PRlSClLEO ROSKEUY AE SP. NOV. (THYLACOLEONillAE, MARSUPIALIA) FROMTHE OLIGOCENE-MIOCENE OF RIVERSLEIGH, NORTHWESTERN QUEENSLAND

ANNA GILLESPIE

Gillespie, A., 19970630. Priscileo roskellyae sp. nov. (Thylacoleonidae, Marsupialia) fromthe 0ligocene-Miocene of Riversleigh, northwestern Queensland Memoirs of the Queens-land Museum 41(2): 321-327. Brisbane. ISSN 0079-8835.

Upper dentition of the marsupial lion Priscileo roskellyae sp. nov. from the Upper Site LocalFauna of Riversleigh provides the first detailed infonnation about upper dentition of thegenus. The upper adult dental fonnula is 11-3. C I, PI-3, M 1-4. This species is smaller thanP. pitikantensis and is the most plesiomorphic thylacoleonid. Relative to Wakaleo, P3 is lessbowed and molars are square and have a metaconule at their posterior margin.OThylacoleonidae. Wakaleoninae, Priscileo. Riversleigh. Oligocene. Miocene.

Anna Gillespie, School of Biological Science, University of New South Wales, New SouthWales 2052, Australia; received 15 February 1997.

outline, with a posterolingual metaconule; ante-rior root of the zygomatic arch projecting an-terolaterally dorsal to M2-3.

The marsupial lion genus Priscileo Rauscher ,1987 contains only P. pitikantensis Rauscher,1987, from the late Oligocene Ngapakaldi LocalFauna, S. Aust which is known only from a max-illary fragment, a few teeth, and a number of postcranial elements. Additional Priscileo materialhas been recovered from the Oligocene-Mioceneof Riversleigh, northwestern Queensland. Thismaterial includes a near complete skull from theUpper Site Local Fauna representing Priscileoroskellyae sp. nov.

Dental terminology for molars and the last pre-molar follows Luckett (1993) who has shown thata molariform dP3 (MI of Archer, 1978) in mar-supials is replaced by P3. Accordingly, the re-maining molars represent MI-4. However,homology of the other premolars follows Flower( 1867). Material is housed in the CommonwealthPalaeontological Collection, Bureau of MineralResources, Canberra (CPC), Northern TerritoryMuseum (NTM), Queensland Museum (QMF),South Australian Museum (SAMP), Museum ofPalaeontology, University of California, Berke-ley (UCMPB).

SYSTEMATICS

Superorder MARSUPIALIA IIliger, 1811Order DIPROTODONTIA Owen, 1866

Family THYLACOLEONIDAE Gill, 1872

Priscileo Rauscher, 1987

TYPE SPECIES. Priscileo pitikantensis Rauscher,

1987.

Priscileo roskellyae sp. nov.

(Figs 1-3)

MATERIAL. Holotype QMF23453, a skull with leftand right P3, Ml-2, alveoli for left and right 12-3, CI,Pl-2, M3-4, and partial alveoli for the left and right IIfrom early Miocene Upper Site, Godthelp Hill,Riversleigh.

ETYMOLOGY. For the former Australian Minister ofArts, Sport, the Environment, Tourism and Territories,the Hon. Ros Kelly, who provided significant supportfor the Riversleigh Project.

DIAGNOSIS (by comparison with the type andonly other species). Smaller; P3 approximately2/3 as long; metaconule on MI and M2; alveolusof PI closer to the P2 alveolus than to the caninealveolus; lingual root on MI smaller, not intrud-ing as far medially into the palate.

DESCRIPTION. Upper dentition. Formula 11-3,CI, PI-3, MI-4. Alveoli for II large and incom-plete. Alveolus for 12 smallest of incisor alveoli.Alveolus for C 1 ovoid, larger than alveolus for13, smaller than that for I I. Canine alveolus closerto 13 alveolus than to PI alveolus. Two smallalveoli for two single-rooted premolars betweenthecanineandP3.CI and PI alveoli separated byan approximately 3 mm. P2 alveolus close behindthat for PI, abutting the anterior base of P3.

P3. As in Wakaleo but 25-66% smaller. Posteriorportion only slightly broader than the anterior

DIAGNOSIS. Small; P3 length usually less than12mm; MI and M2 relatively square in basal

322 MEMOIRS OF THE QUEENSLAND MUSEUM

FIG. I. Priscileo roske//yae sp. nov., holotype, QMF23453, partial skull, from Upper Site, Godthelp Hill,Riversleigh. Ventral view stereopair, showing upper dentition.

curving slightly anteriorly as it ascends andmerges with the base of the crown. Many T.carnif ex and T. crassidentatus also with lingualblade in contrast to W. alcootaensis and W.vanderleueri in which it is absent. Posterior to thelingual blade the lingual flank of P3 formiing asharp depression extending from the base to thecrown. Lingual flank following the curve of theposterior root, curving convexly to the posteriorborder. Buccal blade of the anterior cusp ascend-ing in a slight posterior direction, merging withthe crown midway up the tooth. Short buccalblade also ascending from the posterior cusp,merging with the crown midway up the tooth, notas prominent as the anterior buccal blade. Similaranterior and posterior buccal blades in Wakaleo.Posterior blade running posterolaterally from theposterior cusp to the posterior margin of the tooth,an extension of the longitudinal blade, contiguouswith the preparacrista of MI, in P3 of Wakaleobut absent in Thylacoleo. Short oblique blade attermination of posterior blade at the posteriormargin of P3, ascending anterolaterally on thebuccal flank, merging midway with the base of

portion (unlike Wakaleo where the posterior ismuch broader). Longitudinal blade slightly in-wardly-curved in contrast to the distinctive in-wardly-curved blade of most Wakaleo.Relatively uniform width with gently curved lon-gitudinal blade giving P3 rectangular shape. Lon-gitudinal blade running between 2 major cusps.In buccal view, the shearing blade of P3 w-shaped, the longitudinal blade forming the rise inthe middle, and the anterior and posterior bladesascending from the major cusps at each end. Theanterior cusp is slightly higher than the posterior(as in W. alcootaensis). In,W. vanderleueri thecusps are approximately equal in height. Threevertical blades, one anterior, one lingual, and onebuccal, ascending from the anterior cusp to thebase of the crown. Anterior blade curving lin-gually as it ascends, bending slightly posteriorlybefore merging with the base of the crown. Lin-gual curvature of blade producing a small verticallip towards the base of the blade. Similar lip insome Riversleigh Wakaleo. Posterior to this bladelingual face of the crown curving concavelyforming an anterolingual basin. Lingual blade

PRJSCJLEO ROSKELLYAE SP. NOV. FROM RIVERSLEIGH 323

TABLE I. Dimensions of upper cheek teeth of speciesof Priscileo and Wakaleo. Data from Clemens &Plane (1974), Archer& Rich (1982), Rauscher(1987)and Murray & Megirian ( 1990). Measurements for P.pitikantensis (except P3) were taken from from a casteof UCMP88448. a=alveolus measurement.

the crown, lacking in Thylacoleo and W. al-cootaensis. W. vanderleueri with a small blade ina similar position, differing by commencing ashort distance before the end of the posteriorblade, more vertically oriented. On the buccalflank of P3, a broad valley running between theanterior and posterior buccal blades, muchbroader, in Wakaleo.

trigon basin. W. vanderleueri and RiversleighWakaleo with much straighter and longer bladeascending lingually from the paracone. Pre-protocrista arising from the anterior edge of thetrigon basin medial to the paraconule, runningposteromedially to the protocone. From the pro-tocone a postprotocrista running posteriorly to ametaconule. Postmetaconulecrista curvingposterolaterally from the metaconule, ascendingto merge with the posterior margin of thepostmetacrista. Short crescent-shaped ridge as-cending lingual face of metacone, terminatingmidway between metacone and metaconule. MIof W. vanderleueri and Riversleigh Wakaleo withsimilar ridge. Blades joining the 4 major cuspsforming margins of a deep, square trigon basin.Within the basin, fine enamel crenulations radiateoutwards. Similar crenulated trigon basins occurin Wakaleo and T. crassidentatus. Buccal flankofMI, especially anteriorly, swollen resulting ina broad base for the stylar shelf. A stylar basinrunning from the posterobuccal face of theparacone to the posterobuccal margin of themetacone, becoming shallower posteriorly. Lat-eral wall of the basin lined with small verticalridges.

M2. M2 smaller than MI, lacking the distinctivebroad stylar shelf and basin. Paracone highestcusp, more lateral than in MI. Short, semicircularpreparacrista running anteromedially from theparacone. Small ridge buttressing lingual base ofthe paracone. Medial to this ridge a preprotocristaarising, running posteromedially to the pro-tocone. Protocone prominent, more anteriorlyplaced than in MI. Protocone lingually bulbousas in P. pitikantensis and Wakaleo. A narrowanterior shelf running from the base of the pre-paracrista to the protocone. Postprotocrista run-ning posterobuccally to a gently-rounded,posterior metaconule, producing squaring of thelingual outline. No metaconule on M2 of P.pitikantensis but could be lost by damage to rearportion of the tooth. Short postmetaconulecristarunning posterolaterally, merging with the poste-rior margin of the tooth. Metacone rounded andmore posteriorly situated than in M I, with lingualblade running medially, connecting with a smallblade running laterally from the metaconule,forming anterior border of a small, oval, basin atthe posterior. Postparacrista runningposterolaterally to the buccal margin of the stylarshelf, converging with anterolaterally orientatedpremetacrista. Deep, square, trigon basin be-tween the major cusps with fine enamel crenula-

Molars. Left and right MI and M2 relativelyunworn. Alveoli for M3 and M4 indicating 3roots for each; 2 equal anterior roots, with slightlylarger posterior one. In Wakaleo vanderleuerianterior roots of M3 larger. Molar gradient steep,similar to P. pitikantensis and Wakaleo. MI andM2 square, unlike the triangular molars inWakaleo. Molar morphology similar to Wakaleo.MI wider anteriorly than posteriorly. Paraconehighest cusp. Small blade ascending anteriorlyfrom the paracone to the anterior edge, joiningstylar cusp B, contiguous with brade ascendingfrom the posterior cusp ofP3. Postparacrista run-ning- posteriorly, meeting the ascending pre-metacrista, forming a notch midway along thestraight centrocrista. Metacone well-developed.Postmetacrista ascending posteriorly from themetacone to the posterior margin ofMI. Buttress-ing the steep lingual face of the paracone a short

crescent-shaped preparaconulecrista straighten-ing medially, terminating at a paraconule. Shortpostparaconulecrista running posteriorly into the

MEMOIRS OF THE QUEENSLAND MUSEUM324

FIG. 2. Priscileo roskellyae sp. nov., holotype, QMF23453, measurements (mm) of left tooth row.p3 on left, Miand M2.

crenulate, anteroposteriorly broad trigon basin.Some of the new Riversleigh Wakaleo specimenshave these features. Two Wakaleo specimenshave an M4 (Table I ), and most have a relativelybroad crenulated basin on M2. All species ofWakaleohaveaP3/M1 ratio of less than 1.70. Thevalue for P. roskellyae ( 1.41) falls midway withinthis range.

Rauscher (1987) distinguished Priscileo fromWakaleo by the loss of PI or 2 and M4 in thelatter. Although some new Riversleigh Wakaleospecimens have these teeth, the plesiomorphicfeatures of P. roskellyae exhibits (significantlysmaller size, square molar shape, metaconule andrelatively straight cutting blade on P3) requiregeneric distinction. P. pitikantensis and P.roskellyae share generic features of dental dimen-sions, shape of M2 and position of the anteriorbase of the zygomatic arch. Specific distinctionof P. roskellyae is based on the size differencebetween these two species,P. pitikantensis being33% larger.

tions concentrated on the lateral and posteriorwalls. Crenulated basins in M2 of P. pitikantensisand Wakaleo. On the buccal margin of M2 asmall, elongate, stylar basin parallel to thepostparacrista, terminating midway between theparacone and metacone. Similar basin inRiversleigh Wakaleo, difficult to discern in theheavily worn M2 of W. vanderleueri.

COMPARISON. P. roskellyae differs from allspecies of Wakaleo in: being smaller; the P3 of P.roskellyae is approximately 1/3 length of P3 ofW alcootaensis, 1/2 the length of P3 of Wvanderleueri, and 2/3 the length of P3s ofRiversleigh Wakaleo; having a lingual crest as-cend from the anterior cusp of P3; having theshearing blade of P3 straighter; having the poste-rior root of P3 only slightly enlarged; having theposterior half of P3 relatively square in basaloutline; having MI and M2 relatively square inbasal outline. P. roskellyae differs from Thy-lacoleo in: being smaller; P3 being approxi-mately 1/31ength ofP3 ofT. hilli and l/61engthofP3 ofT. carnifex; having M3+4; having Ml+2relatively square in basal outline.

INTRAF AMILIAL RELATIONSHIPS

Rauscher (1987) found no synapomorphies unit-ing Priscileo and Wakaleo, or uniting Priscileoand Thylacoleo. Analysis of Priscileo and Thy-lacoleo included comparison of postcrania1 ma-terial and for a number of character-states,Thylacoleo exhibited the plesiomorphic condi-tion while Priscileo was derived. Rauscher con-

DISCUSSION

The diagnosis of Priscileo is amended to includeP. roskellyae. Rauscher ( 1987) distinguishedPriscileo from other thylacoleonids by M4, aP3/M 1 length ratio less than 1.70, and M2 with a

PRISClLEO ROSKELLYAE SP. NOV. FROM RIVERSLEIGH 325

prpac

me

I

Smm

FIG: 3. Priscileo roskellyae sp. nov., holotype, QMF23453, left cheek dentition. Ib=longitudinal blade; ab=an-tenor blade; pb=posterior blade; ac=anterior cusp; pc=posterior cusp; abb=anterior buccal blade; linb=lingualblade; pbb=posterior buccal blade; alb=anterior lingual basin; pa=paracone; pacl=paraconule; prpac=pre-paracrista; popac=postparacrista; prpaclc=preparaconulecrista; popaclc=postparaconulecrista; pr=protocone;mcl=metaconule; pomclc=postmetaconulecrista; me=metacone; pomc=postmetacrista; prmc=premetacrista;stB=stylar cusp B; trb=trigone basin.

cluded that Thylacoleo's primitive features were Thylacoleoninae which includes Thylacoleo andsecondarily deri ved and not a retained possibly Priscileo. Wakaleonines were regardedplesiomorphic condition. Because Wakaleo and to differ from thylacoleonines in absence of PIThylacoleo share the synapomorphy of loss of and formation of a tympanic wing composed ofM4, Rauscher (1987) considered them to be sister alisphenoid and squamosal contributions. Fea-groups. Priscileo was regarded as the sister group lures distinguishing thylacoleonines fromof a Wakaleonhylacoleo clade. wakaleonines include PI, squamosal contribu-

Rauscher (1987) suggested that loss of the lion to the tympanic wing and frontal-squamosalmetaconule could be a diagnostic feature for the contact on the lateral cranial wall. The new thy-Thylacoleonidae based on the tritubercular upper lacoleonid specimens from Riversleigh indicatemolars of Wakaleo and Priscileo and the second- that, in terms of dental morphology, Priscileoarily quadritubercular MI of Thylacoleo. How- exhibits no features that prevent it from beingever, M 1 and M2 of P. roskellyae have a ancestral to Wakaleo and Thylacoleo. The dentalmetaconule and are basicalIy square in outline. features of Priscileo, including small P3 andThe metaconule on these molars, especially on molar size, square (nearly bunodont) molarM2, is posteriorly positioned and its seeming shape, metaconule, and full premolar and molarabsence from M2 of P. pitikantensis may be a complement are almost certainly plesiomorphicresult of damage which is evident at the rear features within the family.margin of this tooth. Consequently, loss of the However, these same features clarify somemetaconule can no longer be considered a syn- questions about relationships of the family withapomorphy for the family. the Order Diprotodontia. 11 was once commonly

Murray et al. (1987) placed Wakaleo and Thy- believed that thylacoleonids evolved from alacoleo in separate subfamilies: the Waka- phalangerid-like diprotodontian which hadleoninae includes Wakaleo; and the quadritubercularuppermolarsincludingahyper-

MEMOIRS OF THE QUEENSLAND MUSEUM326

Beavis, Martin Dickson, Sue & Jim Lavarack andSue & Don Scott-Orr. Invaluable assistance in thefield has come from numerous volunteers, staffand postgraduate students of the University ofNew South Wales.

LITERATURE CITED

trophied metaconule (Krefft, 1872; Broom, 1898;Bensley, 1903; Ride, 1964; Archer, 1976).Archer & Rich ( 1982) hypothesi sed that thetritubercular shape of the molars of W. alcootaen-sis were secondarily derived from an ancestralquadritubercular shape through suppression ofthe metaconule. It has been suggested that thetriangular molars of Wakaleo are plesiomorphicfor the family (Murray et al., 1987). The primitivedental features of P. roske//yae. especially themetaconule and square molar shape, provide sup-port for Archer & Rich ( 1982).

Priscileo and Wakaleo have been collectedfrom Riversleigh's System B sites indicatingoverlapping of early Miocene thylacoleonid lin-eages. Temporal overlapping of species of Thy-lacoleo (T. crassidentatus and T. hi//i) alsooccurred in the early Pliocene (Archer & Daw-son, 1982). In each case there was a distinct sizedifference in the lineages involved. In termsofP3length, System B specimens of Wakaleo are ap-proximately 1.5 times larger than P. roske//yae.Similarly, P3 of T. crassidentatus is twice thelength of that tooth in T. hi//i (Pledge, 1977). It ispossible that size differences of this magnitudeamong sympatric thylacoleonids were an import-ant factor in reducing competition. Morphologi-cal studies of the limbs of P. pitikantensis suggestit was arboreal (Rauscher, 1987). Wakaleo, beinglarger and no doubt heavier, may have been moreterrestrial. Murray & Megirian ( 1990) also inti-mated a terrestrial existence for Wakaleo basedon the wrist joint and heavily-wom dentitionwhich they consider may indicate a scavengingmode of life.

ACKNOWLEDGEMENTS

I thank Michael Archer and Henk Godthelp forconstructive comments and Stephan Williams,Karen Black and Jenni Brammall for assistancewith photography. Support for research atRiversleigh has come from the Australian Re-search Grant Scheme; the National Estate GrantsScheme (Queensland); the University of NewSouth Wales; the Commonwealth Department ofEnvironment, Sports, and Territories; theQueensland National Parks and Wildlife Service;the Commonwealth Heritage Unit; ICI Australia;the Australian Geographic Society; the Queens-land Museum; the Australian Museum; the RoyalZoological Society ofNSW; the Linnean SocietyofNSW; Century Zinc; Mount Isa Mines; SurreyBeatty & Sons; the Riversleigh Society; and pri-vate supporters including Elaine Clark, Margaret

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