Ganawamaya, Cooke, 1992

Butler, Kaylene, Travouillon, Kenny J., Price, Gilbert J., Archer, Michael & Hand, Suzanne J., 2018, Revision of Oligo-Miocene kangaroos, Ganawamaya and Nambaroo (Marsupialia: Macropodiformes, Balbaridae), Palaeontologia Electronica (8 A) 21 (1), pp. 1-58 : 4

Genus GANAWAMAYA Cooke, 1992

Type Species. Ganawamaya acris Cooke, 1992 , by original description.

Emended Generic Diagnosis. Species of Ganawamaya differ from all other balbarids in having the following unique combination of features: a poorly developed hypocingulid; a lack of a neometaconule and postlink; a short buccally flexed p3 with five cuspids along the occlusal margin; pronounced lingual cingulum on P3; a well-developed posterobuccal transcrista on P3; a rectilinear P3; a poorly developed preprotocrista; a postprotocrista that extends into the interloph valley; a pronounced nuchal crest; and well-developed postorbital processes.

Remarks. While species of Ganawamaya and Balbaroo all have a pronounced nuchal crest, it is less developed in Ganawamaya . However, it is better developed than in several macropodiform groups (e.g., macropodines). Species of Ganawamaya also have a more gracile cranium and smaller molars than those of Balbaroo . Species of Ganawamaya differ from species of Nambaroo in having a rectilinear p3 as opposed to a more plagiaulacoid form, a less developed preprotocrista, and a postprotocrista on the M1 that extends into the interloph valley and in lacking a neometaconule and postlink. Herein ‘plagiaulacoid’ is used in this study to refer to a shorter tooth with a recurved crown and many cuspids and transcristae, while ‘rectilinear’ refers to a tooth with a straight crown and less cuspids and transcristae than premolars with a plagiaulacoid form. For example, the p3 of NMV P157559, referred to N. tarrinyeri by Flannery and Rich (1986), has a recurved crown with seven cuspids with associated transcristae anterior to the large posterior cuspid.

In this study, we also examined the holotype and sole specimen of Galanarla tessellata, QM F 10644. The distinguishing features of Gal. tessellata proposed by Flannery et al. (1982) are shared with species of Nambaroo and Ganawamaya . Those include: lophodont molars, a convex ventral margin of the dentary, a small buccal opening for the masseteric canal, a p3 flexed buccally out of alignment with the molar row. The holotype of Gal. tessellata is a heavily damaged jaw with two very worn molars. It is closest to Gan. aediculis in size and morphology. However, because most diagnostic features distinguishing balbarids (those of p3 and m1) are not preserved, its relationship to other balbarid taxa cannot, at present, be determined. However, the type locality for Gal. tessellata , Riversleigh’s D Site, is no longer accessible for fossil collection. Additionally, more informative specimens may in the future be recovered from other Depositional Phase 1 deposits such as Hiatus and White Hunter Sites (e.g., Arena et al., 2015). We suggest Gal. tesselata might be considered as a nomen dubium as the holotype specimen cannot be confidently ascribed to a single taxon.