Gumardee pascuali Flannery et al., 1983

Travouillon, Kenny J., Butler, Kaylene, Archer, Michael & Hand, Suzanne J., 2016, New material of Gumardee pascuali Flannery et al., 1983 (Marsupialia: Macropodiformes) and two new species from the Riversleigh World Heritage Area, Queensland, Australia, Memoirs of Museum Victoria 74, pp. 189-207 : 191-193

Gumardee pascuali Flannery et al., 1983

Table 1, Figure 1

Holotype. QM F10646 , partial right maxilla with worn P3 and M1-4.

Additional material. QM F30421, right juvenile maxilla with P2, dP3, P3 removed from crypt, M1; QM F45107, right p3; QM F12422, left dentary with m1-4.

Revised species diagnosis. Gumardee with 11 cuspules and associated lingual and buccal transcristae on the occlusal margin of P3/p3, deep buccinator sulcus, six cuspules on P2, no StC (stylar cusp C) on M2-3, postprotocrista not connected to the metaconule on upper molars, and metaloph connects metacone to metaconule on M4.

Age and distribution. All specimens are from the Riversleigh World Heritage Area, north-western Queensland, Australia (18°15'35"S, 138°06' 41"E). The holotype ( QM F10646) and QM F12422 are from D-Site. QM F30421 is from Dirk’s Towers Site and QM F45107 is from Bone Reef Site. D-Site’s Riversleigh Local Fauna and Bone Reef Local Fauna are part of Riversleigh’s Faunal Zone A (interpreted to be late Oligocene in age), and Dirk’s Towers is part of Faunal Zone B (early Miocene in age) as distinguished by Archer et al. (1989); Archer et al. (1997), Arena (2004) and Travouillon et al. (2006, 2011).

Remarks. QM F12422 was first assigned to Wabularoo naughtoni by Flannery et al. (1984). The specimen is heavily worn and damaged, making comparisons difficult. Nevertheless, dental size and shape of QM F12422 are quite different from those of the holotype of W. naughtoni , suggesting that it represents a different taxon. Further, the molar row in W. naughtoni is straight in lateral view, but is it is convex in QM F12422, as it is in all Gumardee specimens. We assign this specimen to G. pascuali because it is from the type locality and its lower molar dimensions match those for the holotype’s upper molars. The length and width of the p3 roots also match those of QM F45107 from Bone Reef Site.

Description. The maxilla and upper dentition was described by Flannery et al. (1983), including P3, M1-4. However, the holotype is very worn (figs. 1A–C), and thus most of the dental features are obscured. Here we describe an unworn juvenile specimen ( QM F30421) referred to this taxon from Dirk’s Towers Site.

P2 is almond shaped in occlusal view, almost plagiaulacoid-like in shape, but with a straight occlusal outline (figs.1D–F). The tooth is almost as wide as it is long with its lingual margin steeper than its buccal margin. The occlusal ridge increases in height posteriorly, and has six cuspules present along its length, with the anterior five having associated lingual and buccal transcristae. The posterior cuspule is the largest.

The dP3 is molariform, and almost square in occlusal outline (figs. 1D–F). The paracone is the tallest cusp on the crown, followed in decreasing order by the metacone, neometaconule, metaconule and protocone. A slight anterior cingulum is present just lingual to the preparacrista. The preparacrista is almost horizontal as it runs from the paracone anteriorly. The postparacrista descends the posterior face of the paracone, and meets an anteriorly directed premetacrista from the metacone in the interloph valley. No stylar cups are present on the buccal margin of the tooth. The protoloph runs from the protocone buccally, rising gently for half its length and then steeply before contactingtheparacone.Thepostprotocristarunsposterobuccally before curving posteriorly midway in the interloph valley, forming a mid-link contacting the anterior face of the metaloph. A large neometaconule occurs midway along the metaloph, with an associated postlink descending the metaloph posteriorly. The postmetaconulecrista is posterobuccally directed before curving bucally to meet the postmetacrista.

A cap of P3 is represented and matches the description by Flannery et al. (1983) in having 11 cuspules on its occlusal edge (figs. 1D–F). Buccal and lingual transcristae are associated with each cuspule. The posterolingual-most transcrista is likely to be equivalent to the posterolingual ridge found in most Riversleigh macropodoids (e.g. Ganguroo species) but this transcrista is not as well developed here and contributes much less to the posterolingual heel of the tooth.

M1 is almost square in occlusal outline, but slightly wider anteriorly (figs. 1D–F). The paracone is the tallest cusp followed in decreasing order by the protocone, metaconule, metacone, neometaconule and StC. The preparacrista is straight and runs anteriorly from the paracone to the anterior margin of the tooth. The postparacrista is straight for the first half of its length and slopes directly posteriorly from the paracone apex. There, it forms a T intersection where it meets a crest connecting to a well-developed and buccally positioned StC. The second half of the postparacrista curves lingually toward the interloph valley where it connects to a straight and steep premetacrista. The protoloph is short, slightly inflated on its anterior side and steeply descends the lingual flank of the paracone until it meets the preprotocrista at about one third of its length from the protocone. The preprotocrista runs from the protocone anterobucally, and curves slightly more anteriorly where it meets the protoloph. An anterior cingulum is present anterior to the protoloph and is bordered by the preparacrista bucally and preprotocrista lingually. A short and low precingulum is present lingual to the preprotocrista. The postprotocrista descends posterobuccally from the protocone toward the interloph valley where it forms a distinct wall before rising posteriorly toward the metaloph but ends before reaching it. The metaloph is parallel to the protoloph and descends the lingual flank of the metacone to connect to a tall metaconule. The neometaconule is present midway along the metaloph, with an associated postlink. The postmetacrista runs posteriorly from the apex of the metacone to connect close to the crown base the postmetaconulecrista which sweeps across the posterior face of the loph.

The dentary is damaged anteriorly and posteriorly (figs. 1J–L). The ventral margin is convex in lateral view, and the dorsal margin is concave, with the posterior molars elevated above the anterior molars. A deep but narrow buccinator sulcus is present on the buccal side of the dentary and runs from below the root of p3 to level with the anterior root of m2. The full depth of the masseteric canal is preserved and ends below m2.

The p3 is a sectorial tooth, longer than it is wide (figs. 1G–I). The anterior portion of the tooth is wider than its posterior portion. In lateral view, the occlusal edge is straight and slightly more elevated posteriorly, but in occlusal view, the main crest is posterolingually curved. The posterior part of the tooth is damaged on the lingual side, preventing an accurate assessment of the number of cuspids on the crown. There are at least 11 cuspids with associated coarse lingual and buccal transcristids, descending for two thirds the crown height. The lingual flank of the tooth is much steeper than the buccal flank. A short cristid descends anteriorly from the anterior end of the occlusal margin, but damage prevents an assessment of the presence of a posteriorly orientated cristid.

The m1 is heavily worn (figs. 1J–L). Very little of its morphology can be discerned. The tooth is roughly rectangular in occlusal outline but the talonid is wider than the trigonid. In occlusal view, dentine has been exposed through most of the occlusal surface, except for a thin layer of enamel on the margin of the tooth. The buccal cuspids seem more worn than the lingual.

The m2 is similar to m1 except as follows (figs. 1J–L): the tooth is longer and wider; the trigonid is almost as wide as the talonid; and a precingulid and anterior cingulid are present.

The m3 is similar to m2 except as follows (figs. 1J–L): the tooth is longer and wider; the talonid and trigonid are almost the same width; the tooth is less worn, revealing some of its morphology, such as the presence of a postmetacristid and preentocristid, and the posthypocristid was not connected to the buccal crest from the entoconid.

The m4 is similar to m3 except as follows (figs. 1J–L): the tooth is shorter and narrower; and the trigonid is much wider than the talonid.

Figures

Figure 1. Gumardee pascuali, holotype QM F10646, right maxilla with P3, M1-4: A, buccal, B, lingual, and C, occlusal (stereopair) views; QM F30421, right juvenile maxilla with P2, dP3, P3 removed from its crypt, M1: D, buccal, E, lingual, and F, occlusal (stereopair) views; QM F45107, right p3: G, buccal, H, lingual, and I, occlusal (stereopair) views; QM F12422, left dentary with m1-4: J, buccal, K, lingual, and L, occlusal (stereopair) views. Scale bar equals 10 mm.