Records of the Western Australian Museum Supplement No. 57: 239-253 (1999).

Wanburoo hilarus gen. et sp. nov., a lophodont bulungamayine kangaroo (Marsupialia: Macropodoidea: Bulungamayinae) from the Miocene deposits of Riversleigh, northwestern Queensland

Bernard N. Cooke School of Life Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Qld 4001; email: [email protected] and, School of Biological Science, University of New South Wales, Sydney, NSW 2052

Abstract - Wanburoo hi/ants gen. et sp. novo is described on the basis of specimens recovered from a number of Riversleigh sites ranging in estimated age from early Middle Miocene to early Late Miocene. The new species is characterized by low-crowned, lophodont molars in which hypolophid morphology clearly indicates bulungamayine affinity. The relatively close temporal proximity and lophodont molar morphology of the new species invites comparison with the Late Miocene macropodids, Dorcopsoides fossilis and Hadronomas puckridgi. While there is a number of phenetic similarities between the species, many of these appear to be symplesiomorphic. However, a number of apomorphies are suggested as indicating a phylogenetic relationship between the new species and early, non-balbarine macropodids represented by D. fossilis and H. puckridgi. Of these two taxa, the relationship appears stronger with Hadronomas than with Dorcopsoides. Balbarine-like characters present in Dorcopsoides are likely plesiomorphic or the result of convergence. While bulungamayines are herein regarded as more likely than balbarines to be ancestral to macropodids, the possibility of a diphyletic origin for macropodids cannot be dismissed. The suggested relationship between bulungamayines and macropodids casts doubt on the inclusion of Bulungamayinae within Potoroidae.

INTRODUCTION Possible exceptions to the above are kangaroo The Oligo-Miocene freshwater limestone deposits cranial remains recovered from Gag Site, a site of the Riversleigh World Heritage area of northern within the Riversleigh System C of Archer et al. Australia have yielded a wealth of kangaroo fossil (1989), regarded by those authors as middle material. Sixteen new fossil kangaroo species have Miocene in age. Flannery (1989: 32) provided an been described thus far and more await outline description of these remains, referring to description. Described species include them as belonging to "the Gag Site macropodine". representatives of the Hypsiprymnodontinae: Molar teeth in these remains are low-crowned and bilophodont, but the M trigonid is transversely Hypsiprymnodon bartholomaii Flannery and Archer, 1 broad, in contrast to the transversely narrow M 1987a; Propleopinae: Ekaltadeta ima Archer and 1 Flannery, 1985 and E. jamiemulvaneyi Wroe, 1996; trigonid characteristic of balbarines, considered at Potoroinae: Gumardee pascua/i Flannery, Archer and that time to be the most abundant group of Plane, 1983 and Bettongia moyesi Flannery and lophodont macropodoids occurring at Riversleigh. Archer, 1987b; Bulungamayinae: Wabularoo If the specimens could be shown to be of an naughtoni Archer, 1979, Bulzmgamaya delicata undoubted macropodine they would represent the Flannery, Archer and Plane, 1983, Nowidgee matrix oldest member of the subfamily so far known and Cooke, 1997b and Ganguroo bi/amina Cooke, 1997b; therefore be of considerable phylogenetic and Balbarinae: Ba/banJO gregoriensis Flannery, significance. Archer and Plane, 1983, Nambaroo couperi Cooke, The Gag Site specimens have been re-examined 1997a, Wururoo dayamayi Cooke, 1997a and three and they, together with material from the more species of Ganawamaya Cooke, 1992. Ga/anarla recently discovered Dome and Encore Sites, are tesse/ata Flannery, Archer and Plane, 1983 remains described more fully in this paper. A new genus unassigned to a subfamily. No specimens and species is proposed to accommodate this fossil representing unequivocal macropodines or material. sthenurines have so far been recovered from any QM F prefixes Queensland Museum, Brisbane, pre-Pliocene Riversleigh site. fossil collection catalogue numbers. These 240 B.N. Cooke

supersede the catalogue numbers (prefixed by AR) Carpentaria coastal Aboriginal word wanbu, which of the Vertebrate Palaeontology Laboratory of the means ghost (Breen 1981), and roo, a common University of New South Wales, used by Flannery Australian vernacular diminutive for kangaroo. (1989). Numbers in the latter series are indicated in Gender is considered to be masculine. parentheses where appropriate. The abbreviation UCMP = University of California Museum of Paleontology, Berkeley, California, U.s.A. Wanburoo hilarus sp. noy. Measurements are in millimetres. Figures 1-5; Table 1 Gag macropodine incertae sedis: Flannery 1989: 39

SYSTEMATIC PALAEONTOLOGY Material Examined Suprageneric classification follows Aplin and Archer (1987), molar homology follows Luckett Holotype (1993) and premolar homology follows Flower QM F20525 (formerly AR4965), the badly (1867). Cusp homology of upper molars is that of crushed remains of the skull of a subadult animal Tedford and Woodburne (1987). Molar descriptive (Figure I), including parts of the left premaxilla and terminology is used as in Cooke (1997a). maxilla preserving 13, C], dp2, dp3 (P3), M]·2 and M3 Authorities for higher category names are not within its crypt, isolated right premaxillary teeth included in the References but may be found in including P'3, part of the right maxilla with dp2 and Aplin and Archer (1987). the badly damaged buccal parts of dp3 and Ml, together with the crown of the unerupted right P3. Associated mandibular remains include most of the Supercohort Marsupialia (Illiger, 1811) horizontal ramus and part of the ascending ramus of the left dentary with I], dP , dP and M].2 in situ Order Diprotodontia Owen, 1866 2 3 , and the detached crowns of Py M3 and M4 as well Superfamily Macropodoidea (Gray, 1821) as teeth detached from the right mandible, Family incertae sedis including the tip of I], dPy the crown of the unerupted Py and M]. Subfamily Bulungamayinae Flannery, Archer and Plane, 1983 Paratypes Wanburoo gen. noy. QM F37021 (formerly AR3651), a left dentary including most of the horizontal ramus and much Type Species of the ascending ramus, including the condyle. I], Wanburoo hilarus sp. novo dP2, dP3(P) and M] are present. QM F19942, the anterior portion of the horizontal Diagnosis ramus of a left dentary containing 1 , dP , dP and 1 2 3 Robust, lophodont bulungamayines in which I] is the damaged remains of M] and M2. The crown of deep-bladed in relation to its length, enamel is P3is present and has been removed from its crypt. confined to its buccal surface, and both dorsal and QM F30346, a fragment of a left horizontal ramus ventral enamel flanges are present. The dorsal from an adult animal, preserving I). P3 and flange of I] occludes with cutting edges on P and F. detached M].2' The fragment is in two pieces, P is small and caniniform in shape; P is large, broken just anterior to the M2alveolus. unornamented, with a long occlusal edge, crown shortening towards the base. Upper canines Type Locality and Age present, in close proximity to incisors. Lower The holotype and QM F37021 are from Gag Site, molariform teeth with an anterobuccally directed low in the sequence of Riversleigh System C sites cristid, from the entoconid; hypolophid formed by (Archer et al. 1989) on Gag Plateau. Those authors an elevated, transversely oriented posthypocristid; considered Riversleigh System C to be Early to pre-entocristid, when present, directed anteriorly. Middle Miocene in age. QM F19942 is from Encore In young animals at least, the ventral margin of the Site, and QM F30346 is from Dome Site. A possible dentary is not convex below the cheek teeth and mid to late Middle Miocene age has been suggested may be straight or slightly concave in this region. for Dome Site and a possible early Late Miocene Posterior section of inferior dental canal reduced in age for Encore Site (Anonymous 1994). length to the extent that its anterior opening into the masseteric fossa is overlapped by the Diagnosis mandibular foramen. As for the genus until new species are described.

Etymology Etymology The name Wanburoo is derived from the Gulf of The specific name hilarus is Latin for mirthful or A new bulungamayine kangaroo from Riversleigh 241

A

B

c

o

Figure 1 QM F20525, holotype of Wanburoo hilarus gen. et sp. novo A, B. Buccal and lingual views of left premaxilla and maxilla. C, D. Buccal and lingual views of left dentary. Scale bars = 10 mm.

jocund, a reference to Gag Site from which the two small foramina in the palatine wing of the holotype was recovered. maxilla medial to the diastemal region. Part of the zygomatic process of the maxilla is preserved and does not reach the level of the alveolar Description margin. There appears to be no definite Premaxilla and Maxilla masseteric sulcus between the alveolar process The holotype is very badly fragmented and and the zygomatic process of the maxilla. The little detail of the premaxillary and maxillary lower margin of the infraorbital foramen is regions can be determined (Figure 1). There are visible dorsal to dp3. 242 B.N. Cooke A

B

Figure 2 Isolated right p-3 of QM F20525, holotype of Wanburoo hilarus gen. et sp. novo Teeth have been mounted in plasticene to indicate their original arrangement. A. Buccal view. B. Lingual view. Scale bar = 4 mm.

Upper Dentition vertically up the buccal surface from the occlusal The upper cheek tooth row is straight in lateral margin close to the posterior end. The occlusal view but buccally convex in occlusal view. dp2 is surface is divided by the distal end of this groove aligned with the molar row. into a larger, triangular anterior region and a short, P is the smallest of the incisors (Figure 2). It is diagonal, posterior blade. The enamel in the almost caniniform in shape and slightly recurved. anterior occlusal region is breached by wear, as is Enamel covers most of the crown except for the the enamel of the lingual margin at the level of the lingual surface and is thickest close to the crown posterior groove. The straight lingual margin is apex. There is a recess which neatly accommodates elevated to form a ridge which projects posteriorly the anterior end of 12, in the enamel of the lingual to form a small prominence lingual to a small notch face of the crown apex. There is a narrow in the posterior margin which accommodated the interdental facet on the right P, indicating the area anterior end of 13, helping to lock these teeth in of contact with the missing left P. There is evidence alignment. of slight wear of the enamel of the buccal surface 13 remains in situ in the left premaxilla and the just below the crown apex. crown of the right P has also been preserved. The The crown and part of the root of the right 12 is tooth has a long occlusal edge and is triangular in also preserved. This tooth shows much greater lateral view but the crown is taller posteriorly than wear than is present on other upper incisors. The anteriorly. There are no grooves or ridges crown is triangular in buccal view with an almost ornamenting the buccal surface. In its present vertical posterior margin and a sloping anterior position the in situ tooth is angled anteriorly with margin. There is a short groove rising nearly the occlusal edge sloping ventrally from anterior to A new bulungamayine kangaroo from Riversleigh 243 posterior, but it is not certain that this orientation buccal margin is strongly convex. The lingual has not resulted from deformation occurring during surface of the crown inclines steeply to the occlusal the depositional process. The blade-like occlusal margin from its bulbous base while the less steeply edge of the tooth is straight, but is flexed lingually inclined buccal surface slopes uniformly from the out of alignment with the cheek tooth row ­ crown base to the occlusal margin. There are four possibly also the result of taphonomic deformation. separate cuspules on the occlusal margin anterior The alveolus of Cl lies immediately posterior to to a less-defined cuspule close to the posterior end. that of P. The broken root of Cl is exposed within Transcristae associated with the four anterior the maxilla and runs horizontally posteriorl)'. The cuspules are much longer than those associated crown is short and conical, inclined anteriorly with with the most posterior cuspule. The anterior its apex flexed slightly lingually. The extremely margin of the occlusal blade is delineated by a close proximity of incisor and canine is approached crista sloping from the apex of the most anterior only by that in species of Bettongia among extant cuspule to the crown base. macropodoids, but also occurs in at least one The crowns of both left and right p3 have been undescribed balbarine species from Riversleigh. freed from their crypts. p3 is very long, more than The diastema separating Cl from dp2 is about equal 1.5 times the length of Ml (Figure 3B). The crown is in length to P3. low with a serrated occlusal margin and a large, dp2 is a short, low-crowned, bulbous-based tooth wedge-shaped posterior lingual cuspule. The right with a short occlusal margin which overhangs the p3, although damaged lingually, has a partially posterior crown base (Figure 3A). In occlusal view preserved, broad, lingual cingulum extending the lingual margin is relatively straight while the anteriorly from this cuspule. This portion of the

A'

Figure 3 Stereo views of upper dentition of QM F20525, holotype of Wanburoo hilants gen. et sp. novo AIN. Left maxilla with dp2-3, Ml -2. BIB'. Left P3. Scale bar = 10 mm. 244 B.N. Cooke crown is not preserved in the left P3. In occlusal metaloph on the lingual side of the midline. The view the outline of the crown is elliptical. The eight buccal moiety of the interloph valley is narrower cuspules present on the occlusal margin are more (antero-posteriorly) than the lingual moiety. A closely spaced posteriorly than anteriorly. The six premetacrista runs anteriorly from the metacone to most anterior of these cuspules are clearly defined the interloph valley but does not contact the and have long transcristae reaching from their postparacrista. The metaconule is taller than the apices to the base of the crown and, on the right p3, metacone and there is a distinct neometaconule extending onto the lingual cingulum. The seventh forming a short, rounded ridge on the posterior cuspule has little development of the buccal face of the metaloph at about its midpoint. A component of the transcrista, a shorter lingual prominent postmetaconule crista inclines buccally component, and is itself imperfectly delineated as it runs from the metaconule apex towards the from a longer posterior 'heel' adjacent to the crown base before turning buccally across the posterior lingual cuspule. The anterior end of the crown base to form a posterior cingulum and occlusal blade is defined by a crista sloping meeting the equally prominent postmetacrista anteriorly from the apex of the anterior cuspule to which inclines lingually towards the crown base the crown base. A shorter, more vertical crista from the apex of the metacone. defines the posterior margin. M 1 is a large tooth, almost square in occlusal dp3 is much smaller than M'. It has a straight outline. Protoloph and metaloph are of about equal buccal margin which is longer than the lingual width and all cusps are of about equal height. The margin. The central region of the anterior margin preparacrista inclines slightly lingually as it runs is concave as it abuts the posterior margin of dp2 anteriorly from the paracone apex to the anterior and the posterior margin is convex. The protoloph margin where it meets a long, narrow anterior is narrower than the metaloph. The paracone is cingulum which crosses the entire width of the narrow and is taller than the metacone. The anterior margin. The postparacrista and preparacrista forms a prominent blade-like ridge premetacrista are inflected lingually and meet in which projects beyond the anterior margin, the interloph to form a continuous centrocrista meeting the posterobuccal side of the occlusal linking the apices of protocone and metacone margin of dp2. The preparacrista, paracone and across the interloph valley. Stylar cusp C is visible very prominent postparacrista form a posterior in buccal view as a low prominence on the extension of the occlusal blade of dp2. The posterobuccal flank of the protocone, close to the protoloph is convex anteriorly and lowest just floor of the interloph valley and separated from lingual of its midpoint. Enamel has been broken the postparacrista by a flat, stylar shelf. The from the apex of the protocone. The postprotocrista postprotocrista is prominent as it crosses the is buccally inclined on the posterior face of the interloph valley and meets the crest of the protocone but turns posteriorly to cross the metaloph at a low point just lingual to the interloph valley, meeting the anterior face of the prominent, centrally-positioned neometaconule

Table 1 Dental parameters for type specimens of W. hilarus gen. et sp. novo Abbreviations: h = height; hw =width at hypolophid; I = length; mw = width at metaloph; pw = width at protolophid or protoloph; TCN = no. of transcristids; w =width.

Catalogue No. P P P Cl dP2 p3 dP3 QMF AR h I h I h h I w h TCN I w h TCN I pw mw

20525 4965 5.7 4.8 4.3 6.3 4.7 4.9 5 11.2 6.0 4.3 7 5.8 4.5 5.1 3.6 4.2 3.5 6.2 4.5 11.2 5.8 4.2 7

MI M2 I pw mw I pw mw

20525 4965 6.2 6.9 6.4 6.9 6.6 6.0

I, dP2 P3 dP3 M, M2 I w I w h TCN I w h TCN I pw hw I pw hw I pw hw

19942 15.7 3.8 6.0 4.1 5.1 4 11.8 5.7 5.5 6 5.7 3.4 4.3 6.7 5.4 7.9 20525 4965 13.5 3.1 10.1 4.1 4.7 5 6.8 4.8 4.9 6.3 5.2 5.1 10.3 3.6 4.4 5 37021 3651 15.8 2.8 11.1 3.8 3.6 7 6.3 4.2 4.5 30346 3.4 9.7 5.0 5.5 7 6.7 4.4 4.6 6.5 4.3 4.6 A new bulungamayine kangaroo from Riversleigh 245

which forms a rounded ridge on the posterior face horizontal ramus, common in potoroids and other of the metaloph. The protoloph has a low point on bulungamayines, may be age related. The poor the lingual side of its midpoint. Postmetaconule preservation of the only adult specimen makes crista, posterior cingulum and postmetacrista are assessment of the adult condition speculative. as described for dpJ. There is a small posterior mental foramen below M2 closely resembles Ml in morphology but has a M/M3• The masseteric fossa narrows anteriorly less prominent neometaconule and stylar cusp C, and it is unlikely that masseteric insertion and the centrocrista is interrupted in the interloph reached much farther anteriorly than M • The 3 valley. ascending ramus rises at an angle of 112° relative to a straight line extending along the molar Dentanj occlusal surfaces. The mandibular symphysis Holotype. The angular process of the holotype has extends posteriorly to the level of the anterior margin of dP • been lost, as has the entire dorsal margin of the 2 diastema (Figures 1 and 4). Parts of the anterior and posterior margins of the ascending ramus are Para types. The adult diastema preserved in QM present but the coronoid process and condyle are F30346 exceeds the length of P3 and is longer than missing. The lingual surface of the M alveolus 3 those of the subadult animals. The masseteric canal and the crypt of M 4 have been lost. The ventral in this specimen can be seen to be confluent with margin is relatively straight below the cheek the inferior dental canal as far forward as the M 3 tooth row anterior to the M alveolus but is 3 alveolus. inclined dorsally posterior to this. The absence Most of the dentary is preserved in QM F37021 here of marked ventral convexity of the with the exception of the dorsal margin of the

r+------59.3------_

A

B

------·---80.1-----···---·----··.....,

c

Figure 4 Dimensions of QM F20525, holotype of W. hilarus gen. et sp. novo A. Buccal view of premaxilla and maxilla B, C. Buccal and lingual views of dentary. 246 B.N. Cooke diastema, the dorsal part of the anterior margin of overlapped by the masseteric foramen, the anterior the ascending ramus and the tip of the coronoid opening of this length of canal into the masseteric process. The mandibular symphysis extends fossa. The degree of overlap is such that in • posteriorly to the level of the anterior root of dP3 dorsobuccal view it is possible to see directly from The ventral margin of the dentary is undulating, its the masseteric fossa to the pterygoid fossa, thus , lowest points occurring beneath dP/dP3 and M3 approaching the condition common in Pleistocene the posterior of these points representing the and modem macropodoids, in which there is a digastric process. Beneath the ascending ramus the large opening between the fossae visible in lateral ventral margin curves dorsally in an arc to the view. The condyle is low, elliptical in outline and posterior margin of the angular process. The has a flat surface. Its long axis is markedly inclined alveolar margin of the horizontal ramus is concave anteromesially-posterolaterally relative to the long such that central alveolar margins are lower than axis of the horizontal ramus. In shape and position those at the ends of the molar row. The mental above the molar row, the condyle more closely foramen is close to the dorsal margin of the resembles those of potoroids than those of

diastema, just anterior to P3 and there is a small macropodids. posterior mental foramen below the anterior edge of the M alveolus. The ascending ramus is inclined z Lower dentition at an angle of about 117° relative to a straight line extending along the molar occlusal surfaces. The Holotype. The cheek tooth row is straight in lateral margin of the masseteric fossa is low on the occlusal view (Figure 5). Molar teeth are fully horizontal ramus and is straight antero-posteriorly. bilophodont but crown height is lower than that The masseteric canal opens well anteriorly within seen in most extant macropodids. Molar size

the masseteric fossa and is confluent with the increases from M1 to M2 and then decreases from M M • inferior dental canal. The mandibular foramen 2 to 4

opens into an extremely abbreviated length of the I1 has a short, leaf-shaped crown which is very posterior part of the inferior dental canal and is deep in relation to its length. The anterior tip of the

Figure 5 Stereo views of lower dentition of QM F20525, holotype of WanbllToo hilants gen. et sp. novo AIA'. Left P . 3 BIB'. Left dPZ_3' MI_z' in left dentary. Scale bar = 10 mm. A new bulungamayine kangaroo from Riversleigh 247 crown of the left I) has been lost in the holotype but margin is relatively straight, with the posterior end can be seen to be sharply pointed in the remaining slightly higher than the anterior end, and in occlusal portion of the right 11 and in those of paratypes. view can be seen to curve lingually towards its Enamel is confined to the buccal surface and there posterior end. The anterior two-thirds of the are prominent dorsal and ventral enamel flanges. occlusal margin has five cuspids with which The root is circular in cross section but the crown is transcristids are associated, spacing between both narrowly elliptical in cross section. The dorsal cuspids and transcristids becoming progressively enamel flange forms the occlusal edge of the tooth less from anterior to posterior. Immediately and the enamelled buccal surface is subvertical. The posterior to this region of the occlusal margin there blade-like dorsal enamel flange on this tooth, the is an imperfectly differentiated cuspid lacking long and narrow occlusal edge on P and the wear transcristids, but the remaining portion of the patterns on the occlusal surface of F indicate that occlusal margin is unserrated. Anterior and occlusion of upper and lower incisors induced a posterior margins of the occlusal blade are defined cutting action. by cristids descending to the crown base. dP is a short, blade-like tooth with a convex • 2 M j is larger than dP3 Protolophid and hypolophid buccal margin and a concave lingual margin. The are about equal in width and lingual and buccal lingual face of the occlusal blade is more steeply cuspids are subequal in height. Lingual surfaces of inclined than the buccal face. The occlusal margin the crown are more steeply inclined than the buccal. is relatively straight in lateral view and overhangs The paracristid runs horizontally directly anteriorly the posterior base of the crown. There are four from the base of the protoconid, turns lingually clearly delineated cuspids on the occlusal margin across the anterior margin bordering a short anterior to a posterior 'heel' on which two anterior cingulid, before inclining posterolingually additional cuspids are incompletely differentiated. to terminate at the base of the metaconid. The Distance between cuspids decreases posteriorly. cristid obliqua is lingually inclined as it descends Sharply-defined transcristids are associated with the anterior face of the hypoconid but turns each of the four anterior cuspids. The anterior anteriorly to cross the broad interlophid valley and margin of the occlusal blade is defined by a cristid ascend a short distance on the posterior face of the that slopes anteriorly to the crown base from the protoconid. The hypolophid is formed by the much­ apex of the most anterior cuspid. A shorter cristid elevated posthypocristid which links the apices of defines the posterior margin. hypoconid and entoconid. A short, anterolingually

dP3 is narrower anteriorly than posteriorly. The directed, cristid descends steeply from the trigonid is dominated by a very tall protoconid entoconid apex. There is a slight posterior bulge of from which the short protolophid crest inclines the crown base below the hypolophid.

buccally. A cristid, the presumed postmetacristid, M 2 is larger than M j but closely resembles it in descends to the interlophid valley from the crown morphology except that the paracristid posterior end of the lophid, the metaconid being originates close to the apex of the protoconid.

otherwise undifferentiated. A short paracristid M 3 is smaller than M 2 and is similar to it in descends anteriorly from the protoconid to the morphology apart from having a less obvious prominent paraconid at the anterior margin. A cristid associated with the entoconid and having a cristid descends almost vertically towards the distinct premetacristid whose anterior end is crown base anterobuccal to the paraconid. The separated from the lingual termination of the entoconid is taller than the hypoconid. The cristid paracristid by a narrow cleft. The posterior bulge obliqua runs anterolingually from the apex of the of the crown base below the hypolophid is more hypoconid, crossing the interlophid valley and pronounced on this tooth. ascending the posterobuccal flank of the M4 is smaller than M3 and resembles that tooth in protoconid. The hypolophid is formed by the morphology but has a less distinct cristid obliqua elevated and lingually directed posthypocristid. A and premetacristid. short cristid from the entoconid descends steeply anterobuccally from the entoconid apex. An Para types. Except for the variations noted below, the anteriorly directed pre-entocristid is also present morphology of the lower dentition in the paratypes on the right dPy confirming the separate identities closely resembles that described for the holotype. of the cristids originating from the entoconid. More cuspids are differentiated on the occlusal P, is blade-like, low-crowned and more than half margin of P3 in the paratypes, there being seven as long again as M) (Figure SA). It has a narrow, cuspids anterior to the unserrated, posterior 'heel' crescentic occlusal outline with the buccal margin in QM F37021 and in QM F19942 in which P3 is also convex and the lingual margin concave. Both larger, and six or seven in QM F30346. Conversely, margins are constricted close to the posterior end. dI\ in the holotype has more differentiated Lingual and buccal surfaces are inclined at about posterior cuspids than those of the paratypes. The In the same steep angle. lateral view the occlusal M j anterior cingulid is shorter in paratypes, apart 248 B.N. Cooke

from QM F30346, in which it is longer. The The morphology of the preserved upper incisors paracristid links more strongly to the protoconid of Wanburoo hilarus and patterns of wear on 12, apex in QM F19942 and QM F30346 than it does in indicate that the blade-like occlusal crest of P and QM F37021 and the holotype. the smaller, posterior occlusal crest of F produced a cutting action in occlusion with the dorsal enamel

, flange of 11 Taken together with the bilophodont DISCUSSION molar morphology, this is indicative of a Flannery (1989) considered the lophodont herbivorous diet, but the relatively low condyle balbarines to be ancestral to both macropodines and brachyodont molar morphology suggest that and sthenurines. However, lophodonty also plant material consumed was not high in fibre evolved in Oligo-Miocene bulungamayine content. Wanburoo hilarus was thus most likely a kangaroos in parallel with the evolution of this browser. character within balbarines. Cooke (1997b) Sanson (1989) suggested that basal macropodoids described a mechanism of hypolophid evolution were omnivores in which premolar shearing within Bulungamayinae in which the ancestral played an important role in initial reduction of hypolophid in bunolophodont lower molars, relatively large food items before final processing formed by a strong cristid linking the entoconid through a crushing and grinding action of the apex to the lingual face of the hypoconid, was molars. Elongate premolars, a "twisted" molar row replaced by a neomorphic hypolophid derived and deep insertion of the masseter within the from the posthypocristid which became elevated masseteric canal were postulated as occurring in and transversely oriented. This mechanism is such animals. (Although elongate premolars more clearly different from that proposed by Flannery likely represent the derived macropodoid and Rich (1986) as leading to hypolophid condition, see below.) Sanson's next evolutionary formation in Balbarinae. The lophodont level was a "browser grade" of macropodine in bulungamayine, Bulungamaya delicata retains a which elongate premolars are retained but the remnant of the ancestral bunolophodont molar row is flat and no longer twisted. Dental hypolophid in the form of an anterobuccally morphology in W. hilarus fits this "browser grade" directed cristid, on the anterior face of the model in most respects. However, one of the entoconid. Such a cristid, distinct from the pre­ paratypes, QM F37021, differs from the model in entocristid, is also retained in the lower that the lower molar row is ventrally concave. This molariform teeth of Wanburoo hilarus. It is on that probably represents individual variation since the basis and its possession of elongate and crescentic condition is not obvious on other type specimens, lower premolars, that W. hilarus is assigned to and there is no matching ventral convexity of the Bulungamayinae rather than Macropodinae, upper molar row in the holotype. although it is recognized that monophyly of the Within Bulungamayinae, the lophodont molar Bulungamayinae is not demonstrated. morphology of Wanburoo hilarus ranks it with the The otherwise macropodine-like characters noted derived, lophodont species such as Bulungamaya by Flannery (1989) as occurring in the species now delicata and Ganguroo bilamina. However, it differs described as Wanburoo hilarus, are consistent with from these species in being much larger, having a , the suggestion of Cooke (1997b) that relatively shorter and much more broad-bladed 11 bulungamayines must be considered as potentially and a dentary whose ventral margin is not strongly ancestral to macropodines. This raises doubts convex, at least in subadult individuals. Molar regarding both the monophyly of the subfamily morphology in W. hilarus is more similar to that of Bulungamayinae and its status within Potoroidae. B. delicata in that both species retain traces of their These considerations, discussed more fully below, bunolophodont ancestry in having an anterobuccal are the subject of a phylogenetic analysis (in ridge from the entoconid, a remnant of the ridge preparation) of Macropodoidea which incorporates linking entoconid and hypoconid and forming the morphological data derived from the new species hypolophid crest in bunolophodont lower and other Oligo-Miocene species from Riversleigh molariform teeth. and elsewhere. Postcranial remains of balbarine The macropodid-like characters observed in the and bulungamayine kangaroos from Riversleigh derived, lophodont bulungamayine Wanburoo are currently under study by B. Kear at the hilarus prompt its comparison with more recently University of New South Wales, and the results of evolved bilophodont macropodids. Apart from the that study are likely to impinge significantly on balbarine Balbaroo camfieldensis Flannery, Archer these considerations (Kear pers. comm.). Pending and Plane, 1983, the next oldest such species are the results of these studies and their potential Dorcopsoides fossilis Woodburne, 1967 and impact on macropodoid systematics, the systematic Hadronomas puckridgi Woodburne, 1967, both from position of Bulungamayinae is here regarded as the late Miocene Alcoota Fauna. Although D. fossilis incertae sedis. was originally included in the Potoroinae within A new bulungamayine kangaroo from Riversleigh 249

Macropodidae by Woodburne (1967), Bartholomai older than Late Oligocene are known and the (1978) moved it to the Macropodinae. Hadrollonzas polarity of deep masseteric insertion and pllckridgi was described illcertae sedis by Woodburne confluence of masseteric and inferior dental canals (1967), but Murray (1991) placed it in the can only be argued on the basis of the evidence Sthenurinae within Macropodidae. These two that is available. That evidence favours the view species are here considered collectively as early that this condition is plesiomorphic. It may well macropodids rather than as representives of have evolved quite rapidly among ancestral particular macropodid subfamilies. While there is kangaroos as the developing masseteric fossa considerable phenetic similarity between W. Izilarus breached the inferior dental canal, thereby and both these species, the polarity of the common immediately allowing an anterior insertion of part character states is problematic. of the masseter within the newly common canal. Both Walllmroo Izilarus and Dorcopsoides fossilis In Riversleigh balbarines and most species of have a deeply penetrating masseteric canal bulungamayines, the masseteric foramen opening anterior!y confluent with the inferior dental canal. into the inferior dental canal is distinctly separated The unique significance of masseteric insertion from the mandibular foramen by a short posterior within the body of the dentary in macropodoids length of that canal. In both macropodines and was first noted by Abbie (1939). He postulated a sthenurines, this posterior section of the inferior sequence of development of this insertion in which dental canal is reduced to the extent that there is a deep insertion of the masseter and coalescence of single foramen connecting the masseteric and the masseteric and inferior dental canals to form a pterygoid fossae of the dentary. The condition in common canal (the condition seen in potoroids) W. hilarus, in which there is overlap between the represented the most derived condition. Since that mandibular and masseteric foramina, is time, the latter condition has been widely accepted intermediate between these two states. In view of as a potoroid synapomorphy (e.g., Woodburne the age difference between Riversleigh balbarines 1984; Case 1984; Flannery et al. 1984). Abbie's and bulungamayines, and macropodines and sequence of development of this condition was sthenurines, separation of the two foramina is the based on comparisons of extant species, but the likely plesiomorphic condition, seen also in fossil record of macropodoids, as presently known, Dorcopsoides fossi1is (Woodburne 1967). is not in agreement with this sequence. Deep In both Wallburoo Izilarus and in the figured penetration of the masseter and the development holotype, UCMP 70563, of Hadrollomas pllckridgi of a common canal within the horizontal ramus of (Woodburne 1967: 87), the mental foramen is the mandible can be argued to represent the positioned close to the dorsal margin of the plesiomorphic condition within Macropodoidea: it diastema, just anterior to Py the position in which is apparently universal in the oldest known fossil it occurs consistently in bulungamayines. In kangaroos, including the Oligocene/Miocene balbarines the foramen is consistently lower on the species of Balbarinae, Bulungamayinae, lateral wall of the diastemal region and more Hypsiprymnodontinae, Propleopinae and anterior to Py similar to the position in which it Potoroinae. Conversely, a more shallow occurs in the figured paratype, UCMP 65912, of penetration of the masseter and, probably more Dorcopsoides fossilis (Woodburne 1967: 59). The importantly, separation of the masseteric and position of the mental foramen in phalangerids is inferior dental canals by a bony lamina is the variable, making assessment of the polarity of this condition seen in macropodines and sthenurines character state impossible on the basis of outgroup which appear later in the fossil record. Observation comparison. of deep masseteric penetration within the mandible Elongate premolars, postulated as plesiomorphic prompted Woodburne (1967) to include the late for macropodoids by Sanson (1989), occur in Miocene Dorcopsoides fossilis and the extant species Wallbllroo hi/antS, Dorcopsoides fossilis and of Dorcopsis and Dorcopsulus within his Potoroinae. Hadronomas puckridgi. Similar premolars occur in Macropodoids had already achieved a high level macropodines such as Dorcopsis, Dorcopsulus and of diversity by the Late Oligocene to Early Miocene Dendrolagus, and are universal in both potoroines and their origins are likely to lie much earlier in and bultmgamayines. Their widespread occurrence the Oligocene perhaps even in the Eocene, as in this diversity of macropodoid taxa is in sugg!ested by 1989). It is conceivable that agreement with Sanson's view. However, taller the development of masseteric insertion within the and shorter premolars occur in balbarines, body of the mandible evolved within the ancestral hypsiprymnodontines and propleopines, kangaroos in a manner similar to that described by resembling in shape, if not always in relative size, Abbie (1939), achieving the 'potoroid' condition by those seen in phalangerids or even burramyids. late Oligocene times, with subsequent reversion to While balbarines are truly lophodont, their molar a more plesiomorphic state occurring by about the morphology is in many ways more plesiomorphic Late Miocene. Unfortunately, no kangaroo remains than that of other macropodoid taxa: a narrow M) 250 B.N. Cooke trigonid is universal, a protostylid and a separated by a notch or "emargination", in the hypoconulid on M j are retained in some species, as term of Woodbume (1967). There is very little are stylar cusps C and 0 on upper molars. development of a precingulid in either species. In

Outgroup comparison and the simultaneous W. hilarus and H. puckridgi M j protolophid and occurrence of short premolars and plesiomorphic hypolophid are of similar widths and molar size is molar characters both suggest that elongate least at the ends of the molar row. Lower molars of premolars represent a more derived condition both W. hilarus and H. puckridgi have posterior within Macropodoidea. Flannery (1989), on the bulging of the crown base below the hypolophid, basis of outgroup comparison with phalangerids, although this is more developed in H. puckridgi. In also regarded the hypsiprymnodontine/ Dorcopsoides the M j protolophid is narrower than propleopine premolar type as plesiomorphic. Since the hypolophid, there is a precingulid buccal to the lophodont bulungamayines and early macropodids more centrally positioned paracristid on this tooth, both have the derived premolar condition, this and molar size increases posteriorly. character suggests that such macropodids have a Dorcopsoides fossilis differs from both Wanburoo closer phylogenetic relationship with and Hadronomas in having a posterior cingulid on bulungamayines than with balbarines. lower molars, being, in this character at least, more p3 in both Dorcopsoides fossilis and Wanburoo similar to derived balbarines such as Balbaroo than hilanls has a wedge-shaped posterolingual cuspule. to bulungamayines. This structure may be Similar cuspules occur in this position in other neomorphic in D. fossilis, and its incipient bulungamayines and also in balbarines from development may be represented by the slight Riversleigh. They also presumably represent posterior bulge of the molar crown base in W. retained plesiomorphic characters. Hadronomas hilarus and its stronger development in H. puckridgi is more derived in this respect since the puckridgi. Similar posterior cingulids have arisen cuspule is there reduced to a strong posterolingual apparently independently within other ridge. p3 in W. hilanls has a slight lingual cingulum, macropodid lineages including Protemnodon (e.g. P. a character not present in more plesiomorphic anak Owen, 1874) and Troposodon (e.g. T. bowensis bulungamayines, while p3 of H. puckridgi has both Flannery and Archer, 1983, T. gurar Flannery and lingual and buccal cingula. p3 in D. fossilis has Archer, 1983). There is therefore no conclusive abrupt lateral flarings at the base of the crown, evidence indicating that the posterior cingulid of although Woodbume (1967) hesitated to consider Dorcopsoides is homologous with the posterior these cingula. Well-developed lingual cingula cingulid of balbarines, argued by Cooke (1997a) to occur on upper premolars of early macropodines be a hypocingulid. and sthenurines, and the structures on the upper Increased width of the protolophid relative to the premolars of W. hilanls, D. fossilis and H. puckridgi hypolophid, and lingual extension of the may represent stages in the evolution of such paracristid across the anterior margin to terminate cingula. at the metaconid base, may well represent Upper molars in both Dorcopsoides fossilis and synapomorphies uniting Wanburoo and Wanburoo hilanls retain stylar cusp C (the mesostyle Hadronomas, since a narrow trigonid region has of Woodbume 1967). This cuspule, commonly been regarded as plesiomorphic (Flannery et al. present in bulungamayines, is considered here to 1983, who termed it "a greatly compressed be stylar cusp C since it is associated with the trigonid"). Derivation of the lower molar posterobuccal base of the paracone. In balbarines a morphology of H. puckridgi from that of W. hilanls second cuspule, stylar cusp 0, associated with the would require only minor morphological changes: anterobuccal base of the metacone, is also loss of the remnant of the entoconid crest and commonly present. Woodbume (1967) described expansion of the posterior base of the hypolophid. triangular postparaconal and premetaconal Derivation of a Hadronomas-like morphology from "facettes" in D. fossilis and Hadronomas puckridgi. a derived balbarine, such as a species of Balbaroo,

Similar structures also occur in Riversleigh would also involve increase in the width of the M j bulungamayines and balbarines, in which their protolophid to approximate that of the hypolophid, development is associated with stylar crests linked together with loss of the postentocristid and the to stylar cusps C and D. Molar "facettes" are thus associated hypocingulid. also probably retained plesiomorphies. Derivation of the M j morphology of Dorcopsoides Lower molar morphology in Wanburoo hilanls is from a Wanburoo-like form would require a greater more closely similar to that of Hadronomas puckridgi number of changes. In addition to those listed than that of Dorcopsoides fossilis. In both W. hilanls above for Hadronomas, lingual extension of the and H. puckridgi there is an anterior cingular shelf, paracristid, expansion of the precingulid and bordered anteriorly by a lingual extension of the acquisition of a neomorphic posterior cingulid paracristid which tums posteriorly to terminate at would also be required. Such a cingulid is present the base of the metaconid, from which it is clearly on lower molars of Balbaroo species in which A new bulungamayine kangaroo from Riversleigh 251 trigonid morphology is also more similar to that of parietal contact is plesiomorphic, then squamosal­ Dorcopsoides, the latter resemblance being likely frontal contact must have arisen independently symplesiomorphic. However, evolution of within Balbarinae, Propleopinae, Hypsiprymn­ Dorcopsoides from a Balbaroo-like ancestor would odontinae, Bettongia and, according to Flannery and also require acquisition of elongate premolars, Archer (1987b), the species of Potorous and the regarded here as being the derived condition. Aepyprymnlls / Caloprynmus clade. Besides elongate premolars, lophodont molars As indicated above, Hadronomas and Dorcopsoides and p 3 lingual cingula (incipient only in have been used for comparison with Wanbllroo Dorcopsoides), there are but few potential dental hilarlls on the basis of their status as early, non­ synapomorphies uniting Wanbllroo, Dorcopsoides balbarine, macropodids, closest in age to that of and Hadronomas. However, lateral expansion of the the new taxon. Suggested synapomorphies

M j trigonid represents a further synapomorphy indicating a phylogenetic relationship between suggesting a closer relationship of Wanbllroo with bulungamayines, as represented by Wanburoo, and Hadronomas than with Dorcopsoides. early macropodids, represented by Hadronomas A character potentially of great importance in and Dorcopsoides, include lophodont molars, defining relationships among these taxa IS elongate premolars with at least incipient alisphenoid-parietal contact on the lateral wall of development of lingual cingula on upper the neurocranium. This occurs in Hadronomas premolars, lateral expansion of the M j trigonid pllckridgi and also among all Riversleigh (although Dorcopsoides is closer to the bulungamayines in which this region of the skull is plesiomorphic state for this character), and preserved (including remains referable to possibly alisphenoid-parietal contact on the side BlIlzmgamaya, Ganguroo and probably Wablllaroo). wall of the braincase. Unfortunately, this region of the skull is not known In arguing the case for inclusion of in either Wanburoo or Dorcopsoides. All known Bulungamayinae within Potoroidae, Flannery et a1. Riversleigh balbarine skulls preserving this region (1984) identified three skeletal character states that (including remains referable to Nambaroo and they considered to be synapomorphic for Balbaroo) have squamosal-frontal contact. Hitherto, Potoroidae: a convex ventral margin of the dentary, squamosal-frontal contact has been known to occur deepest below the central portion of the molar row only in potoroids, and previous workers, including (although noting that this is not universal in Pearson (1950), Woodburne (1984) and Case (1984), Potoroidae, being absent from Potorous and have regarded the condition as representing the Propleoplls), deep insertion of the masseter within derived state among Macropodoidea, a view the dentary, and an elongate and finely serrate supported by outgroup comparison with permanent premolar. Elongate premolars are here phalangerids. Discovery of the occurrence of considered to be apomorphic within alisphenoid-parietal contact in skulls of Macropodoidea, not merely Potoroidae, and deep Hypsiprymnodon bartllOlomaii and Bettongia moyesi insertion of the masseter is considered to be prompted Flannery and Archer (1987b) to conclude plesiomorphic for Macropodoidea. While other that squamosal-frontal contact could "clearly no bulungamayines, e.g. BlIlllngamaya delicata, have a longer be recognised as a synapomorphy for convex ventral margin of the dentary, this is not potoroids." However, it is significant that the case in Wanbllroo hilarlls, at least in subadult squamosal-frontal contact has not been observed animals, although its molar and premolar within what are currently regarded as macropodid morphology is closely similar to that of B. delicata. taxa other than balbarines. Dorcopsoides now an accepted macropodid, It may be argued on the basis of parsimony that shows ventral convexity of the dentary squamosal-frontal contact is the plesiomorphic (Woodbume 1967), although maximum convexity condition within Macropodoidea and that is somewhat more posteriorly located in that alisphenoid-parietal contact is derived. If so, then species. Earlier bulungamayines, such as B. delicata, alisphenoid-parietal contact must have evolved share the derived condition of convexity of the independently within Bulungamayinae, ventral margin of the dentary with potoroids, Hypsiprynmodon, the potoroine lineages indicated suggesting a potoroid origin for bulungamayines, above, and, if Balbarinae is considered ancestral to but reversion to the plesiomorphic condition may Macropodinae and Sthenurinae, at least once have occurred in later species such as W. hilarus. If within Macropodidae, possibly in a post-balbarine bulungamayines, in tum, are phylogenetically ancestor common to both those taxa. However, if ancestral to macropodids, the condition in Bulungamayinae is the common ancestor to Dorcopsoides may represent a retention of what Macropodinae and Sthenurinae, then the would then be the plesiomorphic condition for a requirement for independent evolution of the bulungamayine-macropodid clade. condition within Macropodidae is removed. If, on Bulungamayines exhibit variation in other the other hand, it is assumed that alisphenoid- characters, notably in molar morphology, with 252 B.N. Cooke basal members of the group, e.g. Nowidgee matrix, phylogenetic analysis of Macropodoidea than has exhibiting bunolophodont morphology, and more hitherto been possible. It is to be hoped that the derived species such as W. hilarus, Bulungamaya results of such an analysis will clarify the delicata and Ganguroo bilamina exhibiting undoubted phylogenetic relationships of both Bulungamayinae lophodonty. Bulungamayines thus exhibit a and Balbarinae. spectrum of characters ranging (phenetically­ speaking) from potoroid-like to macropodid-like, and it is not surprising that they have been the ACKNOWLEDGEMENTS subject of debate regarding their status as potoroids Research grants provided to Michael Archer by (Flannery et al. 1984) or macropodids (Woodbume the Australian Research Council and the University 1984; Case 1984). The range of variation exhibited of New South Wales have been the primary by the group does cast doubt on its monophyly, mechanism for providing the research material although crescentic lower premolars represent a examined in this study. Additional support for the possible bulungamayine synapomorphy. Evolution Riversleigh project has come from the National of lophodonty within Bulungamayinae is an Estates Program grants to M. Archer and A. example of phyletic gradualism which makes it Bartholomai, the Australian Geographical Society, difficult to establish boundaries for the taxon. The The Australian Museum, The Riversleigh Society, same process appears to continue beyond ICI Pty Ltd, Century Zinc Limited, the Mt Isa Shire Bulungamayinae into basal members of the and private donors. Macropodidae in which molar teeth display no Thanks are due to the palaeontological and trace of bunolophodont ancestry and become photographic staff of the Queensland Museum for increasingly hypsodont, and premolars are elongate their assistance during the course of the (though no longer crescentic) and have developed preparation of this manuscript. Thanks also to elevated lingual cingula. In view of this, and the Mike Archer and all staff, past and present, at the absence of other synapomorphies within Vertebrate Palaeontology Laboratory, University of Bulungamayinae, it is most likely that N.5.W. for their advice, many forms of help, hard Bulungamayinae is a paraphyletic, stem group work in the recovery process and skill in the basal to Macropodidae, occupying the phylogenetic preparation of the fossil material on which this position formerly assigned to Balbarinae by work is based. Flannery (1989). As a corollary to this hypothesis, Ken Aplin, Gavin Prideaux and Alex Baynes the systematic status of Balbarinae within provided much-appreciated constructive criticism Macropodidae is rendered uncertain. of earlier drafts of this paper. The fossil record at Riversleigh and elsewhere provides some circumstantial evidence supporting a likely bulungamayine origin for macropodids. REFERENCES Only a single, and as yet undescribed balbarine Abbie, A.A. (1939). A masticatory adaptation peculiar to species has so far been identified from the younger some diprotodont marsupials. Proceedings of the system C deposits at Riversleigh (Cooke 1997c). Zoological Society of London B 109: 261-279. The Riversleigh record discovered to date suggests Anonymous (1994). List of the principal Riversleigh local that balbarines were in decline by the middle faunas and their interpreted relative ages. Abstracts: Miocene, while the number of lophodont The Riversleigh Symposium 1994: 28-31. bulungamayine species was increasing. However, ApIin, K.P. and Archer, M. (1987). Recent advances in balbarines were present, then and possibly later, as marsupial systematics with a new syncretic indicated by Balbaroo camfieldensis, known from the classification. In Archer, M. (ed.), Possums and Camfield beds at Bullock Creek, estimated by opossums: studies in evolution: xv-lxxii, Surrey Beatty Murray and Megirian (1992) to be middle Miocene & Sons, Chipping Norton, NSW. in age. Several balbarine-like characters, at least Archer, M. (1979). Wabularoo naughtoni gen. et sp. nov., some of which (such as the posterior cingulid on an enigmatic kangaroo (Marsupialia) from the lower molars) are apparently apomorphic, are middle Tertiary Carl Creek Limestone of present in the late Miocene Dorcopsoides. If the northwestern Queensland. Results of the Ray E. homology of these characters can be demonstrated, Lemley expeditions, part 4. Memoirs of the Queensland Museum 19: 299-307. then the uncomfortable possibility of a diphyletic Archer, M. and Flannery, T.F. (1985). Revision of the origin for the early macropodids represented by extinct gigantic rat kangaroos (Potoroidae: Dorcopsoides and Hadronomas must be considered. Marsupialia) with description of a new Miocene Considerable numbers of cranial and postcranial genus and species and a new Pleistocene species of remains of both balbarines and bulungamayines Propleopus. Journal of Paleontology 59: 1331-1349. have now been recovered from Riversleigh. These Archer, M., Godthelp, H., Hand, S.]. and Megirian, D. preserve new morphological data which can (1989). Fossil mammals of Riversleigh, northwestern provide the basis for a more comprehensive Queensland: preliminary overview of A new bulungamayine kangaroo from Riversleigh 253

biostratigraphy, correlation and environmental Australia, and the homology of some dental change. The Australian Zoologist 25: 29-65. structures in kangaroos. Journal of Paleontology 60: Bartholomai, A. (1978). The fossil kangaroos. Australian 418-447. Mammalogy 2: 15-22. Flower, W.H. (1867). On the development and Breen, G. (1981). The Mayi languages of the Queensland succession of teeth in the Marsupialia. Philosphzcal Gulf country. Australian Institute of Aboriginal Studies Transactions of the Royal Society of London B 157: 631­ AlAS new series No. 29: 1-238. 641. Case, J.A. (1984). A new genus of Potoroinae Luckett, W.P. (1993). An ontogenetic assessment of (Marsupialia: Macropodidae) from the Miocene dental homologies in therian mammals. In Szalay, Ngapakaldi Local Fauna, South Australia, and a F.S., Novacek, M.J. and McKenna, M.C. (eds), definition of the Potoroinae. Journal of Paleontology 58: Mammalian phylogeny. 1. Mesozoic differentiation, 1074-1086. multituberculates, monotremes, early therians, and Cooke, B.N (1992) Primitive macropodids from marsupials: 182-204, Springer-Verlag, New York, Riversleigh, northwestern Queensland. Alcheringa 16: N.Y., U.5.A. 201-217. Murray, P.F. (1991). The sthenurine affinity of the Late Cooke, B.N. (1997a). Two new balbarine kangaroos and Miocene kangaroo, Hadronomas puckridgi Woodburne molar evolution within the subfamily. Memoirs of the (Marsupialia, Macropodidae). Alcheringa 15: 255-283. Queensland Museum 41: 269-280. Murray, P.F. and Megirian, D. (1992). Continuity and Cooke, B.N. (l997b). New Miocene bulungamayine contrast in middle and late Miocene vertebrate kangaroos (Marsupialia: Potoroidae) from communities from the Northern Territory. The Beagle, Riversleigh, northwestern Queensland. Memoirs of the Records of the Northern Territory Museum of Arts and Queensland Museum 41: 281-294. Sciences 9(1): 195-217. Cooke, B.N. (1997c). Biostratigraphic implications of Owen, R. (1874). On the fossil mammals of Australia, fossil kangaroos at Riversleigh, northwestern Part VIII. Family Macropodidae: genera Macropus, Queensland. Memoirs of the Queensland Museum 41: Osphranter, Phascolagus, Sthenurus and Protemnodon. 295-302. Philosophical Transactions of the Royal Society of London Flannery, T.F. (1989). Phylogeny of the Macropodoidea; B 164: 245-287. a study in convergence. In Grigg, G.J., Jarman, P. Pearson, J. (1950). The relationships of the Potoroidae to and Hume, I. (eds), Kangaroos, wallabies and rat­ the Macropodidae (Marsupialia). Papers and kangaroos: 1-46, Surrey Beatty & Sons, Chipping Proceedings of the Royal Society of Tasmania 1949: 211­ Norton, NSW. 229. Flannery, T.F. and Archer, M. (1983). Revision of the Sanson, G.D. (1989). Morphological adaptations of teeth genus Troposodon Bartholomai (Macropodidae: to diets and feeding in the Macropodoidea. In Grigg, Marsupialia). Alcheringa 7: 263-279. G.J., Jarman, P. and Hume, I. (eds), Kangaroos, Flannery, T.F. and Archer, M. (1987a). Hypsiprymnodon wallabies and rat-kangaroos: 151-168, Surrey Beatty & bartholomaii (Potoroidae: Marsupialia), a new species Sons, Chipping Norton, N.5.W. from the Miocene Dwarnamor Local Fauna and a Tedford, R.H. and Woodburne, M.O. (1987). The reassessment of the phylogenetic position of H. Ilariidae, a new family of vombatiform marsupials moschatus. In Archer, M. (ed.), Possums and opossums: from Miocene strata of South Australia and an studies in evolution: 749-758, Surrey Beatty & Sons, evaluation of the homology of molar cusps in the Chipping Norton, NSW. Diprotodontia. In Archer, M. (ed.), Possums and Flannery, T.F. and Archer, M. (1987b). Bettongia moyesi, a opossums: studies in evolution: 401-418, Surrey Beatty new and plesiomorphic kangaroo (Marsupialia: & Sons, Chipping Norton, N.5.W. Potoroidae) from Miocene sediments of northwestern Woodburne, M.O. (1967). The Alcoota Fauna, central Queensland. In Archer, M. (ed.), Possums and Australia. An integrated palaeontological and opossums: studies in evolution: 759-767, Surrey Beatty geological study. Bulletin. Bureau of Mineral & Sons, Chipping Norton, N.5.W. Resources, Geology and Geophysics, Australia 87: 1-187. Flannery, T.F., Archer, M. and Plane, M.D. (1983). Middle Woodburne, M.O. (1984). Wakiewakie lawsoni, a new Miocene kangaroos (Macropodoidea: Marsupialia) genus and species of Potoroinae (Marsupialia: from three localities in northern Australia, with a Macropodidae) of medial Miocene age, South description of two new subfamilies. Bureau of Mineral Australia. Journal of Paleontology 58: 1062-1073. Resources Journal of Australian Geology & Geophysics 7: Wroe, S. (1996). An investigation of phylogeny in the 287-302 giant rat kangaroo Ekaltadeta (Propleopinae, Flannery, T.F., Archer, M. and Plane, M.D. (1984). Potoroidae, Marsupialia). Journal of Paleontology 70: Phylogenetic relationships and a reconsideration of 681-690. higher level systematics within the Potoroidae (Marsupialia). Journal of Paleontology 58: 1087-1097. Flannery, T.F. and Rich, T.H.V. (1986). Macropodoids Manuscript received 24 December 1997; accepted 3 September from the middle Miocene Namba Formation, South 1998.