Ganawamaya gillespieae, Butler & Travouillon & Price & Archer & Hand, 2018

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 : 17-18

Ganawamaya gillespieae comb. nov.

v* 2007 Nambaroo gillespieae ; Kear, Cooke, Archer, and Flannery, p. 1147, figs. 1–10.

Holotype. QM F35432 , cranium, left dentary and postcranial material from Quantum Leap Site , Riversleigh WHA, northwestern Queensland, Australia ( Kear et al., 2007).

Referred specimens. Dirk’s Tower Site: QM F13099, right dentary with p3, m1–m4; QM F13100, left maxilla with M2–M4; QM F16912, right maxilla with M1–M2; QM F20036, left dentary with m1–m3; QM F24178, right maxilla with M1–M2, M4; QM F24180, right maxilla with M2–M3; QM F24185, left maxilla with P3 and M1; QM F24479, left maxilla with broken M2, M3; QM F29661, right dentary with m2–m4; QM F30289, left dentary with p3, m1–m4; QM F36233, left dentary with i1, p3; QM F36339, left dentary with i1, dp2, unerupted p3, m1–m3.

Emended species diagnosis. Ganawamaya gillespieae comb nov. differs from all other species of Ganawamaya in having the following unique combination of features: no distinct masseteric process; poorly-developed sulcus on anterior extremity of zygomatic arch; a large zygomatic epitympanic sinus with a thick mesial wall; a small mastoid foramen on the mastoid/squamosal suture; prominent hypocristid on m1 and m2; reduced paraconidon m1; long and sinuous i1 with dorsal and ventral flanges; no hypoconulid; no marked convexities on lateral margins of interlophid valley of lower molars; poorly developed anterior cingulum of M1; stylar cusp C on M1 reduced and connected to postparacrista; no additional cuspid on the posterior of p3 below the occlusal margin; m1 anterior cingulid extends from the paracristid right across to buccal surface of tooth; curved occlusal edge on p3; no inclined ridge from the anteriormost cuspid on p3.

Description

The lower dentition resembles that described by Kear et al. (2007) other than as follows: The p2 (preserved in QM F36339) is a very short but broad tooth with steeply sloping buccal and lingual faces. Two prominent cuspids are evident along the blade of the tooth, each with associated transcristae. In buccal view the occlusal surface is slightly convex. Remarks. Specimens here referred to species of Ganawamaya (and some previously referred to Nambaroo ) from Quantum Leap and Dirk’s Tower also exhibit cusp morphology variation that can be attributed to differences in dental wear similar to that of specimens reassigned to Gan. acris and Gan. aediculis . These variations include the presence, or apparent absence, of the protostylid on m1, the shape of the paracristid on m1 and the complexity of enamel ridges on i1. Both QM F13099 and 20036 for example have no protostylid but are otherwise similar to the holotype of Gan. gillespieae comb. nov. A second specimen referred to N. gillespieae from Wayne’s Wok Site (AR 12829) by Kear et al. (2007) could not be located for the present study. This specimen is therefore not included in the revised specimen list of Gan. aediculis .

Age and distribution. The holotype of Ganawamaya gillespieae comb. nov. is from Quantum Leap Site, Riversleigh WHA, northwestern Queensland. The Quantum Site was initially interpreted to be part of Faunal Zone A ( Travouillon et al., 2006, 2011). However, recent studies indicate that it is part of intervals B2 or B3 of Faunal Zone B ( Travouillon et al., 2010, 2013; Arena et al., 2015). Other referred specimens from Dirk’s Tower Site are interpreted to represent part of interval B1 of Faunal Zone B by Arena et al. (2015).