Figure 1.
(A) Single most parsimonious tree from the cladistic analysis, with Proailurus lemanensis as the outgroup. Felinae is treated as a single operational taxonomic unit (OTU) in the analysis, but is replaced with the topology in (B) for phylogenetic comparative analyses. Bootstrap percent support values and decay index values (in bold) are shown above and below each node respectively. (B) Internal relationships of Felinae based on [1], with extinct taxa inserted into relevant positions [27]–[29]. Asterisks denote taxa not included in the morphometric analysis, but employed in the phylogeny for dating nodes. Felid lineages are color-coded as follows: black, Machairodontinae; red, ‘Panthera’; sky blue, ‘Bay Cat’; maroon, ‘Caracal’; blue, ‘Ocelot’; orange, ‘Lynx’; green, ‘Puma’; pink, ‘Domestic Cat’; light green, ‘Leopard Cat’.
Figure 2.
Scaled, pruned composite tree used in phylogenetic comparative methods.
The OTU, Felinae, in the single MPT (Fig. 1A) was replaced with the whole tree of Johnson et al. [1] and the branches were scaled following Sakamoto et al. [6]. Extant nodes were dated using either first occurrence or molecular divergence dates, whichever is the older, and terminal branches were extended to their last occurrence dates (i.e. modern time). Since temporal ranges of fossil taxa often have large margins of uncertainties (e.g., Pleistocene: 1.81-0.0117 Ma), the midpoint value of the age range was used to date each node and terminal fossil branches were not extended to their younger limit of the age range. Taxa not represented in the morphometric data were pruned from the scaled, composite tree. Color codings are as in Fig. 1.
Figure 3.
Description of cranial measurements.
A skull of a lion is shown with diagrammatic representations of the 29 cranial measurements used in the morphometric analyses. The actual measurements are Euclidean distances between two points on the skull specimen and are not two-dimensional projections as depicted here. 1, LSkT: total skull length (distance between inion and prosthion). 2, LFace: face length (distance between prosthion and naso-frontal suture). 3, Wiof: distance between infraorbital foramina. 4, Wo: distance between orbits. 5, WPOC: width across postorbital constriction. 6, WPOP: width across postorbital processes. 7, WBC: maximum braincase width (greatest distance between lateral margins of braincase). 8, Wsn: snout width (measured at level of snout mid-length). 9, WC1s: width across the snout (measured between bases of upper canines [C1s]). 10, WNA: nasal aperture width (measured at rostral projection of nasals). 11, LN: nasal length (measured parasagittally between naso-frontal suture and dorsal margin of external narial opening). 12, LNT: total nasal length (measured parasagittally as the distance between the naso-frontal suture and the anteriormost tip of the nasal). 13, WMFS: width across the nasals (measured between the left and right maxillo-frontal sutures [MFS]). 14, WIC1s: inter-canine width (measured between the upper canines). 15, WI3s-I3s: width across the incisor arcade (measured between left and right third upper incisors [I3s]). 16, LC1sP3s: length of upper ‘diastema’ (measured as the distance between C1s and upper third premolars [P3s]); although species that possess upper second premolars (P2s) do not show a diastema, we regarded their LC1sP3s as the topological equivalent of the mandibular diastema. 17, WSk: maximum skull width across zygomatic arches. 18, WP4s-P4s: palate width (measured between labial surfaces of upper fourth premolars [P4s]). 19, WPal: palate width (measured posterior to P4s and between lateral surfaces of maxillae). 20, LPal: palate length (measured parasagittally as the distance between the prosthion and the posterior extremity of the palatal surface). 21, WPN: internal width of postnarial opening (measured as the distance between left and right pterygoid flanges). 22, WPN.ant: internal width of anterior postnarial opening (measured immediately posterior to palate). 23, WMP: width across mastoid processes. 24, WPocP: width across paroccipital processes. 25, WOC: occipital condyle width. 26, HOC: occipital condyle height. 27, WFM: internal width (transverse diameter) of foramen magnum. 28, WFMV: ventral width of foramen magnum (distance between left and right occipital condyles). 29, LP4s: length of superior fourth premolar or carnassial.
Figure 4.
Two-dimensional morphospace plots of species centroids (color-coded spheres) based upon PCA of 29 size-adjusted cranial linear variables in 332 specimens of extant and fossil felids.
(A) Two-dimensional morphospace plot delimited by PC1 and PC2, with contour lines showing the spatial density of the specimen-level distribution. (B) Two-dimensional morphospace plot delimited by PC1 and PC3. (C) Two-dimensional morphospace plot delimited by PC1 and PC4. Taxa labels are the same as in Fig. 2, except as follows: D, Dinobastis serus; M, Metailurus IVPP-5679; P, Panthera paleosinensis; these three taxa were not included in the phylogeny. Color codings are as in Fig. 2.
Figure 5.
Two-dimensional phylomorphospace plot.
The felid phylogeny (Fig. 2) was superimposed onto the two-dimensional morphospace delimited by the first two PC axes (Fig. 4A) using maximum likelihood ancestor character estimation. Arrows indicate ancestral nodes for clades of interest and color-coded as in Fig. 2 but also: open, Felidae; and grey, Felinae. Numbers and colors are as in Fig. 2.
Figure 6.
Chronophylomorphospace of Felidae.
The transition of two-dimensional morphospace occupation through time can be visualised as a chronophylomorphospace plot. Positions in morphospace of ancestors were estimated using maximum likelihood and a composite phylogeny of Felidae with scaled branch lengths (Fig. 2). Two-dimensional coordinates of ancestors and terminals were then plotted against time as the third axis. Color-coded arrows point to the latest common ancestor of each lineage. The grey arrow points to the last common ancestor of Felinae. The drop-down shadow shows a planar projection of the chronophylomorphospace on the two-dimensional morphospace area delimited by the PC1 and PC2 axes. Numbers and colors are as in Fig. 2.