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A tiny new marsupial lion (Marsupialia, Thylacoleonidae) from the early Miocene of Australia

Anna K. Gillespie, Michael Archer, and Suzanne J. Hand

Plain Language Abstract

Marsupial lions (Thylacoleonidae) are an extinct family of marsupials that are found in late Oligocene to Pleistocene deposits of Australia. Previously, this family consisted of three genera and eight species, ranging from domestic cat to lion in size. The paper describes a new genus and species of marsupial lion, Microleo attenboroughi, recovered from early Miocene freshwater limestones of the Riversleigh World Heritage Area of Australia. This possum-sized new species is strikingly diminutive compared to other marsupial lions. It exhibits the elongated, trenchant, upper third premolar (P3) and subtriangular, bunodont molars that are characteristic of the family, but other features of its P3 are distinctively different. Analysis of its relationships suggest that it is the most primitive member of its family and on a broader scale, and in contrast to previous hypotheses, that marsupial lions are the sister-taxon to a diverse yet entirely herbivorous group that contains all wombat-like marsupials and koalas.

Resumen en Español

Un nuevo pequeño león marsupial (Marsupialia, Thylacoleonidae) del Mioceno temprano de Australia

Se describe a Microleo attenboroughi, un nuevo género y especie de un diminuto león marsupial (Marsupialia: Thylacoleonidae) proveniente de calizas dulceacuícolas del Mioceno temprano del Área Patrimonio de la Humanidad Riversleigh, noroeste de Queensland, Australia. Un paladar roto que retiene filas de postcaninos incompletas demuestra que este nuevo león marsupial muy pequeño poseía el P3 agudo y elongado y molares superiores predominantemente subtriangulares característicos de los thilacoleónidos, mientras que otras características del premolar apoyan su inclusión en un género nuevo. Los análisis filogenéticos sugieren que Microleo attenboroughi es el taxón hermano de todos los otros thilacoleónidos, y que Thylacoleonidae podría situarse por fuera de Vombatomorphia como el taxón hermano de todos los marsupiales vombátidos, incluyendo koalas. Sin embargo, dada la información limitada sobre la morfología craneal de M. attenboroughi, conservadoramente se concluye que Thylacoleonidae es parte del clado vombatomorpho. Este nuevo thilacoleónido aumenta a tres el número de especies de leones marsupiales que se han recuperado de los depósitos del Mioceno temprano de Riversleigh e indica un nivel de diversidad no observado previamente para este grupo. Es probable que el tamaño y morfología diferentes de los tres taxones simpátricos refleje una partición de nicho y una consecuente reducción en la competencia. Los thilacoleónidos pueden haber sido los predadores arbóreos dominantes del Cenozoico de Australia.

Palabras clave: Thylacoleonidae; león marsupial; género nuevo; especie nueva; Mioceno temprano; Riversleigh

Traducción: Diana Elizabeth Fernández

Résumé en Français

Un nouveau lion marsupial (Marsupialia, Thylacoleonidae) de très petite taille du Miocène ancien d'Australie

Microleo attenboroughi gen. nov., sp. nov., un lion marsupial (Marsupialia : Thylacoleonidae) de très petite taille, est décrit à partir de restes provenant de calcaires d'eau douce du Miocène ancien de la "Riversleigh World Heritage Area", nord-ouest du Queensland, Australie. Un palais cassé préservant les rangées dentaires jugales incomplètes démontre que ce nouveau lion marsupial de très petite taille possède la P3 allongée et tranchante et les molaires supérieures majoritairement subtriangulaires caractéristiques des thylacoléonidés, alors que d'autres caractères de la P3 soutiennent son placement dans un nouveau genre. Une analyse phylogénétique suggère que Microleo attenboroughi gen. nov., sp. nov., est le groupe-frère de tous les autres thylacoléonidés, et que Thylacoleonidae pourrait être placé à l'extérieur de Vombatomorphia comme groupe-frère de tous les autres marsupiaux ressemblant à des wombats, dont les koalas. Cependant, étant donné les données limitées sur la morphologie crânienne de M. attenboroughi gen. nov., sp. nov., il est conclu provisoirement ici que Thylacoleonidae fait partie du clade Vombatomorphia. Ce nouveau thylacoléonidé porte à trois le nombre d'espèces de lions marsupiaux qui ont été trouvées dans les dépôts du Miocène ancien à Riversleigh, et indique un niveau de diversité non observé jusqu'à présent dans ce groupe. Il est probable que les différences de taille et de morphologie de ces trois taxons sympatriques reflètent un partage des niches, et donc une compétition réduite. Les thylacoléonidés étaient peut-être les prédateurs arboricoles dominants en Australie pendant le Cénozoïque.

Mots-clés : Thylacoleonidae ; lion marsupial ; nouveau genre ; nouvelle espèce ; Miocène ancien ; Riversleigh

Translator: Antoine Souron

Deutsche Zusammenfassung

Ein kleiner neuer Beutellöwe (Marsupialia, Thylacoleonidae) aus dem frühen Miozän von Australien

Microleo attenboroughi, eine neue Gattung und Art kleiner Beutellöwen (Marsupialia: Thylacoleonidae), wird aus den frühmiozänen Frischwasser-Kalken des Riversleigh Welterbestätten Gebietes (nordwestliches Queensland, Australien) beschrieben. Ein zerbrochener Gaumen mit lückenhaften Backenzahnreihen zeigt, dass dieser neue, sehr kleine Beutellöwe die länglichen, scharfen P3 und die überwiegend subtriangularen oberen Molaren, die für die Thylacoleoniden typisch waren, besaß, während andere Merkmale des Premolaren die Einordnung in einer neuen Gattung unterstützen. Phylogenetische Analyse legt nahe, dass Microleo attenboroughi das Schwestertaxon zu allen anderen Thylacoleoniden ist, und dass die Thylacoleonidae möglicherweise außerhalb der Vombatomorphia als das Schwestertaxon zu allen anderen Wombat-ähnlichen Beuteltieren inklusive der Koalas liegen. Wegen der begrenzten Datenmenge zur Schädelanatomie von M. attenboroughi, werden die Thylacoleonidae hier konservativ miteingeschlossen als Teil der vombatomorphen Klade.

Dieser neue Thylacoleonide erhöht die Anzahl der Beutellöwen auf drei Arten aus den frühmiozänen Ablagerungen von Riversleigh und weist auf ein Diversitätslevel hin, wie man es für diese Gruppe bis jetzt nicht angenommen hatte. Es ist wahrscheinlich, dass die unterschiedliche Größe und Morphologie der drei sympatrischen Taxa Nischenaufteilung abbildet und damit verringerte Konkurrenz. Thylacoleoniden waren möglicherweise die vorherrschenden baumbewohnenden Raubtiere des känozoischen Australien.

Schlüsselwörter: Thylacoleonidae; Beutellöwe; neue Gattung; neue Art; frühes Miozän; Riversleigh

Translator: Eva Gebauer

Arabic

Translator: Ashraf M.T. Elewa

 

 

 

TABLE 1. Dental dimensions (mm) for Microleo attenboroughi QM F41143 and QM F42676. Abbreviations: l = length; w = width; a = alveolar measurement; [ ] = estimate. Measurements are of maximum dimensions.

  P3 M1 M2 M3 P3-M4 m3
Specimen # l w l w l w l w l l w
QM F41143                      
(left) 4.7a 2.0a 3.5a 2.9a 3.3 3.6 2.8 3.0 [16] - -
(right) 4.6 2.7 3.6a 2.8a 3.3 3.6 - - - - -
QM F42676 - - - - - - - - - 3.0 2.5

TABLE 2. Comparative measurements (mm) of P3 length of thylacoleonid species. Abbreviations: a = alveolus measure; ^ = P3/P3-M3; # =P3/P3+M1+M2; ^^ = P3/P3 +M1 (in Thylacoleo carnifex M1 lies anterior to the posterior end of P3 hence individual tooth lengths are summed for cheektooth row length); ** = measurements from Archer and Dawson (1982).

Species Specimen number P3 length P3:M1 P3: cheektooth row length
(P3-M4)
Microleo attenboroughi QM F41143 4.6 1.2 0.29
Priscileo roskellyae QM F23453 8.2 1.4 0.35
Priscileo pitikantensis SAM P37719 11.2a 1.8a 0.36
Wakaleo oldfieldi QM F11852 14.1 1.3 -
Wakaleo vanderleueri CPC 26604 17.4 1.5 0.45^
Wakaleo alcootaensis NTM P1 23.3 1.6 0.49^
Thylacoleo hilli SAM P17621 24.4 - -
Thylacoleo crassidentatus QM F10622** 41.0 2.7 0.70#
Thylacoleo carnifex AR 21609 55.4 3.9 0.78^^
 

APPENDIX 1

Phylogenetic Analysis of Microleo attenboroughi: Results and Description of Characters

The phylogenetic relationships of Microleo attenboroughi within the Thylacoleonidae were assessed as well as the relationships of thylacoleonids within the Suborder Vombatiformes, using a branch-and-bound search in PAUP * 4.0b10 (Swofford, 2002) based on a modified data matrix of Black et al. (2012) employing a total of 93 characters. Thirty characters were designated ordered. All characters were equally weighted and parsimony-informative. Five phascolarctid taxa in that matrix were not included in this analysis because many had high levels of missing data and the phascolarctids that were included were deemed informative for that taxon. The Oligo-Miocene peramelid Galadi speciosus and dasyurid Barinya wangala were used as outgroups. Within the thylacoleonid ingroup taxa, Priscileo pitikantensis, Wakaleo alcootaensis and Thylacoleo hilli have relatively high levels of missing data because they are only known from relatively incomplete specimens. The dentary specimen of Thylacoleo sp. cf. T. hilli (AM F63584) was used to code characters for the lower dentition of T. hilli on the basis of the assumption that it is likely to be representative of that species. Sixty five of the 71 characters of the original data matrix (Black et al., 2012) analysis were utilised. Six characters were removed because they either related to phascolarctid taxa not included in the analysis or were uninformative. One character relating to P3 morphology (ch.14) was modified to incorporate states in newly included taxa. A heuristic search was performed using branch and bound analysis. New characters relating to dental morphology (ch. 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 17 18, 27, 28, 30, 38, 39, 40, 41, 42, 43, 44, 48, 50, 53, 57, 58, 59) were included in the data matrix. Bootstrap values were calculated using 1000 replicates.

Results

Our phylogenetic analysis recovered nine most-parsimonious trees (see consensus tree in Supplementary Figure 2: tree length = 272 steps, consistency index = 0.580, rescaled consistency index = 0.435, retention index = 0.750) in all of which Microleo attenboroughi is recovered as the sister taxon to all other known thylacoleonid taxa. Unequivocal thylacoleonid apomorphies (node 10) include bunodont molars and features of P3, including its length relative to M1 length (> 1.2), a longitudinal blade that has a long v-shaped (notched) occlusal edge and lack of a basal posterior cingulum. Autapomorphies distinguishing Microleo from all other thylacoleonids are features of the P3; its fusiform shape, medial cuspule, a posterolingual crest and steep posterobuccal crest at the rear of the crown. Bootstrap support was relatively strong for the thylacoleonid clade (91%) and for the Priscileo - Wakaleo - Thylacoleo clade (70%; see Supplementary Figure 2). Synapomorphies for the Priscileo - Wakaleo - Thylacoleo clade are: a posterior longitudinal blade on P3 that is gently-angled and M2 with confluent postprotocrista and premetaconulecrista. Priscileo roskellyae is recovered as the sister taxon to P. pitikantensis which in turn is recovered as the sister taxon to a Wakaleo/Thylacoleo clade. Unequivocal synapomorphies of the Wakaleo - Thylacoleo clade are increased P3 length relative to cheektooth row (> 0.4) and loss of M4/m4. Bootstrap support for this clade was moderate (83%). Species of Wakaleo form a clade (bootstrap support 62%) but their relationships are unresolved probably as a result of the limited data for both W. oldfieldi and W. alcootaensis. Synapomorphies for the Wakaleo clade include; reduced number of upper and lower premolars, development of an anterolingual cuspule and a moderately-developed posterobuccal crest on P3. Monophyly for species of Thylacoleo was well-supported (bootstrap frequency = 97%) and based on synapomorphies of P3 including: width greater anteriorly than posteriorly, a convex posterior longitudinal blade, a posterolingual crest, a significant increase in length, and reduction of the number of lower incisors to one.

Vombatiform Relationships. The strict consensus tree (Supplementary Figure 2) places thylacoleonids as the sister taxon to all other vombatiform families. This phylogeny differs from previous phylogenies (e.g., Aplin and Archer, 1987; Marshall et al., 1990; Gillespie, 2007; Black et al., 2012) which place thylacoleonids within the vombatomorphian clade. In our analysis, synapomorphies that united phascolarctomorphians and vombatomorphian families (excluding thylacoleonids, node 2) include presence of a single upper and lower premolar, presence of a lingual cusp on P3, a rectangular M2, lower incisors reduced to one, mandibular symphysis that extends to below m1 and a diastema that is < 30% the length of the horizontal ramus. Bootstrap support for this clade was weak (59%). Black et al. (2012) found phascolarctids were united by characters of the lower molars and were the sister group to all other vombatiform families. Bootstrap support for the phascolarctomorphian clade was strong (100%) but was weaker (63%) for the vombatomorphian clade (excluding thylacoleonids). With the exception of thylacoleonids and Marada arcanum, the relationships of all the other vombatomorphian families agree with those presented by Black et al. (2012). Our analysis was unable to resolve the position of Marada with respect to vombatids, diprotodontids and palorchestids.In previous analyses (Aplin and Archer, 1987; Black et al., 2012) thylacoleonids have been united with other vombatomorphian families predominantly on the basis of cranial characters and their repositioning in this analysis may be due to the large number of dental characters in the data matrix. The results of this analysis suggest that thylacoleonids possibly form a clade within Vombatiformes that has similar taxonomic status to phascolarctomorphians. However, in contrast to thylacoleonids, phascolarctomorphians show a greater diversity at the generic level and, at present, stronger support for the clade is required before erecting a possible new thylacoleonid infraorder.

Character Description

Description of 93 characters used in the phylogenetic analysis. Reference is given to characters used in previous analyses and whether they are modified.* Indicates ordered characters. Abbreviations for references: A84b, Archer (1984b); AD82, Archer and Dawson (1982); B07, Black (2007); B12, Black et al. (2012); BA97a, Black and Archer (1997a); BA97b, Black and Archer (1997b); G07, Gillespie (2007); H93, Hand et al. (1993); HSV03, Horovitz and Sanchez-Villagra (2003); HW82, Hope and Wilkinson (1982); L02, Luo et al. (2002); L04, Louys (2004); M86, Murray (1986); M90, Marshall et al. (1990); M94, Myers (1994); MA97, Myers and Archer (1997); R87, Reig et al. (1987), R98, Rougier et al. (1998); S97, Springer et al. (1997); SVW02, Sánchez-Villagra and Wible, (2002); T10, Travouillon et al. (2010); WD 87, Woodburne et al. (1987); W98, Wroe et al. (1998); W00, Wroe et al. (2000).

1.* Number of upper incisors: five (0); four (1); three (2); two (3); one (4). (S97, R98, W00, HSV03, B12)
2. Size of I1/ relative to I2-3/: equal/similar length (0); large, elongate (1). (B12)
3. Upper canine: present (0); absent/vestigial (1). (Modified: S97, HSV03, B12)
4.* Number of upper premolars: three (0); two (1); one (2). (B12, AD82, B12)
5. Number of primary cusps on longitudinal blade: one (0); two (1); three (2); four (3).
6. P3/ occlusal shape: wider posteriorly than anteriorly (0); anterior and posterior widths similar, broadest centrally (1); wider anteriorly than posteriorly (2). (G07)
7.* Absolute size of P3: small (< 5mm) (0); moderate (5-10mm); (1); large (10-20mm) (2); very large (20-30mm) (3); extremely large (>30mm) (4).
8.* Size of P/p3 relative to cheektooth row length: very short (0); short (1); long (2); very long (3). (G07)
9. Curvature of the longitudinal blade of P3: straight (0); buccally convex (1); lingually convex (2).
10.* Development of the anterolingual crest on P3: absent (0); weak, long crest (1); moderate, long crest (2); cuspule (3). (G07)
11. Slope of the posterior end of P3 longitudinal blade: steep (0); gently-angled (1); gently convex (2). (G07)
12. Long v-shaped longitudinal blade on P3: absent (0); present (1).
13. P3 Posterolingual crest: absent (0); present (1).
14. P3 Lingual cusp: absent (0); present (1). (Modified: MA97, B12)
15. P3 posterobuccal crest: absent (0); well developed (1); moderately developed (2); weakly developed (3). (G07)
16. P3 transverse parametacone crest: absent (0); present (1). (Modified: H93, BA97a, B12)
17. P3 medial cuspule: absent (0); present (1).
18. Posterior cingulum development on P3: buccal and lingual (0); lingual (1); absent (2).
19.* Size of P3/ relative to M1/: P3L/M1L ≤ 0.8 (0); 0.9 < P3L/M1L < 1.1 (1); 1.1< P3L/ M1L≤ 1.2 (2); 1.2 < P3L/M1L≤ 1.4 (3); 1.4< P3L/ M1L≤ 1.5 (4); 1.5 < P3L/ M1L≤ 1.6 (5) P3L/ M1L > 1.6 (6). (Modified: BA97a, B12)
20.* Molar morphology: tribosphenic (0); selenodont (1); semi-lophodont (2); lophodont but stylar cusps evident on lophs (3); fully lophodont (4); bunodont (5). (Modified: B12)
21. Anteriorly concave lower/ anteriorly convex upper molar lophs: absent (0); present (1). (B12)
22. Ever-growing unrooted cheekteeth: absent (0); present (1). (B12)
23. Enamel crenulations: small (0); strong, crest-like (1). (Modified: S97, B12)
24.* Stylar cusp development: strong (0); moderate (1); weak/absent (2). (Modified: BA97b, B12)
25.* Parastyle development on M1: absent/small (0); moderately developed with expansion of anterobuccal tooth corner (1); large, cuspate and pyramid-like (2). (BA97b, B12)
26. Separation of stylar cusps C and D: close together (0); separated by large trough (1). (MA97, B12)
27.* M1 occlusal outline: triangular (0); subtriangular/subsquare (1); square (2); rectangular (3). (G07)
28. M1 metacone: moderate (0); large (1).
29.* M1 paraconule: absent/weak (0); moderate/strong, linear (1); strong, crescentic (2). (Modified: BA9, B12)
30. M1 anteroposterior buccal gradient: paracone much shorter than metacone (0); paracone slightly shorter than metacone (1); paracone and metacone similar height (2); paracone slightly taller than metacone (3); paracone much taller than metacone (4). (G07)
31.* M1 neometaconule: absent (0); weak/small (1); moderate/well developed (2). (Modified: WD87, BA97b, S97)
32. Protostyle: absent (0); present (1). (WD87, BA97b, B12)
33. Paracone and metacone placement: medial (0); buccal (1). (S97, HSV03, B12)
34. Paracone buccal basin on M1 deep, enclosed: absent (0); present (1). (B12)
35. Posterolingual paracristae: absent/weak (0); strongly developed (1). (BA97b, B12)
36. Postprotocrista: present (0); absent (1). (A84b, B12)
37.* M2 occlusal shape: triangular (0); subtriangular (1); rectangular i.e., longer than wide (2); square i.e., width ≥ length (3). (Modified: S97, HSV03, B12)
38.* M2 buccal height vs lingual height: similar (0); slightly taller (1); moderately taller (2); much taller (3). (G07)
39.* M2 buccal inflation of crown below paracone: absent (0); present (1). (G07)
40.* M2 postprotocrista and premetaconule crista: confluent (0); not confluent, separated (1).
41. M2 postparacrista direction: posterobuccal (0); posterior (1).
42. M2 width of trigon basin relative to crown width: broad (0); narrow (1).
43. m3: present (0); absent (1). (AD82, G07)
44. M/m4: present (0); absent (1). (AD82, G07)
45. M4 metaconule: absent or significantly reduced and retracted towards posterior cingulum (0); distinct, cuspate (1). (B12)
46.* Number of lower incisors: three (0); two (1); one (2). (S97, R98, W00, L02, HSV03, B12)
47. Inclination angle of i1: high, ≥ 30 degrees (0); low < 30 degrees (1). (M90, B07, B12)
48. Number of lower premolars: three (0); two (1); one (2).
49. p3 morphology: bicuspid, simple (0); multicusped/bladed (1). (B07, B12)
50. p3 anterolingual crest: well-developed (0); weakly-developed: absent (1); absent (2).
51. Posterior cingulum on p3: absent/weak (0); present (1). (M94, B12)
52. Molar gradient: ratio m4/m1 < 1 (0); m4/m1 ≥ 1 (1). (B07, B12)
53. m2 talonid height relative to paraconid and trigonid: slightly shorter (0); similar (1); much shorter (2).
54. Development of paraconid and paracristid on m1: paraconid present and paracristid well-developed (0); paraconid weak or absent, paracristid present but low (1); paraconid and paracristid absent (2). (B0, B12)
55. Position of protoconid on m1: buccal half of trigonid (0); lingual third of trigonid (1). (BA97b, B12)
56.* Protostylid on m1: absent (0); small (1); moderate (2); large (3). (WD87, S97, BA97b, MA97, B0, B12)
57.* m1 talonid basin width between entocristid and hypocristid: broad (0); slightly narrowed (1); narrow (2). (G07)
58.* m1 talonid width relative to trigonid width: broader (0); slightly narrower (1); much narrower (2). (G07)
59.* m3 talonid basin: broad (0); narrow (1); absent/lost (2).
60.* Metastylid development: absent (0); present, cuspate (1); present, metastylid fold (2). (Modified: BA97b, B12)
61. Entostylid ridge on m1: absent (0); present (1). (BA97b, B12)
62. Cristid obliqua: well-developed, does not meet postprotocristid (0); well-developed, meets postprotocristid lingual to horizontal tooth midline (1); well-developed, meets postprotocristid at or buccal to horizontal tooth midline (2); weak/absent (3). (B12)
63. Internal ribs on conids of lower molars: absent (0); present, meet in longitudinal valley (1); present, do not meet (2). (B12)
64.* Nasal aperture retracted beyond incisor arcade: absent (0); retracted to above diastema (1); retracted to above cheek tooth row (2). (B12)
65.* Masseteric process: absent/weak- dorsal to molar row (0); at level of molar row (1); elongate- extends ventral to molar row (2). (W98, B12)
66. Lacrimal tuberosity: absent (0); present (1). (R98; HSV03, B12)
67. Infraorbital shelf: well-developed (0); weak (1). (B12)
68.* Posterior palatal vacuities: anteriorly extensive to opposite or anterior to M1 (0); extends anteriorly to opposite M2 (1); confined within palatine, opposite M3-4 (2); absent (3). (A84b, R87, R98, W00, HSV03, B12)
69. Frontal/squamosal contact: absent, alisphenoid-parietal contact (0); present (1). (S97, W98, HSV03, B12)
70. Infratemporal crests: weak/absent (0); well-developed (1). (B12)
71. Postglenoid constriction: absent (0); present (1). (B12)
72. Glenoid fossa: flat articular eminence, shallow mandibular fossa (0); flat articular eminence, deep mandibular fossa (1); prominent articular eminence, mandibular fossa absent (2). (B12)
73.* Postglenoid process: elongate (0); short (1); absent (2). (Modified: S97, HSV03, B12)
74. Medial glenoid process: absent (0); present (1). (M86, B12)
75. Well-developed postglenoid cavity: absent (0); present (1). (L04, B12)
76. Position of postglenoid foramen: posterior to PGP and bounded medially by petrosal (0); anteromedial to or in line with postglenoid process (1); posteromedial to postglenoid process within squamosal (2); within epitympanic fenestra, surrounded by bony septum (3). (Modified: S97, W98, HSV03, B12)
77. Tympanic cavity roof elements: alisphenoid and petrosal (0); alisphenoid and squamosal (1); squamosal (2). (Modified: T10, B12)
78. Tympanic floor elements: alisphenoid (0); alisphenoid and squamosal (1); squamosal (2). (B12)
79.* Alisphenoid tympanic wing: absent (0); short (1); moderate, extends under periotic (2); elongate, completely floors middle ear (3). (S97, W98, HSV03, B12)
80. Epitympanic fenestra: absent (0); present (1). (B12)
81. Non auditory sinuses: absent (0); present (1). (M86, B12)
82.* Posterior epitympanic fossa: absent (0); present, shallow (1); deep, perforating squamosal and mastoid (2) (M86, B12)
83. Rostral tympanic process of periotic: strong (0); absent/weak (1). (R98, SVW02, HSV03, B12)
84. Posterior parietal width: broad (0); narrow (1). (B12)
85. Interparietal: present (0); absent (1). (L04, B12)
86. Narrow mastoid strip on occiput: absent (0); present (1). (M86, B12)
87. Ventrolaterally flared mastoid process on occiput: absent (0); present (1). (M86, B12)
88. Angle of the anterior border of the ascending ramus: < 70 degrees (0); ≥ 70 degrees (1). (HW82, B07, B12)
89.* Posterior extent of mandibular symphysis: anterior to p3 (0); below p3 (1); below m1 (2); below m2-3 (3). (B07, B12)
90.* Diastema (between i1 and p3): absent (0); present, length < 30% of horizontal ramus length (1); present, length > 30% of horizontal ramus length (2). (B07, B12)
91. Tooth row length (p3-m4) relative to horizontal ramus length: > 60% (0); ≤ 60% (1). (B12)
92. Masseteric foramen: absent (0); present (1). (B07, B12)
93. Flared masseteric eminences: absent/weak (0); moderately to strongly flared (1). (M98, B12)

APPENDIX 2

Data Matrix

Data matrix used for phylogenetic analysis of Vombatiformes. Abbreviations: '?' signifies 'missing data'; '-' signifies 'inapplicable'. Polymorphic states indicated by: A, (0,1).

  1
0
2
0
3
0
4
0
5
0
6
0
7
0
Barinya wangala 1000000000 0000000010 00-00-0100 0000000101 010000?002 011000000- -20100?110
Galadi speciosus 0000000000 0000000000 -0-0001000 00000012-0 010000?002 0000000000 0200000000
Litokoala kutjamarpensis ??? 2201012 0011001101 -012202121 21011032-1 00000???1? 00?0130002 112?1?0100
Nimiokoala greystanesi 2002200011 2002200011 -012202121 21011031-1 0000020212 0000130001 1120000?00
Vombatus ursinus 4 -121010-0 -000000- 02 01-2003102 00100020-- - -00121202 00210000-0 02-1010211
Warendja wakefieldi 4 -12- 000-0 - 000000212 01-2003- 02 00100020-- - -00121202 00210000-0 02-?00020?
Kuterintja ngama ??? 22010 -3 0001000011 0000112101 00010021-1 0000121212 1021000000 01-?2?0???
Namilamadeta albivenator 2002302001 0011001022 00-0112102 00000021-0 0000121210 1021000000 02-1210111
Marada arcanum ???2?0?0?? ?????????2 00-??????2 ??????? ??? ??00?21202 1001000000 02-???????
Propalorchestes novaculacephalus ??12022?20 0011000003 10-1013102 0010012001 - -00121?0? 1102000000 02-2??1301
Ngapakaldia tedfordi 2112001000 0011010004 10-2013102 0010012001 1-00121202 1102000000 03-1111311
Nimbadon lavarackorum 2112002000 0011010014 10-2013102 0010012001 --0012120- 1101000000 03-0211311
Microleo attenboroughi ??? 0110111 0110101235 - 002002??? ?0?? 001001 0000 ?????? ???????? 0? ?? 0???????
Priscileo roskellyae 2100101122 1100300235 -002001003 0000001000 0000?10000 0011100000 02- 0000001
Priscileo pitikantensis ? 100? 021?? ????????? 5 -00 ????? ?? ????0002? 0 ?100?????? ?????? ?? ?? ?????? ?? ??
Wakaleo oldfieldi 210A102223 1100200235 -002000103 0000002110 1101-10201 0011102110 020 ???????
Wakaleo vanderleueri 210A102223 1100200235 -002000104 0000003110 1101-10202 0011102120 0200000101
Wakaleo alcootaensis ?10 2103223 1100200235 -002?00??? ?????? ?? ?? ??11-??2?? ??????2?-? ??0???????
Thylacoleo hilli ???? 123? 21 21100002 ?? -0???????? ?????? ?? ?? ?????20000 0???0????? ?????? ????
Thylacoleo crassidentatus 2100124321 2110000245 -002100104 000000???? ?111-20?00 00111022-0 020????0??
Thylacoleo carnifex 2100124321 2110000245 -002103104 000000???? ??11-20001 00111022 -0 0200010011
               
  8
0
9
0
9
3
       
Barinya wangala 0100000020 00000?0000 100        
Galadi speciosus 0100000020 0000100?00 100        
Litokoala kutjamarpensis 0100111020 0000000??? ???        
Nimiokoala greystanesi ????1?1??0 0?000??021 010        
Vombatus ursinus 1221122200 0110111132 111        
Warendja wakefieldi ???11?2200 0??01??022 111        
Kuterintja ngama ????? ?? ?? ?????? ?12? ???        
Namilamadeta albivenator 1001122120 0110111021 010        
Marada arcanum ?????? ?? ?? ?????? ?012 110        
Propalorchestes novaculacephal 11111?21?1 1211111122 111        
Ngapakaldia tedfordi 1111132201 1211110122 110        
Nimbadon lavarackorum 1111132111 1211110121 1A0        
Microleo attenboroughi ?????? ?? ?? ?????? ?? ?? ???        
Priscileo roskellyae 0001122120 0010100?10 010        
Priscileo pitikantensis ?????? ?? ?? ?????? ?? ?? ???        
Wakaleo oldfieldi ?????? ?? ?? ?????? ?010 010        
Wakaleo vanderleueri 0001122120 0001110010 010        
Wakaleo alcootaensis ?????? ?? ?? ?????? ?? 1? ???        
Thylacoleo hilli ?????? ?? ?? ?????? ?? ?0 ???        
Thylacoleo crassidentatus ?????? ?? ?? ?????? ?? 10 010        
Thylacoleo carnifex 0001022200 0011110010 010        

List of Synapomorphies

List of nodal apomorphies resulting from the phylogenetic analysis. Node numbers refer to Supplementary Figure 2.

Node Character Change
1 1 1→2
  10 0→1
  20 0→2
  24 0→2
  42 1→0
  46 0→1
  73 0→1
  75 0→1
  76 0→2
  77 0→2
  89 0→1
  91 1→0
  92 0→1
2 4 0→2
  14 0→1
  37 1→2
  46 1→2
  48 0→2
  89 1→2
  90 0→1
3 17 0→1
  18 0→1
  23 0→1
  25 1→2
  29 0→2
  31 0→2
  32 0→1
  34 0→1
  35 0→1
  37 2→3
  56 0→3
  60 0→1
  61 0→1
  62 2→1
  77 2→1
  85 1→0
4 45 0→1
  47 0→1
  51 0→1
  64 0→1
  66 0→1
  71 0→1
  82 0→1
  86 0→1
  87 0→1
5 24 2→0
  53 0→2
  65 1→2
6 3 0→1
  10 1→0
  27 2→3
  33 0→1
  38 1→0
  68 1→2
  73 0→1
  79 2→0
  90 1→2
  91 0→1
7 13 0→1
  20 2→3
  21 0→1
  36 0→1
  52 0→1
  67 0→1
  68 2→3
  80 0→1
  81 0→1
  82 1→2
  84 0→1
8 16 0→1
  20 3→4
  62 2→3
9 1 2→4
  14 1→0
  22 0→1
  51 1→0
  53 0→2
  78 1→2
  93 0→1
10 12 0→1
  18 0→2
  19 0→3
  20 2→5
11 11 0→1
  40 1→0
12 7 1→2
  37 1→0
  38 0→2
  42 0→1
13 8 1→2
  44 0→1
14 4 0→2
  10 2→3
  15 0→2
  48 0→2
15 6 0→2
  7 2→3
  11 1→2
  13 0→1
  46 1→2
16 7 3→4

APPENDIX 3

Body Mass Estimate

An estimate of the body mass of Microleo attenboroughi, Priscileo roskellyae and Wakaleo sp. nov. was made using a regression equation formulated by Myers (2001) from correlations of marsupial body mass with cranio-dental measurements. The equation used for the analysis was the highest possible ranked regression from the ‘Diprotodontians data set’ of Myers (2001, table 5, p.106) and employed the measurement for upper molar row length (UMRL, i.e., M1-M4). This equation (log y = -0.418 + 3.011 [log x], where x equals UMRL) was chosen because it was based on alveolar measurements rather than molar measurements; the posterior teeth are missing in both fossil taxa. The UMRL measurements (average of the left and right lengths) for M. attenboroughi (11.3 mm) P. roskellyae (QM F23453, 16.4 mm) and Wakaleo sp. nov. (QM F45200, 23.3 mm) resulted in body weight estimates of 590 g, 1813 g, and 5221 g, respectively. As recommended by Myers (2001), a smearing estimate (4.4%) was applied to the equation. Myers (2001) indicates that the regression equations are not appropriate for the larger species of marsupial lions (based on their unusual reduced molar numbers that result in large underestimates of body mass), hence, an estimate was not calculated for Wakaleo vanderleueri.

 

 

 

gillespieAnna K. Gillespie*, Palaeontology, Geobiology and Earth Archives (PANGEA) Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; This email address is being protected from spambots. You need JavaScript enabled to view it., *corresponding author

Anna Gillespie is a research assistant and senior preparator at the Vertebrate Palaeontology Laboratory at the University of New South Wales. She received her PhD from the University of New South Wales in 2007. Her doctorate focussed on the marsupial lions recovered from the Riversleigh World Heritage Area of Australia. She has been one of the chief preparators of the Riversleigh WHA fossil material since 1992. Her fields of interest include the evolution of Australian vertebrates and in particular, the evolution of marsupials, marsupial lion taxonomy and systematics, and functional morphology.

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archerMichael Archer, Palaeontology, Geobiology and Earth Archives (PANGEA) Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; This email address is being protected from spambots. You need JavaScript enabled to view it.

Mike Archer was born in Sydney but lived in the USA until 1967 when he moved back to Australia. By age 11 he was addicted to fossil and living animals. Degrees: Princeton University BA, University of Western Australia PhD. Key positions: Professor, University of New South Wales; Director of the Australian Museum, Sydney; Dean of Science, University of New South Wales. Research foci (~16 books & >300 refereed journal articles) include: evolution of mammals, in particular monotremes and marsupials; evolution of Australia's terrestrial environments; biocorrelation of Australia's Cenozoic vertebrates; impacts of palaeoclimate; paleoconservation; innovative biofuel company; conservation through sustainable use of native resources; native animals as pets; battling Creationism; dental function and ontogeny; megafaunal extinctions; biogeographic history of New Zealand; early Cenozoic biotas of Argentina; megatsunamis; lacustrine and karst geology; etcetera. We started the Thylacine & Lazarus Projects to see how far we could get in efforts to recover, revitalize and enable ancient DNA to reconstruct living organisms. For more info: http://www.bees.unsw.edu.au/michael-archer, http://www.create.unsw.edu.au/team/marcher/.

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handSuzanne J. Hand, Palaeontology, Geobiology and Earth Archives (PANGEA) Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; This email address is being protected from spambots. You need JavaScript enabled to view it.

Suzanne Hand is a vertebrate palaeontologist and Professor at the University of New South Wales where she teaches zoology and geology. Her research interests are largely in the areas of evolutionary biology, functional morphology, phylogenetics, and biogeography, with a special interest in fossil and modern mammals, particularly bats. She co-leads research of the World Heritage-listed Riversleigh fossil deposits of northern Australia, and is also currently researching fossil mammal faunas in Europe, Asia, New Zealand and New Caledonia. She is the author of 150+ publications on Australian fossil mammals including several books.

 

 

FIGURE 1. Microleo attenboroughi n. gen. et sp., Holotype QM F41143: 1) right maxilla and 2) left maxilla in occlusal view, stereo images; 3) interpretive drawing of right maxilla; 4) interpretive drawing of left maxilla. 5) Paratype QM F42676, occlusal views of m3 (stereophotos). Abbreviations: aabc, accessory anterobuccal cusp; ac, anterior cusp; lb, longitudinal blade; mcl, metaconule; mcus, medial cusp; me, metacone; pa, paracone; pc, posterior cusp; pr, protocone.

 figure1

FIGURE 2. Microleo attenboroughi n. gen. et sp., Holotype QM F41143, right maxilla. 1) buccal view; 2) interpretive drawing in buccal view; 3) lingual view; 4 ) interpretive drawing in lingual view. Abbreviations: aabc, accessory anterobuccal cusp; abc, anterobuccal blade; ac, anterior cusp; alc, anterolingual crest; lb, longitudinal blade; mcl, metaconule; mcus, medial cusp; me, metacone; pa, paracone; pbb, posterobuccal basin; pbc, posterobuccal crest; pc, posterior cusp; plc, posterolingual crest; pr, protocone. Scale bar equals 5 mm.

 figure2

FIGURE 3. Cladistic relationships of Microleo attenboroughi within Thylacoleonidae and Vombatiformes: 1) strict consensus tree of nine most parsimonious trees obtained in the phylogenetic analysis (tree length = 272 steps; see Appendices 1, 2); 2) time-tree of thylacoleonid phylogeny.

figure3

 

SUPPLEMENTARY FIGURE 1. Accessory anterobuccal cusp development on P3s of Thylacoleo carnifex ( 1-4) and Microleo attenboroughi ( 5, buccal view; 6, occlusal view). In a sample of 14 Thylacoleo carnifex P3s examined in the Australian Museum collection, an anterobuccal cusp was distinct in two specimens: AM F106836 (1, occlusal view; 3, buccal view); and AM F16609 (2, occlusal view; 4, buccal view). However, in T. carnifex premolars exhibiting relatively little wear, a short, broad, gently-rounded swelling was present in this region and in heavily worn specimens the entire anterobuccal surface was smooth which suggests that this feature may be relatively common but obliterated early by wear. Arrows indicate accessory anterobuccal crest (aabc).

supplemental1

 

SUPPLEMENTARY FIGURE 2. Strict consensus tree of nine most-parsimonious trees obtained from the phylogenetic analysis. Tree length = 272 steps; CI = 0.580, RI = 0.750, RSI = 0.435. Unequivocal apomorphies for nodes (circled) are listed in Appendix 2; bootstrap support values for clades in the consensus tree are indicated in italics (50% majority rule).

supplemental2