Sicuro and Oliveira - Skull Morphology and Functionality of Extant Felidae 2010

Skull morphology and functionality of extant felidae(mammalia: carnivora): a phylogenetic andevolutionary perspective

FERNANDO LENCASTRE SICURO1* and LUIZ FLAMARION B. OLIVEIRA2

1Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro,RJ 20550-013, Brazil2Museu Nacional, Universidade Federal do Rio de Janeiro, RJ 20940-040, Brazil

Received 15 June 2009; accepted for publication 7 October 2009

Felids morphology and ecological role as hypercarnivores are quite constant, despite considerable body sizevariation among species. Skull morphological and functional features of 34 extant cat species were evaluated undera phylogenetic framework of the Felidae. Twenty skull measurements were analysed through Principal ComponentAnalysis to assess the species morphofunctional spaces. Force indexes were obtained from static equilibriumequations to infer jaw mechanics. Correlations between morphological, functional, and ecological traits were testedby phylogenetically independent contrasts. In spite of the general cat-like pattern, specific features on the skullsallowed differentiation among groups. Acinonyx jubatus, for instance, showed a shorter and shallower temporalfossa than other big cats, and their bite functionality is marked by an increased contribution of the massetericsystem. A morphofunctional dichotomy between Neotropical and Eurasian/African small cats was detected, and isassociated with the major transversal axes of the skulls. According to the contrast analyses, the skull size iscorrelated with the bite force and prey size, but it is uncorrelated with the variations on jaw mechanics (fromtemporalis or masseter muscle optimizations). Also, there was no correlation between functional differences on jawmuscles and the ratio of prey weight to cat weight. The efficiency of the jaw apparatus among cats is quiteconsistent; therefore, the different evolutionary trends of jaw mechanics seem to be caused by the casuistic fixationof phenotypical variations, rather than by specific adaptative selections.

© 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010.doi: 10.1111/j.1096-3642.2010.00636.x

ADDITIONAL KEYWORDS: functional morphology – morphometrics – phylogenetically independentcontrasts.

INTRODUCTION

Regardless of size and form variations, all cats lookalike, and they are easily recognized as members ofthe Felidae. The cat-like ecomorph suggested byMartin (1989) is consistent throughout the felidspecies, and is one of the most conspicuous among thefamilies of the order Carnivora. Many cat species arequite distinguishable by differences in their bodymass and colour pattern. However, the variations intheir skeletal design are less evident, as well as the

ecomorphological implications associated with these.Although cats show several ecological particularitiesalong their distribution in many biomes worldwide,they are consistently successful hypercarnivores(Guggisberg, 1975; Neff, 1982; Sunquist & Sunquist,2002).

Both big and small cats show similarities on theirhunting strategy: it starts with prey stalking, fol-lowed by a variable range sprint, and then theycapture their prey with the anterior limbs and claws,holding it for the fatal neck bite. Usually, this attackinjures the spinal cord, but some large cats bite thethroat in order to suffocate the prey (Guggisberg,*Corresponding author. E-mail: [email protected]

Zoological Journal of the Linnean Society, 2010. With 26 figures

© 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010 1

1975; Neff, 1982; Sunquist & Sunquist, 2002). Minorvariations are observed in some cat species, such asthe powerful bite to the prey’s head made by Pantheraonca and the suffocating muzzle clamp performed bylions (Schaller, 1976; Turner & Antón, 1997, 1998;Anton, Garcia-perea & Turner, 1998). Cooperativehunting is sometimes observed in a few species, butlions display this behaviour more often, and in a moreorganized way, than other cats (Schaller, 1972;Stander, 1992). Hunting strategies used by small catsfor birds, reptiles and fishes are very consistentamong species, usually involving stalking and sit-and-wait ambushes.

CAT PHYLOGENY AND TAXONOMY

Felids form a monophyletic group and, according tofossil records and molecular data, the adaptativeradiation of extant taxa started in the last 10 millionyears (Johnson et al., 2006; Johnson & O’Brien, 1997).Salles (1992) was the first one to use a cladisticapproach to infer felid phylogenetic structure basedon a qualitative analysis of skull morphology. Theauthor pointed out ten skull synapomorphies amongextant species: six tooth characters and four osteo-logical features. Johnson & O’Brien (1997), usingmitochondrial DNA sequences and fossil information,proposed a comprehensive phylogeographical analy-sis. They proposed names to eight main lineages:Panthera lineage, Ocelot lineage, Puma group,Lynxes group, Bay cat group, Domestic cat lineage,Caracal group, and Asian Leopard cat group. Thelatest complete phylogenetic hypothesis was proposedby Johnson et al. (2006) using nuclear genes (nDNA),which confirmed the eight lineages proposed byJohnson & O’Brien (1997). Nevertheless, the relation-ship among these lineages changed significantly, andthe major topological consensus between these twolast phylogenies remains in the basal position of thePanthera lineage.

The most recent taxonomic reviews of the familyFelidae differ in the number of extant genera andspecies (Wozencraft, 1993, 2005). In the formerreview, the family was organized into 18 genera and36 species, and many synonymies were clarified(Wozencraft, 1993). The later review includes novel-ties on the taxonomic structure: 14 genera and 40species, where four subspecies were elevated to thestatus of species (Wozencraft, 2005). This newapproach raises important matters, and has had apositive repercussion on the conservation efforts ofendangered species (sensu Beer, 2002), e.g. the recog-nition of the geographic morphotypes of pampas cat(Oncifelis colocolo) as different species (sensu Garcia-Perea, 1994), and the the Iriomote cat (Prionailurusiriomotensis) as a distinct species from the leopard cat

(Prionailurus bengalensis). Nevertheless, an unusualchange in this later taxonomical review was the real-location of jaguarundi (Herpailurus yagouaroundi) tothe genus Puma. Jaguarundis and pumas are veryapomorphic in their general morphology, despite theirphylogenetic closeness (Johnson & O’Brien, 1997;Mattern & McLennan, 2000; Johnson et al., 2006).Furthermore, with strictly phylogenetic logic appliedto taxonomy, all the species of this clade would beplaced on the most senior genus: Acinonyx.

On the other hand, the debate regarding the lowertaxa of felids becomes more controversial after therecent record of natural hybridization and gene intro-gression among small Neotropical cats species – Leop-ardus tigrinus, Leopardus geoffroyi, and Leoparduscolocolo – in overlapping areas of occurrence, detectedby Trigo and colleagues (Trigo, Freitas, Kunzler,Cardoso, Silva, Johnson, O’Brien, Bonatto & Eizirik,2008).

CAT JAW MECHANICS

The cat jaw mechanics follow the general carnivorepattern suggested by Maynard-Smith & Savage(1959), Turnbull (1970), and Greaves (1980a; 1980b;1982; 1983; 1995), i.e. a high coronoid process, ahinge-like jaw condyle, and the tooth row at the samelevel of this condyle. A high coronoid process (i.e. alarge ‘in-force’ moment arm), is related to an improve-ment on the mechanical leverage of the temporalismuscle. In this arrangement, the resultant forcevector of this muscle has a vertical component for jawelevation, and a backward component that resistsagainst the contrary forward forces of a strugglingprey. The moment arm of masseteric complex andpterygoideus muscular systems are shorter than themoment arm of the temporalis muscle, but the mas-seter and pterygoideus muscles have a crucial role inthe lateral stabilization of the jaw. In cats, the mas-seter superficialis is the next-largest jaw adductor,and it is related to the angular process and posteriormandible (Turnbull, 1970).

Felids have a short rostrum and, consequently, ashort jaw out-force moment arm. For a given muscu-lar ‘in-force’ moment, the ‘out-force’ effect on a shortjaw is stronger than on a long one. A short rostrum ina predator is less effective than a longer one forcatching a running prey, but cats compensate for thiswith powerful and agile limbs with curved retractileclaws at the paws (Neff, 1982). Sharp-edged carnas-sials provide a shear cut on prey meat. In both theFelidae and the Nimravidae there is an optimizationof carnassial action by the presence of carnassialnotches between the metastyle and paracone of theP4, and between the protoconid and paraconid of M1,that arrange the food items for more efficient shear-

2 F. L. SICURO and L. F. B. OLIVEIRA

© 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010

ing action by the carnassials (Bryant & Russell, 1995;Evans & Sanson, 2003; Evans & Fortelius, 2008;Evans & Sanson, 2006).

Some morphometric studies of skulls have shownecomorphological differences in the felid speciesaccording to their size ratios (Christiansen & Adolfs-sen, 2005; Christiansen & Wroe, 2007; Dayan et al.,1990; Radinsky, 1981a; Radinsky, 1981b; Kiltie, 1984;Larson, 1997; O’Regan, 2002; Therrien, 2005). Noneof these studies dealt with the phylogenetic integra-tion of morphofunctional patterns in a comprehensiveexamination of the species in the family.

The present study evaluates the skull functionalmorphology of 34 extant cat species through a classicalmorphometric approach. Inferences about the evolu-tion of cat skull design and function are proposedthrough contrasts analysis based on Johnson et al.’s(2006) phylogeny of the Felidae (Fig. 1). The currentstudy analyses the interspecific craniomandibular dif-ferences in a broad evolutionary context. Thus, it is notconcerned with the differences at the subspecific level(e.g. sexual dimorphism, geographic distribution, andparticular ecotypes). On that matter, we followedWozencraft’s (1993) former taxonomical review.

MATERIAL AND METHODS

Twenty skull measurements (Fig. 2) were used todescribe skull morphology, and to evaluate the per-formance of the masticatory muscle groups androbustness of the neck (Radinsky, 1981a; 1981b,Kiltie, 1982, 1984, 1989; Sicuro & Oliveira, 2002). Alist of descriptions and acronyms for these measure-ments are listed in Appendix 1.

Skulls of adult felids were studied in the followingzoological collections: American Museum of NaturalHistory (AMNH), NY, USA; Field Museum ofNatural History (FMNH), Chicago, USA; MuseuNacional (MN), Rio de Janeiro, Brazil; and Museude Zoologia of University of São Paulo (MZUSP),São Paulo, Brazil. The species and the specimensused are presented in Appendix 2. The small samplesize of some species denotes the scarcity of thespecimens in the collections visited. We includedindividuals from different geographic regions to takeinto account the morphotype variations of eachspecies. The lack of specimens of Felis bieti, Oreailu-rus jacobitus, and Neofelis diardi forced the exclu-sion of these taxa from the analysis.

Figure 1. Cladogram of the family Felidae, after Johnson et al. ’s (2006) phylogeny, adjusted to the number of speciesanalysed. Values on the branches indicate the divergence time between nodes; node numbers are parenthetic.

FELID SKULL MORPHOLOGY, FUNCTIONALITY, AND EVOLUTION 3


The use of fresh muscle samples or reconstructionsbased on osteological analysis to estimate the contrac-tion force of a muscle is a simplification of the mus-cular mechanic system (Hildebrand, 1988; Bryant &Seymour, 1990; Bryant & Russell, 1995). This is espe-cially true considering the muscle architecture, e.g.the degree of pennation, angles of origin and insertionof the aponeuroses or tendons (Gans & Bock, 1965;Herring, 1972), and differences in the response of thefibres during the muscle contraction (Gorniak &Gans, 1980; Weijs, 1980; Wieshampel, 1993).

Nevertheless, it is very useful when employed inmorphofunctional comparisons between morphologi-cally or phylogenetically related individuals (Radin-sky, 1981a; 1981b; Kiltie, 1982, 1984, 1989;Eisenberg, 1985; Hildebrand, 1988; Bryant &Seymour, 1990, Bryant & Russell, 1995; Sicuro &Oliveira, 2002). Muscle scars and dimensions offossae measured on the skull were associated withoriginal muscle cross-sectional areas (Gans & Bock,1965). The distances between the jaw condyle and thepoint of insertion of the temporalis muscle (coronoidprocess of the jaw), superficial masseter muscle(angular process of the jaw), and deep massetermuscle (along the coronoid fossa and lower mandibu-lar rim) were associated with the ‘in-force’ momentarms (Wieshampel, 1993). The ‘out-force’ moment arm

was defined as the distance from the jaw condyle tothe canines. This assumption is acceptable for bidi-mensional models of jaws with orthal movement.

The action of the pterygoideus muscle is similar tothe action of the masseter (Turnbull, 1970; Herring,1972). Nevertheless, the origin of this muscle on theventral surface of the skull is not clearly seen. More-over, in felids, the mass of masseter muscle, in par-ticular its pars superficialis, is well above thepterygoideus, which is the smallest of the adductors(Turnbull, 1970). The pterygoideus muscle representsless than 10% of total masticatory muscle mass (Turn-bull, 1970), and thus it was not included in ourfunctional model.

The equation of static equilibrium (sum of momentsequal to zero) was used to predict the theoreticalmaximum force performed by jaw muscles. The forceindexes (FIs) are derived variables, and their compu-tation presumes the maximum resistance torque of afood item (prey) during the bite. The origin areasubstitutes muscle ‘in force’ in the equations; there-fore, the FIs are estimators of the potential bitestrength, according to the craniomandibular morphol-ogy of the species. The FIs general equation isFI = (LS ¥ L1)/L2, where LS is the linearized (squareroot) muscle origin area (S), L1 is the muscle momentarm, and L2 is the resistance moment arm of the jaw.

Figure 2. Diagram showing the 20 skull measurements used in the analysis (see Appendix 1 for definitions).



The FIs of the masticatory muscles are corrected bythe ‘second moment of area’ (SMA) of the dentarybone. The SMA is an estimator of resistance of thedentary to the bending forces that act on this boneduring the bite. If one assumes that there is a corre-lation between variation in the robustness of aspecies’ jawbone and the loads involved in mastica-tion, thus SMA could be used to adjust the FIs.Therefore, the corrected FIs (CFIs) are functionalestimators that include more morphological informa-tion about the potential bite force (Sicuro & Oliveira,2002).

Our functional model does not compare the action ofthe temporal and the masseteric muscular systemswith each other because of the anatomical differencesbetween them (e.g. areas of origin and insertion,muscle architecture, degrees of pennation, and anglesof action). Furthermore, Becht (1953), Maynard-Smith& Savage (1959), Davis (1955, 1964), and Turnbull(1970) clearly pointed out the main participation of thetemporal complex in carnivoran masticatory mechan-ics. This method evaluates the potential performanceof these muscular mechanical systems along theFelidae, regarding the skull design of each species.

The derived variables, their acronyms, and FI equa-tions, based on the skull measurements, are alsodescribed in Appendix 1.

The samples had their normality and homoscedas-ticity tested (Shapiro–Wilk W and Levene tests,respectively), as well as the skewness and kurtosis ofthe frequency distributions. Morphometrical datawere log-transformed in order to reduce the varianceheterogeneity caused by size differences between thespecies. Minor normality problems were detected, butthey were associated with the small sample sizes ofsome species, sexual dimorphism, and/or influence ofgeographic variations. These problems were regardedas aspects of the morphological diversity, and asimportant to the morphometrical characterization ofthe species as a whole. Larson (1997), in his study onthe taxonomical status of Panthera onca, discussesthe lowermost influence of a lack of normally distrib-uted samples in multivariate analysis results.

Principal component analysis (PCA) was performedusing standardized measurements of the individualsall together. The principal component eigenvalue indi-cates the variance that it accounts for out of the totalvariance (Manly, 1994; Mcgarigal, Cushman &Stafford, 2000), so the components with lesser eigen-values were discarded. The contributions of theoriginal measurements and FIs to the principal com-ponents (PCs) are indicated by their coefficients.

The PCs were interpreted according to the associ-ated skull measurements and species PC scores.Species were also compared through univariate sta-tistical analyses. The PC scores, the original measure-

ments, FIs, and ratios between skull measurementsand the condylobasal length (CBL) were tested byanalysis of variance (ANOVA) or Kruskal-Wallis non-parametric ANOVA by ranks. The post hoc tests tothese analyses were Tukey HSD and Dunn, respec-tively (Sokal & Rohlf, 1995). Mann-Whitney’s U testwere also used to pairwise comparisons. Parametricor non-parametric methods were used regarding fre-quency distribution, homogeneity of variances amonggroups, and sample sizes. Parametric or nonparamet-ric methods were also used for frequency distribution,homogeneity of variances among groups, and samplesizes.

The maximum prey weight (MPW) was inferredfrom the body mass of the largest species captured(not scavenged). Prey species with no reference tobody mass had their weights averaged from thegeneral literature (Table 1) regarding special charac-teristics of the individuals killed (calves, yearlings, orfemales). In cases of very large prey species, thelowermost body weights were considered. Large preykilled from cooperative hunting was not included, andonly species reported as having been captured bysingle individuals were accounted. The minimumweight was arbitrarily limited to 1 kg, even to thosecat species with a diet described as ‘rodents andbirds’. Therefore, MPW assumes that a given speciesof cat would be able to dispatch any sort of small prey,and, at least, the smaller individuals among the largeprey. The ratio between MPW and the average weightof the respective cat species is a theoretical attempt toestimate their capture performance. Ratio values ofaround 1 indicate a similarity between MPW and catmean weight. The MPW was used to discuss possibleecological and adaptive correlations with the morpho-functional patterns observed. Cat size categories fol-lowed Mattern & McLennan (2000): small (< 10 kg),medium (11–40 kg), and large (> 40 kg).

Principal component scores from morphofunctionalanalyses and predator–prey ratios (MPW/cat bodymass) were used as continuous characters in phylo-genetically independent contrasts analysis (Felsen-stein, 1985). This was performed to eliminate theinfluence of the evolutionary framework between thespecies, and to bring statistical independence to thestudy of the co-evolution of the skull–jaw complextraits (Felsenstein, 1985, 2003). The main assumptionof Felsenstein’s method is the stochastic evolution ofa phenotypic trait, which can be described by theBrownian motion model. The variation of a given traitis normally distributed, and its variance is a functionof the time of divergence and the expected variance ofchange (Felsenstein, 1985, 2003; Garland, Harvey &Ives, 1992).

The expected variance of change was inferred fromthe divergence times between nodes based on Johnson



Table 1. Ratios between the maximum average prey weight (MPW) and body mass of the cat. The weights of cats wereaveraged from Guggisberg (1975), Heptner & Sludskii (1992), Nowak (1999), and Nowell & Jackson (1996). Prey weightswere averaged from Nowak (1999), Hayssen et al. (1993), and Weigl (2005); exceptions are cited. References used to assessprey capture are listed for each cat species. Rodents and birds were arbitrarily defined as 1 kg. Eventually, more than onespecies was used to infer the prey sizes

Cat species Weight Prey species MPW References Ratio

Pan

ther

a

Panthera onca 105.7 Tapirus terrestris, cattle 213.5 Schaller, 1983; Taber et al., 1997 2.0Panthera leo 185.0 Syncerus caffer, Giraffa

camelopardalis425.0 Ewer, 1973; Owen-Smith & Mills, 2008;

Schaller, 19722.3

Panthera pardus 59.0 Rusa unicolor, Bos gaur (calves),Connochaetes sp.

120.5 Karanth & Sunquist 1995, Mills 1984,Owen-Smith & Mills 2008

2.0

Panthera tigris 185.5 Bos gaur 500.0 Karanth & Sunquist, 1995; Mazák, 1981 2.7Uncia uncia 50.0 Capra ibex 92.5 Hemmer, 1972; Heptner & Sludskii,

19921.9

Neofelis nebulosa 19.5 Sus barbatus, Rusa unicolor(calves ?), Axis porcinus

52.0 Grassman et al., 2005; Rabinowitz et al.,1987

2.7

Oce

lot

Oncifelis colocolo 2.4 Cavia sp. 1.0 Bagno et al., 2004 0.4Oncifelis geoffroyi 4.0 Myocastor coypus, Lepus

capensis (exotic)4.0 Sousa & Bager, 2008 1.0

Oncifelis guigna 2.3 Rodents and birds 1.0 Sanderson et al., 2002 0.4Leopardus pardalis 13.6 Agouti paca 8.0 Emmons, 1987 0.6Leopardus tigrinus 2.3 Cavia sp. 1.0 Trigo, 2008 0.4Leopardus wiedii 3.3 Didelphis marsupialis 3.0 Oliveira, 1998a 0.9

Pu

ma

Puma concolor 67.5 Alces alces (calves andyearlings)

115.6 Ross & Jalkotzy, 1996 1.7

Herpailurus yagouaroundi 4.8 Didelphis sp. 3.0 Oliveira, 1998b 0.6Acinonix jubatus 53.5 Gazella thomsonii, Gazella

granti, Aepycerus melampus56.0 Hayward et al., 2006; Marker, 2002 1.0

Lyn

x

Lynx canadensis 11.2 Rangifer tarandus (calves andyearlings)

13.3 Bergerud, 1983; Stephenson et al., 1991 1.2

Lynx pardinus 11.5 Dama dama, Cervus elaphus(calves)

19.0 Beltran et al., 1985 1.7

Lynx lynx 23.0 Cap. capreolus, Rup. rupicapra,Cervus elaphus (calves)

23.7 Jobin et al., 2000; Okarma et al., 1997 1.0

Lynx rufus 11.2 Odocoileus virginianus 27.0 Labisky & Boulay, 1998 2.4

Dom

.ca

t Felis chaus 7.3 Lepus europaeus 3.8 Heptner & Sludskii, 1992 0.5Felis margarita 2.4 Lepus capensis tolai 2.3 Heptner & Sludskii, 1992 1.0Felis nigripes 2.2 Lepus capensis 2.3 Sliwa, 1994 1.1Felis silvestris 5.5 Lepus europaeus 3.8 Biró et al., 2005; Tryjanowski et al., 2002 0.7

Car

acal

Caracal caracal 17.0 Redunca fulvorufula 25.5 Mukherjee et al., 2004 1.5Leptailurus serval 13.4 Lepus saxatilis, Thryonomys

swinderianus, Cephalophus sp(fawn)

4.8 Smithers, 1983; York, 1973 0.4

Profelis aurata 10.7 Cephalophus callipygus 16.5 Ray & Sunquist, 2001 (prey weight:Noss, 1998)

1.5

Leo

p.ca

t

Otocolobus manul 3.3 Lepus capensis tolai 2.3 Flux & Angermann, 1990; Heptner &Sludskii, 1992

0.7

Prionailurus bengalensis 5.0 Tragulus javanicus 1.5 Grassman et al., 2005 0.3Prionailurus planiceps 1.9 Fish, rodents, and small aquatic

vertebrates1.0 Muul & Lim, 1970 0.5

Prionailurus viverrinus 10.9 Fish, molluscs, rodents, Axisaxis (calves and yearlings)

15.1 Nowell & Jackson, 1996; Pocock, 1939 1.4

Prionailurus rubiginosus 1.4 Rodents, birds, and domesticfowl

1.0 Pocock, 1939 0.7

Bay

cat Catopuma temminckii 11.8 Bubalus bubalis (calves) 27.9 Sharma et al., 2004 2.4

Catopuma badia 3.5 Rodents and birds (supposed) 1.0 Sunquist & Sunquist, 2002 0.3Pardofelis marmorata 3.5 Rodents and birds 1.0 Nowell & Jackson, 1996; Pocock, 1939 0.3



et al.’s (2006: supplement) phylogeny. Their cla-dogram was modified to accommodate the absence ofFelis bieti, Oreailurus jacobitus, Neofelis diardi, andthe unification of Felis silvestris lybica, Felis silvestriscatus, and Felis silvestris silvestris, under the specificname Felis silvestris, as used in this study (Fig. 1).

Correlation analyses were performed with PDAPv1.14 (Midford, Garland Jr. & Maddison, 2008) inMESQUITE v2.6 (Maddison & Maddison, 2009). Theassumptions and statistical approach follow Felsen-stein (1985, 2003) and Garland et al. (1992). Thenumber of contrasts is the number of species minusone, and refers to the number of nodes on the phylog-eny. Despite the gain on statistical analysis and evo-lutionary inference, the interpretation of the meaningof the contrast and its relation with the original traitvalue of each species is less intuitive. Contrasts showthe variation between adjacent branches, and areweighed by the evolution rate (usually proportional tothe divergence time between groups). Thus, accordingto the amount of difference on a given trait andevolution rate, contrast values could show expressivevariation between sister groups.

The standardized contrasts were regressed againstthe square root of the sum of corrected branch lengths(standard deviation of the contrast). Nonsignificantcorrelations indicate an adequate standardization,and suggest the phylogenetic independence of theobtained contrasts (Garland et al., 1992). Ordinaryleast-square (OLS) regression through the origin wasperformed using positivized contrasts versus contrastvalues to access the correlation between differenttraits (Garland et al., 1992).

RESULTS AND DISCUSSIONMORPHOLOGICAL ANALYSES

Skull morphological variation according to sex wasquite common among the cat species tested (Table 2),except for Herpailurus yagouaroundi and Prionailu-rus bengalensis, which showed no variation betweensexes, and the bobcat (Lynx rufus), in which malesand females differed only in occipital height (OCH).The sexual dimorphism on skull traits were inter-preted as the main determinants of the bimodal dis-tributions found in some species.

The PCA coefficient matrix is presented in Table 3.The first two PCs show the highest eigenvalues, andare associated with 99.5% of the total variation in thedata. They were considered as the main descriptors ofthe Felidae morphology.

All skull measurements are highly associated withPC1, and the species scores are consistent with sizevariations among cat species. Thus, the concept of‘size’ is strongly associated with PC1. The centroids of

the species scores were plotted over a Cartesiandiagram, where the axes are the first two PCs, accord-ing to its phylogenetic lineages (Fig. 3). The mostnegative scores are related to big panthers and themost positive ones belong to the tiny rusty-spotted cat(Prionailurus rubiginosus). The middle-sized speciesappear as a gradient along this axis.

The size influence is much lower in PC2, and dis-tinctive morphological features could be identifiedamong the species. The measurements mainly asso-ciated with PC2 were: anterior width across parietals,just behind the supraorbital process (POC) and themasseteric scar width (MSW), both with negativecoefficients; and temporal fossa length (TFL), with apositive coefficient. PC2 is associated with thebreadth of the anterior part of the braincase, mas-seter robustness, and the elongation of the posteriorhalf of the skull (denoted by the length of the tempo-ral fossa). The coefficient of POC was considerablyhigher than the others, indicating a leading role inthe morphological aspect depicted by this PC. On theother hand, postorbital constriction is quite invariantbetween males and females in the 14 species tested inrelation to the sexual dimorphism (Table 2). This factcould suggest a constrained pattern of this featurewithin each species, despite the importance of thepostorbital constriction as a variant feature amongspecies.

PANTHERA LINEAGE: The PC1 scores (Fig. 4)reflect the size superiority of the panthers among thefelids (F7, 607 = 240.61, P < 0.0000001; Tukey’s HSDtest, P < 0.0001). Lions and tigers are the largestspecies, and the clouded leopard is the smallest one(F5, 118 = 138.30, P < 0.00001). There is no difference inthe overall skull size between lions (Panthera leo) andtigers (Panthera tigris), and both are bigger than allof the other cat species (Tukey’s HSD test, P < 0.001).The jaguar (Panthera onca) is the second biggest cat(P < 0.001), followed by leopards (Panthera pardus)and snow leopards (Uncia uncia), which are of thesame size (P < 0.001).

The PC2 scores denote a marked dichotomybetween the elongated skull pattern of the cloudedleopard (Neofelis nebulosa), with a narrow width ofanterior portion of braincase, and the short and broadskull of U. uncia. The intermediate-sized panthers (P.onca and P. pardus) show a bias to the elongated/narrow pattern, whereas the big panthers have moreregular skulls. The PC2 scores indicate no significantdifferences between lions and tigers (F5, 118 = 45.16,P < 0.00001; Tukey’s HSD test, P > 0.18), regardingthe skull measurements associated with the secondprincipal component. This could be noted as anoverall morphological similarity between the skulls ofP. leo and P. tigris, despite the conspicuous features



Tab

le2.

Sex

ual

vari

atio

nin

the

sku

llm

orph

olog

yam

ong

the

best

sam

pled

cat

spec

ies

(n>

6)

Spe

cies

Tota

lN

Mal

esn

Fem

ales

nL

inea

geB

BC

CB

LC

CL

CM

1LJH

M1

JLJW

M1

MB

MF

LM

MA

Pan

ther

ale

o25

108

Pan

ther

a0.

001

0.01

0.01

0.01

0.01

0.01

0.02

0.01

0.01

0.01

Pan

ther

apa

rdu

s25

117

Pan

ther

a0.

001

0.00

10.

001

0.00

10.

001

0.00

10.

010.

001

0.00

10.

01O

nci

feli

sge

offr

oyi

209

6O

celo

t0.

720.

050.

030.

030.

020.

030.

480.

020.

060.

02L

eopa

rdu

spa

rdal

is57

1516

Oce

lot

0.01

0.01

0.01

0.01

0.00

10.

010.

010.

010.

020.

04L

eopa

rdu

sti

grin

us

3817

8O

celo

t0.

700.

150.

450.

320.

080.

290.

010.

770.

180.

60L

eopa

rdu

sw

ied

ii42

176

Oce

lot

0.07

0.04

0.06

0.03

0.06

0.06

0.10

0.04

0.07

0.05

Her

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exhibited by these species. However, this resulttakes into account the pooled within variance amongthe very diverse panther species. The direct compari-son between the PC2 scores of P. leo and P. tigrisindicates that they are clearly different (F1, 41 = 6.81,P < 0.01).

The comparison of measurement ratios allowed fora better perception of the panthers skull design. Forinstance, U. uncia shows the largest postorbital con-striction (POC/CBL, F5, 118 = 33.51, P < 0.00001;Tukey’s HSD test, P < 0.001) among the panthers;N. nebulosa possesses the highest proportion oftemporal fossa length (TFL/CBL, F5, 118 = 33.80,P < 0.00001; Tukey’s HSD test, HSD test, P < 0.04).Panthera leo and P. onca equally show the largestratios of height of jaw bone at M1 (JHM1/CBL,F5, 118 = 24.54, P < 0.00001; Tukey’s HSD test,P < 0.04); whereas P. tigris exhibits the widest jawbone at M1 (JWM1/CBL, F5, 118 = 13.14, P < 0.00001;Tukey’s HSD test, P < 0.04). These two latter mea-surements are related to the robustness of the dentalbone, and, together, they are indicative of the poten-tial load that a jaw could resist during the bite.

Comparisons between the Panthera lineage andother felids indicate that panthers have the smallestanterior temporal fossa length ratio (TFL/CBL,F7, 607 = 31.85, P < 0.000001; Tukey’s HSD test,

P < 0.0001), and their mean value lies below the lowerquartile value of the family Felidae.

As a matter of fact, lions and snow leopards showedthe smallest temporal fossa length ratios amongalmost all other felid species (TFL/CBL,H29, 606 = 292.93, P < 0.00001; Dunn’s test, P < 0.05,except for the cheetah, Acinonyx jubatus, P > 0.05).This denotes the allometry between the anterior andposterior halves of the skull among different sizedcats. The panthers postorbital constriction wassmaller (POC, F7, 607 = 90.87, P < 0.000001; Tukey’sHSD test, P < 0.0001) than in all other felid groups.The high scores of panthers on PC2 are related to thesynergy between these morphological features.

Panthers also have the narrowest breadth of brain-case (BBC/CBL, F7, 607 = 111.78, P < 0.00001; Tukey’sHSD test, P < 0.0001), as well as the largest ratios ofjaw height at M1 (F7, 607 = 66.59, P < 0.000001; Tukey’sHSD test, P < 0.05) and jaw width at M1 (JWM1/CBL,F7, 607 = 52.89, P < 0.000001; Tukey’s HSD test,P < 0.0001). They also present a higher coronoidprocess than all other lineages (TMA/CBL,F7, 607 = 63.94, P < 0.00001; Tukey’s HSD test,P < 0.001), except for the bay cat group; however, itseems to be caused by the well-developed coronoidprocess of Pardofelis marmorata. The snout of pan-thers is generally longer than all other extant cats,and is denoted by the orbit to premaxillae length ratio(OPL/CBL, F7, 607 = 192.72, P < 0.00001; Tukey’s HSDtest, P < 0.0001), which means the values lie quite abit above the family’s upper quartile, as well as thetooth row length ratio (TRL/CBL).

The panther skull could be summarized as amassive one, but with a relatively narrow postorbitalconstriction and a comparatively short temporal fossalength (related to the allometric effect of the elon-gated rostrum). Panthers also show a powerful jawwith robust dental bones, and thus with a high SMAto resist strong bending loads. Their longer rostrumprovides a wide gape between the canines, and couldbe interpreted as an adaptation for hunting largeprey.

Clouded leopards (N. nebulosa) have one of thewidest gapes during biting (Christiansen, 2006); nev-ertheless, they have a relatively short rostrum whencompared with the other panthers (OPL/CBL,F5, 107 = 175.39, P < 0.000001; Tukey’s HSD test,P < 0.0001). Christiansen (2006) pointed out theimportance of the angle between the upper tooth rowand the basicranial axis to the N. nebulosa wide bitegape. This anatomical arrangement could compensatetheir short rostrum. The elongated temporal fossa,associated with a narrow postorbital constriction, pro-vides an extensive space for the origin of a powerfultemporalis muscle in the clouded leopard skull. Thesmall coronoid process of N. nebulosa is markedly

Table 3. Coefficients of the 20 skull measurementsrelated to the first two principal components

Skull Measurements PC 1 PC 2

CBL -0.96* 0.07TFL -0.98* 0.12*MSL -0.92* -0.02MSW -0.92* -0.20*MB -0.93* 0.05BBC -0.99* -0.03POC -0.89* -0.42*ZIB -0.95* 0.01OPL -0.96* 0.01TRL -0.94* 0.05OCH -0.95* 0.03RWP2 -0.95* -0.01JL -0.98* 0.04TMA -0.95* 0.04MMA -0.99* 0.01CM1L -0.97* 0.02CCL -0.98* 0.03JHM1 -0.92* 0.07JWM1 -0.90* 0.06MFL -0.92* 0.03Eigenvalue 18.9 1.0Cumulative Variation (%) 94.5% 99.5%

*High-value coefficients.



allometric compared with P. onca, P. leo, and P. tigris(TMA/CBL, F5, 118 = 14.01, P < 0.000001; Tukey’s HSDtest, P < 0.001).

Puma lineage: The PCA of morphometrical datashowed a total divergence of skull patterns in thisgroup (Fig. 5), but there is some skull size similaritybetween the puma (Puma concolor) and cheetah (A.jubatus). There are no significant differences betweenthese two species in 12 out of 20 skull measurements(CBL, MSW, BBC, ZIB, OCH, RWP2, JL, TMA, MMA,CCL, JHM1, and MFL) including the main axis of theskull (i.e. length, width, and height). Pumas showhigher mean values on temporal fossa length (TFL,F1, 52 = 15.79, P < 0.001), mastoid breadth (MB,F1, 52 = 8.04, P < 0.01), tooth row length (TRL,F1, 52 = 14.7, P < 0.001), and jaw width at M1 (JWM1,F1, 52 = 9.44, P < 0.01) than cheetahs. On the otherhand, cheetahs have higher mean values on masse-teric scar length (MSL, F1, 52 = 4.06, P < 0.05), postor-

bital constriction breadth (POC, F1, 52 = 133.05,P < 0.000001), orbit to premaxillae length (OPL,F1, 52 = 10.14, P < 0.01), and condyle to M1 length ofjaw (CM1L, F1, 52 = 11.29, P < 0.01) than pumas. Thus,the skulls of pumas and cheetahs are equivalent insize, and Herpailurus yagouaroundi is clearly thesmallest species of this group.

The PC2 scores indicate significant shape differ-ences among the three species (F2, 82 = 128.96,P < 0.00001). The conspicuous morphology of the skullof A. jubatus is marked by a broad postorbital con-striction associated with a short temporal fossa. Chee-tahs show the greatest postorbital constriction ratiosamong the big cats (> 40 kg) (POC/CBL, F7, 170 = 92.20,P < 0.00001; Tukey’s HSD test, P < 0.02). Further-more, the mean ratio of the zygomatic arches breadth(ZIB/CBL) of A. jubatus lies quite a bit above theupper quartile value of the felids as a whole. Chee-tahs also exhibit a well-developed coronoid process(TMA/CBL, F26, 572 = 74.08, P < 0.00001; Tukey’s HSD

Figure 3. Distribution of the 34 cat species, according to their scores from the morphological principal componentanalysis (PCA). Plots represent species’ centroids based on bivariate means of the scores. Arrows indicate the enlargementof the skull measurements related to each axis. Acronyms are defined in the text.



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test, P < 0.01), comparable with the ratios in lions,tigers, jaguars, and manul cats. However, cheetahsshow the smallest ratios of temporal fossa length(F26, 572 = 29.57, P < 0.00001; Tukey’s HSD test,P < 0.04, except in U. uncia). The hypertrophy of thetransversal measurements of the skull (POC and ZIB)and the short temporal fossa contribute to give abroad and high-domed, but compact, look to the chee-tah’s head.

The sinus frontalis in the skull of the big cats isusually located in the region described by the postor-bital constriction. However, the sinus frontalis of A.jubatus is apomorphically placed forwards, across thesupraorbital process (Salles, 1992), and without adirect topological homology with the measurementof postorbital constriction. Nevertheless, the skullanatomy of the cheetah suggests a widening of theentire frontal region, beginning from the anteriorportion of the supraorbital processes up to the pos-torbital constriction. The open angle of the supraor-bital processes also indicates the hypertrophy of thisregion of the skull. The wide postorbital constrictionin the A. jubatus skull seems like a secondary effect ofthe general hypertrophy around the postorbital pro-cesses, and is associated with the development of thesinus frontalis.

The small mandibular diastema in the tooth row ofA. jubatus also contributes to compound the uniquedesign of the cheetah skull. According to PC2, thedevelopment of the width of the masseteric scar(MSW) is also a marked feature of the cheetah skull.They have the highest ratios of MSW among themembers of the Puma lineage (F2, 82 = 48.26,P < 0.00001; Tukey’s HSD test, P < 0.02), and alsoamong the big cats as a whole (F8, 200 = 48.60,P < 0.00001; Tukey’s HSD test, P < 0.02). This denotesthe particular importance of the masseter action onthe cheetah’s bite.

Jaguarundis are the smallest species of the Pumalineage, with an elongated braincase (associated withthe long TFL ratio), and an intermediate postorbitalwidth, but with a relatively narrow masseteric scar atthe zygomatic arch. Herpailurus yagouaroundi has atemporal fossa length ratio similar to P. concolor, andgreater than in cheetahs (TFL/CBL, F2, 82 = 36.47,P < 0.000001; Tukey’s HSD test, P < 0.001). Theirpostorbital constriction width is proportionallysmaller than in A. jubatus (POC/CBL, F2, 82 = 94.72,P < 0.000001; Tukey’s HSD test, P < 0.03), but is largerthan in P. concolor (Tukey’s HSD test, P < 0.001). Theyalso have the smallest width of the masseteric scar ofthis lineage (MSW/CBL, F2, 82 = 48.26, P < 0.000001;Tukey’s HSD test, P < 0.001).

The species of the Puma lineage have the smallestratios of mastoid breadth among the groups (MB/CBL, F7, 607 = 21.35, P < 0.00001; Tukey’s HSD test,

P < 0.03), except for the Caracal lineage. Puma,Caracal, and domestic cat lineage members exhibitthe largest ratios of masseteric moment arm (MMA)among the groups (F7, 607 = 42.44, P < 0.00001). Like-wise, the members of these three lineages show anelongated angular process, which is also associatedwith masseter muscle mechanics.

Herpailurus yagouaroundi has one of the smallestratios between jaw and skull lengths, besides Oncife-lis colocolo, Oncifelis geoffroyi, Oncifelis guigna, Leop-ardus tigrinus, Leopardus wiedii, Prionailurusbengalensis, Prionailurus rubiginosus, and Prionailu-rus planiceps among the other felid species (JL/CBL,H29, 609 = 545.61, P < 0.00001; Dunn’s test P < 0.05).Low ratios between these measurements denote anelongated postorbital area of the skull.

Thus, there is no generalized skull design amongthe members of the Puma lineage, and few featurescould be considered conspicuous to them. This factreinforces the idea of three species with markedlyderived skull patterns, despite of their phylogeneticcloseness.

Lynx lineage: The lynx morphotype is quite conspicu-ous, and the variation among the species is mainlyrelated to size (Fig. 6). The Canada lynx (Lynxcanadensis) and the bobcat (L. rufus) are significantlydifferent according to PC1 (F1, 55 = 9.86, P < 0.01).Despite the small sample, the average PC1 score ofthe Eurasian lynx (Lynx lynx) is, as expected, higherthan the maximum values of both L. rufus and L.canadensis. Moreover, there is a similarity betweenthe skull size of the Canadian and Iberian lynxes(L. canadensis and Lynx pardinus).

There are no significant differences between thePC2 scores of L. canadensis and L. rufus, and it islikely that the same should be valid for L. lynx. TheIberian lynx (L. pardinus) seems to have a broaderskull than the others. The position of the lynxesaccording to PC2 (Fig. 3) is mostly a result of theirdeveloped postorbital constriction, the average ratioof which is near to the upper quartile of all felids.Lynx canadensis and L. rufus show similar or higherpostorbital constriction ratios than 25 species (out ofthe 30 compared), being just smaller than the manulcat (Otocolobus manul), wild cat (Felis silvestris), andmargay (Leopardus wiedii), F. silvestris, and L. wiedii(POC/CBL, F29, 579 = 121.81, P < 0.00001; Tukey’s HSDtest, P < 0.001).

The analysis of other measurements brings addi-tional information about the general lynx morphology.Lynxes have some of the widest zygomatic arches andmastoid process breadths among the felids (ZIB/CBL,F7, 607 = 29.00, P < 0.00001; Tukey’s HSD test,P < 0.001; MB/CBL, F7, 607 = 21.34, P < 0.00001;Tukey’s HSD test, P < 0.0001; exceptions are cited for



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the bay cat, domestic cat, and leopard cat lineages).However, the members of the Lynx lineage, besidesthe bay cat and leopard cat lineages, show some of thesmallest lengths of the angular processes of the jaw(MMA), being just larger than the Ocelot lineage(MMA/CBL, F7, 607 = 42.44, P < 0.00001; Tukey’s HSDtest, P < 0.001).

The lynx skull design could be summarized as beingbroad and robust, with a marked hypertrophy of theanterior portion of the braincase. Their jaw bones arenot projected backwardly, and the angular processesare relatively short.

Ocelot lineage: According with the PC1 scores (Fig. 7),Leopardus pardalis is the largest species(F5, 168 = 379.06, P < 0.000001; Tukey’s HSD test,P < 0.0001), followed by similar intermediate-sized L.wiedii, O. colocolo, and O. geoffroyi (Tukey’s HSD test,P < 0.01), and the smallest ones, L. tigrinus and O.guigna (Tukey’s HSD test, P < 0.01).

The PC2 depicts the marked difference in the skullmorphology between two sister species: L. pardalisand L. wiedii. The conspicuous narrow postorbitalconstriction of L. pardalis contrasts with the broad-headed margay (L. wiedii). According to the postor-bital constriction ratio, L. pardalis has the narrowestpostorbital constriction among Ocelot lineage species(POC/CBL, F5, 168 = 141.55, P < 0.000001; Tukey’s HSDtest, P < 0.02). On the other hand, L. wiedii exhibitsthe higher ratio of this feature (Tukey’s HSD test,P < 0.02). As a matter of fact, margays have thewidest postorbital constriction in the absolute sense(POC, F5, 168 = 28.21, P < 0.000001; Tukey’s HSD test,P < 0.001). On the other hand, the postorbital con-striction of the medium-sized L. pardalis do not differfrom the small O. colocolo. Leopardus wiedii also hasthe smallest ratio of temporal fossa length (TFL/CBL,F5, 168 = 18.50, P < 0.000001; Tukey’s HSD test,P < 0.01), whereas the other species do not show dif-ferences from each other.

Other distinctive skull features can be cited withinthe Neotropical small cats. Leopardus tigrinus has,proportionally, the narrowest skull across the zygo-matic arcs (ZIB/CBL, F5, 168 = 15.74, P < 0.000001;Tukey’s HSD test, P < 0.01). This species and L.wiedii exhibit equally the smallest ratios of the tem-poral moment arm (AMT/CBL, F5, 168 = 57.82,P < 0.000001; Tukey’s HSD test, P < 0.0001). Thegenus Oncifelis shows a very consistent skull design,and no particular feature could be highlighted for anyof its species.

The comparison between Ocelot and domestic catlineages (Fig. 3) – which could be cited as equivalent-sized counterparts of the Neotropical and Palearctic/Ethiopian regions, respectively (PC1 scores, Mann–Whitney’s U = 6117.0, P = 0.08) – denotes a marked

divergence of skull patterns between them, accordingto their PC2 scores (Mann–Whitney’s U = 616.0,P = 0.00001).

The small Neotropical cats showed higher ratios oftemporal fossa length than the African and Eurasiansmall cats, indicating their elongate braincase behindthe supraorbital process (TFL/CBL, F1, 247 = 9.30,P < 0.01). On the other hand, the postorbital widthacross the parietals of the members of the domesticcat lineage is wider than of the Ocelot lineage (POC/CBL, F1, 247 = 82.87, P < 0.00001), which confers tothem a broad constitution of the anterior region ofthe braincase. The same is true for the massetericscar width, which is wider in the domestic cat lineagethan in the small Neotropical cats (F1, 247 = 213.33,P < 0.00001).

Both lineages showed a similarity between themeasurements associated with jaw bone robustness(JHM1 and JWM1). This suggests an equivalentbending stress over the jaws of these cats during thebite.

Ocelot lineage members also show smaller ratios onother skull measurements than the other cat lineages:jaw length (JL/CBL, F7, 607 = 26.97, P < 0.00001;Tukey’s HSD test, P < 0.001), condyle to M1 length ofjaw (CM1L/CBL, Tukey’s HSD test, P < 0.01, except forthe bay cat lineage P > 0.05), and canine length of jaw(CCL/CBL, Tukey’s HSD test, P < 0.01). These mea-surements are three length descriptors on jaw bone,and, in this case, they indicate a short overall jawlength associated with an elongated skull (CBL). TheseNeotropical cats exhibited a short and narrow rostrumwhen compared with other lineages, according to theirorbit to premaxillae length and rostral width at thesecond premolar (P2) ratios (OLP/CBL, F7, 607 = 162.71,P < 0.00001; Tukey’s HSD test, P < 0.01, except for thebay cat and leopard cat lineages; RWP2, F7, 607 = 95.81,P < 0.00001; Tukey’s HSD test, P < 0.0001, except forthe bay cat lineage). Proportionally, their occipitalheight and coronoid process are some of the smallestamong the felids (OCH/CBL, F7, 607 = 63.94,P < 0.00001; Tukey’s HSD test, P < 0.0001, except forthe Caracal lineage; AMT/CBL, F7, 607 = 63.94,P < 0.00001; Tukey’s HSD test, P < 0.01).

The features described above and the narrowness ofthe braincase contribute to the elongated, slender,and low-lined skull design of the members of theOcelot lineage. Their rostrum is also markedly short,as indicated by the average ratio of orbit to premax-illae length (OPL/CBL), which is closer to the lowerquartile of all felids.

Domestic cat lineage: Felis chaus is clearly the largerspecies among the members of this lineage (PC1scores, H2, 73 = 23.27, P < 0.00001; Dunn’s testP < 0.01). Accordingly, F. silvestris and Felis marga-



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rita show no significant size difference (Fig. 8). Felisnigripes (n = 2) was excluded from the univariateanalysis, however, their average PC1 score fallsoutside of the 95% confidence interval of F. silvestrisand F. margarita, reflecting their small size. Directcomparisons of measurements related to the threemajor skull axes (length, width, and height) repre-sented by the condylobasal length (CBL), zygomaticarches internal breadth (ZIB), and occipital height(OCH) corroborate the multivariate analysis. Felischaus has a longer (CBL) and higher (OCH) skullthan the other two species (H2, 73 = 27.11, P < 0.0001;Dunn’s test P < 0.01 for F. silvestris and P < 0.05 forF. margarita; H2,73 = 30.43, P < 0.0001; Dunn’s testP < 0.01). There is no difference in the condylobasallength between F. silvestris and F. margarita. Thezygomatic arches breadth (ZIB) of F. margarita issimilar to F. chaus and to F. silvestris, but this featurewas wider in F. chaus than in F. silvestris(H2, 73 = 9.12, P < 0.01; Dunn’s test P < 0.01). This sug-gests allometry of these skull traits in sand cats whencompared with the larger-sized F. chaus.

The ratio between the PC1 scores and average bodymass of F. margarita is more than three times greaterthan the upper quartile limit of this ratio in thedomestic cat lineage (H2, 73 = 50.25, P < 0.00001,Dunn’s test P < 0.01). Thus, there is marked allom-etry between the overall skull size and the body massin sand cats, regarding the mean body weights of theother cats of this lineage (F. chaus ~7.3 kg, F. silves-tris ~5.5 kg, and F. margarita ~2.4 kg, after Guggis-berg, 1975; Heptner & Sludskii, 1992; Nowak, 1999;Sunquist & Sunquist, 2002). The skull-size/body-massratio of F. nigripes indicates they are more similar tothe general head–body pattern of F. margarita, thanto the other species of the domestic cat lineage.

Nonparametric analysis of the PC2 scores indicatedno significant differences between F. chaus, F. marga-rita, and F. silvestris. However, these three speciesand F. nigripes are strongly associated with the nega-tive part of the PC2 axis (Figs 3, 8), denoting a broadpostorbital constriction width and shortened temporalfossa.

Comparisons between domestic cat and leopard catlineages (Fig. 9) indicate different morphological pat-terns in PC2 (F1, 130 = 145.28, P < 0.00001), despite thephylogenetic proximity between them.

The members of the domestic cat lineage exhibitedone of the highest ratios in both masseteric scarlength and width among the felids (MSL/CBL,F7, 607 = 18.56, P < 0.00001; Tukey’s HSD test, P < 0.03;MSW/CBL, F7, 607 = 60.93, P < 0.00001; Tukey’s HSDtest, P < 0.0001), being comparable only with theleopard cat lineage. These features are somewhatrelated to the development of the zygomatic arches.As a matter of fact, members of the domestic cat

lineage show a broad face, and the ratio of theirzygomatic arches breadth (ZIB) to skull length issignificantly larger than in most species of otherlineages (ZIB/CBL, F7, 607 = 29.0, P < 0.00001; Tukey’sHSD test, P < 0.03, except for the bay cat and Lynxlineages).

The domestic cat lineage members could bedescribed as possessing a broad skull, with widebraincase and robust cheek bones, typically associ-ated with the allocation of strong masseters. Actually,the ratios of the transversal distances across the skullof domestic cats, i.e. zygomatic arches internalbreadth (ZIB), postorbital breadth (POC), breadth ofbraincase (BBC), and mastoid breadth (MB), arehigher than the limits of upper quartiles for the wholefelid family. The same is observed on the measure-ments of length and width of the masseteric scar atthe zygomatic arch.

Leopard cat lineage: The PC1 scores of the fishing cat(Prionailurus viverrinus) are distinguishably higherthan the values in the other species (H4, 48 = 41.24,P < 0.0001; Dunn’s test P < 0.01), except for O. manul(Fig. 9). The small rusty-spotted cat (Prionailurusrubiginosus) differed significantly from the othersspecies (Dunn’s test P < 0.05, except Prionailurusbengalensis), despite the limited number of specimens(n = 3). Otocolobus manul does not show significantsize dissimilarities from the flat-headed cat (Prion-ailurus planiceps), despite the evident sagittal lengthdifference between these two species. It suggests anunusual expression in PC1 of dissimilarities on theskull shape of O. manul, rather than simply sizeallometry between the species.

Analysis of original measurements of the threemain axes of the skull indicate significant differencesbetween these four species (CBL, H4, 48 = 34.78,P < 0.0001; ZIB, H4, 48 = 35.64, P < 0.0001; OCH,H4, 48 = 32.58, P < 0.0001). Prionailurus viverrinusshowed the largest skull according to these threemeasurements (Dunn’s test P < 0.01), except for itsinternal breadth of the zygomatics, which is similar tothat of the manul cat. The skull of O. manul is clearlyshorter than P. viverrinus and P. planiceps (CBL,Dunn’s test P < 0.01); however, the three speciespresent the same internal breadth of zygomaticarches (ZIB). The occipital height (OCH) of O. manulis similar to P. planiceps, but is smaller than P.viverrinus (Dunn’s test P < 0.05). Considering thebreadths across the transversal plane of the braincase(POC and BBC), O. manul’s postorbital constriction isbroader than that of other leopard cat lineage species(H4, 48 = 37.28, P < 0.0001, Dunn’s test P < 0.01; exceptP. viverrinus, not significant), as is its breadth ofbraincase (H4, 48 = 32.58, P < 0.0001, Dunn’s testP < 0.01; except P. viverrinus, not significant). Thus,



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despite the short condylobasal length, the manul catskull is markedly broad. This strong allometricpattern therefore demands a less straightforwardreading of the first PC than being merely indicative ofsize between the species.

The PC2 denotes the presence of three subgroups,ranging from species with a wider postorbital con-striction to those with a more elongated posterior halfof the skull (H4, 48 = 30.99, P < 0.00001). Prionailurusplaniceps differed from the other four species (Dunn’sP < 0.05), with a markedly elongated temporal fossaand narrow postorbital constriction. There is no sig-nificant difference between the scores of P. viverrinus,P. bengalensis, and P. rubiginosus, and the most dis-tinctive feature of these species is the elongated pos-terior half of the skull. The negative scores from O.manul were higher than all other species of thislineage (Dunn’s test P < 0.05) because of its broad-shaped skull.

The analysis of the leopard cat lineage pointed outtwo extreme allometric patterns among phylogeneti-cally close species: O. manul and P. planiceps. Thesingular look of the skull of O. manul within theleopard cat lineage suggests a convergent pattern tothe wide skulls of the members of the genus Felis.Thus, in some comparisons between Leopard cat andthe other lineages, the manul cat (O. manul) wasremoved from the analyses.

The other members of the leopard cat lineage havethe shortest jaws among other cat lineages. This isdenoted by their small ratios of jaw length andcondyle to canine length (JL/CBL, F7, 601 = 99.98,P < 0.00001; Tukey’s HSD test, P < 0.01; and CCL/CBL, F7, 601 = 83.54, P < 0.00001; Tukey’s HSD test,P < 0.001), except for the bay cat and Puma lineages.Low ratios between jaw and skull length are anindication of an elongated posterior portion of theskull behind the postorbital processes. Short jawscould limit the bite gape, but it also means a short‘out-force’ moment arm and an improvement on themechanical efficiency of the jaw.

The temporal fossa length ratio to skull length ofPrionailurus species is higher than the limit of theupper quartile of the family Felidae. This confers tothem an elongated profile on the posterior portion ofthe skull. Nevertheless, manul cats (O. manul) alsohave an elongated temporal fossa, but their broadskull confers to them a distinctive bulky head. Theratios of features related to the transversal plane oftheir skull, such as the postorbital constriction (POC),breadth of braincase (BBC), zygomatic arches inter-nal breadth (ZIB), and mastoid breadth (MB), arequite a bit higher than the limits of the upper quartileof these measurements for the Felidae family.

The skull of the flat-headed cat (P. planiceps) has adeveloped temporal crest and narrow postorbital con-

striction (both related to a more extensive origin areaof the temporalis muscle). On the other hand, theyshow a distinctive low ratio of the MMA, beingsmaller than almost all felid species (MMA/CBL,H29, 609 = 335.89, P < 0.00001, Dunn’s test P < 0.05,except for L. wiedii and P. marmorata, not signifi-cant.). These features suggest an increased impor-tance of temporal mechanics (or reduced participationof masseter) in the bite of the flat-headed cats.

The members of the leopard cats group show agreat diversity of skull designs, and therefore theconnected (or partially connected) supra- and infra-postorbital processes remain the major similarityamong them.

Caracal lineage: The members of the Caracal lineage(Fig. 10) share a similar overall skull size according tothe PC1 scores (H2, 40 = 5.68, P = 0.06).

The PC2 scores indicate a slight difference betweenthe three species (H2, 40 = 9.53, P < 0.01). Profelisaurata and Leptailurus serval show significant differ-ences (Dunn’s test P < 0.05), but neither differ fromCaracal caracal. Nevertheless, the ratios of skullmeasurements associated with PC2 indicate differ-ences between species in temporal fossa length(TFL/CBL, F2, 34 = 8.71, P < 0.0001) and postorbitalconstriction (POC/CBL, F2, 34 = 16.59, P < 0.000001).

Profelis aurata shows the smallest postorbital con-striction of the three species (Tukey’s HSD test,P < 0.02 for C. caracal, and P < 0.001 for L. serval),and the temporal fossa of C. caracal is shorter thanthat of L. serval (Tukey’s HSD test, P < 0.01).

Compared with the other lineages, the Caracalmembers show a particularly narrow massetermuscle scar width for their skull size (MSW/CBL,F7, 607 = 60.93, P < 0.000001; Tukey’s HSD test,P < 0.02; except for Panthera and bay cat lineages,P > 0.88). This characteristic is evinced by their posi-tive scores on PC2.

Aside of this, the skull design of Caracal lineagemembers is quite ordinary among other medium-sizedcats. The species skulls are moderately elongated, butnot markedly narrow across the zygomatic arches,and almost all skull measurement ratios of thislineage lie between the lower and upper quartiles ofthe other felids.

Bay cat lineage: The small sample size of Catopumabadia hindered a more detailed morphological analy-sis (Fig. 11); even so, the Asiatic golden cat(Catopuma temminckii) is the largest species ofthis lineage when compared with the marbled cat(Pardofelis marmorata) (PC1 scores, Mann–Whitney’sU = 0, P < 0.01).

Both species, however, do not show differences inPC2 scores (Mann–Whitney’s U = 17, P = 0.66). The



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PC2 score value of the single specimen of C. badia liescompletely outside the quartile range of the other twospecies, and it indicates the hypertrophy of the pos-torbital width. It also denotes the morphological dif-ferences and the size allometry between the sistertaxa (C. badia and C. temminckii).

The temporal fossa length and postorbital constric-tion ratios of the Asiatic golden cat are smaller thanthose of the marbled cat (TFL/CBL, Mann–Whitney’sU = 1, P < 0.02; POC/CBL, U = 1, P < 0.02), but theyhave similar masseteric scar width ratios (MSW/CBL). The bay cat (C. badia) ratios of postorbitalconstriction, masseteric scar width, and temporalfossa lie above the upper quartile of the ratios of thesemeasurements for C. temminckii and P. marmorata.

Bay cat lineage members could be described ashaving an elongated skull with a well-developedoccipital region. Indeed, the temporal fossa lengthand mastoid breadth ratios of this lineage lie abovethe values of the upper quartiles of these measure-ments of the family.

FUNCTIONAL ANALYSES

The coefficient matrix of the PCA based on the FIs ispresented in Table 4. The first two PCs were associ-ated with 98.9% of the total variation. The FIs of boththe temporalis (CFTC) and the masseter muscles(CFMC), and the attachment area of head–neck mus-cular system (AHN), are highly correlated with PC1,suggesting the association between ‘skull size’ and‘bite force’. The PC1 could be easily labelled as ‘bitestrength and neck muscle robustness’. The second PCshows a meaningful difference between the two majorindicators of jaw muscles mechanics. PC2 could belabelled as ‘contribution of the temporalis and mas-seter mechanical systems to the final bite force’ or as‘the influence of the skull design to the jaw musclesperformance’. The centroids of the species scores wereplotted over a Cartesian diagram, where the axes arethe first two PCs (PC1 and PC2). The species arepresented according to their phylogenetic lineages(Fig. 12).

Panthera lineage: Panthers, as expected, have themost powerful bite and neck robustness among felids(Fig. 13). Lions (P. leo) and tigers (P. tigris) show asimilar final bite force, with both of them being morepowerful than all other cats (H26, 599 = 563.97,P < 0.0001, Dunn’s test P < 0.01). A bite strength gra-dient is observed on other panthers, with an obviouscorrelation to their skull and body sizes. Leopards (P.pardus) and snow leopards (U. uncia) show a similarefficiency on jaw occlusion (Dunn’s test P > 0.05),despite their skull shape differences.

Lions and tigers share an overall similarity in skullmorphology and size, and have the same potential forstrong bites at the canines. However, according toPC2, the jaw occlusion of P. leo is greatly influencedby the action of the masseteric complex, which isquite different from that of P. tigris (F5, 118 = 57.97,P < 0.0001; Tukey’s HSD test, P < 0.001).

Tigers (P. tigris) show the same pattern in jawocclusion that is observed in jaguars (P. onca), leop-ards (P. pardus), and snow leopards (U. uncia). Allthese species display a smaller contribution of themasseteric muscle system to the bite than thatobserved in lions (P. leo).

On the other hand, the jaw occlusion of cloudedleopards is deeply marked by the mechanical systemof the temporalis muscle (PC2 scores, Tukey’s HSDtest, P < 0.001), and the participation of the masse-teric complex is much less substantial than thatobserved in other panthers.

The coronoid process of the toothy N. nebulosa isone of the smallest among panthers, and, in somesense, resembles the trend observed in the saber-toothed Machairodontinae, and is related to thedemands of a wide bite gape (see Christiansen, 2006).Despite the importance of the size of the coronoid(‘in-force’ moment arm) to the temporalis mechanics,there are other skull features involved that arecrucial to the performance of this muscle. Cloudedleopards show the largest temporal fossa length ratioto skull length as well as the smallest postorbitalconstriction ratio among the panthers (TFL/CBL,F5, 118 = 33.80, P < 0.00001; Tukey’s HSD test, P < 0.01;POC/CBL, F5, 118 = 33.51, P < 0.00001; Tukey’s HSDtest, P < 0.03). These two features define the limits ofthe origin of the temporalis muscle in the skull. Thus,the large temporal fossa and the small postorbitalconstriction of the clouded leopards indicate the pres-ence of a robust temporalis muscle. This provides agreat temporal system ‘in force’, and compensates forthe small coronoid process in the equation of staticequilibrium. Furthermore, the short coronoid processof N. nebulosa forms an angle of 90 ° with the line ofaction of the temporalis muscle during the wide gape,which maximizes the leverage of this muscle. Theseobservations bring additional support to Christians-

Table 4. Coefficients of the force indexes related to thefirst two principal components

Force-indexes PC1 PC2

CFTC -0.96* 0.19*CFMC -0.96* -0.17*AHN -0.96* -0.13*Eigenvalue 2.87 0.10Cumulative Variation (%) 95.7% 98.9%

*High-value coefficients.



en’s (2006) proposal for an adaptative convergencebetween clouded leopards and saber-toothed cats inrelation to wide bite gapes.

Puma lineage: The bite force and neck robustness ofP. concolor do not differ from those of A. jubatus (PC1scores, H2, 85 = 59.43, P < 0.001, Dunn’s test P > 0.05),with both species being superior to H. yagouaroundi(Dunn’s test P < 0.01), Fig. 14.

The PC2 scores indicate a similarity in jaw mechan-ics between the sister species P. concolor and H.yagouaroundi (H2, 85 = 23.60, P < 0.00001, Dunn’s testP > 0.05), and both show a slight optimization of themasseter muscle system during the bite.

Pumas and cheetahs show similarities in overallskull size (Fig. 5), in spite of differences in bodymass (average weight: P. concolor = 67.5 kg; A.jubatus = 53.5 kg; Guggisberg, 1975). However, thefinal bite force of A. jubatus is deeply influenced by

the action of the masseteric complex (PC2 scores,Dunn’s test P < 0.01).

The analyses of the raw values of the FIs, however,indicate a similarity in the action of the massetermuscle between pumas and cheetahs (CFMC,F2, 82 = 489.90, Tukey’s HSD test, P > 0.05), but thecheetah’s temporalis muscle FI is significantly lowerthan that of the puma (CFTC, F2, 82 = 327.80, Tukey’sHSD test, P < 0.02). The short temporal fossa lengthand the broad postorbital constriction of A. jubatusreduce the available origin area of the temporalismuscle in the skull, and it may decrease its mechani-cal performance. The conspicuous A. jubatus skulldesign magnifies the importance of the massetericsystem on their jaw mechanics.

The influence of the masseter muscular complex isremarkable in the Puma lineage, despite the skulldesign differences among the three species. This isparticularly dramatic in A. jubatus, in which the

Figure 12. Distribution of the 34 cat species, according to their scores from the functional principal component analysis(PCA). Plots represent species’ centroids based on bivariate means of the scores. The abscissa arrow indicates the biteperformance and the area of neck muscles, and ordinate arrows describe the mechanical optimization of the jaw muscles.Acronyms are defined in the text.



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temporal mechanics are compromised by the reduc-tion of the origin area of this muscle in the skull. Thedistinguished elongated angular processes (masse-teric ‘in-force’ arm), present in the members of thelineage, could also contribute to the ‘masseteric’ opti-mization of bite mechanics.

Lynx lineage: The potential bite force and neckrobustness of lynxes are consistent with cats of theirsize (Fig. 15). Despite the small samples of L. pardi-nus, its scores lie inside the 95% confidence limits ofL. rufus and L. canadensis. The Canada lynx showshigher potential related to the bite strength and neckrobustness than the bobcat (F1, 55 = 5.38, P < 0.03),even though their Maximum Average Prey Weight(MPW) used to be smaller than that associated withL. rufus (Table 1). The mean PC1 scores of the twospecimens of L. lynx lie outside the 95% confidencelimits of L. canadensis. This denotes a strong biteforce for the Eurasian lynx, which would be congruentwith their skull and body sizes.

According to PC2, the skulls of all lynx species donot show any marked maximization concerning theaction of the temporalis and masseter muscles. Nev-ertheless, the mean scores values of the two individu-als of L. lynx are higher than the upper quartile of L.canadensis and L. rufus. This could indicate a differ-ence on the masticatory pattern of the Eurasian lynx,and thus a lesser influence of the masseteric system.The opposite is observed on the Iberian lynx (L.pardinus), the PC2 score of which lies bellow thelower quartile of the other lynx scores. This could beinterpreted as a possible higher influence of the mas-seteric system to final bite force in L. pardinus thanin other lynxes.

Ocelot lineage: The morphofunctional analysis ofmedium-sized L. pardalis indicates a stronger biteand tougher neck than other cats of this lineage(F5, 168 = 321.76, P < 0.00001, Tukey’s HSD test,P < 0.0001, except L. geoffroyi, not significant),the opposite is valid for the small L. tigrinus andO. guigna (Fig. 16).

The second PC, however, indicates the presence ofdifferent bite patterns along this lineage, and there-fore variations on the contribution of temporal andmasseteric mechanical systems.

Kodkods (O. guigna) show an intermediate skullmorphofunctional pattern, and their scores do notdiffer significantly from the other species of thislineage. Comparison of ratios between temporalis andmasseter muscle FIs indicates a similar higher opti-mization of masseteric mechanics on margays (L.wiedii) and oncillas (L. tigrinus) than on other cats ofthis lineage (CFTC/CFMC, F5, 168 = 52.58, Tukey’s HSDtest, P < 0.01, except on O. guigna, not significant). On

the other hand, comparatively, L. pardalis, O. colocolo,and O. geoffroyi show skull designs equally less favour-able for the action of the masseteric system (CFTC/CFMC, Tukey’s HSD test, P > 0.07).

Some skull features could be highlighted as themain factors in the difference on jaw functionalityamong Neotropical small cats. The coronoid process(temporalis muscle moment arm) of L. tigrinus andL. wiedii, for instance, are some of the smallestamong all cat species analysed regarding the skulllength (AMT/CBL, H29, 608 = 463.47, Dunn’s testP < 0.05; except for H. yagouaroundi and P. plan-iceps). Furthermore, the oncillas (L. tigrinus) havethe narrowest internal breadth of zygomatic archesamong the Ocelot lineage (ZIB/CBL, F5, 168 = 15.74,Tukey’s HSD test, P < 0.01), which means a limitedspace for the temporalis muscle in the skull.Margays (L. wiedii) have a well-developed zygomaticarches breadth, but their short temporal fossa lengthand hypertrophied braincase also reduces the spacefor the temporalis muscle. These skull designs com-promise the performance of the temporal system inboth species.

Nevertheless, the skull pattern of the Ocelotlineage as a whole suggests a bite action less influ-enced by the masseteric mechanical system, in spiteof a slight optimization of this muscle in some species.

Domestic cat lineage: The bite strength and necktoughness of Eurasian and African small cats(Fig. 17) are greater than those of their Neotropicalrelatives of the Ocelot lineage, excluding the medium-sized L. pardalis (PC1 scores, Mann–Whitney’sU = 2043.0, P < 0.00001).

The PC2 scores of the Felis lineage, however, indi-cate an increased influence of the masseter mechanicson the jaw occlusion process. This is corroborated bythe comparison of ratios of the temporalis FIs andmasseter FIs between the domestic cat and Ocelotlineages (CFTC/CFMC, F1, 190 = 9.88, P < 0.01). The twolineages do not show differences in temporalis FIs(CFTC, F1, 190 = 1.81, P > 0.05), but they do differ in themasseter FIs (CFMC, F1, 190 = 77.81, P < 0.000001).Thus, Felis skull design has a marked increment inmasseter mechanics performance, when they are com-pared with the same-sized Neotropical small cats. Felisspecies show some improvements in skull featuresdirectly associated with masseteric optimization thatare not present in the Ocelot lineage: massetericmoment arm (MMA, F1, 190 = 124.73, P < 0.000001),masseteric scar length (MSL, F1, 190 = 208.66,P < 0.000001), and masseter muscle scar width (MSW,F1, 190 = 164.23, P < 0.000001).

Although there are similarities in overall size andecology of Neotropical and Eurasian/African smallcats, the evolution of jaw mechanics in both lineages



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seems to have followed divergent trends. The masse-teric mechanical advantage in the Felis skull guaran-tees a superior bite force for these species than thatestimated for the Neotropical small cats.

Leopard cat lineage: The variation in the estimatedbite forces along PC1 (Fig. 18) reflects the wide rangeof body sizes, from the small rusty-spotted cat (P.rubiginosus, average weight 1.4 kg) to the medium-sized fishing cat (P. viverrinus, average weight10.9 kg).

The flat-headed cat (P. planiceps) shows an unusu-ally strong bite force and neck robustness for a felidof its small body size (~1.9 kg), suggesting morpho-functional allometry. Comparison of raw values oftemporalis muscle FIs denotes the powerful bite of P.planiceps in relation to other larger cats of thislineage (CFTC, H4, 48 = 33.12, P < 0.0001). Prionailu-rus planiceps presents higher temporalis FIs than P.bengalensis (Dunn’s test P < 0.01), and similar FIs tothose of O. manul and the medium-sized P. viverrinus.The flat-headed cat (P. planiceps) exhibits a lowermasseter muscle FI than O. manul (CFMC,H4, 48 = 31.75, P < 0.0001, Dunn’s test P < 0.01) and P.viverrinus (Dunn’s test P < 0.01), but comparable withP. bengalensis. As a matter of fact, the temporal FI ofP. planiceps is higher than that of some same-sizedsmall cat species such as O. guigna, L. tigrinus, andL. wiedii (H20, 434 = 441.41, P < 0.00001; Dunn’s testP < 0.01), but is comparable with medium-sized cats,such as C. caracal, Lep. serval, Ly. canadensis, andLy. rufus.

The PC2 scores indicate an overall optimization ofthe temporalis muscle mechanical system among themembers of the leopard cat lineage. The PC2 scores ofmanul cats (O. manul) denote a slight maximizationof the masseteric system. Nevertheless, in spite of thebroad face with developed zygomatic arches, O.manul does not show any marked influence of themasseteric mechanical system. The hypertrophy ofthe zygomatic arches seems to counterbalance thereduction of the space of the temporalis muscle,because of the wide postorbital constriction.

Flat-headed cats show a marked maximization ofthe temporal action, and possess a unique skulldesign that is distinct from the other members of thislineage. Their masseteric mechanical system seems tohave the lowermost influence in bite strength. One ofthe most distinctive features of flat-headed cats, forinstance, is the small ratio to the skull length ofmasseter MMA, the value of which lies quite belowthe lower quartile limit of the Felidae. The functionaleffect of this is a small ‘in-force’ momentum to themasseter muscle mechanics in this species.

Muul & Lim (1970) associated the habit of these catsof seizing slippery prey (e.g. fishes) to some anatomical

traits, such as parallel toothrows, developed first andsecond upper premolars, and a pronounced rostrum.The authors also describe the flat-headed cat as pos-sessing short legs, permanent partially exposed claws,and an overall mustelid-like look. Sunquist & Sunquist(2002) pointed out that P. planiceps possesses greatbiting power, based on the well-developed sagittalcrest and strong zygomatic arches. The morphofunc-tional analysis corroborates the statement that skulldesign contributes to the powerful bite of P. planiceps;however, it seems much more associated with thetemporal mechanics than with the masseteric systemor development of zygomatic arches.

Caracal lineage: The skull design of P. aurata indi-cates a stronger bite force and neck robustness thanin L. serval (PC1 scores, H2, 37 = 9.33, P < 0.01, Dunn’stest P < 0.05); however, both species do not differ fromC. caracal (Fig. 19).

There is no difference among the three speciesaccording to the PC2 scores (H2, 37 = 5.59, P > 0.06),mostly because of the considerable intraspecific varia-tion found in the specimens of C. caracal, P. aurata,and L. serval. Thus, despite the size and shape varia-tions, no significant difference on jaw functionalitywas found among the Caracal lineage members.

The skull design of the Caracal lineage does notshow any remarkable improvement to the massetericmechanics. In agreement with this result, one featurewas highlighted in the morphological analysis as beenconspicuous to them: their masseter muscle scarwidth is one of the smallest among other cats. Thisdenotes less robustness in the masseteric complexand a bite action that is associated more with thetemporalis muscle mechanics.

Bay cat lineage: The medium-sized Asian golden cat(C. temminckii) presents superiority in bite strengthand neck robustness over the marbled cat (P. marmo-rata), according to PC1 (Mann–Whitney’s U = 0.0,P < 0.01; Fig. 20). The potential bite performance ofthe bay cat (C. badia) suggested by the analysis isconsistent with its small-sized skull.

The PC2 scores of P. marmorata indicate themarked optimization of its temporalis musclemechanical system (Mann–Whitney’s U = 2.0,P < 0.02). Accordingly, they show a high coronoidprocess, an elongated temporal fossa, and wide zygo-matic arches, the ratios of which lie quite a bit abovethe upper quartile values of the family Felidae. Thecoronoid process is the ‘in-force’ lever-arm of the tem-poralis muscle, and the following two traits are indi-cators of the anatomical limits of this muscle originarea.

The PC2 score of the single specimen of theBornean bay cat (C. badia) is three times smaller



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than the lower quartile limit of this lineage. It indi-cates a high influence of the masseteric mechanicalsystem on the jaw occlusion of the bay cat, anddenotes a diverging trend from its sister species, theAsian golden cat (C. temminckii).

Comparisons between P. marmorata and C. tem-minckii indicate the superiority of the Asian goldencat in both the masseter FI (CFMC, Mann–Whitney’sU = 0, P < 0.01) and the estimated area of neck mus-culature (AHN, Mann–Whitney’s U = 0, P < 0.01).However, there are no significant differences in theraw values of temporal FI between these two species(CFTC, Mann–Whitney’s U = 7, P > 0.05). The bodymass and skull volume differences are remarkablebetween the small marbled cat (P. marmorata) andthe medium-sized Asian golden cat (C. temminckii)(Fig. 11; Table 1). The similarity in the temporal FIobserved in these two cats indicates a morphofunc-tional allometry in the P. marmorata skull, and cor-roborates the mechanical maximization of theirtemporalis muscle.

PHYLOGENETIC INDEPENDENT CONTRASTS

Contrasts were obtained from the first two PC scoresof both morphological and functional analyses, as wellas the MPW ratios (Table 1). Each contrast wasregressed against its respective standard deviation(square root of the sum of corrected branch lengths)and no significant correlations were found. Pearson’scorrelation coefficient (R) values were usually lowerthan 0.20 (F1, 31 = 1.62, P > 0.22). The absence of cor-relation between the contrasts and their standarddeviations indicates an adequate independence andstandardization of the traits (Diaz-Uriarte &Garland, 1996; Diaz-Uriarte & Garland, 1998;Garland et al., 1992).

The positivized contrast of the trait ‘Skull OverallSize’ (PC1 in the morphological analysis) was used asan independent variable in OLS regressions against‘skull morphology’ (morphological PC2), ‘bite force’(functional PC1), ‘jaw muscle optimization’ (functionalPC2), and ‘prey/predator weight ratio’ (MPW/cataverage weight). ‘Bite force’ positivized contrast wasregressed against ‘jaw muscle optimization’ and ‘prey/predator weight ratio’. Finally, the positivized con-trast on the independent variable ‘jaw muscleoptimization’ was regressed against ‘prey/predatorweight ratio’.

Contrasts from the OLS regression corroborate thealready high correlation expected between the skullsize and bite force (R = 0.91, F1, 32 = 151.66,P < 0.000001; Fig. 21). Nevertheless, there is no sig-nificant correlation between the contrasts in skullsize and skull morphology (R = 0.17, F1, 32 = 0.96,P > 0.34), as well as with the mechanical configura-

tion of how the bite is produced (R = 0.05, F1, 32 = 0.08,P > 0.76; Fig. 22). These findings indicate a non-associative evolutionary process between the skullsize variation and morphological differentiation, i.e.cat skull design evolution goes beyond mere sizeallometry. Accordingly, cat skull size evolution is notcorrelated with the jaw lever system optimization andmechanics.

There is also no correlation between bite force andjaw muscle optimization (R = -0.25, F1, 32 = 2.14,P > 0.15; Fig. 23), suggesting that differences in theindividual contributions of temporalis and massetermuscles do not affect the final bite force. This meansthat bite strength among the cat species did notevolve as a function of how the resultant ‘in force’ isgenerated by the jaw muscles. On the other hand, themuscular functionality during the bite is correlatedwith the evolution of the skull design (R = 0.77,F1, 32 = 45.53, P < 0.0001).

A significant correlation is observed on the regres-sion between contrasts of prey/predator weight ratioand overall skull size (R = -0.41, F1, 32 = 6.37,P < 0.02). This result indicates an evolutionary depen-dence between the size variation of cat species andtheir selection of prey size and diet (Fig. 24). Thesame is observed in the correlation between contrastsin the bite force and the prey/predator weight ratio(R = -0.45, F1, 32 = 8.17, P < 0.01) (Fig. 25).

Among sister groups, small contrast values in biteforce and high values in the MPW ratio indicate a bigvariation in the maximum prey weight, despite thesimilar potential bite strength. This is the case in theLynx and Caracal lineages. Sister groups with highcontrast values in bite force but small contrasts inMPW ratio are usually those with greater size varia-tion, but with some isometry between prey/catweights among the species (i.e. similar MPW ratiosbetween the sister taxa). This could be observed insome clades in the Ocelot, Puma, and Panthera lin-eages. In some clades, great contrasts in bite forceand also in the MPW ratios denote an expressivevariation in the cat size and/or bite force, and verydifferent ratios between the cat body mass and theprey selected (e.g. some members of bay cat, leopardcat, and Ocelot lineages). The domestic cat lineageseems to be the most consistent group: small varia-tion in bite force contrasts and in MPW ratios. Thesmall Eurasian/African cats differ from the Ocelotlineage mostly because the contrast between themedium-sized L. pardalis and its sister species, thesmall L. wiedii. Nevertheless, among clades withmedium- and large-sized species (e.g. Lynx, Caracal,Puma, bay cat, Panthera lineages), the variationseems to be greater than in those composed of smallcats. The prey size is very constrained by bite force insmall cats. In medium- to large-sized cat lineages, the



body mass or bite force are not constraining factorsfor the capture of bigger prey, and so the dietaryspectrum is much more diverse among the sisterspecies. Modern big cats prey on both small and largeprey, and food items could virtually range frominsects to large mammals.

Finally, prey/predator weight ratio is not correlatedwith how the bite is performed at the muscular level(Fig. 26). Regression between contrasts in prey/predator ratio and in jaw muscle optimization showsno significant correlation (R = -0.04, F1, 32 = 0.06,P > 0.81). It suggests the low adaptative importanceof how the bite is executed by the jaw muscle groupsamong cat species, and raises the supposition that thevariations in bite patterns may have originated fromcasuistic phenotypic fluctuations fixed along the spe-ciation process.

Accordingly, it would be reasonable to interpretboth temporal and masseteric jaw muscular systems

as a single unity that evolved along the lineages,where selection acts over the maximization of bitestrength, rather than the design variation itself;therefore, muscular group optimizations would be aconsequence of the skull design phenotypic fluctua-tions, and the maintenance of a powerful bite remainsthe leading evolutionary trend.

CONCLUSION

Dispersal and sympatric evolution are the mainfactors associated with modern cats speciation in thepast 10 million years (Salles, 1992; Johnson &O’Brien, 1997; Turner & Antón, 1997; Johnson et al.,2006). Despite the similarity in general physical andbehavioral characteristics, felids show a notorioussize variation among species. Size differences betweenphylogenetically closely related species are usuallyinterpreted as an evolutionary attempt to reduce the

Figure 21. Ordinary least-square (OLS) regressions between standardized contrasts in bite force and the positivizedstandardized contrasts in skull size. Plots indicate the nodes and lineages of the phylogeny. Nodes connecting differentcat lineages are indicated by the age of cladogenesis (Myr), according the cladogram of Johnson et al. (2006) presentedin Figure 1.



niche overlap as a result of character displacement orsize assortment (Dayan & Simberloff, 1994; Dayan &Simberloff, 1998; Dayan et al., 1990; Losos, 1990,2000; Schluter, 2000; Dayan & Simberloff, 2005). Theorigins of this selective pressure are variable. Inter-specific killing in carnivores, for instance, is related tobody size and diet overlap, and is usually foundamong those species with similar behaviour and/orphylogenetic closeness (Donadio & Buskirk, 2006). Onthe other hand, if there is a size gap in the nichespectrum, selective pressure will act, favouring sizediversification of small or large organisms in order tofill the gap (Bonner & Horn, 2000).

Whatever the main pressure for size diversificationamong cats, it is an example of minor influence of anallometric size change to the performance of acomplex mechanical system, such as the jaw move-ment. Therefore, the diversity of extant felids sug-gests morphological variation along the size axis,

rather than a character displacement related to theclassical ecomorphological binomial: skull–jaw designversus dietary preferences. Unexpectedly, the varia-tions in the performance of jaw muscles are not cor-related with their predatory performance and/or preychoice. Furthermore, contrasts analysis does not indi-cate a clear adaptative correlation between differentpatterns of jaw mechanics and size evolution amongthe cat species. According to the data presented, onlyskull size and bite force show a correlation withprey/predator weight ratio. Regardless of someremarkable exceptions (e.g. the Lynx and bay catlineages), the direct association ‘big cats–strongerbites–fewer constraints in prey selection’ is theleading pattern, but even so, the relation between sizeand shape changes is not necessarily a linear function(see Koehl, 2000).

The casuistic nature of morphofunctional variationcould be exemplified by the comparison between the

Figure 22. Ordinary least-square (OLS) regressions between standardized contrasts in jaw muscle optimization and thepositivized standardized contrasts in skull size. Plots indicate the nodes and lineages of the phylogeny. Nodes connectingdifferent cat lineages are indicated by the age of cladogenesis (Myr), according the cladogram of Johnson et al. (2006)presented in Figure 1.



domestic cat and Ocelot lineages. The diet of all smallcats worldwide is composed of rodents and othersmall vertebrates, and the general predation strategyis the same. Despite this, small cats from the Neo-tropics (genera Leopardus and Oncifelis) show aslender skull with a narrower braincase and postor-bital constriction than African and Eurasian smallcats. In contrast to the Neotropical small cats, thebite mechanics in the African and Eurasian small catsshows a marked participation of the massetericcomplex. Nevertheless, there is no reason to supposethat any advantage in prey capturing performance ineither lineage results from these different functionaltrends. More likely these divergent patterns seem tobe caused not by an adaptative process, but from thefixation of phenotypic variations along the naturalhistory of these two lineages, independently. Thesame logic could be used to explain the functionaldifferences in P. leo and P. tigris, where – despite

having a comparably powerful bite – the optimizedparticipation of the masseteric muscular complex inthe lion’s bite is evident. The influence of differenthunting strategies (e.g. cooperative hunting),however, was not included in the analysis, and itspossible influences could not be assessed by themodel.

The radiation of the different skull designs andfunctional performances are more likely to have fol-lowed a Brownian model of evolution, than to haveresulted from an ecomorphological fit to fill a specificniche. Therefore, size and bite force are the mainsources of variation and niche differentiation amongcats.

On the other hand, the variation in the breadth ofthe postorbital constriction is remarkable amongfelids (but quite constant among sexes of the samespecies), ranging from the broad state found in chee-tahs (A. jubatus) to the narrow state found in

Figure 23. Ordinary least-square (OLS) regressions between standardized contrasts in jaw muscle optimization and thepositivized standardized contrasts in bite force. Plots indicate the nodes and lineages of the phylogeny. Nodes connectingdifferent cat lineages are indicated by the age of cladogenesis (Myr), according the cladogram after Johnson et al. (2006)presented on Figure 1.



clouded leopards (N. nebulosa), for instance. Theimportance of this feature is highlighted in both themorphological and the functional analyses. The pos-torbital constriction is directly related to the spaceavailable for the temporal muscle, and, conse-quently, is related to the functional differencesamong cat species. O’Regan (2002), studying theskull morphology of big cats, also observed an asso-ciation of the postorbital indicators with thedetached position of A. jubatus. However, the selec-tive pressures that lead to the allometry of thisfeature are controversial.

Salles (1992) demonstrated the close relationshipbetween the hypertrophied frontal, postorbital pro-cesses, and postorbital constriction, and the sinusfrontalis space, among the cat species. The position ofthe frontal sinus of A. jubatus lies centralized in theregion of the postorbital process, being the largestamong cats.

The vascular surface of this well-developed sinusfrontalis (as well as other paranasal cavities) wouldheat and moisten inhaled air before it flows to thelungs (Rae & Koppe, 2004). On the other hand, theflow of cold air would involve heat transfer from thebloodstream, and, together with the evaporation ofmoisture on the surface of the sinus, would act as avascular mechanism for brain cooling (Rae & Koppe,2004). Certainly, these functional aspects would beuseful for a fast running cat in semi-arid regions. Thebody temperature of cheetahs at the end of a sprint isclose to 41 °C (Hildebrand, 1959; Taylor & Rowntree,1973), and a large frontal sinus with a developedvascular surface could also perform an important rolein preventing dangerous heating of the brain. Thismarked hypertrophied frontal sinus is conspicuousalong the cheetah evolutionary lineage (Christiansen& Mazák, 2009). A phylogenetic contrast analysesbetween frontal sinus and limb adaptations for fast

Figure 24. Ordinary least-square (OLS) regressions between standardized contrasts in the ratios of maximum preyweight (MPW)/cat average weight and the positivized standardized contrasts in skull size. Plots indicate the nodes andlineages of the phylogeny. Nodes connecting different cat lineages are indicated by the age of cladogenesis (Myr), accordingthe cladogram of Johnson et al. (2006) presented in Figure 1.



running, as well as their paleodistribution, should beaddressed to enlighten a possible coevolution of thesetraits along the cheetah lineage.

The overall bite performance of cheetahs, however,is not compromised by these skull modifications, oncethe masseteric system compensates for the lessfavoured temporal mechanics. Therefore, variationsin a given trait are compensated for by variation inothers, and the overall adaptative efficiency of cat jawmechanics is preserved.

The basic hunting strategy of cats includes thefunctional performance of skull–jaw and limb–clawsystems, as well as complex behavioural displays.These different sets could be interpreted as a singlepredatory functional unit. Thus, some changes in thepattern of the bite mechanics are less relevant to afull-scale ecomorphological scenario. A quantitativeapproach to Felidae limb biomechanics, despite thescarcity of specimens, would result in a better

understanding of cat predatory behaviour, and couldprovide new insights into the interpretation of evolu-tionary ecomorphological trends.

ACKNOWLEDGEMENTS

This study has taken a long time to prepare, andmany people contributed to its development. Wewould like to express our gratitude to RonaldoFernandes, Leandro R. Monteiro, Leslie Marcus (inmemoriam), and P. David Polly for their suggestionsregarding the analytical approach used to analyse thedata. We thank the curators and museum staff whogranted us access to the felid collections in their care:João A. de Oliveira and Leandro O. Salles (MuseuNacional, Federal University of Rio de Janeiro);Mario de Vivo (Museu de Zoologia of University of SãoPaulo); Ross MacPhee and Robert Voss (AmericanMuseum of Natural History), and Bruce Patterson

Figure 25. Ordinary least-square (OLS) regressions between standardized contrasts in the ratios of maximum preyweight (MPW)/cat average weight and the positivized standardized contrasts in bite force. Plots indicate the nodes andlineages of the phylogeny. Nodes connecting different cat lineages are indicated by the age of cladogenesis (Myr), accordingthe cladogram of Johnson et al. (2006) presented in Figure 1.



and William Stanley (Field Museum of NaturalHistory).

Unfortunately, most of the original photographs ofspecimens were lost; this fumble, however, led us tocontact people whose kindness and scientific collabo-rative sense allowed us to replace the images of allspecies we have worked on. Therefore, we would liketo express our gratitude to the authors of photo-graphs, institutions, and to all that courteouslyallowed us to reproduce images of specimens to illus-trate this study. We credit them, as follows: AshleyGosselin-Ildari, Pamela Owen and Timothy Rowe(Digimorph.org/University of Texas at Austin, USA)for images of Neofelis nebulosa, Panthera pardus(lateral view), and Felis silvestris lybica (lateral view);Elena I. Zholnerovskaya (Siberian Museum ofZoology, Russia) for images of Panthera pardus(dorsal view), Felis margarita (skull and jaw origi-nally separated), and Felis silvestris lybica (dorsal

view); Igor Y. Pavlinov and Olga Nanova (MoscowMuseum of Zoology, Russia) for images of Unciauncia, Otocolobus manul, Felis chaus, and Lynx lynx;Mammalian Crania Photographic Archive of theDepartment of Anatomy – Dokkyo Medical Univer-sity, Japan (http://1kai.dokkyomed.ac.jp) for images ofOncifelis geoffroyi (dorsal view) and Leptailurusserval (dorsal view); Marcelo Weksler (AmericanMuseum of Natural History, USA) for images ofCatopuma temminckii, Pardofelis marmorata, Profe-lis aurata (dorsal view), and Felis nigripes; Fabio O.do Nascimento (Museu de Zoologia of University ofSão Paulo, Brazil) for images of Oncifelis geoffroyi(lateral view); José Cabot (Estación Biologica deDoñana, Spain) for images of Lynx pardinus; JoséLuis Brito (Museo Municipal de Ciencias Naturales eArqueología de San Antonio, Chile) for images ofOncifelis guigna (lateral view); Bruce Patterson (FieldMuseum of Natural History, USA) for images of

Figure 26. Ordinary least-square (OLS) regressions between standardized contrasts in the ratios of maximum preyweight (MPW)/cat average weight and the positivized standardized contrasts in jaw muscle optimization. Plots indicatethe nodes and lineages of the phylogeny. Nodes connecting different cat lineages are indicated by the age of cladogenesis(Myr), according the cladogram of Johnson et al. (2006) presented in Figure 1.



Oncifelis guigna (dorsal view), Catopuma badia, andPrionailurus rubiginosus (skull and jaw originallyseparated); Vu Ngoc Thanh (Zoology Museum ofVietnam National University) for images of Prionai-lurus bengalensis; Emmanuel Gilissen and WimWendelen (Africamuseum, Belgian) for images of Lep-tailurus serval (lateral view) and Profelis aurata(lateral view); Georges Lenglet (Royal Belgian Insti-tute of Natural Sciences) for images of Prionailurusviverrinus and Prionailurus planiceps; and NicoAvenant (National Museum of Bloemfontein, SouthAfrica) for images of Caracal caracal. Many of thosecited above have sent us several images not includedin the final form of this work. We extend our gratitudeto James P. Dines (Natural History Museum of LosAngeles County, USA), Louise Tomsett (NaturalHistory Museum, UK), and Lucas Thibedi (AmatholeMuseum, South Africa) who sent us many images ofskulls of rare cats not included in this paper, but thathelped us to assemble a precious source of qualitativemorphological information.

Teresa R. Gaskill, Aki Ohnuki, and RonaldoFernandes provided helpful revisions of the manu-script. We also thank Eliete Bouskela and the staff ofBioVasc, University of the State of Rio de Janeiro, forall their support.

This research was supported by the BrazilianNational Council to Scientific and TechnologicalDevelopment (CNPq) and the American Museum ofNatural History Grant Program.

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APPENDIX 1

Skull measurement Acronym Description

Breadth of braincase BBC The widest point across parietalsCondylobasal length CBL From the anterior edge of the premaxillae to the posteriormost

projection of the occipital condyle – it is an estimatorcorrelated with specimen size

Condyle to caninelength of jaw

CCL From the posterior margin of the alveolus of the canine to theposteriormost edge of the jaw condyle – it measures theresistance moment arm when an animal is biting with canineteeth

Condyle to M1 lengthof jaw

CM1L From the anterior margin of the alveolus of M1 to theposteriormost edge of the jaw condyle – it measures theresistance moment arm when an animal is biting at the lowercarnassial molar

Jaw height at M1 JHM1 Measured about the midpoint of the dentary between M1 and P4

Jaw length JL From the anterior limit of the dentary bone between I1 to theposterior end of the jaw condyle – it is another estimatorcorrelated with specimen size

Jaw width at M1 JWM1 Measured near the point of JHM1 – it estimates the crosssection of dentary bone and the second moment of area of jaw(SMA)

Masseteric fossa length MFL From the lateral limit of the jaw condyle to the anterior limit ofthe masseteric fossa in the dentary – it is a complementaryestimator of masseter muscle length

Masseteric momentarm

MMA From the dorsal surface of the condyle to the ventral border ofthe angular process – it estimates the moment arm of thismuscle



APPENDIX 1 Continued

Skull measurement Acronym Description

Masseteric scar length MSL Measured on the ventral face of the zygomatic arch, from theanterior limit of the muscle scar in the jugal to the anteriorend of the glenoid fossa (temporomandibular fossa)

Masseteric scar width MSW The widest point of the masseteric scar in the jugal bone – it isan estimator, with anterior measurement, of the area of crosssection of the masseter muscle

Mastoid breadth MB Greatest width of skull including the mastoids – it is anestimator, with the anterior measurement, of the attachmentarea of the head–neck muscular system (AHN)

Occipital height OCH From the ventral border of foramen magnus to the lowest limitof the middle of the complex muscle scar

Orbit to premaxillaelength

OPL From the anterior end of the premaxilla to the anterior orbitrim – it indicates the length of the rostrum

Postorbital constriction POC The shortest distance across the top of the skull posterior tothe postorbital process

Rostral width at thesecond premolar P2

RWP2 Width between external limits of maxillary bones about P2,indicates robustness of rostrum

Temporal fossa length TFL From the posteriormost point of the temporal fossa to thesupraorbital process – it is an estimator of the temporalismuscle size

Temporalis musclemoment arm

TMA From the posterior end of the condyle to the apex of thecoronoid process – it estimates the moment arm of thetemporalis muscle

Tooth row length TRL From the anterior end of I1 to the posterior end of M1, bothnear the alveolus – it estimates the functional bite space

Zygomatic archesinternal breadth

ZIB The largest distance between the inner margins of thezygomatic arches, with two anterior measurements – itestimates the temporalis muscle width (TMW)

SKULL MEASUREMENTS

DERIVED VARIABLES

Variable Acronym Equation

Temporalis muscle width TMW {ZIB - [(BBC + POC)/2]}/2Force index of masseter muscle at canines FMC {[(MSW + MFL)/2 ¥ MSL]1/2 ¥ MMA}/CCLForce index of temporalis muscle at canines FTC [(TFL ¥ TMW)1/2 ¥ TMA]/CCLSecond moment of area of dentary bone at M1 SMA {[p ¥ (JWM1/2) ¥ (JWM1/2)3]/4}1/4

Corrected force index of masseter muscle at canines CFMC (SMA ¥ FMC)1/2

Corrected force index of temporalis muscle at canines CFTC (SMA ¥ FTC)1/2

Attachment area of head–neck muscular system AHN (OCH ¥ MB)1/2

APPENDIX 2LIST OF MEASURED SPECIMENS

Abbreviations: AMNH, American Museum of Natural History, USA; FMNH, Field Museum of Natural History,USA; MN, Museu Nacional, Brazil; MZUSP, Museu de Zoologia of University of São Paulo, Brazil; �, male (m);�, female (f); ?, no data record (nd).

Acinonyx jubatus (n = 17: m = 7, f = 3, nd = 7): AMNH 119656, �; AMNH 119657, �; AMNH 114517, ?; AMNH161139, �; AMNH 35998, ?; AMNH 35997, ?; AMNH 27897, �; AMNH 119655, �; AMNH 36426, ?; AMNH



100309, �; FMNH 29633, �; FMNH 29635, �; FMNH 89918, ?; FMNH 34589, �; FMNH 26900, ?; FMNH39475, ?; FMNH 29634, �.

Caracal caracal (n = 9: m = 2, f = 4, nd = 3): AMNH 89841, ?; AMNH 24220, ?; AMNH 116512, �; AMNH 187788,�; AMNH 113794, �; FMNH 32945, �; FMNH 105607, �; FMNH 135042, ?; FMNH 95922, �.

Catopuma badia (n = 1: nd = 1): FMNH 8378, ?.

Catopuma temminckii (n = 7: m = 3, f = 3, nd = 1): AMNH 84396, �; AMNH 84394, �; AMNH 84393, �; AMNH84395, �; AMNH 17103, �; FMNH 75826, �; FMNH 89919, ?.

Felis chaus (n = 25: m = 15, f = 8, nd = 2): AMNH 171166, �; AMNH 238649, �; AMNH 184683, �; AMNH54553, �; AMNH 163169, ?; AMNH 54759, ?; FMNH 84811, �; FMNH 105559, �; FMNH 94103, �; FMNH104412, �; FMNH 105558, �; FMNH 114385, �; FMNH 104413, �; FMNH 97866, �; FMNH 97864, �; FMNH99027, �; FMNH 99026, �; FMNH 91256, �; FMNH 29754, �; FMNH 83100, �; FMNH 29789, �; FMNH29755, �; FMNH 29753, �; FMNH 91252, �; FMNH 91257, �.

Felis margarita (n = 3: m = 2, f = 1): FMNH 107299, �; FMNH 60613, �; FMNH 127296, �.

Felis nigripes (n = 2: nd = 2): AMNH 214380, ?; AMNH 214381, ?.

Felis silvestris (n = 45: m = 20, f = 13, nd = 12): AMNH 80893, ?; AMNH 169458, �; FMNH 107294, �; FMNH106749, �; FMNH 107295, �; FMNH 123384, �; FMNH 95877, �; FMNH 95878, �; FMNH 98740, �; FMNH101877, ?; FMNH 140228, ?; FMNH 105529, ?; FMNH 107296, ?; FMNH 123383, �; FMNH 57696, �; FMNH104579, �; FMNH 104712, �; FMNH 104719, �; FMNH 104720, �; FMNH 96260, �; FMNH 104005, �; FMNH98755, ?; FMNH 38197, ?; FMNH 97872, �; FMNH 112453, �; AMNH 160967, �; AMNH 83634, ?; AMNH 51970,�; AMNH 185173, �; AMNH 89007, ?; AMNH 161125, ?; AMNH 116519, ?; AMNH 81233, �; AMNH 179132, �;AMNH 179131, �; AMNH 179134, �; AMNH 187787, �; AMNH 187785, �; AMNH 187786, �; AMNH 55851,�; AMNH 82404, �; AMNH 82410, �; AMNH 51971, �; AMNH 161769, ?; AMNH 185173, �.

Herpailurus yagouaroundi (n = 31: m = 7, f = 6, nd = 18): MN 24885, �; MN 24901, �; MN 33513, ?; MN 1039,?; MN 3142, ?; MN 3153, ?; MN 49076, ?; MN 49316, ?; MN 384, ?; MZUSP 5176, �; MZUSP 5175, �; MZUSP13481, ?; MZUSP 3692, ?; MZUSP 13606, �; MZUSP 13598, �; MZUSP 13607, �; MZUSP 2647, �; MZUSP2441, ?; MZUSP 1272, �; MZUSP 7351, �; MZUSP 1648, ?; MZUSP 3800, ?; MZUSP 7203, ?; MZUSP 2916, �;MZUSP 2978, �; MZUSP 7388, �; MZUSP 2031, ?; MZUSP 1399, ?; MZUSP 37, ?; MZUSP 1003, ?; MZUSP1647, ?

Leopardus pardalis (n = 57: m = 15, f = 16, nd = 26): MN 4812, �; MN 4811, �; MN 7630, ?; MN 625, ?; MN624, ?; MN 622, ?; MN 25691, ?; MN 24883, ?; MN 24882, ?; MN 24881, ?; MN 48873, ?; MN 48874, ?; MN48875, ?; MN 48877, ?; MN 48880, ?; MN 48894, �; MZUSP 11472, ?; MZUSP 5553, �; MZUSP 13595, ?;MZUSP 13470, ?; MZUSP 20427, �; MZUSP 2733, �; MZUSP 3070, �; MZUSP 3069, �; MZUSP 4232, �;MZUSP 4239, �; MZUSP 7027, �; MZUSP 13673, �; MZUSP 8879, ?; MZUSP 3113, �; MZUSP 2964, �;MZUSP 2963, �; MZUSP 9422, �; MZUSP 9414, ?; MZUSP 1167, ?; MZUSP 2914, �; MZUSP 2913, �;MZUSP 2968, �; MZUSP 2966, �; MZUSP 2931, ?; MZUSP 10354, ?; MZUSP 1937, ?; MZUSP 2962, �;MZUSP 2967, �; MZUSP 9423, �; MZUSP 9684, �; MZUSP 9012, �; MZUSP 1936, �; MZUSP 1805, �;MZUSP 6277, ?; MZUSP 2839, �; MZUSP 9615, �; MZUSP 2465, �; MZUSP 2467, �; MZUSP 440, ?; MZUSP11825, ?; MZUSP 13601, ?.

Leopardus tigrinus (n = 38: m = 17, f = 8, nd = 13): MN 24894, �; MN 6693, �; MN 3133, ?; MN 24896, ?; MN5885, �; MN 25651, �; MN 25650, �; MN 7261, �; MN 5145, ?; MN 610, ?; MN 49356, �; MN 49354, ?;MZUSP 2810, �; MZUSP 2646, �; MZUSP 1877, �; MZUSP 1393, ?; MZUSP 2362, ?; MZUSP 6262, �; MZUSP2321, �; MZUSP 1395, ?; MZUSP 2320, �; MZUSP 3299, �; MZUSP 1878, �; MZUSP 1168, ?; MZUSP 6728,�; MZUSP 22416, ?; MZUSP 2971, �; MZUSP 3811, ?; MZUSP 401, �; MZUSP 13796, �; MZUSP 810, �;MZUSP 396, �; MZUSP 6549, ?; AMNH 80396, �; AMNH 34349, �; AMNH 181498, �; AMNH 33896, ?;AMNH 69166, �.



Leopardus wiedii (n = 42: m = 17, f = 6, nd = 19): MN 6084, �; MN 5114, ?; MN 25725, �; MN 4816, �; MN5621, �; MN 24910, ?; MN 24887, ?; MN 24890, �; MN 24886, �; MN 25726, �; MZUSP 34, �; MZUSP 10426,�; MZUSP 28311, ?; MZUSP 5561, �; MZUSP 2645, �; MZUSP 5562, �; MZUSP 5560, �; MZUSP 2644, ?;MZUSP 3503, �; MZUSP 1936, ?; MZUSP 2969, �; MZUSP 2915, �; MZUSP 2686, ?; MZUSP 1169, ?; MZUSP19906, �; MZUSP 6649, �; MZUSP 467, ?; MZUSP 468, �; MZUSP 9998, ?; MZUSP 2840, �; MZUSP 2242,�; MZUSP 1765, ?; MZUSP 1677, �; MZUSP 1764, ?; MZUSP 2901, �; MZUSP 1398, ?; MZUSP 1397, ?;MZUSP 1400, ?; MZUSP 1649, ?; MZUSP 40, ?; MZUSP 22413, ?; MZUSP 22414, ?.

Leptailurus serval (n = 23: m = 9, f = 6, nd = 8): AMNH 119872, ?; AMNH 81672, ?; AMNH 81674, ?; AMNH85166, ?; AMNH 27837, �; AMNH 34767, �; AMNH 36369, �; AMNH 51984, �; AMNH 88382, ?; FMNH18956, �; FMNH 29629, �; FMNH 29632, ?; FMNH 79415, �; FMNH 127844, �; FMNH 127843, �; FMNH93309, �; FMNH 93310, �; FMNH 27165, �; FMNH 27164, �; FMNH 18862, �; FMNH 38191, ?; FMNH90022, �; FMNH 38192, ?.

Lynx canadensis (n = 31: m = 18, f = 11, nd = 2): MN 49353, ?; MZUSP PL898, �; MZUSP PL899, �; MZUSPPL910, �; MZUSP PL918, �; MZUSP PL924, ?; AMNH 239791, �; AMNH 239784, �; AMNH 239788, �;AMNH 239786, �; AMNH 239783, �; AMNH 239797, �; AMNH 239793, �; AMNH 239792, �; AMNH 239795,�; AMNH 239798, �; AMNH 239799, �; AMNH 239800, �; AMNH 239801, �; AMNH 239802, �; AMNH239804, �; AMNH 239805, �; AMNH 239806, �; AMNH 239807, �; AMNH 239808, �; AMNH 239809, �;AMNH 239764, �; AMNH 29048, �; AMNH 29037, �; AMNH 239769, �; AMNH 239757, �.

Lynx lynx (n = 2: m = 1, nd = 1): AMNH 41337, ?; FMNH 51820, �.

Lynx pardinus (n = 1: m = 1): AMNH 169482, �.

Lynx rufus (n = 26: m = 10, f = 10, nd = 6): MN 49355, �; AMNH 1344, �; AMNH 1352, �; AMNH 2245, �;AMNH 5512, ?; AMNH 6420, �; AMNH 144930, �; AMNH 144932, �; AMNH 31765, �; AMNH 24664, �;AMNH 24666, �; AMNH 24066, �; AMNH 24067, �; AMNH 255666, �; AMNH 255671, �; AMNH 255663,�; AMNH 255670, �; AMNH 189301, ?; AMNH 214941, ?; AMNH 148937, �; AMNH 128527, ?; AMNH 11060,�; AMNH 237993, ?; AMNH 164480, ?; AMNH 164720, �; AMNH 2443, �.

Neofelis nebulosa (n = 9: m = 3, f = 2, nd = 4): AMNH 184931, ?; AMNH 22919, ?; AMNH 35808, �; AMNH35273, �; AMNH 19383, ?; AMNH 22916, �; FMNH 75830, �; FMNH 42583, �; FMNH 75831, ?.

Oncifelis colocolo (n = 11: m = 9, f = 2): MZUSP 13671, �; MZUSP 7786, �; AMNH 189394, �; AMNH 76150,�; AMNH 16695, �; AMNH 133977, �; AMNH 243110, �; FMNH 80994, �; FMNH 52488, �; FMNH 68318,�; FMNH 43291, �.

Oncifelis geoffroyi (n = 20: m = 9, f = 6, nd = 5): MZUSP 1432, ?; MZUSP 1443, ?; MZUSP 111, ?; MZUSP 110, ?;AMNH 205904, �; AMNH 205903, �; AMNH 205905, �; AMNH 205907, �; AMNH 205908, �; AMNH 205909,�; AMNH 205910, �; AMNH 205911, �; AMNH 205913, �; AMNH 205914, �; AMNH 39010, �; AMNH39004, �; AMNH 80298, ?; AMNH 16696, �; FMNH 28404, �; FMNH 24360, �.

Oncifelis guigna (n = 6: nd = 6): MZUSP 43, �; AMNH 33283, �; AMNH 33285, �; AMNH 93323, �; FMNH24359, �; FMNH 24417, �.

Otocolobus manul (n = 6: m = 1, f = 3, nd = 2): AMNH 180268, ?; AMNH 185371, ?; FMNH 60734, �; FMNH125386, �; FMNH 135319, �; FMNH 135737, �.

Panthera leo (n = 25: m = 10, f = 8, nd = 7): AMNH 80609, �; AMNH 83617, �; AMNH 83620, �; AMNH 83618,�; AMNH 161003, �; AMNH 161011, �; AMNH 81836, ?; AMNH 28151, �; AMNH 81837, �; AMNH 169463,?; AMNH 17274, ?; AMNH 52073, �; AMNH 83410, ?; AMNH 52074, �; AMNH 52077, �; AMNH 52078, �;AMNH 52082, �; AMNH 30241, �; AMNH 30242, �; AMNH 30244, ?; AMNH 30245, ?; AMNH 30247, ?;AMNH 85141, �; AMNH 85144, �; AMNH 54996, �.

Panthera onca (n = 40: m = 9, f = 4, nd = 27): MN 1007, ?; MN 634, ?; MN 633, ?; MN 1013, ?; MN 1017, ?; MN1021, ?; MN 3349, ?; MN 1023, ?; MN 13508, ?; MN 24861, ?; MN 36218, ?; MN 48868, ?; MN 48869, ?; MN



48870, ?; MN 48871, ?; MN 32707, �; MN 32705, ?; MN 24860, �; MN 6021, �; MN 628, ?; MZUSP 22452,?; MZUSP 469, �; MZUSP 2332, ?; MZUSP NP 1, ?; MZUSP 13600, ?; MZUSP 3752, �; MZUSP 17550, ?;MZUSP 11844, ?; MZUSP 11843, ?; MZUSP 3685, �; MZUSP 3330, ?; MZUSP 19853, ?; MZUSP 11469, ?;MZUSP 6806, �; MZUSP 2330, �; MZUSP 7161, �; MZUSP 3420, �; MZUSP 2551, �; MZUSP 3331, �;MUZUSP 28869, �.

Panthera pardus (n = 25: m = 11, f = 7, nd = 7): AMNH 167357, ?; AMNH 170293, ?; AMNH 170296, ?; AMNH170301, ?; AMNH 170297, ?; AMNH 170298, ?; AMNH 52010, �; AMNH 52012, �; AMNH 52006, �; AMNH52009, �; AMNH 52013, �; AMNH 52023, �; AMNH 52024, �; AMNH 52039, �; AMNH 60774, ?; AMNH47864, �; AMNH 90017, �; AMNH 57008, �; AMNH 54854, �; AMNH 81006, �; AMNH 52041, �; AMNH34745, �; AMNH 34746, �; AMNH 89009, �; AMNH 165112, �.

Panthera tigris (n = 18: m = 8, f = 4, nd = 6): AMNH 85396, �; AMNH 85405, �; AMNH 45519, �; AMNH45520, ?; AMNH 85404, �; AMNH 60771, ?; AMNH 201798, �; AMNH 61, ?; AMNH 90016, ?; AMNH 119680,?; AMNH 113743, �; AMNH 113744, �; AMNH 54459, �; AMNH 54458, �; AMNH 54460, �; FMNH 31153,�; FMNH 31798, ?; FMNH 31152, �.

Pardofelis marmorata (n = 4: m = 3, f = 1): AMNH 102844, �; AMNH 106615, �; FMNH 68728, �; FMNH60358, �.

Prionailurus bengalensis (n = 24: m = 10, f = 10, nd = 4): AMNH 35327, �; AMNH 163609, �; AMNH 87351, �;AMNH 87355, �; AMNH 55564, ?; AMNH 83999, �; AMNH 84398, �; AMNH 57062, �; AMNH 59959, �;AMNH 59957, �; AMNH 60054, ?; AMNH 57376, �; AMNH 58371, �; AMNH 185464, ?; AMNH 110458, ?;AMNH 101628, �; AMNH 102072, �; AMNH 102085, �; AMNH 102073, �; AMNH 102458, �; AMNH 102212,�; AMNH 104000, �; AMNH 103709, �; AMNH 106063, �.

Prionailurus planiceps (n = 5: m = 2, f = 2, nd = 1): AMNH 173515, ?; FMNH 58951, �; FMNH 60476, �; FMNH127432, �; FMNH 127433, �.

Prionailurus rubiginosus (n = 3: m = 1, f = 2): FMNH 95137, �; FMNH 96334, �; FMNH 96335, �.

Prionailurus viverrinus (n = 10: m = 6, f = 4): AMNH 102691, �; AMNH 101627, �; AMNH 102181, �; AMNH106323, �; AMNH 70128, �; FMNH 96332, �; FMNH 96331, �; FMNH 99533, �; FMNH 105561, �; FMNH105562, �.

Profelis aurata (n = 5: m = 1, f = 3, nd = 1): AMNH 51998, �; AMNH 51993, �; AMNH 51994, �; AMNH 89441,�; AMNH 54332, ?

Puma concolor (n = 37: m = 15, f = 7, nd = 15): MN 1016, ?; MN 1014, ?; MN 381, ?; MN 1025, ?; MN 1029, ?;MN 24867, �; MN 49075, ?; MN 6023, �; MN 17506, �; MN 49073, ?; MZUSP 8878, �; MZUSP 3801, �;MZUSP 11470, �; MZUSP 9010, �; MZUSP 3334, �; MZUSP 9425, �; MZUSP 7343, ?; MZUSP 2687, �;MZUSP 9637, �; MZUSP 9811, �; MZUSP 10352, �; MZUSP 9418, �; MZUSP 1637, ?; MZUSP 28868, ?;MZUSP 20935, ?; MZUSP 10467, ?; MZUSP 19854, ?; AMNH 17459, �; AMNH 17458, �; AMNH 73221, �;AMNH 144512, �; AMNH 206992, ?; AMNH 92205, �; AMNH 130147, ?; AMNH 188349, �; AMNH 188351,�; AMNH 188349, �.

Uncia uncia (n = 7: m = 4, f = 1, nd = 2): AMNH 35360, �; AMNH 24215, ?; AMNH 35529, �; AMNH 35476, �;AMNH 100110, �; AMNH 119662, ?; FMNH 122235, �.



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Sicuro and Oliveira - Skull Morphology and Functionality of Extant Felidae 2010