of NMV P216005, an associated DP2, unerupted P3 and M1 from Nelson Bay and NMV P201862b, an associated M1 and M3 from Dog Rocks.

The following is an extract from the specific diagnosis: ‘…differs from all other known species of Protemnodon , except P. otibandus and P. chinchillaensis , in possessing a P3 that is relatively more elongate compared to upper molars (see table 2), and from all species in having upper molars that are more rounded in occlusal outline (i.e. unconstricted across the [interloph] valley—base of lophs expanded lingually and swollen in the [buccal] moiety of the [interloph] valley, forming a convex [buccal] margin in occlusal view). Differs from all species except P. otibandus and P. tumbuna in having gently sloping lingual loph margins and a variably developed postlink on anterior molars in some individuals’ ( Piper 2016, p. 243). Our morphological comparisons suggest that the dental material allocated by Piper (2016) to Protemnodon n. sp. A most likely represents two or three species of Protemnodon from the Pliocene and Pleistocene, as discussed below.

Piper (2016) identified the mean ratio of M1 length to P3 length in Protemnodon n. sp. A as 0.54, in contrast to the more similar lengths in all taxa except P. otibandus and P. chinchillaensis . However, the teeth identified as M1s have narrow protoloph bases relative to the metalophs, very narrow anterior cingula, anterior moieties rotated distinctly toward the lingual side and overall anteroposterior constriction, consistent with the morphology of the DP 3 in species of Protemnodon , particularly that of P. viator sp. nov. (e.g. SAMA P53836) and P.mamkurra sp. nov. (e.g. SAMAP21863).Therefore, the apparent great difference in relative size between the P3 and M 1 in this taxon is a result of the accidental comparison of the dimensions of the P3 with those of the DP3 rather than the larger and more elongate M1.

Two DP2s from Nelson Bay LF with distinct morphologies were allocated to this taxon; one was included due to its association with diagnostic material, the other by morphological association ( Piper 2016, fig. 8, a–c and d–f respectively). The former of the DP2s, NMV P216005, is associated with an unerupted P3 and what was listed as an M3 ( Piper 2016, fig. 8m –o, fig. 9p–r respectively). This DP2, which is broad and rounded in occlusal view, falls within the morphological definitions of P. mamkurra sp. nov. and P. viator sp. nov. Based on its relative loph widths and the slight rotation of its anterior moiety towards the lingual side, the ‘M3’ of this specimen is in fact an M1. The associated unerupted P3 and the DP2 are within the morphological bounds of both P. mamkurra sp. nov. and P. viator sp. nov. The second DP2 is attributable to P. sp. cf. P. anak due to its small size, narrow posterior relative to total length, and anteroposteriorly short lingual valley. Thus, although the material used to describe this species is definitely of the genus Protemnodon , the isolated nature of all but five of the teeth has been a factor in its misidentification as a new species. We conclude that none of the material listed under ‘ Protemnodon n. sp. A’ reflects a hitherto unrecognised species of Protemnodon .