ORIGINAL PAPER

The Bony Labyrinth in Diprotodontian Marsupial Mammals:Diversity in Extant and Extinct Forms and Relationshipswith Size and Phylogeny

Léanie Alloing-Séguier & Marcelo R. Sánchez-Villagra &

Michael S. Y. Lee & Renaud Lebrun

# Springer Science+Business Media New York 2013

Abstract The shape of the bony labyrinth of the inner ear wasquantified using geometric morphometrics in a sample of 16species of living marsupial diprotodontians, the extinctDiprotodon and Thylacoleo, and four outgroups. X-raymicro-computed tomography (μCT) and conventional comput-ed tomography (CT) were used to acquire 3D data. The anal-yses of 22 landmarks revealed a strong body-mass relatedallometric pattern. A discriminant analysis on allometry-freelabyrinthine shape served to evaluate the phylogenetic signalportion of the labyrinth for Macropodiformes, Phalangeroidea,Petauroidea, and Vombatiformes. The inner shape ofThylacoleo is consistent with its phylogenetic placement as avombatiform.

Keywords Inner ear . Diprotodontia .Diprotodon .

Thylacoleo . Geometric morphometrics . Allometry

Introduction

With more than 125 recognized species, diprotodontians makeup at present the most taxonomic and ecologically diverse orderof marsupials (Meredith et al. 2009), even though their distri-bution is limited to Australasia (Australia, New Guinea, and

neighboring islands). They exploit a wide variety of food re-sources and modes of locomotion, ranging from the nectivoroushoney possum to the carnivorous Thylacoleo, and fromburrowingwombats, to aboreal gliders (Szalay 1994). The fossilrecord of diprotodontians is equally rich, with an even moreimpressive morphofunctional diversity; some of the knownforms are the Pleistocene carnivores such as Thylacoleo carnifex(Wroe et al. 2004a, 2005) or the megaherbivore Diprotodonoptatum (Wroe et al. 2004b; Price 2008; Price and Piper 2009).When combined, these taxa offer the largest bodymass range ofall terrestrial therian orders (Sánchez-Villagra et al. 2003), fromnine grams in the honey possum (Fisher et al. 2001) to anestimated three tons for Diprotodon (Wroe et al. 2004b).

In light of such extensive extant and extinct diversity, thestudy ofmorphological variation in diprotodontians in relationto phylogeny and ecology is a rich subject of investigation onmammalian evolution. In other groups, particularly Primates(e.g., Spoor and Zonneveld 1998; Spoor et al. 2007; Silcox etal. 2009; Lebrun et al. 2010), the analysis of the morphologyand size of the bony labyrinth of the inner ear has revealedcorrelations between the variations in size and morphology ofthis structure with body mass on the one hand and with themode of locomotion on the other.

From a physiological point of view, the inner ear (Fig. 1)brings together two sense organs of utmost importance, relat-ed to the sense of hearing in the case of the cochlea (e.g..,Ulfendahl 1997; Manoussaki et al. 2008) and to balance in thecase of the vestibular system (e.g., Schwarz and Tomlinson1994; Yang and Hullart 2007; David et al. 2010). The latter isinvolved in the perception of changes in velocity, and studiessupport a link between semicircular canal ducts morphologyand the sensitivity of the vestibular system to movement (e.g.,Baird 1974; Lindenlaub et al. 1995; McVean 1999). The bonysemicircular canals, which contain the membranous semicir-cular ducts, replicate faithfully enough the shape and curva-ture of the ducts to make it possible to infer the sensitivity of

L. Alloing-Séguier :R. Lebrun (*)Université Montpellier 2, Institut des Sciences de l’Evolution(UMR-CNRS 5554), C.C. 64, Place Eugène Bataillon,34095 Montpellier Cedex 05, Francee-mail: renaud.lebrun@univ-montp2.fr

M. R. Sánchez-VillagraPalaeontologisches Institut und Museum, Karl Schmid-Strasse 4,8006 Zürich, Switzerland

M. S. Y. LeeEarth Sciences Section, South Australian Museum, North Terrace,Adelaide, SA 5000, Australia

J Mammal EvolDOI 10.1007/s10914-013-9228-3

the vestibular system to movement in both extant and fossilspecies (Spoor 2003).

This sensitivity has been linked with the animal’s locomo-tory agility, a correspondence that has been examined espe-cially among primates (e.g., Spoor et al. 1994; Spoor andZonneveld 1998; Rook et al. 2004; Walker et al. 2008; Ryanet al. 2012). As mentioned above, these studies have alsoshown there is a negative allometric relationship between thesize of the vestibular system and the body mass of the indi-vidual, as well as phylogenetically informative variation ofthis structure (Lebrun et al. 2010). Lastly, the study of thesemicircular canals is possible within the framework of thefossil record because it is a structure frequently preservedthrough time due to its location inside the petrosal (Muller2000; Ladevèze 2004; Graf and Klam 2006).

If the inner ears in living diprotodontians vary with ecology(as in primates), this will open up new horizons for theinterpretation of the morphology found among their extinctrepresentatives. Lastly, because of their large range ofmorphofunctional variation, the inner ears in diprotodontianscould form a useful benchmark in which to test for similarvariations in other mammalian groups.

A correlation between the morphology of the semicircularcanals and the mode of locomotion has already been examinedfor diprotodontians (Schmelzle et al. 2007). This study atom-ized the recorded variation into discrete characters after acomprehensive consideration of morphological variation in asample of eight living diprotodontians (Fig. 2). We aim to testif this variation is correlated with body mass, and if it carries a

phylogenetic signal. For this, we expand on sampling and onmethods.

Among extinct diprotodontians, we investigate two ‘ex-treme’ forms. One is Diprotodon optatum. Its reconstructedecology and the range of its body mass are dramaticallydifferent from those of living forms (Wroe et al. 2004b). Theother is the carnivorous Thylacoleo carnifex, one of thelargest extinct mammalian predators of Australia, for whichthe average weight for the species ranged from 101 kg to130 kg (Wroe et al. 1999). Again, there is no close livinganalogue. The morphology of the inner ears of both taxacould therefore be novel.

In order to better characterize the variation, an ap-proach using geometric morphometrics was chosen, inorder to distinguish the variabilty in the morphology ofthe bony labyrinth linked to phylogeny and to allometry(Lebrun et al. 2010). The measurements were made onthree-dimentional models of the bony labyrinth obtainedby microtomography; this method has been confirmedas being accurate enough to allow an effective analysisof the inner ear morphology (Spoor and Zonneveld1995; Spoor et al. 2000).

Materials and Methods

Comparative Sample

The studied sample (Fig. 2) comprises 16 genera of livingdiprotodontians (with a total of 19 individuals), representingall the families currently recognized for this order with theexception of Hypsiprymnodontidae (Meredith et al. 2009).Also, two fossil species, Diprotodon optatum and Thylacoleocarnifex, were included in the specimen sample. Four genera ofliving non-diprotodontian marsupials serve as outgroups. As awhole, 25 specimens were studied.

Data Acquisition

X-ray micro-computed tomography (μCT) and conventionalcomputed tomography (CT) were used to acquire 3D data.Extraction of the inner ear was performed manually with thesoftware Avizo 6.3 (VSG Inc.), allowing us to obtain models inthree dimensions of the left bony labyrinth for each specimen.Nine of the models used in this study were already reported bySánchez-Villagra and Schmelzle (2007) and by Schmelzle et al.(2007); the specimens of Diprotodon optatum and Thylacoleocarnifex were scanned in Australia by R. Harper at the LyellMcEwin hospital and that of Dactylopsila sp. was scanned byR. Lebrun at the Anthopological Institut and Museum inZurich.

Labyrinthine shape was quantified with 22 land-marks, following the protocol of Lebrun et al. (2010):

Fig. 1 Lateral view of a schematic left inner ear. Yellow: cochlea; grey:vestibule; blue: anterior bony semicircular canal; green: lateral bonysemicircular canal; red: posterior bony semicircular canal; violet: cruscommune; light grey: membranous portion of canals (modified afterDavid et al. 2010)

J Mammal Evol

the location of these points was determined followingthe principal axes of the inner ear (Fig. 3), placing thelateral semicircular canal horizontally (this position isusually estimated in a resting position, with the lateralcanal parallel to the horizon; Graf and Klam 2006;Hullar 2006; David et al. 2010), as well as at the centerof specific anatomical structures.

Data Analysis

Using generalized least-squares fitting (Rohlf 1990),the form of each specimen’s landmark configurationwas represented by its centroid size S, and by itsmultidimensional shape vector v in linearized Procrustesshape space.

Dendrolagus sp.Dorcopsis muelleriMacropus eugeniiBettongia penicillataBettongia sp.Spilocuscus maculatusPhalanger orientalisAilurops ursinusCercartetus nanusPseudocheirus peregrinusPetauroides volansDactylopsila sp.Tarsipes rostratusDistoechurus pennatusAcrobates pygmaeusVombatus ursinusDiprotodon optatum

Phascolarctos cinereusThylacoleo carnifex

Pseudantechinus macdonnellensisAntechinus minimusPerameles sp.Caluromys philander

Macropodidae

Potoroidae

Phalangeridae

Burramyidae

Pseudocheiridae

PetauridaeTarsipedidae

Acrobatidae

VombatidaeDiprotodontidaeThylacoleontidae

Dasyuridae

PeramelidaeDidelphidae

Phascolarctidae

Diprotodontia

Macropodiformes

Families

Petauroidea

Phalangeroidea

Dasyuroidea

PerameloideaDidelphoidea

High-level groups

Vombatiformes

Fig. 2 Phylogeny of taxaconsidered in this study,after Meredith et al. (2009).Thylacoleo and Diprotodonwere placed within thisphylogeny followingMunson (1992)

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Definition

Center of the first turn of the cochlea (within the plane defined by the first turn of the cochlea)Center of the last turn of the cochlea (within the plane defined by the last turn of the cochlea)Anteromedialmost point at the center of the lumen of the first turn of the cochleaPosterolateralmost point at the center of the lumen of the first turn of the cochleaInferiormost point at the center of the lumen of the first turn of the cochleaSuperiormost point at the center of the lumen of the first turn of the cochleaCenter of the round windowCenter of the oval windowOpening of the vestibular aqueduct in the vestibular wallBifurcation point of the common crusCenter of the ampulla of the lateral semicircular canalPosteromedialmost point at the center of the lumen of the lateral semicircular canalPosterolateralmost point at the center of the lumen of the lateral semicircular canalAnterolateralmost point at the center of the lumen of the lateral semicircular canalCenter of the ampulla of the anterior semicircular canalAnterolateralmost point at the center of the lumen of the anterior semicircular canalSuperiormost point at the center of the lumen of the anterior semicircular canalInferiormost point of the vestibular wall lying in the anterior semicircular canal planeCenter of the ampulla of the posterior semicircular canalInferiormost point at the center of the lumen of the posterior semicircular canalSuperiormost point at the center of the lumen of the posterior semicircular canalPosterolateralmost point at the center of the lumen of the posterior semicircular canal

N°

12345678910111213141516171819202122

Name

Helix basis Helix apex Helix anteromedial Helix posterolateral Helix inferior Helix superior Fenestra cochlea Fenestra vestibuliAquaeductus vestibuli Crus commune apex Canalis lateralis ampullaCanalis lateralis posteromedialCanalis lateralis posterolateralCanalis lateralis anterolateralCanalis anterior ampullaCanalis anterior anterolateralCanalis anterior superiorCanalis anterior inferiorCanalis posterior ampullaCanalis posterior inferiorCanalis posterior superiorCanalis posterior posterolateral

Fig. 3 Landmarks used forgeometric morphometricanalysis of the bony labyrinth(specimen: Dactylopsila sp.).Grey arrows: anteromedial-to-posterolateral andanterolateral-to-posteromedialdirections

J Mammal Evol

In order to evaluate the presence and impact of a negativeallometry related to the body mass in the morphology of thediprotodontian labyrinth (relationship already shown for alarge sample of mammals by Spoor et al. 2002), we studieda linear regression of the average radius of curvature of thesemicircular canals by the logarithm of the body mass.Furthermore, a regression of shape (multivariate regressionof Procrustes residuals on an external variable, in this casethe logarithm of body mass; Claude et al. 2003; Lebrun et al.2010) was conducted, yielding an allometric shape vector(ASV). The ASV represents a direction in shape spacewhich characterizes allometric patterns of labyrinthineshape variation. All labyrinths were then projected onASV, the residuals representing the body mass independentcomponent of labyrinthine shape. Body mass independentshape variation was analyzed by principal components anal-ysis (PCA, Dryden and Mardia 1998) of shape using theinteractive software package MORPHOTOOLS (Specht2007; Specht et al. 2007; Lebrun 2008).

In order to evaluate whether the labyrinth is a good taxo-nomic marker, a discriminant analysis was performed on the PCscores of shape data corrected for allometry. The first 15 PCaxes, which account for 98.84 % of shape variability, were usedin this analysis. Discriminant analysis describes differencesbetween predefined groups and evaluates how well specimenscan be classified to these groups, following the Mahalanobisdistance between each specimen and the average for each group.The specimen is classified as belonging to the group to which itis closest (see Zelditch et al. 2004 for a description of theprotocol). We predefined four high-level monophyletic taxa asgroups to be discriminated (Macropodiformes, Phalangeroidea,Petauroidea, Vombatiformes). If these clades are correctly dis-criminated on the basis of themorphology of their labyrinth, onewill be able to conclude that this morphology carries a phylo-genetic signal. Only diprotodontian labyrinths were used in thisanalysis. Concerning Thylacoleo and Diprotodon, no a priorihypothesis was made concerning the high-level group to whichthey belong: they were not used to compute the discriminantaxes, and were projected a posteriori on these axes. Doing so,we assessed to which high-level group they are the closest interms of labyrinthine morphology.

The geometric morphometric analyses were performedusing the interactive software package MORPHOTOOLS(Specht 2007; Specht et al. 2007; Lebrun 2008).

Results

Inner Ears of Diprotodon and Thylacoleo

The inner ears of Diprotodon optatum and Thylacoleocarnifex are illustrated in Fig. 4. Both exhibit longcommon crura, a posterior canal placed in a high

position relative to the lateral canal, resulting in partialfusion of the posteriormost part of the lateral canal andthe inferiormost part of the posterior canal, and a rela-tively small cochlea oritented ventrally. The inner ear ofThylacoleo is more extended in the anteromedial toposterolateral direction than that of Diprotodon. Theanterior canal of Thylacoleo is less extended in thesuperior direction relative to that of Diprotodon.

Allometry

The linear regression of the mean of the radius of curvature ofthe semicircular canals by the logarithm of the body mass(R2=0.95 for the collection of the studied marsupials; Fig. 5)suggests an allometric relationship between the size of thesemicircular canals (represented here by the average radius ofcurvature of the canals) and body mass.

Body mass explains 24.5 % of the labyrinthine shapevariation (Fig. 6a), which also suggests a strong allometricrelationship. A pattern of morphological variation related toallometry is similar to that found among primates (Lebrun etal. 2010): labyrinths of larger specimens possess anteriorand posterior semicircular canals proportionally more devel-oped and a lateral semicircular canal proportionally lessdeveloped (see Fig. 6b). The posterior canal of smallerspecimens is positioned in a lower position relative to thelateral semicircular canal. Also, similar to what can beobserved in primates, larger marsupial inner ears displayrelatively smaller and laterally oriented cochleae and longercommon crura.

a

b

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Superior

InferiorAnterior

Posterior

Medial Lateral

Superior

InferiorAnterior

Posterior

Fig. 4 Left bony labyrinths of a Diprotodon optatum and bThylacoleo carnifex. The labyrinth is positioned in superior (left) andlateral (right) views (by convention, the lateral semicircular canal ispositioned horizontally). Scale bar=5 mm

J Mammal Evol

Morphological Disparity and Taxonomic Signal

Figure 7 shows a clear separation between high-leveldiprotodontian taxonomic groups: Macropodiformes,Phalangeroidea, Petauroidea, and Vombatiformes are welldiscriminated in PC1-PC2 space (35.99 % of total shapevariation), with one outlier (see below). The labyrinths ofDiprotodon and Thylacoleo and other Vombatiformes exhibitrelatively long common crura, high anterior canals com-pressed in the anteromedial to posterolateral direction, highlypositioned posterior canals, and relatively small lateral canals.

Macropodiform labyrinths are characterized by relativelysmall lateral canals and relatively larger anterior canals, andposterior canals in a low position relative to the lateral canal.Phalangeroidea inner ears exhibit low anterior canals, elon-gated in an anteromedial to the posterolateral direction, andposterior canals placed in a high position relatively to thelateral canal. Petauroid labyrinths are characterized by shortcommon crura, large lateral canals, small anterior canals andposterior canals placed in a low position relatively to thelateral canal, and ventrally oriented cochlea. Only inner ears

AS

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MacropodidaePotoroidaePhalangeridaeBurramyidaePseudocheiridaePetauridaeTarsipedidaeAcrobatidaeVombatidaeDiprotodontidae

DasyuridaePhascolarctidae

PeramelidaeDidelphidae

Thylacoleontidae

2 3 4 5 6 7

Fig. 6 Body mass dependent component of labyrinthine shape varia-tion. a 24.5 % of labyrinthine shape variation can be explained byvariation in body mass in the present sample of specimens. See Fig. 1for color coding. b differences in labyrinthine shape between small(left) and large (right) taxa. ASV, allometric shape vectors

PC

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PC1: 26.39%

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7.03.70.4

MacropodidaePotoroidaePhalangeridaeBurramyidaePseudocheiridaePetauridaeTarsipedidaeAcrobatidaeVombatidaeDiprotodontidae

DasyuridaePhascolarctidae

PeramelidaeDidelphidae

Thylacoleontidae

Fig. 7 Principal Components Analysis (PCA) of body-mass independentlabyrinthine shape variation. a graphing the first two components ofshape space, PC1 and PC2, shows differences in labyrinthinemorphologyacross most diprotodontian high-level taxonomic groups (see Fig. 1 forcolor coding). b patterns of labyrinthine shape variation associated withPC1 and PC2, respectively

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MacropodidaePotoroidaePhalangeridaeBurramyidaePseudocheiridaePetauridaeTarsipedidaeAcrobatidaeVombatidaeDiprotodontidae

DasyuridaePhascolarctidae

Peramelidae

Thylacoleontidae

BA

CDidelphidae

Fig. 5 Linear regression of the average of radius or curvature of thesemicircular canals by the logarithm of the body mass of the sample ofmarsupials studied (R2=0,95 ; f(x)=0,49x+0,013). See Fig. 1 for colorcoding

J Mammal Evol

belonging to tarsipedid specimens show marked differencesfrom those belonging to other Petauroidea and instead plotnear Dasyuridae: their common crura are oriented posteri-orly, and their anterior canals are low and show extremeelongation in the anteromedial to posterolateral direction.

A few diprotodontians (Ailurops ursinus,Cercartetus nanus,Phalanger orientalis, Spilocuscus maculatus, and Tarsipesrostratus) display a particular conformation in the posterior areaof their lateral semicircular canal and the lower area of theirposterior semicircular canal, in such a way that these two partsform a bony « second crus commune » (Schmelzle et al. 2007).This character has also been confirmed in the four genera ofnon-diprotodontian marsupials examined here.

All extant diprotodontians specimens but one were cor-rectly reallocated to their original high-level taxon (wilk’slambda: 0.026; F=14; p<0.001), showing that labyrinthineshape data convey a substantial phylogenetic signal. OnlyDactylopsila was wrongly classified as a Phalangeroidea.Thylacoleo and Diprotodon were classified as vombatiforms.

Discussion

The inner ear of diprotodontians carries a significant phylo-genetic signal. Indeed, the morphology of the inner ear, mea-sured after the landmarks protocol presented above, proves tobe a good taxonomic marker at the superfamily and sub-orderlevel among diprotodontian marsupials. Tarsipes rostratus,the only living representative of Tarsipedidae, is very diver-gent. It displays a very peculiar inner ear in comparison withits closest taxa, both from phylogenetic and locomotor pointsof view; the cochlea is connected to the vestibule in a uniqueway among diprotodontians and the anterior canal is stronglycompressed superiorly, producing a unique subrectangulargeneral shape. Another specific feature is the presence of whatis sometimes referred to as a « second crus commune » in theliterature and it is the only diprotodontian examined here thathas this structure outside of Phalangeroidea (Spilocuscusmaculatus, Phalanger orientalis, Ailurops ursinus, andCercartetus nanus). The presence of a bony « second cruscommune », however does not imply a confluence of themembranous ducts, and this terminology may thus be mis-leading, as it represents in most cases only a partial fusion ofthe bony posterior and lateral semicircular canals. This struc-ture has also been observed in the non-diprotodontian marsu-pials Pseudantechinus macdonnellensis, Antechinus minimus,Perameles sp. (this study), Caluromys philander (Sánchez-Villagra and Schmelzle, 2007), Monodelphis, Dasyurus,Isoodon (Schmelzle et al., 2007), Mimoperadectes houdei(early Eocene, Wyoming; Horovitz et al. 2009), andHerpetotherium fugax (Oligocene, Wyoming; Sánchez-Villagra et al. 2007). In fact, in contrast with the propositionby Schmelzle et al. (2007), the absence of this structure is not

necessarily an autapomorphy of diprotodontians. Presence inTarsipes and Phalangeroidea, and absence in all the otherdiprotodontians examined, is consistent with two scenarios:a single loss in the common ancestor of diprotodontians, withre-acquisitions in Tarsipes and phalangeroids (three changes),or convergent loss in vombatiforms, acrobatids, petaurids+pseudocheirids, and macropodiformes (four changes). Thestudy of this character in the fossil record of diprotodontiansand better taxon sampling across the Australidelphia couldhelp clarify this uncertainty. Since the formation of this struc-ture does not represent, however, a complete fusion of thebony semicircular canals (it is always possible to distinguishthe respective curvatures), in contrast with the classic cruscommune, it is well possible that its presence is the conse-quence of a relatively higher position of the posterior bonysemicircular canal, which would therefore be located veryclose to the posterior area of the bony lateral semicircularcanal. The presence or absence of partial fusion of the poste-rior and lateral semicircular canals would therefore not behomologous among the taxa and would not represent a phy-logenetically informative character as such.

The analyses here do not reveal major divergence in theinner ears ofDiprotodon optatum and Thylacoleo carnifex. Thestudy of diprotodontian allometric patterns shows that thesetwo taxa fall along the regression of other diprotodontians, andthe morphology of their labyrinths is consistent with a phylo-genetic position among Vombatiformes. This is particularlysignificant, given past suggestions of Thylacoleo being aphalangeroid (see Murray et al. 1987).

The visual comparison between the inner ear ofDiprotodon and that of a fossil proboscidean (Ekdale2011) shows a similar general morphology, in spite of thephylogenetic distance between these two taxa. It is probable,however, that this resemblance is only superficial and that itis related to large size. As in Diprotodon optatum, theproboscidean follows the common allometric pattern (seeResults above), with its lateral semicircular canal propor-tionally very reduced in comparison with the other twocanals and its long common crus. If this allometric patternis shown to be common among mammals as a whole, itwould be possible to make wider size-corrected compari-sons (e.g., across “orders”) and in this way establish broaderinferences about the modes of locomotion. Indeed, as hasbeen reaffirmed in this study, taking allometry into consid-eration is essential for the comparison of inner ears in thiscontext.

Conclusions

Geometric morphometrics is important in the three-dimensional study of bony biological structures in livingand fossil taxa (Lawing and Polly 2010). This approach

J Mammal Evol

made it possible to discover an allometric pattern linked tobody mass in diprotodontian marsupials and its deep influ-ence on the morphology of the bony labyrinth: the laby-rinths in taxa with a large body mass display anterior andposterior semicircular canals that are proportionally moreimportant than the lateral semicircular canal and the reversein taxa with a smaller body mass. The shape of the inner earwas correlated with phylogeny, being able to distinguish themain diprotodontian clades.

The importance of the allometric pattern in the morphol-ogy of the inner ear poses many questions, which should beexplored in order to better understand the causes of themorphological variation of the labyrinth. This particularpattern could correspond to functional constraints; differentconformations of the semicircular canals would be more orless advantageous for the organisms depending on theirbody mass, or the topology of the terrain depending on thescale in which they are found. Constraints related to devel-opment might also be relevant, because the inner ear iscontained inside the petrosal and cannot therefore developbeyond its limits: for instance, larger animals have thickerskull bones. Diprotodontians, due to their large functionaland phylogenetic diversity, are an ideal group to investigateall these relationships.

Acknowledgments The Swiss National Science Foundationsupported M. R. Sánchez-Villagra (grant No. 31003A-133032/1). Wethank I. Horovitz (Los Angeles) for comments and language correc-tions. We thank the ANR Palasiafrica (ANR-08-JCJC-0017) andLaurent Marivaux for financial support. We express our gratitude toM. Ponce de León and C. Zollikofer (Anthropological Institute andMuseum Zürich) and to the Montpellier RIO Imaging (MRI) platform,and R. Harper (Lyell McEwin Hospital, Adelaide) for giving access toscanning facilities. We thank C. Bens from the Muséum Nationald’Histoire Naturelle (Paris), L. Costeur from the NaturhistorischesMuseumBasel, S. Jiquel from the ISE-M,M.-A. Binnie (South AustralianMuseum), and A. Camens (Flinders University, Adelaide), who kindlypermitted access to the scanned specimens.

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